/*
* Copyright (C) 2007-2008 Sourcefire, Inc.
*
* Authors: Nigel Horne
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
static char const rcsid[] = "$Id: mbox.c,v 1.381 2007/02/15 12:26:44 njh Exp $";
#ifdef _MSC_VER
#include <winsock.h> /* only needed in CL_EXPERIMENTAL */
#endif
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#ifdef CL_THREAD_SAFE
#ifndef _REENTRANT
#define _REENTRANT /* for Solaris 2.8 */
#endif
#endif
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <assert.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <ctype.h>
#include <time.h>
#include <fcntl.h>
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#include "clamav.h"
#ifndef C_WINDOWS
#include <dirent.h>
#endif
#include <limits.h>
#include <signal.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#if defined(HAVE_READDIR_R_3) || defined(HAVE_READDIR_R_2)
#include <stddef.h>
#endif
#ifdef CL_THREAD_SAFE
#include <pthread.h>
#endif
#include "others.h"
#include "str.h"
#include "filetypes.h"
#include "mbox.h"
#include "dconf.h"
#include "md5.h"
#define DCONF_PHISHING mctx->ctx->dconf->phishing
#ifdef CL_DEBUG
#if defined(C_LINUX)
#include <features.h>
#endif
#if __GLIBC__ == 2 && __GLIBC_MINOR__ >= 1
#define HAVE_BACKTRACE
#endif
#endif
#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#include <syslog.h>
static void sigsegv(int sig);
static void print_trace(int use_syslog);
/*#define SAVE_TMP */ /* Save the file being worked on in tmp */
#endif
#if defined(NO_STRTOK_R) || !defined(CL_THREAD_SAFE)
#undef strtok_r
#undef __strtok_r
#define strtok_r(a,b,c) strtok(a,b)
#endif
#ifdef HAVE_STDBOOL_H
#ifdef C_BEOS
#include "SupportDefs.h"
#else
#include <stdbool.h>
#endif
#else
#ifdef FALSE
typedef unsigned char bool;
#else
typedef enum { FALSE = 0, TRUE = 1 } bool;
#endif
#endif
typedef enum {
FAIL,
OK,
OK_ATTACHMENTS_NOT_SAVED,
VIRUS,
MAXREC,
MAXFILES
} mbox_status;
#ifndef isblank
#define isblank(c) (((c) == ' ') || ((c) == '\t'))
#endif
#define SAVE_TO_DISC /* multipart/message are saved in a temporary file */
#include "htmlnorm.h"
#include "phishcheck.h"
#ifndef C_WINDOWS
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifndef C_BEOS
#include <net/if.h>
#include <arpa/inet.h>
#endif
#endif
#ifndef C_WINDOWS
#define closesocket(s) close(s)
#define SOCKET int
#endif
#include <fcntl.h>
#ifndef C_WINDOWS
#include <sys/time.h>
#endif
#ifndef HAVE_IN_PORT_T
typedef unsigned short in_port_t;
#endif
#ifndef HAVE_IN_ADDR_T
typedef unsigned int in_addr_t;
#endif
#if (!defined(EALREADY)) && (defined(WSAEALREADY))
#define EALREADY WSAEALREADY
#endif
#if (!defined(EINPROGRESS)) && (defined(WSAEINPROGRESS))
#define EINPROGRESS WSAEINPROGRESS
#endif
#if (!defined(EISCONN)) && (defined(WSAEISCONN))
#define EISCONN WSAEISCONN
#endif
/*
* Use CL_SCAN_PARTIAL_MESSAGE to handle messages covered by section 7.3.2 of RFC1341.
* This is experimental code so it is up to YOU to (1) ensure it's secure
* (2) periodically trim the directory of old files
*
* If you use the load balancing feature of clamav-milter to run clamd on
* more than one machine you must make sure that .../partial is on a shared
* network filesystem
*/
/*#define NEW_WORLD*/
/*#define SCAN_UNENCODED_BOUNCES *//*
* Slows things down a lot and only catches unencoded copies
* of EICAR within bounces, which don't matter
*/
typedef struct mbox_ctx {
const char *dir;
const table_t *rfc821Table;
const table_t *subtypeTable;
cli_ctx *ctx;
unsigned int files; /* number of files extracted */
} mbox_ctx;
/* if supported by the system, use the optimized
* version of getc, that doesn't do locking,
* and is possibly implemented entirely as a macro */
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L
#define GETC(fp) getc_unlocked(fp)
#define LOCKFILE(fp) flockfile(fp)
#define UNLOCKFILE(fp) funlockfile(fp)
#else
#define GETC(fp) getc(fp)
#define LOCKFILE(fp)
#define UNLOCKFILE(fp)
#endif
static int cli_parse_mbox(const char *dir, int desc, cli_ctx *ctx);
static message *parseEmailFile(FILE *fin, const table_t *rfc821Table, const char *firstLine, const char *dir);
static message *parseEmailHeaders(message *m, const table_t *rfc821Table);
static int parseEmailHeader(message *m, const char *line, const table_t *rfc821Table);
static mbox_status parseEmailBody(message *messageIn, text *textIn, mbox_ctx *mctx, unsigned int recursion_level);
static int boundaryStart(const char *line, const char *boundary);
static int boundaryEnd(const char *line, const char *boundary);
static int initialiseTables(table_t **rfc821Table, table_t **subtypeTable);
static int getTextPart(message *const messages[], size_t size);
static size_t strip(char *buf, int len);
static int parseMimeHeader(message *m, const char *cmd, const table_t *rfc821Table, const char *arg);
static int saveTextPart(mbox_ctx *mctx, message *m, int destroy_text);
static char *rfc2047(const char *in);
static char *rfc822comments(const char *in, char *out);
static int rfc1341(message *m, const char *dir);
static bool usefulHeader(int commandNumber, const char *cmd);
static char *getline_from_mbox(char *buffer, size_t len, FILE *fin);
static bool isBounceStart(mbox_ctx *mctx, const char *line);
static bool exportBinhexMessage(mbox_ctx *mctx, message *m);
static int exportBounceMessage(mbox_ctx *ctx, text *start);
static message *do_multipart(message *mainMessage, message **messages, int i, mbox_status *rc, mbox_ctx *mctx, message *messageIn, text **tptr, unsigned int recursion_level);
static int count_quotes(const char *buf);
static bool next_is_folded_header(const text *t);
static bool newline_in_header(const char *line);
static blob *getHrefs(message *m, tag_arguments_t *hrefs);
static void hrefs_done(blob *b, tag_arguments_t *hrefs);
static void checkURLs(message *m, mbox_ctx *mctx, mbox_status *rc, int is_html);
/* Maximum line length according to RFC2821 */
#define RFC2821LENGTH 1000
/* Hashcodes for our hash tables */
#define CONTENT_TYPE 1
#define CONTENT_TRANSFER_ENCODING 2
#define CONTENT_DISPOSITION 3
/* Mime sub types */
#define PLAIN 1
#define ENRICHED 2
#define HTML 3
#define RICHTEXT 4
#define MIXED 5
#define ALTERNATIVE 6 /* RFC1521*/
#define DIGEST 7
#define SIGNED 8
#define PARALLEL 9
#define RELATED 10 /* RFC2387 */
#define REPORT 11 /* RFC1892 */
#define APPLEDOUBLE 12 /* Handling of this in only noddy for now */
#define FAX MIXED /*
* RFC3458
* Drafts stated to treat is as mixed if it is
* not known. This disappeared in the final
* version (except when talking about
* voice-message), but it is good enough for us
* since we do no validation of coversheet
* presence etc. (which also has disappeared
* in the final version)
*/
#define ENCRYPTED 13 /*
* e.g. RFC2015
* Content-Type: multipart/encrypted;
* boundary="nextPart1383049.XCRrrar2yq";
* protocol="application/pgp-encrypted"
*/
#define X_BFILE RELATED /*
* BeOS, expert two parts: the file and it's
* attributes. The attributes part comes as
* Content-Type: application/x-be_attribute
* name="foo"
* I can't find where it is defined, any
* pointers would be appreciated. For now
* we treat it as multipart/related
*/
#define KNOWBOT 14 /* Unknown and undocumented format? */
static const struct tableinit {
const char *key;
int value;
} rfc821headers[] = {
/* TODO: make these regular expressions */
{ "Content-Type", CONTENT_TYPE },
{ "Content-Transfer-Encoding", CONTENT_TRANSFER_ENCODING },
{ "Content-Disposition", CONTENT_DISPOSITION },
{ NULL, 0 }
}, mimeSubtypes[] = { /* see RFC2045 */
/* subtypes of Text */
{ "plain", PLAIN },
{ "enriched", ENRICHED },
{ "html", HTML },
{ "richtext", RICHTEXT },
/* subtypes of Multipart */
{ "mixed", MIXED },
{ "alternative", ALTERNATIVE },
{ "digest", DIGEST },
{ "signed", SIGNED },
{ "parallel", PARALLEL },
{ "related", RELATED },
{ "report", REPORT },
{ "appledouble", APPLEDOUBLE },
{ "fax-message", FAX },
{ "encrypted", ENCRYPTED },
{ "x-bfile", X_BFILE }, /* BeOS */
{ "knowbot", KNOWBOT }, /* ??? */
{ "knowbot-metadata", KNOWBOT }, /* ??? */
{ "knowbot-code", KNOWBOT }, /* ??? */
{ "knowbot-state", KNOWBOT }, /* ??? */
{ NULL, 0 }
};
#ifdef CL_THREAD_SAFE
static pthread_mutex_t tables_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifdef NEW_WORLD
#include "matcher.h"
#undef PARTIAL_DIR
#if HAVE_MMAP
#if HAVE_SYS_MMAN_H
#include <sys/mman.h>
#else /* HAVE_SYS_MMAN_H */
#undef HAVE_MMAP
#endif
#else /*HAVE_MMAP*/
#undef NEW_WORLD
#endif
#endif
#ifdef NEW_WORLD
/*
* Files larger than this are scanned with the old method, should be
* StreamMaxLength, I guess
* If NW_MAX_FILE_SIZE is not defined, all files go through the
* new method. This definition is for machines very tight on RAM, or
* with large StreamMaxLength values
*/
#define MAX_ALLOCATION 134217728 /* see libclamav/others.c */
#define NW_MAX_FILE_SIZE MAX_ALLOCATION
struct scanlist {
const char *start;
size_t size;
encoding_type decoder; /* only BASE64 and QUOTEDPRINTABLE for now */
struct scanlist *next;
};
static struct map {
const char *offset; /* sorted */
const char *word;
struct map *next;
} *map, *tail;
static int save_text(cli_ctx *ctx, const char *dir, const char *start, size_t len);
static void create_map(const char *begin, const char *end);
static void add_to_map(const char *offset, const char *word);
static const char *find_in_map(const char *offset, const char *word);
static void free_map(void);
/*
* This could be the future. Instead of parsing and decoding it just decodes.
*
* USE IT AT YOUR PERIL, a large number of viruses are not detected with this
* method, possibly because the decoded files must be exact and not have
* extra data at the start or end, which this code will produce.
*
* Currently only supports base64 and quoted-printable
*
* You may also see a lot of warnings. For the moment it falls back to old
* world mode if it doesn't know what to do - that'll be removed.
* The code is untidy...
