michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: // Original author: ekr@rtfm.com
michael@0: 
michael@0: #include "logging.h"
michael@0: #include "SrtpFlow.h"
michael@0: 
michael@0: #include "srtp.h"
michael@0: #include "ssl.h"
michael@0: #include "sslproto.h"
michael@0: 
michael@0: #include "mozilla/RefPtr.h"
michael@0: 
michael@0: // Logging context
michael@0: using namespace mozilla;
michael@0: MOZ_MTLOG_MODULE("mediapipeline")
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: bool SrtpFlow::initialized;  // Static
michael@0: 
michael@0: SrtpFlow::~SrtpFlow() {
michael@0:   if (session_) {
michael@0:     srtp_dealloc(session_);
michael@0:   }
michael@0: }
michael@0: 
michael@0: RefPtr<SrtpFlow> SrtpFlow::Create(int cipher_suite,
michael@0:                                            bool inbound,
michael@0:                                            const void *key,
michael@0:                                            size_t key_len) {
michael@0:   nsresult res = Init();
michael@0:   if (!NS_SUCCEEDED(res))
michael@0:     return nullptr;
michael@0: 
michael@0:   RefPtr<SrtpFlow> flow = new SrtpFlow();
michael@0: 
michael@0:   if (!key) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Null SRTP key specified");
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   if (key_len != SRTP_TOTAL_KEY_LENGTH) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Invalid SRTP key length");
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   srtp_policy_t policy;
michael@0:   memset(&policy, 0, sizeof(srtp_policy_t));
michael@0: 
michael@0:   // Note that we set the same cipher suite for RTP and RTCP
michael@0:   // since any flow can only have one cipher suite with DTLS-SRTP
michael@0:   switch (cipher_suite) {
michael@0:     case SRTP_AES128_CM_HMAC_SHA1_80:
michael@0:       MOZ_MTLOG(ML_DEBUG,
michael@0:                 "Setting SRTP cipher suite SRTP_AES128_CM_HMAC_SHA1_80");
michael@0:       crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtp);
michael@0:       crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtcp);
michael@0:       break;
michael@0:     case SRTP_AES128_CM_HMAC_SHA1_32:
michael@0:       MOZ_MTLOG(ML_DEBUG,
michael@0:                 "Setting SRTP cipher suite SRTP_AES128_CM_HMAC_SHA1_32");
michael@0:       crypto_policy_set_aes_cm_128_hmac_sha1_32(&policy.rtp);
michael@0:       crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtcp); // 80-bit per RFC 5764
michael@0:       break;                                                   // S 4.1.2.
michael@0:     default:
michael@0:       MOZ_MTLOG(ML_ERROR, "Request to set unknown SRTP cipher suite");
michael@0:       return nullptr;
michael@0:   }
michael@0:   // This key is copied into the srtp_t object, so we don't
michael@0:   // need to keep it.
michael@0:   policy.key = const_cast<unsigned char *>(
michael@0:       static_cast<const unsigned char *>(key));
michael@0:   policy.ssrc.type = inbound ? ssrc_any_inbound : ssrc_any_outbound;
michael@0:   policy.ssrc.value = 0;
michael@0:   policy.ekt = nullptr;
michael@0:   policy.window_size = 1024;   // Use the Chrome value.  Needs to be revisited.  Default is 128
michael@0:   policy.allow_repeat_tx = 1;  // Use Chrome value; needed for NACK mode to work
michael@0:   policy.next = nullptr;
michael@0: 
michael@0:   // Now make the session
michael@0:   err_status_t r = srtp_create(&flow->session_, &policy);
michael@0:   if (r != err_status_ok) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Error creating srtp session");
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   return flow;
michael@0: }
michael@0: 
michael@0: 
michael@0: nsresult SrtpFlow::CheckInputs(bool protect, void *in, int in_len,
michael@0:                                int max_len, int *out_len) {
michael@0:   MOZ_ASSERT(in);
michael@0:   if (!in) {
michael@0:     MOZ_MTLOG(ML_ERROR, "NULL input value");
michael@0:     return NS_ERROR_NULL_POINTER;
michael@0:   }
michael@0: 
michael@0:   if (in_len < 0) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Input length is negative");
michael@0:     return NS_ERROR_ILLEGAL_VALUE;
michael@0:   }
michael@0: 
michael@0:   if (max_len < 0) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Max output length is negative");
michael@0:     return NS_ERROR_ILLEGAL_VALUE;
michael@0:   }
michael@0: 
michael@0:   if (protect) {
michael@0:     if ((max_len < SRTP_MAX_EXPANSION) ||
michael@0:         ((max_len - SRTP_MAX_EXPANSION) < in_len)) {
michael@0:       MOZ_MTLOG(ML_ERROR, "Output too short");
michael@0:       return NS_ERROR_ILLEGAL_VALUE;
