/*
  * Copyright (c) 2015 Hendrik Leppkes
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /** Based on the CURL SChannel module */
 
 #include "avformat.h"
 #include "internal.h"
 #include "network.h"
 #include "os_support.h"
 #include "url.h"
 #include "tls.h"
 
 #define SECURITY_WIN32

 #include <windows.h>

 #include <security.h>
 #include <schnlsp.h>
 
 #define SCHANNEL_INITIAL_BUFFER_SIZE   4096
 #define SCHANNEL_FREE_BUFFER_SIZE      1024
 
 /* mingw does not define this symbol */
 #ifndef SECBUFFER_ALERT
 #define SECBUFFER_ALERT                17
 #endif
 
 typedef struct TLSContext {
     const AVClass *class;
     TLSShared tls_shared;
 
     CredHandle cred_handle;
     TimeStamp cred_timestamp;
 
     CtxtHandle ctxt_handle;
     TimeStamp ctxt_timestamp;
 
     ULONG request_flags;
     ULONG context_flags;
 
     uint8_t *enc_buf;
     int enc_buf_size;
     int enc_buf_offset;
 
     uint8_t *dec_buf;
     int dec_buf_size;
     int dec_buf_offset;
 
     SecPkgContext_StreamSizes sizes;
 
     int connected;
     int connection_closed;
     int sspi_close_notify;
 } TLSContext;
 
 static void init_sec_buffer(SecBuffer *buffer, unsigned long type,
                             void *data, unsigned long size)
 {
     buffer->cbBuffer   = size;
     buffer->BufferType = type;
     buffer->pvBuffer   = data;
 }
 
 static void init_sec_buffer_desc(SecBufferDesc *desc, SecBuffer *buffers,
                                  unsigned long buffer_count)
 {
     desc->ulVersion = SECBUFFER_VERSION;
     desc->pBuffers = buffers;
     desc->cBuffers = buffer_count;
 }
 
 static int tls_shutdown_client(URLContext *h)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     int ret;
 
     if (c->connected) {
         SecBufferDesc BuffDesc;
         SecBuffer Buffer;
         SECURITY_STATUS sspi_ret;
         SecBuffer outbuf;
         SecBufferDesc outbuf_desc;
 
         DWORD dwshut = SCHANNEL_SHUTDOWN;
         init_sec_buffer(&Buffer, SECBUFFER_TOKEN, &dwshut, sizeof(dwshut));
         init_sec_buffer_desc(&BuffDesc, &Buffer, 1);
 
         sspi_ret = ApplyControlToken(&c->ctxt_handle, &BuffDesc);
         if (sspi_ret != SEC_E_OK)
             av_log(h, AV_LOG_ERROR, "ApplyControlToken failed\n");
 
         init_sec_buffer(&outbuf, SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer_desc(&outbuf_desc, &outbuf, 1);
 
         sspi_ret = InitializeSecurityContext(&c->cred_handle, &c->ctxt_handle, s->host,
                                              c->request_flags, 0, 0, NULL, 0, &c->ctxt_handle,
                                              &outbuf_desc, &c->context_flags, &c->ctxt_timestamp);
         if (sspi_ret == SEC_E_OK || sspi_ret == SEC_I_CONTEXT_EXPIRED) {
             ret = ffurl_write(s->tcp, outbuf.pvBuffer, outbuf.cbBuffer);
             FreeContextBuffer(outbuf.pvBuffer);
             if (ret < 0 || ret != outbuf.cbBuffer)
                 av_log(h, AV_LOG_ERROR, "Failed to send close message\n");
         }
 
         c->connected = 0;
     }
     return 0;
 }
 
 static int tls_close(URLContext *h)
 {
     TLSContext *c = h->priv_data;
 
     tls_shutdown_client(h);
 