*
* FIXME: Some mailbox scans are slower with this method. I suspect that it's
* because the scan can proceed to the end of the file rather than the end
* of the attachment which can mean than later emails are scanned many times
*
* FIXME: quoted printable doesn't know when to stop, so size related virus
* matching breaks
*
* TODO: Fall through to cli_parse_mbox() too often
*
* TODO: Add support for systems without mmap()
*
* TODO: partial_dir fall through
*
* FIXME: Some EICAR gets through
*/
int
cli_mbox(const char *dir, int desc, cli_ctx *ctx)
{
char *start, *ptr, *line;
const char *last, *p, *q;
size_t size;
struct stat statb;
message *m;
fileblob *fb;
int ret = CL_CLEAN;
int wasAlloced;
struct scanlist *scanlist, *scanelem;
if(dir == NULL) {
cli_dbgmsg("cli_mbox called with NULL dir\n");
return CL_ENULLARG;
}
if(fstat(desc, &statb) < 0)
return CL_EOPEN;
size = statb.st_size;
if(size == 0)
return CL_CLEAN;
#ifdef NW_MAX_FILE_SIZE
if(size > NW_MAX_FILE_SIZE)
return cli_parse_mbox(dir, desc, ctx);
#endif
/*cli_warnmsg("NEW_WORLD is new code - use at your own risk.\n");*/
#ifdef PARTIAL_DIR
cli_warnmsg("PARTIAL_DIR doesn't work in the NEW_WORLD yet\n");
#endif
start = mmap(NULL, size, PROT_READ, MAP_PRIVATE, desc, 0);
if(start == MAP_FAILED)
return CL_EMAP;
cli_dbgmsg("mmap'ed mbox\n");
ptr = cli_malloc(size);
if(ptr) {
memcpy(ptr, start, size);
munmap(start, size);
start = ptr;
wasAlloced = 1;
} else
wasAlloced = 0;
/* last points to the last *valid* address in the array */
last = &start[size - 1];
create_map(start, last);
scanelem = scanlist = NULL;
q = start;
/*
* FIXME: mismatch of const char * and char * here and in later calls
* to find_in_map()
*/
while((p = find_in_map(q, "base64")) != NULL) {
cli_dbgmsg("Found base64\n");
if(scanelem) {
scanelem->next = cli_malloc(sizeof(struct scanlist));
scanelem = scanelem->next;
} else
scanlist = scanelem = cli_malloc(sizeof(struct scanlist));
scanelem->next = NULL;
scanelem->decoder = BASE64;
q = scanelem->start = &p[6];
if(((p = find_in_map(q, "\nFrom ")) != NULL) ||
((p = find_in_map(q, "base64")) != NULL) ||
((p = find_in_map(q, "quoted-printable")) != NULL)) {
scanelem->size = (size_t)(p - q);
q = p;
} else {
scanelem->size = (size_t)(last - scanelem->start) + 1;
break;
}
cli_dbgmsg("base64: last %u q %u\n", (unsigned int)last, (unsigned int)q);
assert(scanelem->size <= size);
}
q = start;
while((p = find_in_map(q, "quoted-printable")) != NULL) {
if(p != q)
switch(p[-1]) {
case ' ':
case ':':
case '=': /* wrong but allow it */
break;
default:
q = &p[16];
cli_dbgmsg("Ignore quoted-printable false positive\n");
continue; /* false positive */
}
cli_dbgmsg("Found quoted-printable\n");
#ifdef notdef
/*
* The problem with quoted printable is recognising when to stop
* parsing
*/
if(scanelem) {
scanelem->next = cli_malloc(sizeof(struct scanlist));
scanelem = scanelem->next;
} else
scanlist = scanelem = cli_malloc(sizeof(struct scanlist));
scanelem->next = NULL;
scanelem->decoder = QUOTEDPRINTABLE;
q = scanelem->start = &p[16];
cli_dbgmsg("qp: last %u q %u\n", (unsigned int)last, (unsigned int)q);
if(((p = find_in_map(q, "\nFrom ")) != NULL) ||
((p = find_in_map(q, "quoted-printable")) != NULL) ||
((p = find_in_map(q, "base64")) != NULL)) {
scanelem->size = (size_t)(p - q);
q = p;
cli_dbgmsg("qp: scanelem->size = %u\n", scanelem->size);
} else {
scanelem->size = (size_t)(last - scanelem->start) + 1;
break;
}
assert(scanelem->size <= size);
#else
if(wasAlloced)
free(start);
else
munmap(start, size);
free_map();
return cli_parse_mbox(dir, desc, ctx);
#endif
}
if(scanlist == NULL) {
const struct tableinit *tableinit;
bool anyHeadersFound = FALSE;
bool hasuuencode = FALSE;
cli_file_t type;
/* FIXME: message: There could of course be no decoder needed... */
for(tableinit = rfc821headers; tableinit->key; tableinit++)
if(find_in_map(start, tableinit->key)) {
anyHeadersFound = TRUE;
break;
}
if((!anyHeadersFound) &&
((p = find_in_map(start, "\nbegin ")) != NULL) &&
(isuuencodebegin(++p)))
/* uuencoded part */
hasuuencode = TRUE;
else {
cli_dbgmsg("Nothing encoded, looking for a text part to save\n");
ret = save_text(ctx, dir, start, size);
if(wasAlloced)
free(start);
else
munmap(start, size);
free_map();
if(ret != CL_EFORMAT)
return ret;
ret = CL_CLEAN;
}
free_map();
type = cli_filetype(start, size, ctx->engine);
if((type == CL_TYPE_TEXT_ASCII) &&
(strncmp(start, "Microsoft Mail Internet Headers", 31) == 0))
type = CL_TYPE_MAIL;
if(wasAlloced)
free(start);
else
munmap(start, size);
if(anyHeadersFound || hasuuencode) {
/* TODO: reduce the number of falls through here */
if(hasuuencode)
/* TODO: fast track visa */
cli_dbgmsg("New world - fall back to old uudecoder\n");
else
cli_dbgmsg("cli_mbox: unknown encoder, type %d\n", type);
if(type == CL_TYPE_MAIL)
return cli_parse_mbox(dir, desc, ctx);
cli_dbgmsg("Unknown filetype %d, return CLEAN\n", type);
return CL_CLEAN;
}
#if 0 /* I don't believe this is needed any more */
/*
* The message could be a plain text phish
* FIXME: Can't get to the option whether we are looking for
* phishes or not, so assume we are, this slows things a
* lot
* Should be
* if((type == CL_TYPE_MAIL) && (!(no-phishing))
*/
if(type == CL_TYPE_MAIL)
return cli_parse_mbox(dir, desc, ctx);
#endif
cli_dbgmsg("cli_mbox: I believe it's plain text (type == %d) which must be clean\n",
type);
return CL_CLEAN;
}
#if 0
if(wasAlloced) {
const char *max = NULL;
for(scanelem = scanlist; scanelem; scanelem = scanelem->next) {
const char *end = &scanelem->start[scanelem->size];
if(end > max)
max = end;
}
if(max < last)
printf("could free %d bytes\n", (int)(last - max));
}
#endif
for(scanelem = scanlist; scanelem; scanelem = scanelem->next) {
if(scanelem->decoder == BASE64) {
const char *b64start = scanelem->start;
size_t b64size = scanelem->size;
cli_dbgmsg("b64size = %lu\n", b64size);
while((*b64start != '\n') && (*b64start != '\r')) {
b64start++;
b64size--;
}
/*
* Look for the end of the headers
*/
while(b64start < last) {
if(*b64start == ';') {
b64start++;
b64size--;
} else if((memcmp(b64start, "\n\n", 2) == 0) ||
(memcmp(b64start, "\r\r", 2) == 0)) {
b64start += 2;
b64size -= 2;
break;
} else if(memcmp(b64start, "\r\n\r\n", 4) == 0) {
b64start += 4;
b64size -= 4;
break;
} else if(memcmp(b64start, "\n \n", 3) == 0) {
/*
* Some viruses are broken and have
* one space character at the end of
* the headers
*/
b64start += 3;
b64size -= 3;
break;
} else if(memcmp(b64start, "\r\n \r\n", 5) == 0) {
/*
* Some viruses are broken and have
* one space character at the end of
* the headers
*/
b64start += 5;
b64size -= 5;
break;
}
b64start++;
b64size--;
}
if(b64size > 0L)
while((!isalnum(*b64start)) && (*b64start != '/')) {
if(b64size-- == 0L)
break;
b64start++;
}
if(b64size > 0L) {
int lastline;
char *tmpfilename;
unsigned char *uptr;
cli_dbgmsg("cli_mbox: decoding %ld base64 bytes\n", b64size);
if((fb = fileblobCreate()) == NULL) {
free_map();
if(wasAlloced)
free(start);
else
munmap(start, size);
return CL_EMEM;
}
tmpfilename = cli_gentemp(dir);
if(tmpfilename == NULL) {
free_map();
if(wasAlloced)
free(start);
else
munmap(start, size);
fileblobDestroy(fb);
return CL_EMEM;
}
fileblobSetFilename(fb, dir, tmpfilename);
free(tmpfilename);
line = NULL;
m = messageCreate();
if(m == NULL) {
free_map();
if(wasAlloced)
free(start);
else
munmap(start, size);
fileblobDestroy(fb);
return CL_EMEM;
}
messageSetEncoding(m, "base64");
messageSetCTX(m, ctx);
fileblobSetCTX(fb, ctx);
lastline = 0;
do {
int length = 0, datalen;
char *newline, *equal;
unsigned char *bigbuf, *data;
unsigned char smallbuf[1024];
const char *cptr;
/*printf("%ld: ", b64size); fflush(stdout);*/
for(cptr = b64start; b64size && (*cptr != '\n') && (*cptr != '\r'); cptr++) {
length++;
--b64size;
}
/*printf("%d: ", length); fflush(stdout);*/
newline = cli_realloc(line, length + 1);
if(newline == NULL)
break;
line = newline;
memcpy(line, b64start, length);
line[length] = '\0';
equal = strchr(line, '=');
if(equal) {
lastline++;
*equal = '\0';
}
/*puts(line);*/
#if 0
if(messageAddStr(m, line) < 0)
break;
#endif
if(length >= (int)sizeof(smallbuf)) {
datalen = length + 2;
data = bigbuf = cli_malloc(datalen);
if(data == NULL)
break;
} else {
bigbuf = NULL;
data = smallbuf;
datalen = sizeof(data) - 1;
}
uptr = decodeLine(m, BASE64, line, data, datalen);
if(uptr == NULL) {
if(bigbuf)
free(bigbuf);
break;
}
/*cli_dbgmsg("base64: write %u bytes\n", (size_t)(uptr - data));*/
datalen = fileblobAddData(fb, data, (size_t)(uptr - data));
if(bigbuf)
free(bigbuf);
if(datalen < 0)
break;
if(fileblobContainsVirus(fb))
break;
if((b64size > 0) && (*cptr == '\r')) {
b64start = ++cptr;
--b64size;
}
if((b64size > 0) && (*cptr == '\n')) {
b64start = ++cptr;
--b64size;
}
if(lastline)
break;
} while(b64size > 0L);
if(m->base64chars) {
unsigned char data[4];
uptr = base64Flush(m, data);
if(uptr) {
/*cli_dbgmsg("base64: flush %u bytes\n", (size_t)(uptr - data));*/
(void)fileblobAddData(fb, data, (size_t)(uptr - data));
}
}
if(fb)
fileblobDestroy(fb);
else
ret = -1;
messageDestroy(m);
free(line);
}
} else if(scanelem->decoder == QUOTEDPRINTABLE) {
const char *quotedstart = scanelem->start;
size_t quotedsize = scanelem->size;
cli_dbgmsg("quotedsize = %lu\n", quotedsize);
while(*quotedstart != '\n') {
quotedstart++;
quotedsize--;
}
/*
* Look for the end of the headers
*/
while(quotedstart < last) {
if(*quotedstart == ';') {
quotedstart++;
quotedsize--;
} else if((*quotedstart == '\n') || (*quotedstart == '\r')) {
quotedstart++;
quotedsize--;
if((*quotedstart == '\n') || (*quotedstart == '\r')) {
quotedstart++;
quotedsize--;
break;
}
}
quotedstart++;
quotedsize--;
}
while(!isalnum(*quotedstart)) {
quotedstart++;
quotedsize--;
}
if(quotedsize > 0L) {
cli_dbgmsg("cli_mbox: decoding %ld quoted-printable bytes\n", quotedsize);
m = messageCreate();
if(m == NULL) {
free_map();
if(wasAlloced)
free(start);
else
munmap(start, size);
return CL_EMEM;
}
messageSetEncoding(m, "quoted-printable");
messageSetCTX(m, ctx);
line = NULL;
do {
int length = 0;
char *newline;
const char *cptr;
/*printf("%ld: ", quotedsize); fflush(stdout);*/
for(cptr = quotedstart; quotedsize && (*cptr != '\n') && (*cptr != '\r'); cptr++) {
length++;
--quotedsize;
}
/*printf("%d: ", length); fflush(stdout);*/
newline = cli_realloc(line, length + 1);
if(newline == NULL)
break;
line = newline;
memcpy(line, quotedstart, length);
line[length] = '\0';
/*puts(line);*/
if(messageAddStr(m, line) < 0)
break;
if((quotedsize > 0) && (*cptr == '\r')) {
quotedstart = ++cptr;
--quotedsize;
}
if((quotedsize > 0) && (*cptr == '\n')) {
quotedstart = ++cptr;
--quotedsize;
}
} while(quotedsize > 0L);
free(line);
fb = messageToFileblob(m, dir, 1);
messageDestroy(m);
if(fb)
fileblobDestroy(fb);
else
ret = -1;
}
}
}
scanelem = scanlist;
/*
* There could be a phish in the plain text part, so save that
* FIXME: Can't get to the option whether we are looking for
* phishes or not, so assume we are, this slows things a
* lot
* Should be
* if((type == CL_TYPE_MAIL) && (!(no-phishing))
*/
ret = save_text(ctx, dir, start, size);
free_map();
while(scanelem) {
struct scanlist *n = scanelem->next;
free(scanelem);
scanelem = n;
}
if(wasAlloced)
free(start);
else
munmap(start, size);
/*
* FIXME: Need to run cl_scandir() here and return that value
*/
cli_dbgmsg("cli_mbox: ret = %d\n", ret);
if(ret != CL_EFORMAT)
return ret;
cli_dbgmsg("New world - don't know what to do - fall back to old world\n");
/* Fall back for now */
lseek(desc, 0L, SEEK_SET);
return cli_parse_mbox(dir, desc, ctx);
}
/*
* Save a text part - it could contain phish or jscript
*/
static int
save_text(cli_ctx *ctx, const char *dir, const char *start, size_t len)
{
const char *p;
if((p = find_in_map(start, "\n\n")) || (p = find_in_map(start, "\r\n\r\n"))) {
const char *q;
fileblob *fb;
char *tmpfilename;
if(((q = find_in_map(start, "base64")) == NULL) &&
((q = find_in_map(start, "quoted_printable")) == NULL)) {
cli_dbgmsg("It's all plain text!\n");
if(*p == '\r')
p += 4;
else
p += 2;
len -= (p - start);
} else if(((q = find_in_map(p, "\nFrom ")) == NULL) &&
((q = find_in_map(p, "base64")) == NULL) &&
((q = find_in_map(p, "quoted-printable")) == NULL))
cli_dbgmsg("Can't find end of plain text - assume it's all\n");
else
len = (size_t)(q - p);
if(len < 5) {
cli_dbgmsg("save_text: Too small\n");
return CL_EFORMAT;
}
if(ctx->scanned)
*ctx->scanned += len / CL_COUNT_PRECISION;
/*
* This doesn't work, cli_scanbuff isn't designed to be used
* in this way. It gets the "filetype" wrong and then
* doesn't scan correctly
*/
if(cli_scanbuff((char *)p, len, 0, ctx, CL_TYPE_BINARY_DATA, NULL) == CL_VIRUS) {
cli_dbgmsg("save_text: found %s\n", *ctx->virname);
return CL_VIRUS;
}
fb = fileblobCreate();
if(fb == NULL)
return CL_EMEM;
tmpfilename = cli_gentemp(dir);
if(tmpfilename == NULL) {
fileblobDestroy(fb);
return CL_ETMPFILE;
}
cli_dbgmsg("save plain bit to %s, %u bytes\n",
tmpfilename, len);
fileblobSetFilename(fb, dir, tmpfilename);
free(tmpfilename);
(void)fileblobAddData(fb, (const unsigned char *)p, len);
fileblobDestroy(fb);
return CL_SUCCESS;
}
cli_dbgmsg("No text part found to save\n");
return CL_EFORMAT;
}
static void
create_map(const char *begin, const char *end)
{
const struct wordlist {
const char *word;
int len;
} wordlist[] = {
{ "base64", 6 },
{ "quoted-printable", 16 },
{ "\nbegin ", 7 },
{ "\nFrom ", 6 },
{ "\n\n", 2 },
{ "\r\n\r\n", 4 },
{ NULL, 0 }
};
if(map) {
cli_dbgmsg("create_map called without free_map\n");
free_map();
}
while(begin < end) {
const struct wordlist *word;
for(word = wordlist; word->word; word++) {
if((end - begin) < word->len)
continue;
if(strncasecmp(begin, word->word, word->len) == 0) {
add_to_map(begin, word->word);
break;
}
}
begin++;
}
}
/* To sort map, assume 'offset' is presented in sorted order */
static void
add_to_map(const char *offset, const char *word)
{
if(map) {
tail->next = cli_malloc(sizeof(struct map)); /* FIXME: verify */
tail = tail->next;
} else
map = tail = cli_malloc(sizeof(struct map)); /* FIXME: verify */
tail->offset = offset;
tail->word = word;
tail->next = NULL;
}
static const char *
find_in_map(const char *offset, const char *word)
{
const struct map *item;
for(item = map; item; item = item->next)
if(item->offset >= offset)
if(strcasecmp(word, item->word) == 0)
return item->offset;
return NULL;
}
static void
free_map(void)
{
while(map) {
struct map *next = map->next;
free(map);
map = next;
}
map = NULL;
}
#else /*!NEW_WORLD*/
int
cli_mbox(const char *dir, int desc, cli_ctx *ctx)
{
if(dir == NULL) {
cli_dbgmsg("cli_mbox called with NULL dir\n");
return CL_ENULLARG;
}
return cli_parse_mbox(dir, desc, ctx);
}
#endif
/*
* TODO: when signal handling is added, need to remove temp files when a
* signal is received
* TODO: add option to scan in memory not via temp files, perhaps with a
* named pipe or memory mapped file, though this won't work on big e-mails
* containing many levels of encapsulated messages - it'd just take too much
* RAM
* TODO: parse .msg format files
* TODO: fully handle AppleDouble format, see
* http://www.lazerware.com/formats/Specs/AppleSingle_AppleDouble.pdf
* TODO: ensure parseEmailHeaders is always called before parseEmailBody
* TODO: create parseEmail which calls parseEmailHeaders then parseEmailBody
* TODO: Handle unepected NUL bytes in header lines which stop strcmp()s:
* e.g. \0Content-Type: application/binary;
*/
static int
cli_parse_mbox(const char *dir, int desc, cli_ctx *ctx)
{
int retcode, i;
message *body;
FILE *fd;
char buffer[RFC2821LENGTH + 1];
mbox_ctx mctx;
#ifdef HAVE_BACKTRACE
void (*segv)(int);
#endif
static table_t *rfc821, *subtype;
#ifdef SAVE_TMP
char tmpfilename[16];
int tmpfd;
#endif
#ifdef NEW_WORLD
cli_dbgmsg("fall back to old world\n");
#else
cli_dbgmsg("in mbox()\n");
#endif
i = dup(desc);
if((fd = fdopen(i, "rb")) == NULL) {
cli_errmsg("Can't open descriptor %d\n", desc);
close(i);
return CL_EOPEN;
}
rewind(fd); /* bug 240 */
#ifdef SAVE_TMP
/*
* Copy the incoming mail for debugging, so that if it falls over
* we have a copy of the offending email. This is debugging code
* that you shouldn't of course install in a live environment. I am
* not interested in hearing about security issues with this section
* of the parser.
