/*
* Copyright (C) 2015-2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2008 Sourcefire, Inc.
*
* Authors: Nigel Horne
*
* Acknowledgements: Some ideas came from Stephen White <stephen@earth.li>,
* Michael Dankov <misha@btrc.ru>, Gianluigi Tiesi <sherpya@netfarm.it>,
* Everton da Silva Marques, Thomas Lamy <Thomas.Lamy@in-online.net>,
* James Stevens <James@kyzo.com>
*
* 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.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#ifdef CL_THREAD_SAFE
#ifndef _REENTRANT
#define _REENTRANT /* for Solaris 2.8 */
#endif
#endif
#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"
#include <dirent.h>
#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 "clamav.h"
#include "others.h"
#include "str.h"
#include "filetypes.h"
#include "mbox.h"
#include "dconf.h"
#include "fmap.h"
#include "json_api.h"
#include "msxml_parser.h"
#if HAVE_LIBXML2
#ifdef _WIN32
#ifndef LIBXML_WRITER_ENABLED
#define LIBXML_WRITER_ENABLED 1
#endif
#endif
#include <libxml/xmlversion.h>
#include <libxml/HTMLtree.h>
#include <libxml/HTMLparser.h>
#include <libxml/xmlreader.h>
#endif
#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 _WIN32
#include <sys/time.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#if !defined(C_BEOS) && !defined(C_INTERIX)
#include <net/if.h>
#include <arpa/inet.h>
#endif
#endif
#include <fcntl.h>
/*
* 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 */
#if HAVE_JSON
json_object *wrkobj;
#endif
} 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, cli_ctx *ctx);
static message *parseEmailFile(fmap_t *map, size_t *at, 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 int parseMHTMLComment(const char *comment, cli_ctx *ctx, void *wrkjobj, void *cbdata);
static mbox_status parseRootMHTML(mbox_ctx *mctx, message *m, text *t);
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, fmap_t *map, size_t *at);
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 const char *getMimeTypeStr(mime_type mimetype);
static const char *getEncTypeStr(encoding_type enctype);
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 }
}, mimeTypeStr[] = {
{ "NOMIME", NOMIME },
{ "APPLICATION", APPLICATION },
{ "AUDIO", AUDIO },
{ "IMAGE", IMAGE },
{ "MESSAGE", MESSAGE },
{ "MULTIPART", MULTIPART },
{ "TEXT", TEXT },
{ "VIDEO", VIDEO },
{ "MEXTENSION", MEXTENSION },
{ NULL, 0 }
}, encTypeStr[] = {
{ "NOENCODING", NOENCODING },
{ "QUOTEDPRINTABLE", QUOTEDPRINTABLE },
{ "BASE64", BASE64 },
{ "EIGHTBIT", EIGHTBIT },
{ "BINARY", BINARY },
{ "UUENCODE", UUENCODE },
{ "YENCODE", YENCODE },
{ "EEXTENSION", EEXTENSION },
{ "BINHEX", BINHEX },
{ NULL, 0 }
};
#ifdef CL_THREAD_SAFE
static pthread_mutex_t tables_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
static table_t *rfc821 = NULL;
static table_t *subtype = NULL;
int
cli_mbox(const char *dir, cli_ctx *ctx)
{
if(dir == NULL) {
cli_dbgmsg("cli_mbox called with NULL dir\n");
return CL_ENULLARG;
}
return cli_parse_mbox(dir, ctx);
}
/*
* 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 unexpected NUL bytes in header lines which stop strcmp()s:
* e.g. \0Content-Type: application/binary;
*/
static int
cli_parse_mbox(const char *dir, cli_ctx *ctx)
{
int retcode;
message *body;
char buffer[RFC2821LENGTH + 1];
mbox_ctx mctx;
size_t at = 0;
fmap_t *map = *ctx->fmap;
cli_dbgmsg("in mbox()\n");
if(!fmap_gets(map, buffer, &at, sizeof(buffer) - 1)) {
/* empty message */
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
return CL_EMEM;
}
}
#ifdef CL_THREAD_SAFE
pthread_mutex_unlock(&tables_mutex);
#endif
retcode = CL_SUCCESS;
body = NULL;
mctx.dir = dir;
mctx.rfc821Table = rfc821;
mctx.subtypeTable = subtype;
mctx.ctx = ctx;
mctx.files = 0;
#if HAVE_JSON
mctx.wrkobj = ctx->wrkproperty;
#endif
/*
* 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)
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-1);
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, map, &at) < 0)
if(messageAddStr(m, buffer) < 0)
break;
} else
/* at this point, the \n has been removed */
if(messageAddStr(m, buffer) < 0)
break;
} while(fmap_gets(map, buffer, &at, sizeof(buffer) - 1));
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(fmap_gets(map, buffer, &at, sizeof(buffer) - 1) &&
