bool ConnectionIn::addPacket(Packet& p){
PacketHeader h;
if(cc.transform){
if(!cc.transform->remove(p, buffer.reset())){
return false; // removal of packet transformation failed.
}
}
Packet& input = cc.transform ? buffer : p;
if(!h.read(input) || h.version != 0){
return false; // packet has invalid header / unknown version.
}
int packet_age = 0;
if(packet_history.none()){ // first packet recieved
cc.seq_num = h.seq_num;
packet_history[0] = 1;
} else {
int16_t seq_dist = static_cast<int16_t>(h.seq_num - cc.seq_num);
if(abs(seq_dist) >= NRG_CONN_PACKET_HISTORY){
return true; // packet is out of history range.
}
// states need to know about retransmissons of the newest packet
if(seq_dist < 0 && (h.flags & PKTFLAG_RETRANSMISSION)){
return true;
}
if(seq_dist > 0){ // new packet
packet_history <<= seq_dist;
packet_history[0] = 1;
cc.seq_num = h.seq_num;
// update ages of reassembly fragments and remove them if they're too old.
for(auto& i : reassembly_buf){
if(i.age >= 0) i.age += seq_dist;
if(i.age > (int)NRG_CONN_PACKET_HISTORY){
i.age = -1;
i.data.reset();
}
}
} else {
if(packet_history[-seq_dist]){ // already recieved this packet.
return true;
} else {
packet_history[-seq_dist] = 1;
packet_age = -seq_dist;
}
}
}
if((h.flags & PKTFLAG_FINISHED) && (cc.seq_num != h.seq_num)){
return false; // packet claims end of stream, but there is a newer one...
}
new_packet = true;
// reconstruct packets that were split into multiple fragments.
if(h.frag_index > 0 || (h.flags & PKTFLAG_CONTINUED)){
if(h.frag_index >= reassembly_buf.size()){
return false;
}
ReassemblyInfo& frag = reassembly_buf[h.frag_index];
if(frag.age >= 0 && packet_age > frag.age){
new_packet = false;
} else {
frag.data.writeArray(input.getPointer(), input.remaining());
frag.age = packet_age;
frag.continued = h.flags & PKTFLAG_CONTINUED;
// check if the newly added fragment completes a full packet.
for(size_t i = 0; i < reassembly_buf.size(); ++i){
NRG_DEBUG("Age calc: [%d, %d]\n", (int)i, reassembly_buf[i].age);
if(reassembly_buf[i].age == -1
|| (i > 0 && reassembly_buf[i].age != reassembly_buf[i-1].age - 1)){
new_packet = false;
}
if(!reassembly_buf[i].continued) break;
}
NRG_DEBUG("Got fragment, idx: %d, continued?: %d, age: %d full?: %d\n",
h.frag_index, h.flags & PKTFLAG_CONTINUED, packet_age, new_packet
);
// write all the fragments out if they do form a full packet.
if(new_packet){
latest.reset();
int age_counter = reassembly_buf[0].age;
for(auto& i : reassembly_buf){
if(i.age != age_counter--) break;
latest.writeArray(i.data.getBasePointer(), i.data.size());
i.data.reset();
i.age = -1;
}
}
}
} else {
latest.reset().writeArray(input.getPointer(), input.remaining());
}
if(cc.seq_num > h.seq_num) h.flags |= PKTFLAG_OUT_OF_ORDER;
latest_flags = static_cast<PacketFlags>(h.flags);
return true;
}