*/
strcpy(tmpfilename, "/tmp/mboxXXXXXX");
tmpfd = mkstemp(tmpfilename);
if(tmpfd < 0) {
perror(tmpfilename);
cli_errmsg("Can't make debugging file\n");
} else {
FILE *tmpfp = fdopen(tmpfd, "w");
if(tmpfp) {
while(fgets(buffer, sizeof(buffer) - 1, fd) != NULL)
fputs(buffer, tmpfp);
fclose(tmpfp);
rewind(fd);
} else
cli_errmsg("Can't fdopen debugging file\n");
}
#endif
if(fgets(buffer, sizeof(buffer) - 1, fd) == NULL) {
/* empty message */
fclose(fd);
#ifdef SAVE_TMP
if (cli_unlink(tmpfilename)) return CL_EUNLINK;
#endif
return CL_CLEAN;
}
#ifdef CL_THREAD_SAFE
pthread_mutex_lock(&tables_mutex);
#endif
if(rfc821 == NULL) {
assert(subtype == NULL);
if(initialiseTables(&rfc821, &subtype) < 0) {
rfc821 = NULL;
subtype = NULL;
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&tables_mutex);
#endif
fclose(fd);
#ifdef SAVE_TMP
if (cli_unlink(tmpfilename)) return CL_EUNLINK;
#endif
return CL_EMEM;
}
}
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&tables_mutex);
#endif
#ifdef HAVE_BACKTRACE
segv = signal(SIGSEGV, sigsegv);
#endif
retcode = CL_SUCCESS;
body = NULL;
mctx.dir = dir;
mctx.rfc821Table = rfc821;
mctx.subtypeTable = subtype;
mctx.ctx = ctx;
mctx.files = 0;
/*
* Is it a UNIX style mbox with more than one
* mail message, or just a single mail message?
*
* TODO: It would be better if we called cli_scandir here rather than
* in cli_scanmail. Then we could improve the way mailboxes with more
* than one message is handled, e.g. giving a better indication of
* which message within the mailbox is infected
*/
/*if((strncmp(buffer, "From ", 5) == 0) && isalnum(buffer[5])) {*/
if(strncmp(buffer, "From ", 5) == 0) {
/*
* Have been asked to check a UNIX style mbox file, which
* may contain more than one e-mail message to decode
*
* It would be far better for scanners.c to do this splitting
* and do this
* FOR EACH mail in the mailbox
* DO
* pass this mail to cli_mbox --
* scan this file
* IF this file has a virus quit
* THEN
* return CL_VIRUS
* FI
* END
* This would remove a problem with this code that it can
* fill up the tmp directory before it starts scanning
*/
bool lastLineWasEmpty;
int messagenumber;
message *m = messageCreate();
if(m == NULL) {
fclose(fd);
#ifdef HAVE_BACKTRACE
signal(SIGSEGV, segv);
#endif
#ifdef SAVE_TMP
if (cli_unlink(tmpfilename)) return CL_EUNLINK;
#endif
return CL_EMEM;
}
lastLineWasEmpty = FALSE;
messagenumber = 1;
messageSetCTX(m, ctx);
do {
cli_chomp(buffer);
/*if(lastLineWasEmpty && (strncmp(buffer, "From ", 5) == 0) && isalnum(buffer[5])) {*/
if(lastLineWasEmpty && (strncmp(buffer, "From ", 5) == 0)) {
cli_dbgmsg("Deal with message number %d\n", messagenumber++);
/*
* End of a message in the mail box
*/
body = parseEmailHeaders(m, rfc821);
if(body == NULL) {
messageReset(m);
continue;
}
messageSetCTX(body, ctx);
messageDestroy(m);
if(messageGetBody(body)) {
mbox_status rc = parseEmailBody(body, NULL, &mctx, 0);
if(rc == FAIL) {
messageReset(body);
m = body;
continue;
} else if(rc == VIRUS) {
cli_dbgmsg("Message number %d is infected\n",
messagenumber);
retcode = CL_VIRUS;
m = NULL;
break;
}
}
/*
* Starting a new message, throw away all the
* information about the old one. It would
* be best to be able to scan this message
* now, but cli_scanfile needs arguments
* that haven't been passed here so it can't be
* called
*/
m = body;
messageReset(body);
messageSetCTX(body, ctx);
cli_dbgmsg("Finished processing message\n");
} else
lastLineWasEmpty = (bool)(buffer[0] == '\0');
if(isuuencodebegin(buffer)) {
/*
* Fast track visa to uudecode.
* TODO: binhex, yenc
*/
if(uudecodeFile(m, buffer, dir, fd) < 0)
if(messageAddStr(m, buffer) < 0)
break;
} else
/* at this point, the \n has been removed */
if(messageAddStr(m, buffer) < 0)
break;
} while(fgets(buffer, sizeof(buffer) - 1, fd) != NULL);
fclose(fd);
if(retcode == CL_SUCCESS) {
cli_dbgmsg("Extract attachments from email %d\n", messagenumber);
body = parseEmailHeaders(m, rfc821);
}
if(m)
messageDestroy(m);
} else {
/*
* It's a single message, parse the headers then the body
*/
if(strncmp(buffer, "P I ", 4) == 0)
/*
* CommuniGate Pro format: ignore headers until
* blank line
*/
while((fgets(buffer, sizeof(buffer) - 1, fd) != NULL) &&
(strchr("\r\n", buffer[0]) == NULL))
;
LOCKFILE(fd);
/* getline_from_mbox could be using unlocked_stdio(3),
* so lock file here */
/*
* Ignore any blank lines at the top of the message
*/
while(strchr("\r\n", buffer[0]) &&
(getline_from_mbox(buffer, sizeof(buffer) - 1, fd) != NULL))
;
buffer[sizeof(buffer) - 1] = '\0';
body = parseEmailFile(fd, rfc821, buffer, dir);
UNLOCKFILE(fd);
fclose(fd);
}
if(body) {
/*
* Write out the last entry in the mailbox
*/
if((retcode == CL_SUCCESS) && messageGetBody(body)) {
messageSetCTX(body, ctx);
switch(parseEmailBody(body, NULL, &mctx, 0)) {
case OK:
case OK_ATTACHMENTS_NOT_SAVED:
break;
case FAIL:
/*
* beware: cli_magic_scandesc(),
* changes this into CL_CLEAN, so only
* use it to inform the higher levels
* that we couldn't decode it because
* it isn't an mbox, not to signal
* decoding errors on what *is* a valid
* mbox
*/
retcode = CL_EFORMAT;
break;
case MAXREC:
retcode = CL_EMAXREC;
break;
case MAXFILES:
retcode = CL_EMAXFILES;
break;
case VIRUS:
retcode = CL_VIRUS;
break;
}
}
if(body->isTruncated && retcode == CL_SUCCESS)
retcode = CL_EMEM;
/*
* Tidy up and quit
*/
messageDestroy(body);
}
if((retcode == CL_CLEAN) && ctx->found_possibly_unwanted && (*ctx->virname == NULL)) {
*ctx->virname = "Phishing.Heuristics.Email";
ctx->found_possibly_unwanted = 0;
retcode = CL_VIRUS;
}
cli_dbgmsg("cli_mbox returning %d\n", retcode);
#ifdef HAVE_BACKTRACE
signal(SIGSEGV, segv);
#endif
#ifdef SAVE_TMP
if (cli_unlink(tmpfilename)) return CL_EUNLINK;
#endif
return retcode;
}
/*
* Read in an email message from fin, parse it, and return the message
*
* FIXME: files full of new lines and nothing else are
* handled ungracefully...
*/
static message *
parseEmailFile(FILE *fin, const table_t *rfc821, const char *firstLine, const char *dir)
{
bool inHeader = TRUE;
bool bodyIsEmpty = TRUE;
bool lastWasBlank = FALSE, lastBodyLineWasBlank = FALSE;
message *ret;
bool anyHeadersFound = FALSE;
int commandNumber = -1;
char *fullline = NULL, *boundary = NULL;
size_t fulllinelength = 0;
char buffer[RFC2821LENGTH + 1];
cli_dbgmsg("parseEmailFile\n");
ret = messageCreate();
if(ret == NULL)
return NULL;
strcpy(buffer, firstLine);
do {
const char *line;
(void)cli_chomp(buffer);
if(buffer[0] == '\0')
line = NULL;
else
line = buffer;
/*
* Don't blank lines which are only spaces from headers,
* otherwise they'll be treated as the end of header marker
*/
if(lastWasBlank) {
lastWasBlank = FALSE;
if(boundaryStart(buffer, boundary)) {
cli_dbgmsg("Found a header line with space that should be blank\n");
inHeader = FALSE;
}
}
if(inHeader) {
cli_dbgmsg("parseEmailFile: check '%s' fullline %p\n",
buffer, fullline);
/*
* Ensure wide characters are handled where
* sizeof(char) > 1
*/
if(line && isspace(line[0] & 0xFF)) {
char copy[sizeof(buffer)];
strcpy(copy, buffer);
strstrip(copy);
if(copy[0] == '\0') {
/*
* The header line contains only white
* space. This is not the end of the
* headers according to RFC2822, but
* some MUAs will handle it as though
* it were, and virus writers exploit
* this bug. We can't just break from
* the loop here since that would allow
* other exploits such as inserting a
* white space line before the
* content-type line. So we just have
* to make a best guess. Sigh.
*/
if(fullline) {
if(parseEmailHeader(ret, fullline, rfc821) < 0)
continue;
free(fullline);
fullline = NULL;
}
if(boundary ||
((boundary = (char *)messageFindArgument(ret, "boundary")) != NULL)) {
lastWasBlank = TRUE;
continue;
}
}
}
if((line == NULL) && (fullline == NULL)) { /* empty line */
/*
* A blank line signifies the end of
* the header and the start of the text
*/
if(!anyHeadersFound)
/* Ignore the junk at the top */
continue;
cli_dbgmsg("End of header information\n");
inHeader = FALSE;
bodyIsEmpty = TRUE;
} else {
char *ptr;
int lookahead;
if(fullline == NULL) {
char cmd[RFC2821LENGTH + 1], out[RFC2821LENGTH + 1];
/*
* Continuation of line we're ignoring?
*/
if(isblank(line[0]))
continue;
/*
* Is this a header we're interested in?
*/
if((strchr(line, ':') == NULL) ||
(cli_strtokbuf(line, 0, ":", cmd) == NULL)) {
if(strncmp(line, "From ", 5) == 0)
anyHeadersFound = TRUE;
continue;
}
ptr = rfc822comments(cmd, out);
commandNumber = tableFind(rfc821, ptr ? ptr : cmd);
switch(commandNumber) {
case CONTENT_TRANSFER_ENCODING:
case CONTENT_DISPOSITION:
case CONTENT_TYPE:
anyHeadersFound = TRUE;
break;
default:
if(!anyHeadersFound)
anyHeadersFound = usefulHeader(commandNumber, cmd);
continue;
}
fullline = cli_strdup(line);
fulllinelength = strlen(line) + 1;
if(!fullline) {
if(ret)
ret->isTruncated = TRUE;
break;
}
} else if(line != NULL) {
fulllinelength += strlen(line);
ptr = cli_realloc(fullline, fulllinelength);
if(ptr == NULL)
continue;
fullline = ptr;
strcat(fullline, line);
}
assert(fullline != NULL);
lookahead = GETC(fin);
if(lookahead != EOF) {
ungetc(lookahead, fin);
/*
* Section B.2 of RFC822 says TAB or
* SPACE means a continuation of the
* previous entry.
*
* Add all the arguments on the line
*/
if(isblank(lookahead))
continue;
}
/*
* Handle broken headers, where the next
* line isn't indented by whitespace
*/
if(fullline[fulllinelength - 2] == ';')
/* Add arguments to this line */
continue;
if(line && (count_quotes(fullline) & 1))
continue;
ptr = rfc822comments(fullline, NULL);
if(ptr) {
free(fullline);
fullline = ptr;
}
if(parseEmailHeader(ret, fullline, rfc821) < 0)
continue;
free(fullline);
fullline = NULL;
}
} else if(line && isuuencodebegin(line)) {
/*
* Fast track visa to uudecode.
* TODO: binhex, yenc
*/
bodyIsEmpty = FALSE;
if(uudecodeFile(ret, line, dir, fin) < 0)
if(messageAddStr(ret, line) < 0)
break;
} else {
if(line == NULL) {
/*
* Although this would save time and RAM, some
* phish signatures have been built which need
* the blank lines
*/
if(lastBodyLineWasBlank &&
(messageGetMimeType(ret) != TEXT)) {
cli_dbgmsg("Ignoring consecutive blank lines in the body\n");
continue;
}
lastBodyLineWasBlank = TRUE;
} else {
if(bodyIsEmpty) {
/*
* Broken message: new line in the
* middle of the headers, so the first
* line of the body is in fact
* the last lines of the header
*/
if(newline_in_header(line))
continue;
bodyIsEmpty = FALSE;
}
lastBodyLineWasBlank = FALSE;
}
if(messageAddStr(ret, line) < 0)
break;
}
} while(getline_from_mbox(buffer, sizeof(buffer) - 1, fin) != NULL);
if(boundary)
free(boundary);
if(fullline) {
if(*fullline) switch(commandNumber) {
case CONTENT_TRANSFER_ENCODING:
case CONTENT_DISPOSITION:
case CONTENT_TYPE:
cli_dbgmsg("parseEmailFile: Fullline unparsed '%s'\n", fullline);
}
free(fullline);
}
if(!anyHeadersFound) {
/*
* False positive in believing we have an e-mail when we don't
*/
messageDestroy(ret);
cli_dbgmsg("parseEmailFile: no headers found, assuming it isn't an email\n");
return NULL;
}
cli_dbgmsg("parseEmailFile: return\n");
return ret;
}
/*
* The given message contains a raw e-mail.
