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7e6941e185
FFmpeg/libavformat/tls_schannel.c
Jan Ekström 6f8826e4aa avformat/tls_schannel: immediately return decrypted data if available 
Until now, we would have only attempted to utilize already decrypted
data if it was enough to fill the size of buffer requested, that could
very well be up to 32 kilobytes.

With keep-alive connections this would just lead to recv blocking
until rw_timeout had been reached, as the connection would not be
officially closed after each transfer. This would also lead to a
loop, as such timed out I/O request would just be attempted again.

By just returning the available decrypted data, keep-alive based
connectivity such as HLS playback is fixed with schannel.
2020-05-13 17:05:23 +03:00

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/*
* 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] = { 0 };
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 we have some left-over data from previous network activity,
* return it first in case it is enough. It may contain
* data that is required to know whether this connection
* is still required or not, esp. in case of HTTP keep-alive
* connections. */
if (c->dec_buf_offset > 0)
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 == AVERROR_EOF) {
c->connection_closed = 1;
ret = 0;
} else if (ret < 0) {
av_log(h, AV_LOG_ERROR, "Unable to read from socket\n");
return ret;
}
c->enc_buf_offset += ret;
}
while (c->enc_buf_offset > 0 && sspi_ret == SEC_E_OK) {
/* 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 : AVERROR_EOF;
}
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,
};
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