(strchr("\r\n", buffer[0]) == NULL))
;
/* 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, map, &at) != NULL))
;
buffer[sizeof(buffer) - 1] = '\0';
body = parseEmailFile(map, &at, rfc821, buffer, dir);
}
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 || SCAN_ALL)) {
retcode = cli_append_virus(ctx, "Heuristics.Phishing.Email");
ctx->found_possibly_unwanted = 0;
}
cli_dbgmsg("cli_mbox returning %d\n", retcode);
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(fmap_t *map, size_t *at, 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;
strncpy(buffer, firstLine, sizeof(buffer)-1);
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;
const char *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) + 1;
ptr = cli_realloc(fullline, fulllinelength);
if(ptr == NULL)
continue;
fullline = ptr;
cli_strlcat(fullline, line, fulllinelength);
}
assert(fullline != NULL);
if((lookahead = fmap_need_off_once(map, *at, 1))) {
/*
* 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[strlen(fullline) - 1] == ';')
/* 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, map, at) < 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, map, at) != 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) + 1;
ptr = cli_realloc(fullline, fulllinelength);
if(ptr == NULL)
continue;
fullline = ptr;
cli_strlcat(fullline, line, fulllinelength);
}
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 *separator;
char *cmd, *copy, tokenseparator[2];
cli_dbgmsg("parseEmailHeader '%s'\n", line);
/*
* In RFC822 the separator 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 possibilities
*/
for(separator = ":= "; *separator; separator++)
if(strchr(line, *separator) != NULL)
break;
if(*separator == '\0')
return -1;
copy = rfc2047(line);
if(copy == NULL)
/* an RFC checker would return -1 here */
copy = cli_strdup(line);
tokenseparator[0] = *separator;
tokenseparator[1] = '\0';
ret = -1;
#ifdef CL_THREAD_SAFE
cmd = strtok_r(copy, tokenseparator, &strptr);
#else
cmd = strtok(copy, tokenseparator);
#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;
}
#if HAVE_LIBXML2
static const struct key_entry mhtml_keys[] = {
/* root html tags for microsoft office document */
{ "html", "RootHTML", MSXML_JSON_ROOT | MSXML_JSON_ATTRIB },
{ "head", "Head", MSXML_JSON_WRKPTR | MSXML_COMMENT_CB },
{ "meta", "Meta", MSXML_JSON_WRKPTR | MSXML_JSON_MULTI | MSXML_JSON_ATTRIB },
{ "link", "Link", MSXML_JSON_WRKPTR | MSXML_JSON_MULTI | MSXML_JSON_ATTRIB },
{ "script", "Script", MSXML_JSON_WRKPTR | MSXML_JSON_MULTI | MSXML_JSON_VALUE }
};
static size_t num_mhtml_keys = sizeof(mhtml_keys) / sizeof(struct key_entry);
static const struct key_entry mhtml_comment_keys[] = {
/* embedded xml tags (comment) for microsoft office document */
{ "o:documentproperties", "DocumentProperties", MSXML_JSON_ROOT | MSXML_JSON_ATTRIB },
{ "o:author", "Author", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:lastauthor", "LastAuthor", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:revision", "Revision", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:totaltime", "TotalTime", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:created", "Created", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:lastsaved", "LastSaved", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:pages", "Pages", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:words", "Words", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:characters", "Characters", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:company", "Company", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:lines", "Lines", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:paragraphs", "Paragraphs", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:characterswithspaces", "CharactersWithSpaces", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:version", "Version", MSXML_JSON_WRKPTR | MSXML_JSON_VALUE },
{ "o:officedocumentsettings", "DocumentSettings", MSXML_IGNORE_ELEM },
{ "w:worddocument", "WordDocument", MSXML_IGNORE_ELEM },
{ "w:latentstyles", "LatentStyles", MSXML_IGNORE_ELEM }
};
static size_t num_mhtml_comment_keys = sizeof(mhtml_comment_keys) / sizeof(struct key_entry);
#endif
/*
* The related multipart root HTML file comment parsing wrapper.