     DeleteSecurityContext(&c->ctxt_handle);
     FreeCredentialsHandle(&c->cred_handle);
 
     av_freep(&c->enc_buf);
     c->enc_buf_size = c->enc_buf_offset = 0;
 
     av_freep(&c->dec_buf);
     c->dec_buf_size = c->dec_buf_offset = 0;
 
     if (c->tls_shared.tcp)
         ffurl_close(c->tls_shared.tcp);
     return 0;
 }
 
 static int tls_client_handshake_loop(URLContext *h, int initial)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     SECURITY_STATUS sspi_ret;
     SecBuffer outbuf[3];
     SecBufferDesc outbuf_desc;
     SecBuffer inbuf[2];
     SecBufferDesc inbuf_desc;
     int i, ret = 0, read_data = initial;
 
     if (c->enc_buf == NULL) {
         c->enc_buf_offset = 0;
         ret = av_reallocp(&c->enc_buf, SCHANNEL_INITIAL_BUFFER_SIZE);
         if (ret < 0)
             goto fail;
         c->enc_buf_size = SCHANNEL_INITIAL_BUFFER_SIZE;
     }
 
     if (c->dec_buf == NULL) {
         c->dec_buf_offset = 0;
         ret = av_reallocp(&c->dec_buf, SCHANNEL_INITIAL_BUFFER_SIZE);
         if (ret < 0)
             goto fail;
         c->dec_buf_size = SCHANNEL_INITIAL_BUFFER_SIZE;
     }
 
     while (1) {
         if (c->enc_buf_size - c->enc_buf_offset < SCHANNEL_FREE_BUFFER_SIZE) {
             c->enc_buf_size = c->enc_buf_offset + SCHANNEL_FREE_BUFFER_SIZE;
             ret = av_reallocp(&c->enc_buf, c->enc_buf_size);
             if (ret < 0) {
                 c->enc_buf_size = c->enc_buf_offset = 0;
                 goto fail;
             }
         }
 
         if (read_data) {
             ret = ffurl_read(c->tls_shared.tcp, c->enc_buf + c->enc_buf_offset,
                              c->enc_buf_size - c->enc_buf_offset);
             if (ret < 0) {
                 av_log(h, AV_LOG_ERROR, "Failed to read handshake response\n");
                 goto fail;
             }
             c->enc_buf_offset += ret;
         }
 
         /* input buffers */
         init_sec_buffer(&inbuf[0], SECBUFFER_TOKEN, av_malloc(c->enc_buf_offset), c->enc_buf_offset);
         init_sec_buffer(&inbuf[1], SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer_desc(&inbuf_desc, inbuf, 2);
 
         if (inbuf[0].pvBuffer == NULL) {
             av_log(h, AV_LOG_ERROR, "Failed to allocate input buffer\n");
             ret = AVERROR(ENOMEM);
             goto fail;
         }
 
         memcpy(inbuf[0].pvBuffer, c->enc_buf, c->enc_buf_offset);
 
         /* output buffers */
         init_sec_buffer(&outbuf[0], SECBUFFER_TOKEN, NULL, 0);
         init_sec_buffer(&outbuf[1], SECBUFFER_ALERT, NULL, 0);
         init_sec_buffer(&outbuf[2], SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer_desc(&outbuf_desc, outbuf, 3);
 
         sspi_ret = InitializeSecurityContext(&c->cred_handle, &c->ctxt_handle, s->host, c->request_flags,
                                              0, 0, &inbuf_desc, 0, NULL, &outbuf_desc, &c->context_flags,
                                              &c->ctxt_timestamp);
         av_freep(&inbuf[0].pvBuffer);
 
         if (sspi_ret == SEC_E_INCOMPLETE_MESSAGE) {
             av_log(h, AV_LOG_DEBUG, "Received incomplete handshake, need more data\n");
             read_data = 1;
             continue;
         }
 
