git.sesse.net Git - greproxy/blob - rsencoder.cpp

   1 #include <string.h>
   2 #include <arpa/inet.h>
   3 #include <netinet/in.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <sys/select.h>
   7 #include <sys/socket.h>
   8 extern "C" {
   9 #include <fec.h>
  10 }
  11
  12 #include "reorderer.h"
  13 #include "rsencoder.h"
  14 #include "rs_parm.h"
  15
  16 #include <algorithm>
  17
  18 using namespace std;
  19
  20 void RSEncoder::send_packet(uint16_t proto, const std::string &data, int incoming_seq)
  21 {
  22         if (!packet_history.empty() &&
  23             incoming_seq <= packet_history.back().seq) {
  24                 // Reorderer should have done this for us.
  25                 return;
  26         }
  27         if (!packet_history.empty() &&
  28             incoming_seq / RS_PAYLOAD_SIZE !=
  29                 packet_history.back().seq / RS_PAYLOAD_SIZE) {
  30                 // Received an unfinished group.
  31                 packet_history.clear();
  32         }
  33         sender->send_packet(proto, data, incoming_seq);
  34         packet_history.emplace_back(GREPacket{incoming_seq, proto, data});
  35         if (packet_history.size() == RS_PAYLOAD_SIZE) {
  36                 finish_group();
  37         }
  38 }
  39
  40 void RSEncoder::finish_group()
  41 {
  42         // Our RS packets need to have the same max length as the longest one.
  43         int max_length = 0;
  44         for (int i = 0; i < packet_history.size(); ++i) {
  45                 max_length = max<int>(max_length, packet_history[i].data.size());
  46         }
  47
  48         vector<string> padded_packets;
  49         for (int i = 0; i < packet_history.size(); ++i) {
  50                 string p;
  51                 p.resize(max_length + 4);
  52                 memset(&p[0], 0, max_length + 4);
  53                 uint16_t proto_be = htons(packet_history[i].proto);
  54                 memcpy(&p[0], &proto_be, sizeof(uint16_t));
  55                 uint16_t len_be = htons(packet_history[i].data.size());
  56                 memcpy(&p[2], &len_be, sizeof(uint16_t));
  57                 memcpy(&p[4], packet_history[i].data.data(), packet_history[i].data.size());
  58                 padded_packets.push_back(p);
  59         }
  60
  61         // Now construct RS packets.
  62         vector<string> rs_packets;
  63         for (int i = 0; i < RS_PARITY_SIZE; ++i) {
  64                 string p;
  65                 p.resize(max_length + 4);
  66                 memset(&p[0], 0, max_length + 4);
  67                 rs_packets.push_back(p);
  68         }
  69         string data, parity;
  70         data.resize(RS_PAYLOAD_SIZE);
  71         parity.resize(RS_PARITY_SIZE);
  72         for (int i = 0; i < max_length + 4; ++i) {
  73                 for (int j = 0; j < packet_history.size(); ++j) {
  74                         data[j] = packet_history[j].data[i];
  75                 }
  76                 encode_rs_8(reinterpret_cast<unsigned char *>(&data[0]),
  77                             reinterpret_cast<unsigned char *>(&parity[0]),
  78                             RS_PAD);
  79                 for (int j = 0; j < RS_PARITY_SIZE; ++j) {
  80                         rs_packets[j][i] = parity[j];
  81                 }
  82         }
  83
  84         // Actually send the RS packets.
  85         int start_seq = packet_history[0].seq - 1;
  86         for (int i = 0; i < RS_PARITY_SIZE; ++i) {
  87                 sender->send_packet(0xffff, rs_packets[i], start_seq - i);
  88         }
  89
  90         packet_history.clear();
  91 }
  92