*
* Attempts to leverage msxml parser, cannot operate without LIBXML2.
* This function is only used for Preclassification JSON.
*/
static int
parseMHTMLComment(const char *comment, cli_ctx *ctx, void *wrkjobj, void *cbdata)
{
#if HAVE_LIBXML2
const char *xmlsrt, *xmlend;
xmlTextReaderPtr reader;
#if HAVE_JSON
json_object *thisjobj = (json_object *)wrkjobj;
#endif
int ret = CL_SUCCESS;
UNUSEDPARAM(cbdata);
UNUSEDPARAM(wrkjobj);
xmlend = comment;
while ((xmlsrt = strstr(xmlend, "<xml>"))) {
xmlend = strstr(xmlsrt, "</xml>");
if (xmlend == NULL) {
cli_dbgmsg("parseMHTMLComment: unbounded xml tag\n");
break;
}
reader = xmlReaderForMemory(xmlsrt, xmlend-xmlsrt+6, "comment.xml", NULL, CLAMAV_MIN_XMLREADER_FLAGS);
if (!reader) {
cli_dbgmsg("parseMHTMLComment: cannot initialize xmlReader\n");
#if HAVE_JSON
if (ctx->wrkproperty != NULL)
ret = cli_json_parse_error(ctx->wrkproperty, "MHTML_ERROR_XML_READER_MEM");
#endif
return ret; // libxml2 failed!
}
/* comment callback is not set to prevent recursion */
/* TODO: should we separate the key dictionaries? */
/* TODO: should we use the json object pointer? */
ret = cli_msxml_parse_document(ctx, reader, mhtml_comment_keys, num_mhtml_comment_keys, MSXML_FLAG_JSON, NULL);
xmlTextReaderClose(reader);
xmlFreeTextReader(reader);
if (ret != CL_SUCCESS)
return ret;
}
#else
UNUSEDPARAM(comment);
UNUSEDPARAM(ctx);
UNUSEDPARAM(wrkjobj);
UNUSEDPARAM(cbdata);
cli_dbgmsg("in parseMHTMLComment\n");
cli_dbgmsg("parseMHTMLComment: parsing html xml-comments requires libxml2!\n");
#endif
return CL_SUCCESS;
}
/*
* The related multipart root HTML file parsing wrapper.
*
* Attempts to leverage msxml parser, cannot operate without LIBXML2.
* This function is only used for Preclassification JSON.
*/
static mbox_status
parseRootMHTML(mbox_ctx *mctx, message *m, text *t)
{
cli_ctx *ctx = mctx->ctx;
#if HAVE_LIBXML2
#ifdef LIBXML_HTML_ENABLED
struct msxml_ctx mxctx;
blob *input = NULL;
htmlDocPtr htmlDoc;
xmlTextReaderPtr reader;
int ret = CL_SUCCESS;
mbox_status rc = OK;
#if HAVE_JSON
json_object *rhtml;
#endif
cli_dbgmsg("in parseRootMHTML\n");
if (ctx == NULL)
return OK;
if (m == NULL && t == NULL)
return OK;
if (m != NULL)
input = messageToBlob(m, 0);
else /* t != NULL */
input = textToBlob(t, NULL, 0);
if (input == NULL)
return OK;
htmlDoc = htmlReadMemory((char*)input->data, input->len, "mhtml.html", NULL, CLAMAV_MIN_XMLREADER_FLAGS);
if (htmlDoc == NULL) {
cli_dbgmsg("parseRootMHTML: cannot initialize read html document\n");
#if HAVE_JSON
if (ctx->wrkproperty != NULL)
ret = cli_json_parse_error(ctx->wrkproperty, "MHTML_ERROR_HTML_READ");
if (ret != CL_SUCCESS)
rc = FAIL;
#endif
blobDestroy(input);
return rc;
}
#if HAVE_JSON
if (mctx->wrkobj) {
rhtml = cli_jsonobj(mctx->wrkobj, "RootHTML");
if (rhtml != NULL) {
/* MHTML-specific properties */
cli_jsonstr(rhtml, "Encoding", (const char*)htmlGetMetaEncoding(htmlDoc));
cli_jsonint(rhtml, "CompressMode", xmlGetDocCompressMode(htmlDoc));
}
}
#endif
reader = xmlReaderWalker(htmlDoc);
if (reader == NULL) {
cli_dbgmsg("parseRootMHTML: cannot initialize xmlTextReader\n");
#if HAVE_JSON
if (ctx->wrkproperty != NULL)
ret = cli_json_parse_error(ctx->wrkproperty, "MHTML_ERROR_XML_READER_IO");
if (ret != CL_SUCCESS)
rc = FAIL;
#endif
blobDestroy(input);
return rc;
}
memset(&mxctx, 0, sizeof(mxctx));
/* no scanning callback set */
mxctx.comment_cb = parseMHTMLComment;
ret = cli_msxml_parse_document(ctx, reader, mhtml_keys, num_mhtml_keys, MSXML_FLAG_JSON | MSXML_FLAG_WALK, &mxctx);
switch (ret) {
case CL_SUCCESS:
case CL_ETIMEOUT:
case CL_BREAK:
rc = OK;
break;
case CL_EMAXREC:
rc = MAXREC;
break;
case CL_EMAXFILES:
rc = MAXFILES;
break;
case CL_VIRUS:
rc = VIRUS;
break;
default:
rc = FAIL;
}
xmlTextReaderClose(reader);
xmlFreeTextReader(reader);
xmlFreeDoc(htmlDoc);
blobDestroy(input);
return rc;
#else /* LIBXML_HTML_ENABLED */
UNUSEDPARAM(m);
UNUSEDPARAM(t);