*
* Returns the message's body with the correct arguments set, empties the
* given message's contents (note that it isn't destroyed)
*
* TODO: remove the duplication with parseEmailFile
*/
static message *
parseEmailHeaders(message *m, const table_t *rfc821)
{
bool inHeader = TRUE;
bool bodyIsEmpty = TRUE;
text *t;
message *ret;
bool anyHeadersFound = FALSE;
int commandNumber = -1;
char *fullline = NULL;
size_t fulllinelength = 0;
cli_dbgmsg("parseEmailHeaders\n");
if(m == NULL)
return NULL;
ret = messageCreate();
for(t = messageGetBody(m); t; t = t->t_next) {
const char *line;
if(t->t_line)
line = lineGetData(t->t_line);
else
line = NULL;
if(inHeader) {
cli_dbgmsg("parseEmailHeaders: check '%s'\n",
line ? line : "");
if(line == NULL) {
/*
* A blank line signifies the end of
* the header and the start of the text
*/
cli_dbgmsg("End of header information\n");
if(!anyHeadersFound) {
cli_dbgmsg("Nothing interesting in the header\n");
break;
}
inHeader = FALSE;
bodyIsEmpty = TRUE;
} else {
char *ptr;
if(fullline == NULL) {
char cmd[RFC2821LENGTH + 1];
/*
* Continuation of line we're ignoring?
*/
if(isblank(line[0]))
continue;
/*
* Is this a header we're interested in?
*/
if((strchr(line, ':') == NULL) ||
(cli_strtokbuf(line, 0, ":", cmd) == NULL)) {
if(strncmp(line, "From ", 5) == 0)
anyHeadersFound = TRUE;
continue;
}
ptr = rfc822comments(cmd, NULL);
commandNumber = tableFind(rfc821, ptr ? ptr : cmd);
if(ptr)
free(ptr);
switch(commandNumber) {
case CONTENT_TRANSFER_ENCODING:
case CONTENT_DISPOSITION:
case CONTENT_TYPE:
anyHeadersFound = TRUE;
break;
default:
if(!anyHeadersFound)
anyHeadersFound = usefulHeader(commandNumber, cmd);
continue;
}
fullline = cli_strdup(line);
fulllinelength = strlen(line) + 1;
} else if(line) {
fulllinelength += strlen(line);
ptr = cli_realloc(fullline, fulllinelength);
if(ptr == NULL)
continue;
fullline = ptr;
strcat(fullline, line);
}
assert(fullline != NULL);
if(next_is_folded_header(t))
/* Add arguments to this line */
continue;
lineUnlink(t->t_line);
t->t_line = NULL;
if(count_quotes(fullline) & 1)
continue;
ptr = rfc822comments(fullline, NULL);
if(ptr) {
free(fullline);
fullline = ptr;
}
if(parseEmailHeader(ret, fullline, rfc821) < 0)
continue;
free(fullline);
fullline = NULL;
}
} else {
if(bodyIsEmpty) {
if(line == NULL)
/* throw away leading blank lines */
continue;
/*
* Broken message: new line in the
* middle of the headers, so the first
* line of the body is in fact
* the last lines of the header
*/
if(newline_in_header(line))
continue;
bodyIsEmpty = FALSE;
}
/*if(t->t_line && isuuencodebegin(t->t_line))
puts("FIXME: add fast visa here");*/
cli_dbgmsg("parseEmailHeaders: finished with headers, moving body\n");
messageMoveText(ret, t, m);
break;
}
}
if(fullline) {
if(*fullline) switch(commandNumber) {
case CONTENT_TRANSFER_ENCODING:
case CONTENT_DISPOSITION:
case CONTENT_TYPE:
cli_dbgmsg("parseEmailHeaders: Fullline unparsed '%s'\n", fullline);
}
free(fullline);
}
if(!anyHeadersFound) {
/*
* False positive in believing we have an e-mail when we don't
*/
messageDestroy(ret);
cli_dbgmsg("parseEmailHeaders: no headers found, assuming it isn't an email\n");
return NULL;
}
cli_dbgmsg("parseEmailHeaders: return\n");
return ret;
}
/*
* Handle a header line of an email message
*/
static int
parseEmailHeader(message *m, const char *line, const table_t *rfc821)
{
int ret;
#ifdef CL_THREAD_SAFE
char *strptr;
#endif
const char *separater;
char *cmd, *copy, tokenseparater[2];
cli_dbgmsg("parseEmailHeader '%s'\n", line);
/*
* In RFC822 the separater between the key a value is a colon,
* e.g. Content-Transfer-Encoding: base64
* However some MUA's are lapse about this and virus writers exploit
* this hole, so we need to check all known possiblities
*/
for(separater = ":= "; *separater; separater++)
if(strchr(line, *separater) != NULL)
break;
if(*separater == '\0')
return -1;
copy = rfc2047(line);
if(copy == NULL)
/* an RFC checker would return -1 here */
copy = cli_strdup(line);
tokenseparater[0] = *separater;
tokenseparater[1] = '\0';
ret = -1;
#ifdef CL_THREAD_SAFE
cmd = strtok_r(copy, tokenseparater, &strptr);
#else
cmd = strtok(copy, tokenseparater);
#endif
if(cmd && (strstrip(cmd) > 0)) {
#ifdef CL_THREAD_SAFE
char *arg = strtok_r(NULL, "", &strptr);
#else
char *arg = strtok(NULL, "");
#endif
if(arg)
/*
* Found a header such as
* Content-Type: multipart/mixed;
* set arg to be
* "multipart/mixed" and cmd to
* be "Content-Type"
*/
ret = parseMimeHeader(m, cmd, rfc821, arg);
}
free(copy);
return ret;
}
/*
* This is a recursive routine.
*
* This function parses the body of mainMessage and saves its attachments in dir
*
* mainMessage is the buffer to be parsed, it contains an e-mail's body, without
* any headers. First time of calling it'll be
* the whole message. Later it'll be parts of a multipart message
* textIn is the plain text message being built up so far
*/
static mbox_status
parseEmailBody(message *messageIn, text *textIn, mbox_ctx *mctx, unsigned int recursion_level)
{
mbox_status rc;
text *aText = textIn;
message *mainMessage = messageIn;
fileblob *fb;
bool infected = FALSE;
const struct cl_engine *engine = mctx->ctx->engine;
const int doPhishingScan = engine->dboptions&CL_DB_PHISHING_URLS && (DCONF_PHISHING & PHISHING_CONF_ENGINE);
cli_dbgmsg("in parseEmailBody, %u files saved so far\n",
mctx->files);
/* FIXMELIMITS: this should be better integrated */
if(engine->maxreclevel)
/*
* This is approximate
*/
if(recursion_level > engine->maxreclevel) {
cli_dbgmsg("parseEmailBody: hit maximum recursion level (%u)\n", recursion_level);
return MAXREC;
}
if(engine->maxfiles && (mctx->files >= engine->maxfiles)) {
/*
* FIXME: This is only approx - it may have already
* been exceeded
*/
cli_dbgmsg("parseEmailBody: number of files exceeded %u\n", engine->maxfiles);
return MAXFILES;
}
rc = OK;
/* Anything left to be parsed? */
if(mainMessage && (messageGetBody(mainMessage) != NULL)) {
mime_type mimeType;
int subtype, inhead, htmltextPart, inMimeHead, i;
const char *mimeSubtype;
char *boundary;
const text *t_line;
/*bool isAlternative;*/
message *aMessage;
int multiparts = 0;
message **messages = NULL; /* parts of a multipart message */
cli_dbgmsg("Parsing mail file\n");
mimeType = messageGetMimeType(mainMessage);
mimeSubtype = messageGetMimeSubtype(mainMessage);
/* pre-process */
subtype = tableFind(mctx->subtypeTable, mimeSubtype);
if((mimeType == TEXT) && (subtype == PLAIN)) {
/*
* This is effectively no encoding, notice that we
* don't check that charset is us-ascii
*/
cli_dbgmsg("text/plain: Assume no attachements\n");
mimeType = NOMIME;
messageSetMimeSubtype(mainMessage, "");
} else if((mimeType == MESSAGE) &&
(strcasecmp(mimeSubtype, "rfc822-headers") == 0)) {
/*
* RFC1892/RFC3462: section 2 text/rfc822-headers
* incorrectly sent as message/rfc822-headers
*
* Parse as text/plain, i.e. no mime
*/
cli_dbgmsg("Changing message/rfc822-headers to text/rfc822-headers\n");
mimeType = NOMIME;
messageSetMimeSubtype(mainMessage, "");
} else
cli_dbgmsg("mimeType = %d\n", (int)mimeType);
switch(mimeType) {
case NOMIME:
cli_dbgmsg("Not a mime encoded message\n");
aText = textAddMessage(aText, mainMessage);
if(!doPhishingScan)
break;
/*
* Fall through: some phishing mails claim they are
* text/plain, when they are in fact html
*/
case TEXT:
/* text/plain has been preprocessed as no encoding */
if(doPhishingScan) {
/*
* It would be better to save and scan the
* file and only checkURLs if it's found to be
* clean
*/
checkURLs(mainMessage, mctx, &rc, (subtype == HTML));
/*
* There might be html sent without subtype
* html too, so scan them for phishing
*/
if(rc == VIRUS)
infected = TRUE;
}
break;
case MULTIPART:
cli_dbgmsg("Content-type 'multipart' handler\n");
boundary = messageFindArgument(mainMessage, "boundary");
if(boundary == NULL) {
cli_dbgmsg("Multipart/%s MIME message contains no boundary header\n",
mimeSubtype);
/* Broken e-mail message */
mimeType = NOMIME;
/*
* The break means that we will still
* check if the file contains a uuencoded file
*/
break;
}
/* Perhaps it should assume mixed? */
if(mimeSubtype[0] == '\0') {
cli_dbgmsg("Multipart has no subtype assuming alternative\n");
mimeSubtype = "alternative";
messageSetMimeSubtype(mainMessage, "alternative");
}
/*
* Get to the start of the first message
*/
t_line = messageGetBody(mainMessage);
if(t_line == NULL) {
cli_dbgmsg("Multipart MIME message has no body\n");
free((char *)boundary);
mimeType = NOMIME;
break;
}
do
if(t_line->t_line) {
if(boundaryStart(lineGetData(t_line->t_line), boundary))
break;
/*
* Found a binhex file before
* the first multipart
* TODO: check yEnc
*/
if(binhexBegin(mainMessage) == t_line) {
if(exportBinhexMessage(mctx, mainMessage)) {
/* virus found */
rc = VIRUS;
infected = TRUE;
break;
}
} else if(t_line->t_next &&
(encodingLine(mainMessage) == t_line->t_next)) {
/*
* We look for the next line
* since later on we'll skip
* over the important line when
* we think it's a blank line
* at the top of the message -
* which it would have been in
* an RFC compliant world
*/
cli_dbgmsg("Found MIME attachment before the first MIME section \"%s\"\n",
lineGetData(t_line->t_next->t_line));
if(messageGetEncoding(mainMessage) == NOENCODING)
break;
}
}
while((t_line = t_line->t_next) != NULL);
if(t_line == NULL) {
cli_dbgmsg("Multipart MIME message contains no boundary lines (%s)\n",
boundary);
free((char *)boundary);
mimeType = NOMIME;
/*
* The break means that we will still
* check if the file contains a yEnc/binhex file
*/
break;
}
/*
* Build up a table of all of the parts of this
* multipart message. Remember, each part may itself
* be a multipart message.
*/
inhead = 1;
inMimeHead = 0;
/*
* Re-read this variable in case mimeSubtype has changed
*/
subtype = tableFind(mctx->subtypeTable, mimeSubtype);
/*
* Parse the mainMessage object and create an array
* of objects called messages, one for each of the
* multiparts that mainMessage contains.
*
* This looks like parseEmailHeaders() - maybe there's
* some duplication of code to be cleaned up
*
* We may need to create an array rather than just
* save each part as it is found because not all
* elements will need scanning, and we don't yet know
* which of those elements it will be, except in
* the case of mixed, when all parts need to be scanned.
*/
for(multiparts = 0; t_line && !infected; multiparts++) {
int lines = 0;
message **m;
mbox_status old_rc;
m = cli_realloc(messages, ((multiparts + 1) * sizeof(message *)));
if(m == NULL)
break;
messages = m;
aMessage = messages[multiparts] = messageCreate();
if(aMessage == NULL) {
multiparts--;
/* if allocation failed the first time,
* there's no point in retrying, just
* break out */
break;
}
messageSetCTX(aMessage, mctx->ctx);
cli_dbgmsg("Now read in part %d\n", multiparts);
/*
* Ignore blank lines. There shouldn't be ANY
* but some viruses insert them
*/
while((t_line = t_line->t_next) != NULL)
if(t_line->t_line &&
/*(cli_chomp(t_line->t_text) > 0))*/
(strlen(lineGetData(t_line->t_line)) > 0))
break;
if(t_line == NULL) {
cli_dbgmsg("Empty part\n");
/*
* Remove this part unless there's
* a binhex portion somewhere in
* the complete message that we may
* throw away by mistake if the MIME
* encoding information is incorrect
*/
if(mainMessage &&
(binhexBegin(mainMessage) == NULL)) {
messageDestroy(aMessage);
--multiparts;
}
continue;
}
do {
const char *line = lineGetData(t_line->t_line);
/*cli_dbgmsg("multipart %d: inMimeHead %d inhead %d boundary '%s' line '%s' next '%s'\n",
multiparts, inMimeHead, inhead, boundary, line,
t_line->t_next && t_line->t_next->t_line ? lineGetData(t_line->t_next->t_line) : "(null)");*/
if(inMimeHead) { /* continuation line */
if(line == NULL) {
/*inhead =*/ inMimeHead = 0;
continue;
}
/*
* Handle continuation lines
* because the previous line
* ended with a ; or this line
* starts with a white space
*/
cli_dbgmsg("Multipart %d: About to add mime Argument '%s'\n",
multiparts, line);
/*
* Handle the case when it
* isn't really a continuation
* line:
* Content-Type: application/octet-stream;
* Content-Transfer-Encoding: base64
*/
parseEmailHeader(aMessage, line, mctx->rfc821Table);
while(isspace((int)*line))
line++;
if(*line == '\0') {
inhead = inMimeHead = 0;
continue;
}
inMimeHead = FALSE;
messageAddArgument(aMessage, line);
} else if(inhead) { /* handling normal headers */
/*int quotes;*/
char *fullline, *ptr;
if(line == NULL) {
/*
* empty line, should the end of the headers,
* but some base64 decoders, e.g. uudeview, are broken
* and will handle this type of entry, decoding the
* base64 content...
