tor_multipath_voip/src/packet.c

#include "packet.h"

size_t get_full_size(struct buffer_packet* bp) {
  union abstract_packet* ap = &bp->ip.ap;
  for (int i = 0; i < bp->ap_count; i++) {
    ap = (union abstract_packet*)(&ap->raw + ap->fmt.headers.size);
  }
  return &ap->raw - &bp->ip.ap.raw;
}

enum FD_STATE read_packet_from_tcp(int fd, struct buffer_packet* bp) {
  ssize_t nread;
  size_t pkt_size_size = sizeof(bp->ip.ap.fmt.headers.size);
  if (bp->mode != BP_READING) return FDS_ERR;

  while (bp->aread < pkt_size_size) {
    nread = read(fd, &(bp->ip.ap.raw) + bp->aread, pkt_size_size - bp->aread);
    if (nread == 0) return FDS_AGAIN;
    if (nread == -1 && errno == EAGAIN) return FDS_AGAIN;
    if (nread == -1) return FDS_ERR;
    bp->aread += nread;
  }

  while (bp->aread < bp->ip.ap.fmt.headers.size) {
    nread = read(fd, &(bp->ip.ap.raw) + bp->aread, bp->ip.ap.fmt.headers.size - bp->aread);
    if (nread == 0) return FDS_AGAIN;
    if (nread == -1 && errno == EAGAIN) return FDS_AGAIN;
    if (nread == -1) return FDS_ERR;
    bp->aread += nread;
  }

  bp->mode = BP_WRITING;
  bp->awrite = 0;
  bp->ap_count = 1;

  return FDS_READY;
}

enum FD_STATE write_packet_to_tcp(int fd, struct buffer_packet* bp) {
  ssize_t nwrite;

  if (bp->mode != BP_WRITING) return FDS_ERR;
  while (bp->awrite < get_full_size(bp)) {
    nwrite = send(fd, &(bp->ip.ap.raw) + bp->awrite, get_full_size(bp) - bp->awrite, 0);
    if (nwrite == -1 && errno == EAGAIN) return FDS_AGAIN;
    if (nwrite == -1) return FDS_ERR;
    bp->awrite += nwrite;
  }
  bp->mode = BP_READING;
  bp->aread = 0;
  bp->ap_count = 0;

  return FDS_READY;
}

enum FD_STATE write_packet_to_udp(int fd, struct buffer_packet* bp, struct udp_target* udp_t) {
  ssize_t nwrite;
  size_t bytes_to_send;
  assert(bp->ip.ap.fmt.headers.cmd == CMD_CLEAR);
  size_t pkt_header_size = sizeof(bp->ip.ap.fmt.headers) + sizeof(bp->ip.ap.fmt.content.clear) - sizeof(char);
  struct sockaddr* addr = NULL;
  socklen_t addrlen = 0;
  if (udp_t->set) {
    addr = (struct sockaddr*) &udp_t->addr;
    addrlen = sizeof(struct sockaddr_in);
  }

  if (bp->mode != BP_WRITING) return FDS_ERR;

  bytes_to_send = bp->ip.ap.fmt.headers.size - pkt_header_size;
  nwrite = sendto(fd,
                  &(bp->ip.ap.fmt.content.clear.payload),
                  bytes_to_send,
                  0,
                  addr,
                  addrlen);

  if (nwrite == -1 && errno == EAGAIN) return FDS_AGAIN;
  if (nwrite != bytes_to_send) return FDS_ERR;

  bp->mode = BP_READING;
  bp->aread = 0;
  bp->ap_count = 0;

  return FDS_READY;
}

enum FD_STATE read_packet_from_udp (int fd, struct buffer_packet* bp, struct udp_target* udp_t) {
  ssize_t nread;
  if (bp->mode != BP_READING) {
    fprintf(stderr, "Buffer packet is not in reading mode (mode: %d)\n", bp->mode);
    return FDS_ERR;
  }

  size_t pkt_header_size = sizeof(bp->ip.ap.fmt.headers) + sizeof(bp->ip.ap.fmt.content.clear) - sizeof(char); // We remove the payload
  size_t udp_packet_size = sizeof(struct internet_packet) - pkt_header_size;
  socklen_t addrlen = sizeof(struct sockaddr_in);

  nread = recvfrom(fd,
                   &(bp->ip.ap.fmt.content.clear.payload),
                   udp_packet_size,
                   MSG_TRUNC,
                   (struct sockaddr*)&udp_t->addr,
                   &addrlen);

  if ((int)nread > (int)udp_packet_size) {
    fprintf(stderr, "Packet has been truncated (%ld instead of %d)\n", nread, (int)udp_packet_size);
    return FDS_ERR;
  }
  if (nread == -1 && errno == EAGAIN) return FDS_AGAIN;
  if (nread == -1 && errno == EAGAIN) return FDS_AGAIN;
  if (nread == -1) {
    fprintf(stderr, "A system error occured\n");
    return FDS_ERR;
  }

  udp_t->set = 1;
  udp_t->addrlen = addrlen;
  bp->ip.ap.fmt.headers.size = nread + pkt_header_size;
  bp->ip.ap.fmt.headers.cmd = CMD_CLEAR;

  bp->mode = BP_WRITING;
  bp->awrite = 0;
  bp->ap_count = 1;

  return FDS_READY;
}