cli_dbgmsg("in parseRootMHTML\n");
cli_dbgmsg("parseRootMHTML: parsing html documents disabled in libxml2!\n");
#endif /* LIBXML_HTML_ENABLED */
#else /* HAVE_LIBXML2 */
UNUSEDPARAM(m);
UNUSEDPARAM(t);
cli_dbgmsg("in parseRootMHTML\n");
cli_dbgmsg("parseRootMHTML: parsing html documents requires libxml2!\n");
return OK;
#endif /* HAVE_LIBXML2 */
}
/*
* 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);
#if HAVE_JSON
json_object *saveobj = mctx->wrkobj;
#endif
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);
#if HAVE_JSON
if (mctx->wrkobj != NULL) {
mctx->wrkobj = cli_jsonobj(mctx->wrkobj, "Body");
cli_jsonstr(mctx->wrkobj, "MimeType", getMimeTypeStr(mimeType));
cli_jsonstr(mctx->wrkobj, "MimeSubtype", mimeSubtype);
cli_jsonstr(mctx->wrkobj, "EncodingType", getEncTypeStr(messageGetEncoding(mainMessage)));
cli_jsonstr(mctx->wrkobj, "Disposition", messageGetDispositionType(mainMessage));
cli_jsonstr(mctx->wrkobj, "Filename", messageHasFilename(mainMessage) ?
messageGetFilename(mainMessage): "(inline)");
}
#endif
/* 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 attachments\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 HAVE_JSON
if (mctx->wrkobj != NULL)
cli_jsonstr(mctx->wrkobj, "Boundary", boundary);
#endif
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;
}
cli_chomp(boundary);
/* 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;
size_t datasz;
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;
}
datasz = strlen(fullline) + strlen(data) + 1;
ptr = cli_realloc(fullline, datasz);
if(ptr == NULL)
break;
fullline = ptr;
cli_strlcat(fullline, data, datasz);
/*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, unrecognized 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);
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
/*
* 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 {
#if HAVE_JSON
/* Send root HTML file for preclassification */
if (mctx->ctx->wrkproperty)
parseRootMHTML(mctx, aMessage, aText);
#endif
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);
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
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);
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
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(mainMessage->body_first != NULL &&
(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(mainMessage->body_last != NULL && (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;
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
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];
char *newline;
if(line == NULL || *line == '\0')
return 0; /* empty line */
if(boundary == NULL)
return 0;
newline = strdup(line);
if (!(newline))
newline = (char *)line;
if (newline != line && strlen(line)) {
char *p;
/* Trim trailing spaces */
p = newline + strlen(line) - 1;
while (p >= newline && *p == ' ')
*(p--) = '\0';
}
if (newline != line)
cli_chomp(newline);
/* cli_dbgmsg("boundaryStart: line = '%s' boundary = '%s'\n", line, boundary); */
if((*newline != '-') && (*newline != '(')) {
if (newline != line)
free(newline);
return 0;
}
if(strchr(newline, '-') == NULL) {
if (newline != line)
free(newline);
return 0;
}
if(strlen(newline) <= sizeof(buf)) {
out = NULL;
ptr = rfc822comments(newline, buf);
} else
ptr = out = rfc822comments(newline, NULL);
if(ptr == NULL)
ptr = newline;
if((*ptr++ != '-') || (*ptr == '\0')) {
if(out)
free(out);
if (newline != line)
free(newline);
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(newline, 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);
if (newline != line)
free(newline);
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;
char *newline, *p, *p2;
if(line == NULL || *line == '\0')
return 0;
p = newline = strdup(line);
if (!(newline)) {
p = (char *)line;
newline = (char *)line;
}
if (newline != line && strlen(line)) {
/* Trim trailing spaces */