* Content-Type: application/octet-stream; name=text.zip
* Content-Transfer-Encoding: base64
* Content-Disposition: attachment; filename="text.zip"
*
* Content-Disposition: attachment;
* filename=text.zip
* Content-Type: application/octet-stream;
* name=text.zip
* Content-Transfer-Encoding: base64
*
* UEsDBAoAAAAAAACgPjJ2RHw676gAAO+oAABEAAAAbWFpbF90ZXh0LWluZm8udHh0ICAgICAgICAg
*/
const text *next = t_line->t_next;
if(next && next->t_line) {
const char *data = lineGetData(next->t_line);
if((messageGetEncoding(aMessage) == NOENCODING) &&
(messageGetMimeType(aMessage) == APPLICATION) &&
data && strstr(data, "base64")) {
/*
* Handle this nightmare (note the blank
* line in the header and the incorrect
* content-transfer-encoding header)
*
* Content-Type: application/octet-stream; name="zipped_files.EXEX-Spanska: Yes
*
* r-Encoding: base64
* Content-Disposition: attachment; filename="zipped_files.EXE"
*/
messageSetEncoding(aMessage, "base64");
cli_dbgmsg("Ignoring fake end of headers\n");
continue;
}
if((strncmp(data, "Content", 7) == 0) ||
(strncmp(data, "filename=", 9) == 0)) {
cli_dbgmsg("Ignoring fake end of headers\n");
continue;
}
}
cli_dbgmsg("Multipart %d: End of header information\n",
multiparts);
inhead = 0;
continue;
}
if(isspace((int)*line)) {
/*
* The first line is
* continuation line.
* This is tricky
* to handle, but
* all we can do is our
* best
*/
cli_dbgmsg("Part %d starts with a continuation line\n",
multiparts);
messageAddArgument(aMessage, line);
/*
* Give it a default
* MIME type since
* that may be the
* missing line
*
* Choose application to
* force a save
*/
if(messageGetMimeType(aMessage) == NOMIME)
messageSetMimeType(aMessage, "application");
continue;
}
inMimeHead = FALSE;
assert(strlen(line) <= RFC2821LENGTH);
fullline = rfc822comments(line, NULL);
if(fullline == NULL)
fullline = cli_strdup(line);
/*quotes = count_quotes(fullline);*/
/*
* Fold next lines to the end of this
* if they start with a white space
* or if this line has an odd number of quotes:
* Content-Type: application/octet-stream; name="foo
* "
*/
while(t_line && next_is_folded_header(t_line)) {
const char *data;
t_line = t_line->t_next;
data = lineGetData(t_line->t_line);
if(data[1] == '\0') {
/*
* Broken message: the
* blank line at the end
* of the headers isn't blank -
* it contains a space
*/
cli_dbgmsg("Multipart %d: headers not terminated by blank line\n",
multiparts);
inhead = FALSE;
break;
}
ptr = cli_realloc(fullline,
strlen(fullline) + strlen(data) + 1);
if(ptr == NULL)
break;
fullline = ptr;
strcat(fullline, data);
/*quotes = count_quotes(data);*/
}
cli_dbgmsg("Multipart %d: About to parse folded header '%s'\n",
multiparts, fullline);
parseEmailHeader(aMessage, fullline, mctx->rfc821Table);
free(fullline);
} else if(boundaryEnd(line, boundary)) {
/*
* Some viruses put information
* *after* the end of message,
* which presumably some broken
* mail clients find, so we
* can't assume that this
* is the end of the message
*/
/* t_line = NULL;*/
break;
} else if(boundaryStart(line, boundary)) {
inhead = 1;
break;
} else {
if(messageAddLine(aMessage, t_line->t_line) < 0)
break;
lines++;
}
} while((t_line = t_line->t_next) != NULL);
cli_dbgmsg("Part %d has %d lines, rc = %d\n",
multiparts, lines, (int)rc);
/*
* Only save in the array of messages if some
* decision will be taken on whether to scan.
* If all parts will be scanned then save to
* file straight away
*/
switch(subtype) {
case MIXED:
case ALTERNATIVE:
case REPORT:
case DIGEST:
case APPLEDOUBLE:
case KNOWBOT:
case -1:
old_rc = rc;
mainMessage = do_multipart(mainMessage,
messages, multiparts,
&rc, mctx, messageIn,
&aText, recursion_level);
if((rc == OK_ATTACHMENTS_NOT_SAVED) && (old_rc == OK))
rc = OK;
if(messages[multiparts]) {
messageDestroy(messages[multiparts]);
messages[multiparts] = NULL;
}
--multiparts;
if(rc == VIRUS)
infected = TRUE;
break;
case RELATED:
case ENCRYPTED:
case SIGNED:
case PARALLEL:
/* all the subtypes that we handle
* (all from the switch(tableFind...) below)
* must be listed here */
break;
default:
/* this is a subtype that we
* don't handle anyway,
* don't store */
if(messages[multiparts]) {
messageDestroy(messages[multiparts]);
messages[multiparts] = NULL;
}
--multiparts;
}
}
free((char *)boundary);
/*
* Preprocess. Anything special to be done before
* we handle the multiparts?
*/
switch(subtype) {
case KNOWBOT:
/* TODO */
cli_dbgmsg("multipart/knowbot parsed as multipart/mixed for now\n");
mimeSubtype = "mixed";
break;
case -1:
/*
* According to section 7.2.6 of
* RFC1521, unrecognised multiparts
* should be treated as multipart/mixed.
*/
cli_dbgmsg("Unsupported multipart format `%s', parsed as mixed\n", mimeSubtype);
mimeSubtype = "mixed";
break;
}
/*
* We've finished message we're parsing
*/
if(mainMessage && (mainMessage != messageIn)) {
messageDestroy(mainMessage);
mainMessage = NULL;
}
cli_dbgmsg("The message has %d parts\n", multiparts);
if(infected || ((multiparts == 0) && (aText == NULL))) {
if(messages) {
for(i = 0; i < multiparts; i++)
if(messages[i])
messageDestroy(messages[i]);
free(messages);
}
if(aText && (textIn == NULL))
textDestroy(aText);
/*
* Nothing to do
*/
switch(rc) {
case VIRUS: return VIRUS;
case MAXREC: return MAXREC;
default: return OK_ATTACHMENTS_NOT_SAVED;
}
}
cli_dbgmsg("Find out the multipart type (%s)\n", mimeSubtype);
/*
* We now have all the parts of the multipart message
* in the messages array:
* message *messages[multiparts]
* Let's decide what to do with them all
*/
switch(tableFind(mctx->subtypeTable, mimeSubtype)) {
case RELATED:
cli_dbgmsg("Multipart related handler\n");
/*
* Have a look to see if there's HTML code
* which will need scanning
*/
aMessage = NULL;
assert(multiparts > 0);
htmltextPart = getTextPart(messages, multiparts);
if(htmltextPart >= 0 && messages) {
if(messageGetBody(messages[htmltextPart]))
aText = textAddMessage(aText, messages[htmltextPart]);
} else
/*
* There isn't an HTML bit. If there's a
* multipart bit, it'll may be in there
* somewhere
*/
for(i = 0; i < multiparts; i++)
if(messageGetMimeType(messages[i]) == MULTIPART) {
aMessage = messages[i];
htmltextPart = i;
break;
}
if(htmltextPart == -1)
cli_dbgmsg("No HTML code found to be scanned\n");
else {
rc = parseEmailBody(aMessage, aText, mctx, recursion_level + 1);
if((rc == OK) && aMessage) {
assert(aMessage == messages[htmltextPart]);
messageDestroy(aMessage);
messages[htmltextPart] = NULL;
} else if(rc == VIRUS) {
infected = TRUE;
break;
}
}
/*
* The message is confused about the difference
* between alternative and related. Badtrans.B
* suffers from this problem.
*
* Fall through in this case:
* Content-Type: multipart/related;
* type="multipart/alternative"
*/
case DIGEST:
/*
* According to section 5.1.5 RFC2046, the
* default mime type of multipart/digest parts
* is message/rfc822
*
* We consider them as alternative, wrong in
* the strictest sense since they aren't
* alternatives - all parts a valid - but it's
* OK for our needs since it means each part
* will be scanned
*/
case ALTERNATIVE:
cli_dbgmsg("Multipart alternative handler\n");
/*
* Fall through - some clients are broken and
* say alternative instead of mixed. The Klez
* virus is broken that way, and anyway we
* wish to scan all of the alternatives
*/
case REPORT:
/*
* According to section 1 of RFC1892, the
* syntax of multipart/report is the same
* as multipart/mixed. There are some required
* parameters, but there's no need for us to
* verify that they exist
*/
case ENCRYPTED:
/* MUAs without encryption plugins can display as multipart/mixed,
* just scan it*/
case MIXED:
case APPLEDOUBLE: /* not really supported */
/*
* Look for attachments
*
* Not all formats are supported. If an
* unsupported format turns out to be
* common enough to implement, it is a simple
* matter to add it
*/
if(aText) {
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
mainMessage = NULL;
}
cli_dbgmsg("Mixed message with %d parts\n", multiparts);
for(i = 0; i < multiparts; i++) {
mainMessage = do_multipart(mainMessage,
messages, i, &rc, mctx,
messageIn, &aText, recursion_level + 1);
if(rc == VIRUS) {
infected = TRUE;
break;
}
if(rc == MAXREC)
break;
if (rc == OK_ATTACHMENTS_NOT_SAVED)
rc = OK;
}
/* rc = parseEmailBody(NULL, NULL, mctx, recursion_level + 1); */
break;
case SIGNED:
case PARALLEL:
/*
* If we're here it could be because we have a
* multipart/mixed message, consisting of a
* message followed by an attachment. That
* message itself is a multipart/alternative
* message and we need to dig out the plain
* text part of that alternative
*/
if(messages) {
htmltextPart = getTextPart(messages, multiparts);
if(htmltextPart == -1)
htmltextPart = 0;
rc = parseEmailBody(messages[htmltextPart], aText, mctx, recursion_level + 1);
}
break;
default:
assert(0);
}
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
if(aText && (textIn == NULL)) {
if((!infected) && (fb = fileblobCreate()) != NULL) {
cli_dbgmsg("Save non mime and/or text/plain part\n");
fileblobSetFilename(fb, mctx->dir, "textpart");
/*fileblobAddData(fb, "Received: by clamd (textpart)\n", 30);*/
fileblobSetCTX(fb, mctx->ctx);
(void)textToFileblob(aText, fb, 1);
fileblobDestroy(fb);
mctx->files++;
}
textDestroy(aText);
}
for(i = 0; i < multiparts; i++)
if(messages[i])
messageDestroy(messages[i]);
if(messages)
free(messages);
return rc;
case MESSAGE:
/*
* Check for forbidden encodings
*/
switch(messageGetEncoding(mainMessage)) {
case NOENCODING:
case EIGHTBIT:
case BINARY:
break;
default:
cli_dbgmsg("MIME type 'message' cannot be decoded\n");
break;
}
rc = FAIL;
if((strcasecmp(mimeSubtype, "rfc822") == 0) ||
(strcasecmp(mimeSubtype, "delivery-status") == 0)) {
message *m = parseEmailHeaders(mainMessage, mctx->rfc821Table);
if(m) {
cli_dbgmsg("Decode rfc822\n");
messageSetCTX(m, mctx->ctx);
if(mainMessage && (mainMessage != messageIn)) {
messageDestroy(mainMessage);
mainMessage = NULL;
} else
messageReset(mainMessage);
if(messageGetBody(m))
rc = parseEmailBody(m, NULL, mctx, recursion_level + 1);
messageDestroy(m);
}
break;
} else if(strcasecmp(mimeSubtype, "disposition-notification") == 0) {
/* RFC 2298 - handle like a normal email */
rc = OK;
break;
} else if(strcasecmp(mimeSubtype, "partial") == 0) {
if(mctx->ctx->options&CL_SCAN_PARTIAL_MESSAGE) {
/* RFC1341 message split over many emails */
if(rfc1341(mainMessage, mctx->dir) >= 0)
rc = OK;
} else {
cli_warnmsg("Partial message received from MUA/MTA - message cannot be scanned\n");
}
} else if(strcasecmp(mimeSubtype, "external-body") == 0)
/* TODO */
cli_warnmsg("Attempt to send Content-type message/external-body trapped\n");
else
cli_warnmsg("Unsupported message format `%s' - if you believe this file contains a virus, submit it to www.clamav.net\n", mimeSubtype);
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
if(messages)
free(messages);
return rc;
default:
cli_dbgmsg("Message received with unknown mime encoding - assume application\n");
/*
* Some Yahoo emails attach as
* Content-Type: X-unknown/unknown;
* instead of
* Content-Type: application/unknown;
* so let's try our best to salvage something
*/
case APPLICATION:
/*cptr = messageGetMimeSubtype(mainMessage);
if((strcasecmp(cptr, "octet-stream") == 0) ||
(strcasecmp(cptr, "x-msdownload") == 0)) {*/
{
fb = messageToFileblob(mainMessage, mctx->dir, 1);
if(fb) {
cli_dbgmsg("Saving main message as attachment\n");
if(fileblobScanAndDestroy(fb) == CL_VIRUS)
rc = VIRUS;
mctx->files++;
if(mainMessage != messageIn) {
messageDestroy(mainMessage);
mainMessage = NULL;
} else
messageReset(mainMessage);
}
} /*else
cli_warnmsg("Discarded application not sent as attachment\n");*/
break;
case AUDIO:
case VIDEO:
case IMAGE:
break;
}
if(messages) {
/* "can't happen" */
cli_warnmsg("messages != NULL\n");
free(messages);
}
}
if(aText && (textIn == NULL)) {
/* Look for a bounce in the text (non mime encoded) portion */
const text *t;
/* isBounceStart() is expensive, reduce the number of calls */
bool lookahead_definately_is_bounce = FALSE;
for(t = aText; t && (rc != VIRUS); t = t->t_next) {
const line_t *l = t->t_line;
const text *lookahead, *topofbounce;
const char *s;
bool inheader;
if(l == NULL) {
/* assert(lookahead_definately_is_bounce == FALSE) */
continue;
}
if(lookahead_definately_is_bounce)
lookahead_definately_is_bounce = FALSE;
else if(!isBounceStart(mctx, lineGetData(l)))
continue;
lookahead = t->t_next;
if(lookahead) {
if(isBounceStart(mctx, lineGetData(lookahead->t_line))) {
lookahead_definately_is_bounce = TRUE;
/* don't save worthless header lines */
continue;
}
} else /* don't save a single liner */
break;
/*
* We've found what looks like the start of a bounce
* message. Only bother saving if it really is a bounce
* message, this helps to speed up scanning of ping-pong
* messages that have lots of bounces within bounces in
* them
*/
for(; lookahead; lookahead = lookahead->t_next) {
l = lookahead->t_line;
if(l == NULL)
break;
s = lineGetData(l);
if(strncasecmp(s, "Content-Type:", 13) == 0) {
/*
* Don't bother with text/plain or
* text/html
*/
if(cli_strcasestr(s, "text/plain") != NULL)
/*
* Don't bother to save the
* unuseful part, read past
* the headers then we'll go
* on to look for the next
* bounce message
*/
continue;
if((!doPhishingScan) &&
(cli_strcasestr(s, "text/html") != NULL))
continue;
break;
}
}
if(lookahead && (lookahead->t_line == NULL)) {
cli_dbgmsg("Non mime part bounce message is not mime encoded, so it will not be scanned\n");
t = lookahead;
/* look for next bounce message */
continue;
}
/*
* Prescan the bounce message to see if there's likely
* to be anything nasty.