michael@0:     }
michael@0:   }
michael@0:   else {
michael@0:     if (in_len > max_len) {
michael@0:       MOZ_MTLOG(ML_ERROR, "Output too short");
michael@0:       return NS_ERROR_ILLEGAL_VALUE;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult SrtpFlow::ProtectRtp(void *in, int in_len,
michael@0:                               int max_len, int *out_len) {
michael@0:   nsresult res = CheckInputs(true, in, in_len, max_len, out_len);
michael@0:   if (NS_FAILED(res))
michael@0:     return res;
michael@0: 
michael@0:   int len = in_len;
michael@0:   err_status_t r = srtp_protect(session_, in, &len);
michael@0: 
michael@0:   if (r != err_status_ok) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Error protecting SRTP packet");
michael@0:     return NS_ERROR_FAILURE;
michael@0:   }
michael@0: 
michael@0:   MOZ_ASSERT(len <= max_len);
michael@0:   *out_len = len;
michael@0: 
michael@0: 
michael@0:   MOZ_MTLOG(ML_DEBUG, "Successfully protected an SRTP packet of len "
michael@0:             << *out_len);
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult SrtpFlow::UnprotectRtp(void *in, int in_len,
michael@0:                                 int max_len, int *out_len) {
michael@0:   nsresult res = CheckInputs(false, in, in_len, max_len, out_len);
michael@0:   if (NS_FAILED(res))
michael@0:     return res;
michael@0: 
michael@0:   int len = in_len;
michael@0:   err_status_t r = srtp_unprotect(session_, in, &len);
michael@0: 
michael@0:   if (r != err_status_ok) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Error unprotecting SRTP packet error=" << (int)r);
michael@0:     return NS_ERROR_FAILURE;
michael@0:   }
michael@0: 
michael@0:   MOZ_ASSERT(len <= max_len);
michael@0:   *out_len = len;
michael@0: 
michael@0:   MOZ_MTLOG(ML_DEBUG, "Successfully unprotected an SRTP packet of len "
michael@0:             << *out_len);
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult SrtpFlow::ProtectRtcp(void *in, int in_len,
michael@0:                                int max_len, int *out_len) {
michael@0:   nsresult res = CheckInputs(true, in, in_len, max_len, out_len);
michael@0:   if (NS_FAILED(res))
michael@0:     return res;
michael@0: 
michael@0:   int len = in_len;
michael@0:   err_status_t r = srtp_protect_rtcp(session_, in, &len);
michael@0: 
michael@0:   if (r != err_status_ok) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Error protecting SRTCP packet");
michael@0:     return NS_ERROR_FAILURE;
michael@0:   }
michael@0: 
michael@0:   MOZ_ASSERT(len <= max_len);
michael@0:   *out_len = len;
michael@0: 
michael@0:   MOZ_MTLOG(ML_DEBUG, "Successfully protected an SRTCP packet of len "
michael@0:             << *out_len);
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult SrtpFlow::UnprotectRtcp(void *in, int in_len,
michael@0:                                  int max_len, int *out_len) {
michael@0:   nsresult res = CheckInputs(false, in, in_len, max_len, out_len);
michael@0:   if (NS_FAILED(res))
michael@0:     return res;
michael@0: 
michael@0:   int len = in_len;
michael@0:   err_status_t r = srtp_unprotect_rtcp(session_, in, &len);
michael@0: 
michael@0:   if (r != err_status_ok) {
michael@0:     MOZ_MTLOG(ML_ERROR, "Error unprotecting SRTCP packet error=" << (int)r);
michael@0:     return NS_ERROR_FAILURE;
michael@0:   }
michael@0: 
michael@0:   MOZ_ASSERT(len <= max_len);
michael@0:   *out_len = len;
michael@0: 
michael@0:   MOZ_MTLOG(ML_DEBUG, "Successfully unprotected an SRTCP packet of len "
michael@0:             << *out_len);
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: // Statics
michael@0: void SrtpFlow::srtp_event_handler(srtp_event_data_t *data) {
michael@0:   // TODO(ekr@rtfm.com): Implement this
michael@0:   MOZ_CRASH();
michael@0: }
michael@0: 
michael@0: nsresult SrtpFlow::Init() {
michael@0:   if (!initialized) {
michael@0:     err_status_t r = srtp_init();
michael@0:     if (r != err_status_ok) {
michael@0:       MOZ_MTLOG(ML_ERROR, "Could not initialize SRTP");
michael@0:       MOZ_ASSERT(PR_FALSE);
michael@0:       return NS_ERROR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     r = srtp_install_event_handler(&SrtpFlow::srtp_event_handler);
michael@0:     if (r != err_status_ok) {
michael@0:       MOZ_MTLOG(ML_ERROR, "Could not install SRTP event handler");
michael@0:       MOZ_ASSERT(PR_FALSE);
michael@0:       return NS_ERROR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     initialized = true;
michael@0:   }
michael@0: 
michael@0:   return NS_OK;
michael@0: }
michael@0: 
michael@0: }  // end of namespace
michael@0: