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

   1 #include <arpa/inet.h>
   2
   3 #include "reorderer.h"
   4 #include "protocol.h"
   5
   6 #define PACKET_BUFFER_SIZE 100
   7 #define TIMEOUT_SEC 0.100
   8
   9 using namespace std;
  10
  11 double tdiff(const timeval& a, const timeval& b)
  12 {
  13         return b.tv_sec - a.tv_sec +
  14                 1e-6 * (b.tv_usec - a.tv_usec);
  15 }
  16
  17 Reorderer::Reorderer(Sender* sender)
  18         : sender(sender), last_seq(-1)
  19 {
  20 }
  21
  22 void Reorderer::send_packet(uint16_t proto, const string& data, int seq)
  23 {
  24         timeval now;
  25         gettimeofday(&now, NULL);
  26
  27         bool silence = false;
  28         if (packet_buffer.size() >= PACKET_BUFFER_SIZE) {
  29                 printf("Gave up waiting for packets [%d,%d> (buffer full)\n",
  30                         last_seq + 1, packet_buffer.top().seq);
  31                 silence = true;
  32                 last_seq = packet_buffer.top().seq - 1;
  33         } else if (!packet_buffer.empty() &&
  34                    tdiff(packet_buffer.top().ts, now) > TIMEOUT_SEC) {
  35                 printf("Gave up waiting for packets [%d,%d> (timeout)\n",
  36                         last_seq + 1, packet_buffer.top().seq);
  37                 silence = true;
  38                 last_seq = packet_buffer.top().seq - 1;
  39                 // TODO: Rerun immediately after we've cleared out,
  40                 // in case there are more timeouts.
  41         }
  42
  43         GREPacket packet;
  44         packet.seq = seq;
  45         packet.proto = proto;
  46         packet.data = data;
  47         packet.ts = now;
  48         packet_buffer.push(packet);
  49
  50         while (!packet_buffer.empty() &&
  51                (last_seq == -1 || packet_buffer.top().seq <= last_seq + 1)) {
  52                 int front_seq = packet_buffer.top().seq;
  53                 if (front_seq < last_seq + 1) {
  54                         printf("Duplicate packet or way out-of-order: seq=%d front_seq=%d\n",
  55                                 front_seq, last_seq + 1);
  56                         packet_buffer.pop();
  57                         continue;
  58                 }
  59                 //if (packet_buffer.size() > 1) {
  60                 //      printf("seq=%d (REORDER %d)\n", front_seq, int(packet_buffer.size()));
  61                 //} else {
  62                 //      printf("seq=%d\n", front_seq);
  63                 //}
  64                 const string &data = packet_buffer.top().data;
  65                 check_ts_discontinuity(packet_buffer.top().proto, data, silence);
  66                 sender->send_packet(proto, data, seq);
  67                 packet_buffer.pop();
  68                 last_seq = front_seq;
  69                 if (!silence && !packet_buffer.empty()) {
  70                         printf("Reordering with packet buffer size %d: seq=%d new_front_seq=%d\n", int(packet_buffer.size()), front_seq, packet_buffer.top().seq);
  71                         silence = true;
  72                 }
  73         }
  74 }
  75
  76 void Reorderer::check_ts_discontinuity(uint16_t proto, const string &data, bool silence)
  77 {
  78         if (data.size() == 1344) {
  79                 for (int i = 0; i < 7; ++i) {
  80                         const char *pkt = &data[i * 188 + 28];
  81                         int pid = (ntohl(*(uint32_t *)(pkt)) & 0x1fff00) >> 8;
  82                         if (pid == 8191) {
  83                                 // stuffing, ignore
  84                                 continue;
  85                         }
  86                         int has_payload = pkt[3] & 0x10;
  87                         int cc = pkt[3] & 0xf;
  88                         if (has_payload) {
  89                                 int last_cc = ccs[pid];
  90                                 if (!silence && cc != ((last_cc + 1) & 0xf)) {
  91                                         printf("Pid %d discontinuity (expected %d, got %d)\n", pid, (last_cc + 1) & 0xf, cc);
  92                                 }
  93                                 ccs[pid] = cc;
  94                         }
  95                 }
  96         }
  97 }
  98