* This algorithm is hand crafted and may be breakable
* so all submissions are welcome. It's best NOT to
* remove this however you may be tempted, because it
* significantly speeds up the scanning of multiple
* bounces (i.e. bounces within many bounces)
*/
for(; lookahead; lookahead = lookahead->t_next) {
l = lookahead->t_line;
if(l) {
s = lineGetData(l);
if((strncasecmp(s, "Content-Type:", 13) == 0) &&
(strstr(s, "multipart/") == NULL) &&
(strstr(s, "message/rfc822") == NULL) &&
(strstr(s, "text/plain") == NULL))
break;
}
}
if(lookahead == NULL) {
cli_dbgmsg("cli_mbox: I believe it's plain text which must be clean\n");
/* nothing here, move along please */
break;
}
if((fb = fileblobCreate()) == NULL)
break;
cli_dbgmsg("Save non mime part bounce message\n");
fileblobSetFilename(fb, mctx->dir, "bounce");
fileblobAddData(fb, (const unsigned char *)"Received: by clamd (bounce)\n", 28);
fileblobSetCTX(fb, mctx->ctx);
inheader = TRUE;
topofbounce = NULL;
do {
l = t->t_line;
if(l == NULL) {
if(inheader) {
inheader = FALSE;
topofbounce = t;
}
} else {
s = lineGetData(l);
fileblobAddData(fb, (const unsigned char *)s, strlen(s));
}
fileblobAddData(fb, (const unsigned char *)"\n", 1);
lookahead = t->t_next;
if(lookahead == NULL)
break;
t = lookahead;
l = t->t_line;
if((!inheader) && l) {
s = lineGetData(l);
if(isBounceStart(mctx, s)) {
cli_dbgmsg("Found the start of another bounce candidate (%s)\n", s);
lookahead_definately_is_bounce = TRUE;
break;
}
}
} while(!fileblobInfected(fb));
if(fileblobScanAndDestroy(fb) == CL_VIRUS)
rc = VIRUS;
mctx->files++;
if(topofbounce)
t = topofbounce;
}
textDestroy(aText);
aText = NULL;
}
/*
* No attachments - scan the text portions, often files
* are hidden in HTML code
*/
if(mainMessage && (rc != VIRUS)) {
text *t_line;
/*
* Look for uu-encoded main file
*/
if((encodingLine(mainMessage) != NULL) &&
((t_line = bounceBegin(mainMessage)) != NULL))
rc = (exportBounceMessage(mctx, t_line) == CL_VIRUS) ? VIRUS : OK;
else {
bool saveIt;
if(messageGetMimeType(mainMessage) == MESSAGE)
/*
* Quick peek, if the encapsulated
* message has no
* content encoding statement don't
* bother saving to scan, it's safe
*/
saveIt = (bool)(encodingLine(mainMessage) != NULL);
else if((t_line = encodingLine(mainMessage)) != NULL) {
/*
* Some bounces include the message
* body without the headers.
* FIXME: Unfortunately this generates a
* lot of false positives that a bounce
* has been found when it hasn't.
*/
if((fb = fileblobCreate()) != NULL) {
cli_dbgmsg("Found a bounce message with no header at '%s'\n",
lineGetData(t_line->t_line));
fileblobSetFilename(fb, mctx->dir, "bounce");
fileblobAddData(fb,
(const unsigned char *)"Received: by clamd (bounce)\n",
28);
fileblobSetCTX(fb, mctx->ctx);
if(fileblobScanAndDestroy(textToFileblob(t_line, fb, 1)) == CL_VIRUS)
rc = VIRUS;
mctx->files++;
}
saveIt = FALSE;
} else
/*
* Save the entire text portion,
* since it it may be an HTML file with
* a JavaScript virus or a phish
*/
saveIt = TRUE;
if(saveIt) {
cli_dbgmsg("Saving text part to scan, rc = %d\n",
(int)rc);
if(saveTextPart(mctx, mainMessage, 1) == CL_VIRUS)
rc = VIRUS;
if(mainMessage != messageIn) {
messageDestroy(mainMessage);
mainMessage = NULL;
} else
messageReset(mainMessage);
}
}
} /*else
rc = OK_ATTACHMENTS_NOT_SAVED; */ /* nothing saved */
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
if((rc != FAIL) && infected)
rc = VIRUS;
cli_dbgmsg("parseEmailBody() returning %d\n", (int)rc);
return rc;
}
/*
* Is the current line the start of a new section?
*
* New sections start with --boundary
*/
static int
boundaryStart(const char *line, const char *boundary)
{
const char *ptr;
char *out;
int rc;
char buf[RFC2821LENGTH + 1];
if(line == NULL)
return 0; /* empty line */
if(boundary == NULL)
return 0;
/*cli_dbgmsg("boundaryStart: line = '%s' boundary = '%s'\n", line, boundary);*/
if((*line != '-') && (*line != '('))
return 0;
if(strchr(line, '-') == NULL)
return 0;
if(strlen(line) <= sizeof(buf)) {
out = NULL;
ptr = rfc822comments(line, buf);
} else
ptr = out = rfc822comments(line, NULL);
if(ptr == NULL)
ptr = line;
if((*ptr++ != '-') || (*ptr == '\0')) {
if(out)
free(out);
return 0;
}
/*
* Gibe.B3 is broken, it has:
* boundary="---- =_NextPart_000_01C31177.9DC7C000"
* but it's boundaries look like
* ------ =_NextPart_000_01C31177.9DC7C000
* notice the one too few '-'.
* Presumably this is a deliberate exploitation of a bug in some mail
* clients.
*
* The trouble is that this creates a lot of false positives for
* boundary conditions, if we're too lax about matches. We do our level
* best to avoid these false positives. For example if we have
* boundary="1" we want to ensure that we don't break out of every line
* that has -1 in it instead of starting --1. This needs some more work.
*
* Look with and without RFC822 comments stripped, I've seen some
* samples where () are taken as comments in boundaries and some where
* they're not. Irrespective of whatever RFC2822 says, we need to find
* viruses in both types of mails.
*/
if((strstr(&ptr[1], boundary) != NULL) || (strstr(line, boundary) != NULL)) {
const char *k = ptr;
/*
* We need to ensure that we don't match --11=-=-=11 when
* looking for --1=-=-=1 in well behaved headers, that's a
* false positive problem mentioned above
*/
rc = 0;
do
if(strcmp(++k, boundary) == 0) {
rc = 1;
break;
}
while(*k == '-');
if(rc == 0) {
k = &line[1];
do
if(strcmp(++k, boundary) == 0) {
rc = 1;
break;
}
while(*k == '-');
}
} else if(*ptr++ != '-')
rc = 0;
else
rc = (strcasecmp(ptr, boundary) == 0);
if(out)
free(out);
if(rc == 1)
cli_dbgmsg("boundaryStart: found %s in %s\n", boundary, line);
return rc;
}
/*
* Is the current line the end?
*
* The message ends with with --boundary--
*/
static int
boundaryEnd(const char *line, const char *boundary)
{
size_t len;
if(line == NULL)
return 0;
/*cli_dbgmsg("boundaryEnd: line = '%s' boundary = '%s'\n", line, boundary);*/
if(*line++ != '-')
return 0;
if(*line++ != '-')
return 0;
len = strlen(boundary);
if(strncasecmp(line, boundary, len) != 0)
return 0;
/*
* Use < rather than == because some broken mails have white
* space after the boundary
*/
if(strlen(line) < (len + 2))
return 0;
line = &line[len];
if(*line++ != '-')
return 0;
if(*line == '-') {
cli_dbgmsg("boundaryEnd: found %s in %s\n", boundary, line);
return 1;
}
return 0;
}
/*
* Initialise the various lookup tables
*/
static int
initialiseTables(table_t **rfc821Table, table_t **subtypeTable)
{
const struct tableinit *tableinit;
/*
* Initialise the various look up tables
*/
*rfc821Table = tableCreate();
assert(*rfc821Table != NULL);
for(tableinit = rfc821headers; tableinit->key; tableinit++)
if(tableInsert(*rfc821Table, tableinit->key, tableinit->value) < 0) {
tableDestroy(*rfc821Table);
*rfc821Table = NULL;
return -1;
}
*subtypeTable = tableCreate();
assert(*subtypeTable != NULL);
for(tableinit = mimeSubtypes; tableinit->key; tableinit++)
if(tableInsert(*subtypeTable, tableinit->key, tableinit->value) < 0) {
tableDestroy(*rfc821Table);
tableDestroy(*subtypeTable);
*rfc821Table = NULL;
*subtypeTable = NULL;
return -1;
}
return 0;
}
/*
* If there's a HTML text version use that, otherwise
* use the first text part, otherwise just use the
* first one around. HTML text is most likely to include
* a scripting worm
*
* If we can't find one, return -1
*/
static int
getTextPart(message *const messages[], size_t size)
{
size_t i;
int textpart = -1;
for(i = 0; i < size; i++)
if(messages[i] && (messageGetMimeType(messages[i]) == TEXT)) {
if(strcasecmp(messageGetMimeSubtype(messages[i]), "html") == 0)
return (int)i;
textpart = (int)i;
}
return textpart;
}
/*
* strip -
* Remove the trailing spaces from a buffer. Don't call this directly,
* always call strstrip() which is a wrapper to this routine to be used with
* NUL terminated strings. This code looks a bit strange because of it's
* heritage from code that worked on strings that weren't necessarily NUL
* terminated.
* TODO: rewrite for clamAV
*
* Returns it's new length (a la strlen)
*
* len must be int not size_t because of the >= 0 test, it is sizeof(buf)
* not strlen(buf)
*/
static size_t
strip(char *buf, int len)
{
register char *ptr;
register size_t i;
if((buf == NULL) || (len <= 0))
return 0;
i = strlen(buf);
if(len > (int)(i + 1))
return i;
ptr = &buf[--len];
#if defined(UNIX) || defined(C_LINUX) || defined(C_DARWIN) /* watch - it may be in shared text area */
do
if(*ptr)
*ptr = '\0';
while((--len >= 0) && (!isgraph(*--ptr)) && (*ptr != '\n') && (*ptr != '\r'));
#else /* more characters can be displayed on DOS */
do
#ifndef REAL_MODE_DOS
if(*ptr) /* C8.0 puts into a text area */
#endif
*ptr = '\0';
while((--len >= 0) && ((*--ptr == '\0') || isspace((int)(*ptr & 0xFF))));
#endif
return((size_t)(len + 1));
}
/*
* strstrip:
* Strip a given string
*/
size_t
strstrip(char *s)
{
if(s == (char *)NULL)
return(0);
return(strip(s, strlen(s) + 1));
}
/*
* Returns 0 for OK, -1 for error
*/
static int
parseMimeHeader(message *m, const char *cmd, const table_t *rfc821Table, const char *arg)
{
char *copy, *p, *buf;
const char *ptr;
int commandNumber;
cli_dbgmsg("parseMimeHeader: cmd='%s', arg='%s'\n", cmd, arg);
copy = rfc822comments(cmd, NULL);
if(copy) {
commandNumber = tableFind(rfc821Table, copy);
free(copy);
} else
commandNumber = tableFind(rfc821Table, cmd);
copy = rfc822comments(arg, NULL);
if(copy)
ptr = copy;
else
ptr = arg;
buf = NULL;
switch(commandNumber) {
case CONTENT_TYPE:
/*
* Fix for non RFC1521 compliant mailers
* that send content-type: Text instead
* of content-type: Text/Plain, or
* just simply "Content-Type:"
*/
if(arg == NULL)
/*
* According to section 4 of RFC1521:
* "Note also that a subtype specification is
* MANDATORY. There are no default subtypes"
*
* We have to break this and make an assumption
* for the subtype because virus writers and
* email client writers don't get it right
*/
cli_dbgmsg("Empty content-type received, no subtype specified, assuming text/plain; charset=us-ascii\n");
else if(strchr(ptr, '/') == NULL)
/*
* Empty field, such as
* Content-Type:
* which I believe is illegal according to
* RFC1521
*/
cli_dbgmsg("Invalid content-type '%s' received, no subtype specified, assuming text/plain; charset=us-ascii\n", ptr);
else {
int i;
buf = cli_malloc(strlen(ptr) + 1);
if(buf == NULL) {
if(copy)
free(copy);
return -1;
}
/*
* Some clients are broken and
* put white space after the ;
*/
if(*arg == '/') {
cli_dbgmsg("Content-type '/' received, assuming application/octet-stream\n");
messageSetMimeType(m, "application");
messageSetMimeSubtype(m, "octet-stream");
} else {
/*
* The content type could be in quotes:
* Content-Type: "multipart/mixed"
* FIXME: this is a hack in that ignores
* the quotes, it doesn't handle
* them properly
*/
while(isspace(*ptr))
ptr++;
if(ptr[0] == '\"')
ptr++;
if(ptr[0] != '/') {
char *s;
#ifdef CL_THREAD_SAFE
char *strptr = NULL;
#endif
s = cli_strtokbuf(ptr, 0, ";", buf);
/*
* Handle
* Content-Type: foo/bar multipart/mixed
* and
* Content-Type: multipart/mixed foo/bar
*/
if(s && *s) {
char *buf2 = cli_strdup(buf);
if(buf2 == NULL) {
if(copy)
free(copy);
free(buf);
return -1;
}
for(;;) {
#ifdef CL_THREAD_SAFE
int set = messageSetMimeType(m, strtok_r(s, "/", &strptr));
#else
int set = messageSetMimeType(m, strtok(s, "/"));
#endif
#ifdef CL_THREAD_SAFE
s = strtok_r(NULL, ";", &strptr);
#else
s = strtok(NULL, ";");
#endif
if(s == NULL)
break;
if(set) {
size_t len = strstrip(s) - 1;
if(s[len] == '\"') {
s[len] = '\0';
len = strstrip(s);
}
if(len) {
if(strchr(s, ' '))
messageSetMimeSubtype(m,
cli_strtokbuf(s, 0, " ", buf2));
else
messageSetMimeSubtype(m, s);
}
}
while(*s && !isspace(*s))
s++;
if(*s++ == '\0')
break;
if(*s == '\0')
break;
}
free(buf2);
}
}
}
/*
* Add in all rest of the the arguments.
* e.g. if the header is this:
* Content-Type:', arg='multipart/mixed; boundary=foo
* we find the boundary argument set it
*/
i = 1;
while(cli_strtokbuf(ptr, i++, ";", buf) != NULL) {
cli_dbgmsg("mimeArgs = '%s'\n", buf);
messageAddArguments(m, buf);
}
}
break;
case CONTENT_TRANSFER_ENCODING:
messageSetEncoding(m, ptr);
break;
case CONTENT_DISPOSITION:
buf = cli_malloc(strlen(ptr) + 1);
if(buf == NULL) {
if(copy)
free(copy);
return -1;
}
p = cli_strtokbuf(ptr, 0, ";", buf);
if(p && *p) {
messageSetDispositionType(m, p);
messageAddArgument(m, cli_strtokbuf(ptr, 1, ";", buf));
}
if(!messageHasFilename(m))
/*
* Handle this type of header, without
* a filename (e.g. some Worm.Torvil.D)
* Content-ID: <nRfkHdrKsAxRU>
* Content-Transfer-Encoding: base64
* Content-Disposition: attachment
*/
messageAddArgument(m, "filename=unknown");
}
if(copy)
free(copy);
if(buf)
free(buf);
return 0;
}
/*
* Save the text portion of the message
*/
static int
saveTextPart(mbox_ctx *mctx, message *m, int destroy_text)
{
fileblob *fb;
messageAddArgument(m, "filename=textportion");
if((fb = messageToFileblob(m, mctx->dir, destroy_text)) != NULL) {
/*
* Save main part to scan that
*/
cli_dbgmsg("Saving main message\n");
mctx->files++;
return fileblobScanAndDestroy(fb);
}
return CL_ETMPFILE;
}
/*
* Handle RFC822 comments in headers.
