fix recv cycle buffer crash and avoid send nak packet exceed mtu

srt/Packet.cpp

@@ -515,7 +515,7 @@ bool NAKPacket::loadFromData(uint8_t *buf, size_t len) {
 bool NAKPacket::storeToData() {
     control_type = NAK;
     sub_type = 0;
-    size_t cif_size = getCIFSize();
+    size_t cif_size = getCIFSize(lost_list);
 
     _data = BufferRaw::create();
     _data->setCapacity(HEADER_SIZE + cif_size);
@@ -544,9 +544,9 @@ bool NAKPacket::storeToData() {
     return true;
 }
 
-size_t NAKPacket::getCIFSize() {
+size_t NAKPacket::getCIFSize(std::list<LostPair> &lost) {
     size_t size = 0;
-    for (auto it : lost_list) {
+    for (auto it : lost) {
         if (it.first + 1 == it.second) {
             size += 4;
         } else {

srt/Packet.hpp

@@ -275,9 +275,7 @@ public:
     bool storeToData() override;
 
     std::list<LostPair> lost_list;
-
-private:
-    size_t getCIFSize();
+    static size_t getCIFSize(std::list<LostPair> &lost);
 };
 
 /*

srt/PacketQueue.cpp

@@ -243,6 +243,7 @@ PacketRecvQueue::PacketRecvQueue(uint32_t max_size, uint32_t init_seq, uint32_t
     , _pkt_expected_seq(init_seq)
     , _pkt_buf(max_size) {}
 bool PacketRecvQueue::inputPacket(DataPacket::Ptr pkt, std::list<DataPacket::Ptr> &out) {
+    // TraceL << dump() << " seq:" << pkt->packet_seq_number;
     while (_size > 0 && _start == _end) {
         if (_pkt_buf[_start]) {
             out.push_back(_pkt_buf[_start]);
@@ -385,6 +386,8 @@ std::string PacketRecvQueue::dump() {
                 << " first:" << getFirst()->packet_seq_number;
         printer << " last:" << getLast()->packet_seq_number;
         printer << " latency:" << timeLatency() / 1e3;
+        printer << " start:" << _start;
+        printer << " end:" << _end;
     }
     return std::move(printer);
 }
@@ -438,8 +441,20 @@ void PacketRecvQueue::insertToCycleBuf(DataPacket::Ptr pkt, uint32_t diff) {
         return;
     }
     _pkt_buf[pos] = pkt;
-    if (pos >= _end && (_start <= _end || pos < _start)) {
+
+    if (_start <= _end && pos >= _end) {
+        _end = (pos + 1) % _pkt_cap;
+        return;
+    }
+
+    if (_start <= _end && pos < _start) {
         _end = (pos + 1) % _pkt_cap;
+        return;
+    }
+
+    if (_start > _end && _end <= pos && _start > pos) {
+        _end = (pos + 1) % _pkt_cap;
+        return;
     }
 }
 void PacketRecvQueue::tryInsertPkt(DataPacket::Ptr pkt) {

srt/SrtTransport.cpp

 #include "Util/onceToken.h"
+#include <iterator>
 #include <stdlib.h>
 
 #include "Ack.hpp"
@@ -435,15 +436,42 @@ void SrtTransport::sendLightACKPacket() {
 
 void SrtTransport::sendNAKPacket(std::list<PacketQueue::LostPair> &lost_list) {
     NAKPacket::Ptr pkt = std::make_shared<NAKPacket>();
+    std::list<PacketQueue::LostPair> tmp;
+    auto size = NAKPacket::getCIFSize(lost_list);
+    size_t paylaod_size = getPayloadSize();
+    if (size > paylaod_size) {
+        WarnL << "loss report cif size " << size;
+        size_t num = paylaod_size / 8;
+
+        size_t msgNum = (lost_list.size() + num - 1) / num;
+        decltype(lost_list.begin()) cur, next;
+        for (size_t i = 0; i < msgNum; ++i) {
+            cur = lost_list.begin();
+            std::advance(cur, i * num);
+
+            if (i == msgNum - 1) {
+                next = lost_list.end();
+            } else {
+                next = lost_list.begin();
+                std::advance(next, (i + 1) * num);
+            }
+            tmp.assign(cur, next);
+            pkt->dst_socket_id = _peer_socket_id;
+            pkt->timestamp = DurationCountMicroseconds(_now - _start_timestamp);
+            pkt->lost_list = tmp;
+            pkt->storeToData();
+            sendControlPacket(pkt, true);
+        }
 
-    pkt->dst_socket_id = _peer_socket_id;
-    pkt->timestamp = DurationCountMicroseconds(_now - _start_timestamp);
-    pkt->lost_list = lost_list;
-
-    pkt->storeToData();
+    } else {
+        pkt->dst_socket_id = _peer_socket_id;
+        pkt->timestamp = DurationCountMicroseconds(_now - _start_timestamp);
+        pkt->lost_list = lost_list;
+        pkt->storeToData();
+        sendControlPacket(pkt, true);
+    }
 
     // TraceL<<"send NAK "<<pkt->dump();
-    sendControlPacket(pkt, true);
 }
 
 void SrtTransport::sendShutDown() {