         /* remote requests a client certificate - attempt to continue without one anyway */
         if (sspi_ret == SEC_I_INCOMPLETE_CREDENTIALS &&
             !(c->request_flags & ISC_REQ_USE_SUPPLIED_CREDS)) {
             av_log(h, AV_LOG_VERBOSE, "Client certificate has been requested, ignoring\n");
             c->request_flags |= ISC_REQ_USE_SUPPLIED_CREDS;
             read_data = 0;
             continue;
         }
 
         /* continue handshake */
         if (sspi_ret == SEC_I_CONTINUE_NEEDED || sspi_ret == SEC_E_OK) {
             for (i = 0; i < 3; i++) {
                 if (outbuf[i].BufferType == SECBUFFER_TOKEN && outbuf[i].cbBuffer > 0) {
                     ret = ffurl_write(c->tls_shared.tcp, outbuf[i].pvBuffer, outbuf[i].cbBuffer);
                     if (ret < 0 || ret != outbuf[i].cbBuffer) {
                         av_log(h, AV_LOG_VERBOSE, "Failed to send handshake data\n");
                         ret = AVERROR(EIO);
                         goto fail;
                     }
                 }
 
                 if (outbuf[i].pvBuffer != NULL) {
                     FreeContextBuffer(outbuf[i].pvBuffer);
                     outbuf[i].pvBuffer = NULL;
                 }
             }
         } else {
             if (sspi_ret == SEC_E_WRONG_PRINCIPAL)
                 av_log(h, AV_LOG_ERROR, "SNI or certificate check failed\n");
             else
                 av_log(h, AV_LOG_ERROR, "Creating security context failed (0x%lx)\n", sspi_ret);
             ret = AVERROR_UNKNOWN;
             goto fail;
         }
 
         if (inbuf[1].BufferType == SECBUFFER_EXTRA && inbuf[1].cbBuffer > 0) {
             if (c->enc_buf_offset > inbuf[1].cbBuffer) {
                 memmove(c->enc_buf, (c->enc_buf + c->enc_buf_offset) - inbuf[1].cbBuffer,
                         inbuf[1].cbBuffer);
                 c->enc_buf_offset = inbuf[1].cbBuffer;
                 if (sspi_ret == SEC_I_CONTINUE_NEEDED) {
                     read_data = 0;
                     continue;
                 }
             }
         } else {
             c->enc_buf_offset  = 0;
         }
 
         if (sspi_ret == SEC_I_CONTINUE_NEEDED) {
             read_data = 1;
             continue;
         }
 
         break;
     }
 
     return 0;
 
 fail:
     /* free any remaining output data */
     for (i = 0; i < 3; i++) {
         if (outbuf[i].pvBuffer != NULL) {
             FreeContextBuffer(outbuf[i].pvBuffer);
             outbuf[i].pvBuffer = NULL;
         }
     }
 
     return ret;
 }
 
 static int tls_client_handshake(URLContext *h)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     SecBuffer outbuf;
     SecBufferDesc outbuf_desc;
     SECURITY_STATUS sspi_ret;
     int ret;
 
     init_sec_buffer(&outbuf, SECBUFFER_EMPTY, NULL, 0);
     init_sec_buffer_desc(&outbuf_desc, &outbuf, 1);
 
     c->request_flags = ISC_REQ_SEQUENCE_DETECT | ISC_REQ_REPLAY_DETECT |
                        ISC_REQ_CONFIDENTIALITY | ISC_REQ_ALLOCATE_MEMORY |
                        ISC_REQ_STREAM;
 
     sspi_ret = InitializeSecurityContext(&c->cred_handle, NULL, s->host, c->request_flags, 0, 0,
                                          NULL, 0, &c->ctxt_handle, &outbuf_desc, &c->context_flags,
                                          &c->ctxt_timestamp);
     if (sspi_ret != SEC_I_CONTINUE_NEEDED) {
         av_log(h, AV_LOG_ERROR, "Unable to create initial security context (0x%lx)\n", sspi_ret);
         ret = AVERROR_UNKNOWN;
         goto fail;
     }
 