* If out == NULL, return a buffer without the comments, the caller must free
* the returned buffer
* Return NULL on error or if the input * has no comments.
* See secion 3.4.3 of RFC822
* TODO: handle comments that go on to more than one line
*/
static char *
rfc822comments(const char *in, char *out)
{
const char *iptr;
char *optr;
int backslash, inquote, commentlevel;
if(in == NULL)
return NULL;
if(strchr(in, '(') == NULL)
return NULL;
assert(out != in);
while(isspace(*in))
in++;
if(out == NULL) {
out = cli_malloc(strlen(in) + 1);
if(out == NULL)
return NULL;
}
backslash = commentlevel = inquote = 0;
optr = out;
cli_dbgmsg("rfc822comments: contains a comment\n");
for(iptr = in; *iptr; iptr++)
if(backslash) {
if(commentlevel == 0)
*optr++ = *iptr;
backslash = 0;
} else switch(*iptr) {
case '\\':
backslash = 1;
break;
case '\"':
*optr++ = '\"';
inquote = !inquote;
break;
case '(':
if(inquote)
*optr++ = '(';
else
commentlevel++;
break;
case ')':
if(inquote)
*optr++ = ')';
else if(commentlevel > 0)
commentlevel--;
break;
default:
if(commentlevel == 0)
*optr++ = *iptr;
}
if(backslash) /* last character was a single backslash */
*optr++ = '\\';
*optr = '\0';
/*strstrip(out);*/
cli_dbgmsg("rfc822comments '%s'=>'%s'\n", in, out);
return out;
}
/*
* Handle RFC2047 encoding. Returns a malloc'd buffer that the caller must
* free, or NULL on error
*/
static char *
rfc2047(const char *in)
{
char *out, *pout;
size_t len;
if((strstr(in, "=?") == NULL) || (strstr(in, "?=") == NULL))
return cli_strdup(in);
cli_dbgmsg("rfc2047 '%s'\n", in);
out = cli_malloc(strlen(in) + 1);
if(out == NULL)
return NULL;
pout = out;
/* For each RFC2047 string */
while(*in) {
char encoding, *ptr, *enctext;
message *m;
blob *b;
/* Find next RFC2047 string */
while(*in) {
if((*in == '=') && (in[1] == '?')) {
in += 2;
break;
}
*pout++ = *in++;
}
/* Skip over charset, find encoding */
while((*in != '?') && *in)
in++;
if(*in == '\0')
break;
encoding = *++in;
encoding = (char)tolower(encoding);
if((encoding != 'q') && (encoding != 'b')) {
cli_warnmsg("Unsupported RFC2047 encoding type '%c' - if you believe this file contains a virus, submit it to www.clamav.net\n", encoding);
free(out);
out = NULL;
break;
}
/* Skip to encoded text */
if(*++in != '?')
break;
if(*++in == '\0')
break;
enctext = cli_strdup(in);
if(enctext == NULL) {
free(out);
out = NULL;
break;
}
in = strstr(in, "?=");
if(in == NULL) {
free(enctext);
break;
}
in += 2;
ptr = strstr(enctext, "?=");
assert(ptr != NULL);
*ptr = '\0';
/*cli_dbgmsg("Need to decode '%s' with method '%c'\n", enctext, encoding);*/
m = messageCreate();
if(m == NULL)
break;
messageAddStr(m, enctext);
free(enctext);
switch(encoding) {
case 'q':
messageSetEncoding(m, "quoted-printable");
break;
case 'b':
messageSetEncoding(m, "base64");
break;
}
b = messageToBlob(m, 1);
len = blobGetDataSize(b);
cli_dbgmsg("Decoded as '%*.*s'\n", (int)len, (int)len,
(const char *)blobGetData(b));
memcpy(pout, blobGetData(b), len);
blobDestroy(b);
messageDestroy(m);
if(pout[len - 1] == '\n')
pout += len - 1;
else
pout += len;
}
if(out == NULL)
return NULL;
*pout = '\0';
cli_dbgmsg("rfc2047 returns '%s'\n", out);
return out;
}
/*
* Handle partial messages
*/
static int
rfc1341(message *m, const char *dir)
{
char *arg, *id, *number, *total, *oldfilename;
const char *tmpdir;
int n;
char pdir[NAME_MAX + 1];
unsigned char md5_val[16];
cli_md5_ctx md5;
char *md5_hex;
id = (char *)messageFindArgument(m, "id");
if(id == NULL)
return -1;
/* do we need this for C_WINDOWS?
#ifdef C_CYGWIN
if((tmpdir = getenv("TEMP")) == (char *)NULL)
if((tmpdir = getenv("TMP")) == (char *)NULL)
if((tmpdir = getenv("TMPDIR")) == (char *)NULL)
tmpdir = "C:\\";
#else
*/
if((tmpdir = getenv("TMPDIR")) == (char *)NULL)
if((tmpdir = getenv("TMP")) == (char *)NULL)
if((tmpdir = getenv("TEMP")) == (char *)NULL)
#ifdef P_tmpdir
tmpdir = P_tmpdir;
#else
tmpdir = "/tmp";
#endif
snprintf(pdir, sizeof(pdir) - 1, "%s/clamav-partial", tmpdir);
if((mkdir(pdir, S_IRWXU) < 0) && (errno != EEXIST)) {
cli_errmsg("Can't create the directory '%s'\n", pdir);
free(id);
return -1;
} else if(errno == EEXIST) {
struct stat statb;
if(stat(pdir, &statb) < 0) {
char err[128];
cli_errmsg("Partial directory %s: %s\n", pdir,
cli_strerror(errno, err, sizeof(err)));
free(id);
return -1;
}
if(statb.st_mode & 077)
cli_warnmsg("Insecure partial directory %s (mode 0%o)\n",
pdir,
#ifdef ACCESSPERMS
(int)(statb.st_mode&ACCESSPERMS)
#else
(int)(statb.st_mode & 0777)
#endif
);
}
number = (char *)messageFindArgument(m, "number");
if(number == NULL) {
free(id);
return -1;
}
oldfilename = messageGetFilename(m);
arg = cli_malloc(10 + strlen(id) + strlen(number));
if(arg) {
sprintf(arg, "filename=%s%s", id, number);
messageAddArgument(m, arg);
free(arg);
}
if(oldfilename) {
cli_dbgmsg("Must reset to %s\n", oldfilename);
free(oldfilename);
}
n = atoi(number);
cli_md5_init(&md5);
cli_md5_update(&md5, id, strlen(id));
cli_md5_final(md5_val, &md5);
md5_hex = cli_str2hex((const char*)md5_val, 16);
if(!md5_hex) {
free(id);
free(number);
return CL_EMEM;
}
if(messageSavePartial(m, pdir, md5_hex, n) < 0) {
free(md5_hex);
free(id);
free(number);
return -1;
}
total = (char *)messageFindArgument(m, "total");
cli_dbgmsg("rfc1341: %s, %s of %s\n", id, number, (total) ? total : "?");
if(total) {
int t = atoi(total);
DIR *dd = NULL;
free(total);
/*
* If it's the last one - reassemble it
* FIXME: this assumes that we receive the parts in order
*/
if((n == t) && ((dd = opendir(pdir)) != NULL)) {
FILE *fout;
char outname[NAME_MAX + 1];
time_t now;
sanitiseName(id);
snprintf(outname, sizeof(outname) - 1, "%s/%s", dir, id);
cli_dbgmsg("outname: %s\n", outname);
fout = fopen(outname, "wb");
if(fout == NULL) {
cli_errmsg("Can't open '%s' for writing", outname);
free(id);
free(number);
free(md5_hex);
closedir(dd);
return -1;
}
time(&now);
for(n = 1; n <= t; n++) {
char filename[NAME_MAX + 1];
const struct dirent *dent;
#if defined(HAVE_READDIR_R_3) || defined(HAVE_READDIR_R_2)
union {
struct dirent d;
char b[offsetof(struct dirent, d_name) + NAME_MAX + 1];
} result;
#endif
snprintf(filename, sizeof(filename), "_%s-%u", md5_hex, n);
#ifdef HAVE_READDIR_R_3
while((readdir_r(dd, &result.d, &dent) == 0) && dent) {
#elif defined(HAVE_READDIR_R_2)
while((dent = (struct dirent *)readdir_r(dd, &result.d))) {
#else /*!HAVE_READDIR_R*/
while((dent = readdir(dd))) {
#endif
FILE *fin;
char buffer[BUFSIZ], fullname[NAME_MAX + 1];
int nblanks;
struct stat statb;
const char *dentry_idpart;
#ifndef C_WINDOWS
if(dent->d_ino == 0)
continue;
#endif
if(!strcmp(".",dent->d_name) ||
!strcmp("..", dent->d_name))
continue;
snprintf(fullname, sizeof(fullname) - 1,
"%s/%s", pdir, dent->d_name);
dentry_idpart = strchr(dent->d_name, '_');
if(!dentry_idpart ||
strcmp(filename, dentry_idpart) != 0) {
if(!m->ctx->engine->keeptmp)
continue;
if(stat(fullname, &statb) < 0)
continue;
if(now - statb.st_mtime > (time_t)(7 * 24 * 3600)) {
if (cli_unlink(fullname)) {
cli_unlink(outname);
fclose(fout);
free(md5_hex);
free(id);
free(number);
closedir(dd);
return -1;
}
}
continue;
}
fin = fopen(fullname, "rb");
if(fin == NULL) {
cli_errmsg("Can't open '%s' for reading", fullname);
fclose(fout);
cli_unlink(outname);
free(id);
free(number);
closedir(dd);
return -1;
}
nblanks = 0;
while(fgets(buffer, sizeof(buffer) - 1, fin) != NULL)
/*
* Ensure that trailing newlines
* aren't copied
*/
if(buffer[0] == '\n')
nblanks++;
else {
if(nblanks)
do {
if (putc('\n', fout)==EOF) break;
} while(--nblanks > 0);
if (nblanks || fputs(buffer, fout)==EOF) {
fclose(fin);
fclose(fout);
cli_unlink(outname);
free(md5_hex);
free(id);
free(number);
closedir(dd);
return -1;
}
}
fclose(fin);
/* don't unlink if leave temps */
if(!m->ctx->engine->keeptmp) {
if(cli_unlink(fullname)) {
fclose(fout);
cli_unlink(outname);
free(md5_hex);
free(id);
free(number);
closedir(dd);
return -1;
}
}
break;
}
rewinddir(dd);
}
closedir(dd);
fclose(fout);
}
}
free(number);
free(id);
free(md5_hex);
return 0;
}
static void
hrefs_done(blob *b, tag_arguments_t *hrefs)
{
if(b)
blobDestroy(b);
html_tag_arg_free(hrefs);
}
/* extract URLs from static text */
static void extract_text_urls(const unsigned char *mem, size_t len, tag_arguments_t *hrefs)
{
char url[1024];
size_t off;
for (off=0;off + 10 < len;off++) {
/* check whether this is the start of a URL */
int32_t proto = cli_readint32(mem + off);
/* convert to lowercase */
proto |= 0x20202020;
/* 'http:', 'https:', or 'ftp:' in little-endian */
if ((proto == 0x70747468 &&
(mem[off+4] == ':' || (mem[off+5] == 's' && mem[off+6] == ':')))
|| proto == 0x3a707466) {
size_t url_len;
for (url_len=4; off + url_len < len && url_len < (sizeof(url)-1); url_len++) {
unsigned char c = mem[off + url_len];
/* smart compilers will compile this if into
* a single bt + jb instruction */
if (c == ' ' || c == '\n' || c == '\t')
break;
}
memcpy(url, mem + off, url_len);
url[url_len] = '\0';
html_tag_arg_add(hrefs, "href", url);
off += url_len;
}
}
}
/*
* This used to be part of checkURLs, split out, because phishingScan needs it
* too, and phishingScan might be used in situations where checkURLs is
* disabled (see ifdef)
*/
static blob *
getHrefs(message *m, tag_arguments_t *hrefs)
{
unsigned char *mem;
blob *b = messageToBlob(m, 0);
size_t len;
if(b == NULL)
return NULL;
len = blobGetDataSize(b);
if(len == 0) {
blobDestroy(b);
return NULL;
}
/* TODO: make this size customisable */
if(len > 100*1024) {
cli_dbgmsg("Viruses pointed to by URLs not scanned in large message\n");
blobDestroy(b);
return NULL;
}
hrefs->count = 0;
hrefs->tag = hrefs->value = NULL;
hrefs->contents = NULL;
cli_dbgmsg("getHrefs: calling html_normalise_mem\n");
mem = blobGetData(b);
if(!html_normalise_mem(mem, (off_t)len, NULL, hrefs,m->ctx->dconf)) {
blobDestroy(b);
return NULL;
}
cli_dbgmsg("getHrefs: html_normalise_mem returned\n");
if (!hrefs->count && hrefs->scanContents) {
extract_text_urls(mem, len, hrefs);
}
/* TODO: Do we need to call remove_html_comments? */
return b;
}
/*
* validate URLs for phishes
* followurls: see if URLs point to malware
*/
static void
checkURLs(message *mainMessage, mbox_ctx *mctx, mbox_status *rc, int is_html)
{
blob *b;
tag_arguments_t hrefs;
if(*rc == VIRUS)
return;
hrefs.scanContents = mctx->ctx->engine->dboptions&CL_DB_PHISHING_URLS && (DCONF_PHISHING & PHISHING_CONF_ENGINE);
if(!hrefs.scanContents)
/*
* Don't waste time extracting hrefs (parsing html), nobody
* will need it
*/
return;
hrefs.count = 0;
hrefs.tag = hrefs.value = NULL;
hrefs.contents = NULL;
b = getHrefs(mainMessage, &hrefs);
if(b) {
if(hrefs.scanContents) {
if(phishingScan(mctx->ctx, &hrefs) == CL_VIRUS) {
/*
* FIXME: message objects' contents are
* encapsulated so we should not access
* the members directly
*/
mainMessage->isInfected = TRUE;
*rc = VIRUS;
cli_dbgmsg("PH:Phishing found\n");
}
}
}
hrefs_done(b,&hrefs);
}
#ifdef HAVE_BACKTRACE
static void
sigsegv(int sig)
{
signal(SIGSEGV, SIG_DFL);
print_trace(1);
exit(SIGSEGV);
}
static void
print_trace(int use_syslog)
{
void *array[10];
size_t size;
char **strings;
size_t i;
pid_t pid = getpid();
cli_errmsg("Segmentation fault, attempting to print backtrace\n");
size = backtrace(array, 10);
strings = backtrace_symbols(array, size);
cli_errmsg("Backtrace of pid %d:\n", pid);
if(use_syslog)
syslog(LOG_ERR, "Backtrace of pid %d:", pid);
for(i = 0; i < size; i++) {
cli_errmsg("%s\n", strings[i]);
if(use_syslog)
syslog(LOG_ERR, "bt[%u]: %s", i, strings[i]);
}
#ifdef SAVE_TMP
cli_errmsg("The errant mail file has been saved\n");
#endif
/* #else TODO: dump the current email */
free(strings);
}
#endif
/* See also clamav-milter */
static bool
usefulHeader(int commandNumber, const char *cmd)
{
switch(commandNumber) {
case CONTENT_TRANSFER_ENCODING:
case CONTENT_DISPOSITION:
case CONTENT_TYPE:
return TRUE;
default:
if(strcasecmp(cmd, "From") == 0)
return TRUE;
if(strcasecmp(cmd, "Received") == 0)
return TRUE;
if(strcasecmp(cmd, "De") == 0)
return TRUE;
}
return FALSE;
}
/*
* Like fgets but cope with end of line by "\n", "\r\n", "\n\r", "\r"
*/
static char *
getline_from_mbox(char *buffer, size_t len, FILE *fin)
{
char *ret;
/* we check for eof from the result of GETC()
* if(feof(fin))
return NULL;*/
if((len == 0) || (buffer == NULL)) {
cli_errmsg("Invalid call to getline_from_mbox(). Refer to http://www.clamav.net/bugs\n");
return NULL;
}
ret = buffer;
do {
int c = GETC(fin);
switch(c) {
default:
*buffer = (char)c;
buffer += (c != 0);
continue;
case '\n':
*buffer++ = '\n';
c = GETC(fin);
if((c != '\r') && !feof(fin))
ungetc(c, fin);
break;
case EOF:
if(ret == buffer || ferror(fin)) {
/* EOF on first char, or error */
return NULL;
}
break;
case '\r':
*buffer++ = '\n';
c = GETC(fin);
if((c != '\n') && !feof(fin))
ungetc(c, fin);
break;
}
break;
} while(--len > 1);
if(len == 0) {
/* the email probably breaks RFC821 */
cli_dbgmsg("getline_from_mbox: buffer overflow stopped, line lost\n");
return NULL;
}
*buffer = '\0';
if(len == 1)
/* overflows will have appeared on separate lines */
cli_dbgmsg("getline_from_mbox: buffer overflow stopped, line recovered\n");
return ret;
}
/*
* Is this line a candidate for the start of a bounce message?