p2 = newline + strlen(line) - 1;
while (p2 >= newline && *p2 == ' ')
*(p2--) = '\0';
}
/* cli_dbgmsg("boundaryEnd: line = '%s' boundary = '%s'\n", newline, boundary); */
if(*p++ != '-') {
if (newline != line)
free(newline);
return 0;
}
if(*p++ != '-') {
if (newline != line)
free(newline);
return 0;
}
len = strlen(boundary);
if(strncasecmp(p, boundary, len) != 0) {
if (newline != line)
free(newline);
return 0;
}
/*
* Use < rather than == because some broken mails have white
* space after the boundary
*/
if(strlen(p) < (len + 2)) {
if (newline != line)
free(newline);
return 0;
}
p = &p[len];
if(*p++ != '-') {
if (newline != line)
free(newline);
return 0;
}
if(*p == '-') {
/* cli_dbgmsg("boundaryEnd: found %s in %s\n", boundary, p); */
if (newline != line)
free(newline);
return 1;
}
if (newline != line)
free(newline);
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) {
cli_errmsg("parseMimeHeader: Unable to allocate memory for buf %llu\n", (long long unsigned)(strlen(ptr) + 1));
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) {
cli_errmsg("parseMimeHeader: Unable to allocate memory for buf %llu\n", (long long unsigned)(strlen(ptr) + 1));
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 section 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) {
cli_errmsg("rfc822comments: Unable to allocate memory for out %llu\n", (long long unsigned)(strlen(in) + 1));
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) {
cli_errmsg("rfc2047: Unable to allocate memory for out %llu\n", (long long unsigned)(strlen(in) + 1));
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);
if (b == NULL) {
messageDestroy(m);
break;
}
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(len > 0 && 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];
char *md5_hex;
id = (char *)messageFindArgument(m, "id");
if(id == NULL)
return -1;
tmpdir = cli_gettmpdir();
snprintf(pdir, sizeof(pdir) - 1, "%s"PATHSEP"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) {
STATBUF statb;
if(CLAMSTAT(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);
cl_hash_data("md5", id, strlen(id), md5_val, NULL);
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"PATHSEP"%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];
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;
STATBUF statb;
const char *dentry_idpart;
int test_fd;
if(dent->d_ino == 0)
continue;
if(!strcmp(".",dent->d_name) ||
!strcmp("..", dent->d_name))
continue;
snprintf(fullname, sizeof(fullname) - 1,
"%s"PATHSEP"%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 ((test_fd = open(fullname, O_RDONLY)) < 0)
continue;
if(FSTAT(test_fd, &statb) < 0) {
close(test_fd);
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);
close(test_fd);
return -1;
}
}
close(test_fd);
continue;
}
fin = fopen(fullname, "rb");
if(fin == NULL) {
cli_errmsg("Can't open '%s' for reading", fullname);
fclose(fout);
cli_unlink(outname);
free(md5_hex);
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;
UNUSEDPARAM(is_html);
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[%llu]: %s", (unsigned long long)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 buffer_len, fmap_t *map, size_t *at)
{
const char *src, *cursrc;
char *curbuf;
size_t i;
size_t input_len = MIN(map->len - *at, buffer_len + 1);
src = cursrc = fmap_need_off_once(map, *at, input_len);
/* we check for eof from the result of GETC()
* if(feof(fin))
return NULL;*/
if(!src) {
cli_dbgmsg("getline_from_mbox: fmap need failed\n");
return NULL;
}
if((buffer_len == 0) || (buffer == NULL)) {
cli_errmsg("Invalid call to getline_from_mbox(). Refer to https://www.clamav.net/documents/installing-clamav\n");
return NULL;
}
curbuf = buffer;
for(i=0; i<buffer_len-1; i++) {
char c;
if(!input_len--) {
if(curbuf == buffer) {
/* EOF on first char */
return NULL;
}
break;
}
switch((c = *cursrc++)) {
case '\0':
continue;
case '\n':