     ret = ffurl_write(s->tcp, outbuf.pvBuffer, outbuf.cbBuffer);
     FreeContextBuffer(outbuf.pvBuffer);
     if (ret < 0 || ret != outbuf.cbBuffer) {
         av_log(h, AV_LOG_ERROR, "Failed to send initial handshake data\n");
         ret = AVERROR(EIO);
         goto fail;
     }
 
     return tls_client_handshake_loop(h, 1);
 
 fail:
     DeleteSecurityContext(&c->ctxt_handle);
     return ret;
 }
 
 static int tls_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     SECURITY_STATUS sspi_ret;
     SCHANNEL_CRED schannel_cred = { 0 };
     int ret;
 
     if ((ret = ff_tls_open_underlying(s, h, uri, options)) < 0)
         goto fail;
 
     if (s->listen) {
         av_log(h, AV_LOG_ERROR, "TLS Listen Sockets with SChannel is not implemented.\n");
         ret = AVERROR(EINVAL);
         goto fail;
     }
 
     /* SChannel Options */
     schannel_cred.dwVersion = SCHANNEL_CRED_VERSION;
 
     if (s->verify)
         schannel_cred.dwFlags = SCH_CRED_AUTO_CRED_VALIDATION |
                                 SCH_CRED_REVOCATION_CHECK_CHAIN;
     else
         schannel_cred.dwFlags = SCH_CRED_MANUAL_CRED_VALIDATION |
                                 SCH_CRED_IGNORE_NO_REVOCATION_CHECK |
                                 SCH_CRED_IGNORE_REVOCATION_OFFLINE;
 
     /* Get credential handle */
     sspi_ret = AcquireCredentialsHandle(NULL, (TCHAR *)UNISP_NAME, SECPKG_CRED_OUTBOUND,
                                         NULL,  &schannel_cred, NULL, NULL, &c->cred_handle,
                                         &c->cred_timestamp);
     if (sspi_ret != SEC_E_OK) {
         av_log(h, AV_LOG_ERROR, "Unable to acquire security credentials (0x%lx)\n", sspi_ret);
         ret = AVERROR_UNKNOWN;
         goto fail;
     }
 
     ret = tls_client_handshake(h);
     if (ret < 0)
         goto fail;
 
     c->connected = 1;
 
     return 0;
 
 fail:
     tls_close(h);
     return ret;
 }
 
 static int tls_read(URLContext *h, uint8_t *buf, int len)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     SECURITY_STATUS sspi_ret = SEC_E_OK;
     SecBuffer inbuf[4];
     SecBufferDesc inbuf_desc;
     int size, ret;
     int min_enc_buf_size = len + SCHANNEL_FREE_BUFFER_SIZE;
 
     if (len <= c->dec_buf_offset)
         goto cleanup;
 
     if (c->sspi_close_notify)
         goto cleanup;
 
     if (!c->connection_closed) {
         size = c->enc_buf_size - c->enc_buf_offset;
         if (size < SCHANNEL_FREE_BUFFER_SIZE || c->enc_buf_size < min_enc_buf_size) {
             c->enc_buf_size = c->enc_buf_offset + SCHANNEL_FREE_BUFFER_SIZE;
             if (c->enc_buf_size < min_enc_buf_size)
                 c->enc_buf_size = min_enc_buf_size;
             ret = av_reallocp(&c->enc_buf, c->enc_buf_size);
             if (ret < 0) {
                 c->enc_buf_size = c->enc_buf_offset = 0;
                 return ret;
             }
         }
 
         ret = ffurl_read(s->tcp, c->enc_buf + c->enc_buf_offset,
                          c->enc_buf_size - c->enc_buf_offset);
         if (ret < 0) {
             av_log(h, AV_LOG_ERROR, "Unable to read from socket\n");
             return ret;
         } else if (ret == 0)
             c->connection_closed = 1;
 
         c->enc_buf_offset += ret;
     }
 
     while (c->enc_buf_offset > 0 && sspi_ret == SEC_E_OK && c->dec_buf_offset < len) {
         /*  input buffer */
         init_sec_buffer(&inbuf[0], SECBUFFER_DATA, c->enc_buf, c->enc_buf_offset);
 