*/
static bool
isBounceStart(mbox_ctx *mctx, const char *line)
{
size_t len;
if(line == NULL)
return FALSE;
if(*line == '\0')
return FALSE;
/*if((strncmp(line, "From ", 5) == 0) && !isalnum(line[5]))
return FALSE;
if((strncmp(line, ">From ", 6) == 0) && !isalnum(line[6]))
return FALSE;*/
len = strlen(line);
if((len < 6) || (len >= 72))
return FALSE;
if((memcmp(line, "From ", 5) == 0) ||
(memcmp(line, ">From ", 6) == 0)) {
int numSpaces = 0, numDigits = 0;
line += 4;
do
if(*line == ' ')
numSpaces++;
else if(isdigit((*line) & 0xFF))
numDigits++;
while(*++line != '\0');
if(numSpaces < 6)
return FALSE;
if(numDigits < 11)
return FALSE;
return TRUE;
}
return (bool)(cli_filetype((const unsigned char *)line, len, mctx->ctx->engine) == CL_TYPE_MAIL);
}
/*
* Extract a binhexEncoded message, return if it's found to be infected as we
* extract it
*/
static bool
exportBinhexMessage(mbox_ctx *mctx, message *m)
{
bool infected = FALSE;
fileblob *fb;
if(messageGetEncoding(m) == NOENCODING)
messageSetEncoding(m, "x-binhex");
fb = messageToFileblob(m, mctx->dir, 0);
if(fb) {
cli_dbgmsg("Binhex file decoded to %s\n",
fileblobGetFilename(fb));
if(fileblobScanAndDestroy(fb) == CL_VIRUS)
infected = TRUE;
mctx->files++;
} else
cli_errmsg("Couldn't decode binhex file to %s\n", mctx->dir);
return infected;
}
/*
* Locate any bounce message and extract it. Return cl_status
*/
static int
exportBounceMessage(mbox_ctx *mctx, text *start)
{
int rc = CL_CLEAN;
text *t;
fileblob *fb;
/*
* Attempt to save the original (unbounced)
* message - clamscan will find that in the
* directory and call us again (with any luck)
* having found an e-mail message to handle.
*
* This finds a lot of false positives, the
* search that a content type is in the
* bounce (i.e. it's after the bounce header)
* helps a bit.
*
* messageAddLine
* optimisation could help here, but needs
* careful thought, do it with line numbers
* would be best, since the current method in
* messageAddLine of checking encoding first
* must remain otherwise non bounce messages
* won't be scanned
*/
for(t = start; t; t = t->t_next) {
const char *txt = lineGetData(t->t_line);
char cmd[RFC2821LENGTH + 1];
if(txt == NULL)
continue;
if(cli_strtokbuf(txt, 0, ":", cmd) == NULL)
continue;
switch(tableFind(mctx->rfc821Table, cmd)) {
case CONTENT_TRANSFER_ENCODING:
if((strstr(txt, "7bit") == NULL) &&
(strstr(txt, "8bit") == NULL))
break;
continue;
case CONTENT_DISPOSITION:
break;
case CONTENT_TYPE:
if(strstr(txt, "text/plain") != NULL)
t = NULL;
break;
default:
if(strcasecmp(cmd, "From") == 0)
start = t;
else if(strcasecmp(cmd, "Received") == 0)
start = t;
continue;
}
break;
}
if(t && ((fb = fileblobCreate()) != NULL)) {
cli_dbgmsg("Found a bounce message\n");
fileblobSetFilename(fb, mctx->dir, "bounce");
fileblobSetCTX(fb, mctx->ctx);
if(textToFileblob(start, fb, 1) == NULL) {
cli_dbgmsg("Nothing new to save in the bounce message\n");
fileblobDestroy(fb);
} else
rc = fileblobScanAndDestroy(fb);
mctx->files++;
} else
cli_dbgmsg("Not found a bounce message\n");
return rc;
}
/*
* Handle the ith element of a number of multiparts, e.g. multipart/alternative
*/
static message *
do_multipart(message *mainMessage, message **messages, int i, mbox_status *rc, mbox_ctx *mctx, message *messageIn, text **tptr, unsigned int recursion_level)
{
bool addToText = FALSE;
const char *dtype;
#ifndef SAVE_TO_DISC
message *body;
#endif
message *aMessage = messages[i];
const int doPhishingScan = mctx->ctx->engine->dboptions&CL_DB_PHISHING_URLS && (DCONF_PHISHING&PHISHING_CONF_ENGINE);
if(aMessage == NULL)
return mainMessage;
if(*rc != OK)
return mainMessage;
cli_dbgmsg("Mixed message part %d is of type %d\n",
i, messageGetMimeType(aMessage));
switch(messageGetMimeType(aMessage)) {
case APPLICATION:
case AUDIO:
case IMAGE:
case VIDEO:
break;
case NOMIME:
cli_dbgmsg("No mime headers found in multipart part %d\n", i);
if(mainMessage) {
if(binhexBegin(aMessage)) {
cli_dbgmsg("Found binhex message in multipart/mixed mainMessage\n");
if(exportBinhexMessage(mctx, mainMessage))
*rc = VIRUS;
}
if(mainMessage != messageIn)
messageDestroy(mainMessage);
mainMessage = NULL;
} else if(aMessage) {
if(binhexBegin(aMessage)) {
cli_dbgmsg("Found binhex message in multipart/mixed non mime part\n");
if(exportBinhexMessage(mctx, aMessage))
*rc = VIRUS;
assert(aMessage == messages[i]);
messageReset(messages[i]);
}
}
addToText = TRUE;
if(messageGetBody(aMessage) == NULL)
/*
* No plain text version
*/
cli_dbgmsg("No plain text alternative\n");
break;
case TEXT:
dtype = messageGetDispositionType(aMessage);
cli_dbgmsg("Mixed message text part disposition \"%s\"\n",
dtype);
if(strcasecmp(dtype, "attachment") == 0)
break;
if((*dtype == '\0') || (strcasecmp(dtype, "inline") == 0)) {
const char *cptr;
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
mainMessage = NULL;
cptr = messageGetMimeSubtype(aMessage);
cli_dbgmsg("Mime subtype \"%s\"\n", cptr);
if((tableFind(mctx->subtypeTable, cptr) == PLAIN) &&
(messageGetEncoding(aMessage) == NOENCODING)) {
/*
* Strictly speaking, a text/plain part
* is not an attachment. We pretend it
* is so that we can decode and scan it
*/
if(!messageHasFilename(aMessage)) {
cli_dbgmsg("Adding part to main message\n");
addToText = TRUE;
} else
cli_dbgmsg("Treating inline as attachment\n");
} else {
const int is_html = (tableFind(mctx->subtypeTable, cptr) == HTML);
if(doPhishingScan)
checkURLs(aMessage, mctx, rc, is_html);
messageAddArgument(aMessage,
"filename=mixedtextportion");
}
break;
}
cli_dbgmsg("Text type %s is not supported\n", dtype);
return mainMessage;
case MESSAGE:
/* Content-Type: message/rfc822 */
cli_dbgmsg("Found message inside multipart (encoding type %d)\n",
messageGetEncoding(aMessage));
#ifndef SCAN_UNENCODED_BOUNCES
switch(messageGetEncoding(aMessage)) {
case NOENCODING:
case EIGHTBIT:
case BINARY:
if(encodingLine(aMessage) == NULL) {
/*
* This means that the message
* has no attachments
*
* The test for
* messageGetEncoding is needed
* since encodingLine won't have
* been set if the message
* itself has been encoded
*/
cli_dbgmsg("Unencoded multipart/message will not be scanned\n");
assert(aMessage == messages[i]);
messageDestroy(messages[i]);
messages[i] = NULL;
return mainMessage;
}
/* FALLTHROUGH */
default:
cli_dbgmsg("Encoded multipart/message will be scanned\n");
}
#endif
#if 0
messageAddStrAtTop(aMessage,
"Received: by clamd (message/rfc822)");
#endif
#ifdef SAVE_TO_DISC
/*
* Save this embedded message
* to a temporary file
*/
if(saveTextPart(mctx, aMessage, 1) == CL_VIRUS)
*rc = VIRUS;
assert(aMessage == messages[i]);
messageDestroy(messages[i]);
messages[i] = NULL;
#else
/*
* Scan in memory, faster but is open to DoS attacks
* when many nested levels are involved.
*/
body = parseEmailHeaders(aMessage, mctx->rfc821Table);
/*
* We've fininished with the
* original copy of the message,
* so throw that away and
* deal with the encapsulated
* message as a message.
* This can save a lot of memory
*/
assert(aMessage == messages[i]);
messageDestroy(messages[i]);
messages[i] = NULL;
if(body) {
messageSetCTX(body, mctx->ctx);
*rc = parseEmailBody(body, NULL, mctx, recursion_level + 1);
if((*rc == OK) && messageContainsVirus(body))
*rc = VIRUS;
messageDestroy(body);
}
#endif
return mainMessage;
case MULTIPART:
/*
* It's a multi part within a multi part
* Run the message parser on this bit, it won't
* be an attachment
*/
cli_dbgmsg("Found multipart inside multipart\n");
if(aMessage) {
/*
* The headers were parsed when reading in the
* whole multipart section
*/
*rc = parseEmailBody(aMessage, *tptr, mctx, recursion_level + 1);
cli_dbgmsg("Finished recursion, rc = %d\n", (int)*rc);
assert(aMessage == messages[i]);
messageDestroy(messages[i]);
messages[i] = NULL;
} else {
*rc = parseEmailBody(NULL, NULL, mctx, recursion_level + 1);
if(mainMessage && (mainMessage != messageIn))
messageDestroy(mainMessage);
mainMessage = NULL;
}
return mainMessage;
default:
cli_dbgmsg("Only text and application attachments are fully supported, type = %d\n",
messageGetMimeType(aMessage));
/* fall through - we may be able to salvage something */
}
if(*rc != VIRUS) {
fileblob *fb = messageToFileblob(aMessage, mctx->dir, 1);
if(fb) {
/* aMessage doesn't always have a ctx set */
fileblobSetCTX(fb, mctx->ctx);
if(fileblobScanAndDestroy(fb) == CL_VIRUS)
*rc = VIRUS;
if (!addToText)
mctx->files++;
}
if(messageContainsVirus(aMessage))
*rc = VIRUS;
}
messageDestroy(aMessage);
messages[i] = NULL;
return mainMessage;
}
/*
* Returns the number of quote characters in the given string
*/
static int
count_quotes(const char *buf)
{
int quotes = 0;
while(*buf)
if(*buf++ == '\"')
quotes++;
return quotes;
}
/*
* Will the next line be a folded header? See RFC2822 section 2.2.3
*/
static bool
next_is_folded_header(const text *t)
{
const text *next = t->t_next;
const char *data, *ptr;
if(next == NULL)
return FALSE;
if(next->t_line == NULL)
return FALSE;
data = lineGetData(next->t_line);
/*
* Section B.2 of RFC822 says TAB or SPACE means a continuation of the
* previous entry.
*/
if(isblank(data[0]))
return TRUE;
if(strchr(data, '=') == NULL)
/*
* Avoid false positives with
* Content-Type: text/html;
* Content-Transfer-Encoding: quoted-printable
*/
return FALSE;
/*
* Some are broken and don't fold headers lines
* correctly as per section 2.2.3 of RFC2822.
* Generally they miss the white space at
* the start of the fold line:
* Content-Type: multipart/related;
* type="multipart/alternative";
* boundary="----=_NextPart_000_006A_01C6AC47.348CB550"
* should read:
* Content-Type: multipart/related;
* type="multipart/alternative";
* boundary="----=_NextPart_000_006A_01C6AC47.348CB550"
* Since we're a virus checker not an RFC
* verifier we need to handle these
*/
data = lineGetData(t->t_line);
ptr = strchr(data, '\0');
while(--ptr > data)
switch(*ptr) {
case ';':
return TRUE;
case '\n':
case ' ':
case '\r':
case '\t':
continue; /* white space at end of line */
default:
return FALSE;
}
return FALSE;
}
/*
* This routine is called on the first line of the body of
* an email to handle broken messages that have newlines
* in the middle of its headers
*/
static bool
newline_in_header(const char *line)
{
cli_dbgmsg("newline_in_header, check \"%s\"\n", line);
if(strncmp(line, "Message-Id: ", 12) == 0)
return TRUE;
if(strncmp(line, "Date: ", 6) == 0)
return TRUE;
return FALSE;
}