*curbuf++ = '\n';
if(input_len && *cursrc == '\r') {
i++;
cursrc++;
}
break;
case '\r':
*curbuf++ = '\r';
if(input_len && *cursrc == '\n') {
i++;
cursrc++;
}
break;
default:
*curbuf++ = c;
continue;
}
break;
}
*at += cursrc - src;
*curbuf = '\0';
return buffer;
}
/*
* 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
* optimization 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;
}
/*
* Get string representation of mimetype
*/
static const char *getMimeTypeStr(mime_type mimetype)
{
const struct tableinit *entry = mimeTypeStr;
while (entry->key) {
if (mimetype == entry->value)
return entry->key;
entry++;
}
return "UNKNOWN";
}
/*
* Get string representation of encoding type
*/
static const char *getEncTypeStr(encoding_type enctype)
{
const struct tableinit *entry = encTypeStr;
while (entry->key) {
if (enctype == entry->value)
return entry->key;
entry++;
}
return "UNKNOWN";
}
/*
* 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 HAVE_JSON
const char *mtype = NULL;
json_object *thisobj = NULL, *saveobj = mctx->wrkobj;
if (mctx->wrkobj != NULL) {
json_object *multiobj = cli_jsonarray(mctx->wrkobj, "Multipart");
if (multiobj == NULL) {
cli_errmsg("Cannot get multipart preclass array\n");
*rc = -1;
return mainMessage;
}
thisobj = messageGetJObj(aMessage);
if (thisobj == NULL) {
cli_errmsg("Cannot get message preclass object\n");
*rc = -1;
return mainMessage;
}
if (cli_json_addowner(multiobj, thisobj, NULL, -1) != CL_SUCCESS) {
cli_errmsg("Cannot assign message preclass object to multipart preclass array\n");
*rc = -1;
return mainMessage;
}
}
#endif
if(aMessage == NULL) {
#if HAVE_JSON
if (thisobj != NULL)
cli_jsonstr(thisobj, "MimeType", "NULL");
#endif
return mainMessage;
}
if(*rc != OK)
return mainMessage;
cli_dbgmsg("Mixed message part %d is of type %d\n",
i, messageGetMimeType(aMessage));
#if HAVE_JSON
if (thisobj != NULL) {
cli_jsonstr(thisobj, "MimeType", getMimeTypeStr(messageGetMimeType(aMessage)));
cli_jsonstr(thisobj, "MimeSubtype", messageGetMimeSubtype(aMessage));
cli_jsonstr(thisobj, "EncodingType", getEncTypeStr(messageGetEncoding(aMessage)));
cli_jsonstr(thisobj, "Disposition", messageGetDispositionType(aMessage));
cli_jsonstr(thisobj, "Filename", messageHasFilename(aMessage) ?
messageGetFilename(aMessage): "(inline)");
}
#endif
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 finished 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 HAVE_JSON
mctx->wrkobj = thisobj;
#endif
if(body) {
messageSetCTX(body, mctx->ctx);
*rc = parseEmailBody(body, NULL, mctx, recursion_level + 1);
if((*rc == OK) && messageContainsVirus(body))
*rc = VIRUS;
messageDestroy(body);
}
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
#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 HAVE_JSON
mctx->wrkobj = thisobj;
#endif
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;
}
#if HAVE_JSON
mctx->wrkobj = saveobj;
#endif
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 HAVE_JSON
json_object *arrobj;
int arrlen = 0;
if (thisobj != NULL) {
/* attempt to determine container size - prevents incorrect type reporting */
if (json_object_object_get_ex(mctx->ctx->wrkproperty, "ContainedObjects", &arrobj))
arrlen = json_object_array_length(arrobj);
}
#endif
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 HAVE_JSON
if (thisobj != NULL) {
json_object *entry = NULL;
const char *dtype = NULL;
/* attempt to acquire container type */
if (json_object_object_get_ex(mctx->ctx->wrkproperty, "ContainedObjects", &arrobj))
if (json_object_array_length(arrobj) > arrlen)
entry = json_object_array_get_idx(arrobj, arrlen);
if (entry) {
json_object_object_get_ex(entry, "FileType", &entry);
if (entry)
dtype = json_object_get_string(entry);
}
cli_jsonint(thisobj, "ContainedObjectsIndex", arrlen);
cli_jsonstr(thisobj, "ClamAVFileType", dtype ? dtype : "UNKNOWN");
}
#endif
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;
}