RTC: Support ignore padding for RTP header

trunk/src/app/srs_app_rtc_conn.cpp

@@ -1196,21 +1196,24 @@ srs_error_t SrsRtcPublisher::on_rtp(char* data, int nb_data)
         return err;
     }
 
+    // We must parse the TWCC from RTP header before SRTP unprotect, because:
+    //      1. Client may send some padding packets with invalid SequenceNumber, which causes the SRTP fail.
+    //      2. Server may send multiple duplicated NACK to client, and got more than one ARQ packet, which also fail SRTP.
+    // so, we must parse the header before SRTP unprotect(which may fail and drop packet).
     if (0 != twcc_ext_id_) {
         SrsBuffer b0(data, nb_data); SrsRtpHeader h0;
-        h0.set_decode_only_header(true);
+        h0.ignore_padding(true);
         h0.set_extensions(&extension_types_);
         if ((err = h0.decode(&b0)) != srs_success) {
-            return srs_error_wrap(err, "process twcc to decode rtp header");
+            return srs_error_wrap(err, "twcc decode header");
         }
 
         uint16_t twcc_sn = 0;
         if ((err = h0.get_twcc_sequence_number(twcc_sn)) == srs_success) {
             if((err = on_twcc(twcc_sn)) != srs_success) {
-                return srs_error_wrap(err, "fail to process twcc packet");
+                return srs_error_wrap(err, "on twcc");
             }
         } else {
-            // TODO: FIXME: process no twcc seq number for audio ssrc
             srs_error_reset(err);
         }
     }

trunk/src/kernel/srs_kernel_rtc_rtp.cpp

@@ -319,7 +319,7 @@ SrsRtpHeader::SrsRtpHeader()
     sequence         = 0;
     timestamp        = 0;
     ssrc             = 0;
-    decode_only_header_ = false;
+    ignore_padding_  = false;
 }
 
 SrsRtpHeader::~SrsRtpHeader()
@@ -377,7 +377,7 @@ srs_error_t SrsRtpHeader::decode(SrsBuffer* buf)
         }
     }
 
-    if (padding && !buf->empty() && !decode_only_header_) {
+    if (padding && !ignore_padding_ && !buf->empty()) {
         padding_length = *(reinterpret_cast<uint8_t*>(buf->data() + buf->size() - 1));
         if (!buf->require(padding_length)) {
             return srs_error_new(ERROR_RTC_RTP_MUXER, "padding requires %d bytes", padding_length);
@@ -449,9 +449,9 @@ void SrsRtpHeader::set_extensions(const SrsRtpExtensionTypes* extmap)
     }
 }
 
-void SrsRtpHeader::set_decode_only_header(bool only_header)
+void SrsRtpHeader::ignore_padding(bool v)
 {
-    decode_only_header_ = only_header;
+    ignore_padding_ = v;
 }
 
 srs_error_t SrsRtpHeader::get_twcc_sequence_number(uint16_t& twcc_sn)

trunk/src/kernel/srs_kernel_rtc_rtp.hpp

@@ -175,7 +175,7 @@ private:
     uint32_t ssrc;
     uint32_t csrc[15];
     SrsRtpExtensions extensions_;
-    bool decode_only_header_;
+    bool ignore_padding_;
 public:
     SrsRtpHeader();
     virtual ~SrsRtpHeader();
@@ -200,7 +200,7 @@ public:
     void set_padding(uint8_t v);
     uint8_t get_padding() const;
     void set_extensions(const SrsRtpExtensionTypes* extmap);
-    void set_decode_only_header(bool only_header);
+    void ignore_padding(bool v);
     srs_error_t get_twcc_sequence_number(uint16_t& twcc_sn);
     srs_error_t set_twcc_sequence_number(uint8_t id, uint16_t sn);
 };