         /* additional buffers for possible output */
         init_sec_buffer(&inbuf[1], SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer(&inbuf[2], SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer(&inbuf[3], SECBUFFER_EMPTY, NULL, 0);
         init_sec_buffer_desc(&inbuf_desc, inbuf, 4);
 
         sspi_ret = DecryptMessage(&c->ctxt_handle, &inbuf_desc, 0, NULL);
         if (sspi_ret == SEC_E_OK || sspi_ret == SEC_I_RENEGOTIATE ||
             sspi_ret == SEC_I_CONTEXT_EXPIRED) {
             /* handle decrypted data */
             if (inbuf[1].BufferType == SECBUFFER_DATA) {
                 /* grow buffer if needed */
                 size = inbuf[1].cbBuffer > SCHANNEL_FREE_BUFFER_SIZE ?
                        inbuf[1].cbBuffer : SCHANNEL_FREE_BUFFER_SIZE;
                 if (c->dec_buf_size - c->dec_buf_offset < size || c->dec_buf_size < len)  {
                     c->dec_buf_size = c->dec_buf_offset + size;
                     if (c->dec_buf_size < len)
                         c->dec_buf_size = len;
                     ret = av_reallocp(&c->dec_buf, c->dec_buf_size);
                     if (ret < 0) {
                         c->dec_buf_size = c->dec_buf_offset = 0;
                         return ret;
                     }
                 }
 
                 /* copy decrypted data to buffer */
                 size = inbuf[1].cbBuffer;
                 if (size) {
                     memcpy(c->dec_buf + c->dec_buf_offset, inbuf[1].pvBuffer, size);
                     c->dec_buf_offset += size;
                 }
             }
             if (inbuf[3].BufferType == SECBUFFER_EXTRA && inbuf[3].cbBuffer > 0) {
                 if (c->enc_buf_offset > inbuf[3].cbBuffer) {
                     memmove(c->enc_buf, (c->enc_buf + c->enc_buf_offset) - inbuf[3].cbBuffer,
                     inbuf[3].cbBuffer);
                     c->enc_buf_offset = inbuf[3].cbBuffer;
                 }
             } else
                 c->enc_buf_offset = 0;
 
             if (sspi_ret == SEC_I_RENEGOTIATE) {
                 if (c->enc_buf_offset) {
                     av_log(h, AV_LOG_ERROR, "Cannot renegotiate, encrypted data buffer not empty\n");
                     ret = AVERROR_UNKNOWN;
                     goto cleanup;
                 }
 
                 av_log(h, AV_LOG_VERBOSE, "Re-negotiating security context\n");
                 ret = tls_client_handshake_loop(h, 0);
                 if (ret < 0) {
                     goto cleanup;
                 }
                 sspi_ret = SEC_E_OK;
                 continue;
             } else if (sspi_ret == SEC_I_CONTEXT_EXPIRED) {
                 c->sspi_close_notify = 1;
                 if (!c->connection_closed) {
                     c->connection_closed = 1;
                     av_log(h, AV_LOG_VERBOSE, "Server closed the connection\n");
                 }
                 ret = 0;
                 goto cleanup;
             }
         } else if (sspi_ret == SEC_E_INCOMPLETE_MESSAGE) {
             ret = AVERROR(EAGAIN);
             goto cleanup;
         } else {

             av_log(h, AV_LOG_ERROR, "Unable to decrypt message (error 0x%x)\n", (unsigned)sspi_ret);

             ret = AVERROR(EIO);
             goto cleanup;
         }
     }
 
     ret = 0;
 
 cleanup:
     size = FFMIN(len, c->dec_buf_offset);
     if (size) {
         memcpy(buf, c->dec_buf, size);
         memmove(c->dec_buf, c->dec_buf + size, c->dec_buf_offset - size);
         c->dec_buf_offset -= size;
 
         return size;
     }
 
     if (ret == 0 && !c->connection_closed)
         ret = AVERROR(EAGAIN);
 
     return ret < 0 ? ret : 0;
 }
 
 static int tls_write(URLContext *h, const uint8_t *buf, int len)
 {
     TLSContext *c = h->priv_data;
     TLSShared *s = &c->tls_shared;
     SECURITY_STATUS sspi_ret;
     int ret = 0, data_size;
     uint8_t *data = NULL;
     SecBuffer outbuf[4];
     SecBufferDesc outbuf_desc;
 
     if (c->sizes.cbMaximumMessage == 0) {
         sspi_ret = QueryContextAttributes(&c->ctxt_handle, SECPKG_ATTR_STREAM_SIZES, &c->sizes);
         if (sspi_ret != SEC_E_OK)
             return AVERROR_UNKNOWN;
     }
 
     /* limit how much data we can consume */
     len = FFMIN(len, c->sizes.cbMaximumMessage);
 
     data_size = c->sizes.cbHeader + len + c->sizes.cbTrailer;
     data = av_malloc(data_size);
     if (data == NULL)
         return AVERROR(ENOMEM);
 
     init_sec_buffer(&outbuf[0], SECBUFFER_STREAM_HEADER,
                   data, c->sizes.cbHeader);
     init_sec_buffer(&outbuf[1], SECBUFFER_DATA,
                   data + c->sizes.cbHeader, len);
     init_sec_buffer(&outbuf[2], SECBUFFER_STREAM_TRAILER,
                   data + c->sizes.cbHeader + len,
                   c->sizes.cbTrailer);
     init_sec_buffer(&outbuf[3], SECBUFFER_EMPTY, NULL, 0);
     init_sec_buffer_desc(&outbuf_desc, outbuf, 4);
 
     memcpy(outbuf[1].pvBuffer, buf, len);
 
     sspi_ret = EncryptMessage(&c->ctxt_handle, 0, &outbuf_desc, 0);
     if (sspi_ret == SEC_E_OK)  {
         len = outbuf[0].cbBuffer + outbuf[1].cbBuffer + outbuf[2].cbBuffer;
         ret = ffurl_write(s->tcp, data, len);
         if (ret < 0 || ret != len) {
             ret = AVERROR(EIO);
             av_log(h, AV_LOG_ERROR, "Writing encrypted data to socket failed\n");
             goto done;
         }
     } else {
         av_log(h, AV_LOG_ERROR, "Encrypting data failed\n");
         if (sspi_ret == SEC_E_INSUFFICIENT_MEMORY)
             ret = AVERROR(ENOMEM);
         else
             ret = AVERROR(EIO);
         goto done;
     }
 
 done:
     av_freep(&data);
     return ret < 0 ? ret : outbuf[1].cbBuffer;
 }
 

 static int tls_get_file_handle(URLContext *h)
 {
     TLSContext *c = h->priv_data;
     return ffurl_get_file_handle(c->tls_shared.tcp);
 }
 

 static const AVOption options[] = {
     TLS_COMMON_OPTIONS(TLSContext, tls_shared),
     { NULL }
 };
 
 static const AVClass tls_class = {
     .class_name = "tls",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 const URLProtocol ff_tls_protocol = {

     .name           = "tls",
     .url_open2      = tls_open,
     .url_read       = tls_read,
     .url_write      = tls_write,
     .url_close      = tls_close,

     .url_get_file_handle = tls_get_file_handle,

     .priv_data_size = sizeof(TLSContext),
     .flags          = URL_PROTOCOL_FLAG_NETWORK,
     .priv_data_class = &tls_class,
 };