bool unpack_hdr(uint8_t *buf, size_t size, struct hdr *hdr)
{
UNPACKLE32(hdr->magic);
UNPACKN(&hdr->cmd, sizeof(hdr->cmd));
UNPACKLE32(hdr->payload_size);
UNPACKLE32(hdr->cksum);
if (hdr->magic != (uint32_t)HDR_MAGIC) {
printf("unpack_hdr: wrong magic number\n");
return false;
}
if (hdr->payload_size != size) {
printf("unpack_hdr: wrong payload size\n");
return false;
}
uint32_t cksum;
if (hdr->payload_size == 0) {
cksum = PAYLOADLESS_MSG_CKSUM;
} else {
cksum = msg_cksum(buf, hdr->payload_size);
}
if (hdr->cksum != cksum) {
printf("unpack_hdr: payload checksum is invalid, %08x but should be %08x\n", hdr->cksum, cksum);
return false;
}
return true;
}
void tcplib_send_out(struct split_ip_msg *msg, struct tcp_hdr *tcph) {
uint8_t buf[8192];
struct timespec tv;
if (sock <= 0) return;
// printf("sending message\n");
memcpy(msg->hdr.ip6_src.s6_addr, iface_addr, 16);
msg->hdr.ip6_src.s6_addr[15] = 2;
msg->hdr.hlim = 64;
memset(msg->hdr.vlfc, 0, 4);
msg->hdr.vlfc[0] = 6 << 4;
tcph->chksum = htons(msg_cksum(msg, IANA_TCP));
tv.tv_sec = 0;
// sleep for a ms to give up the cpu...
tv.tv_nsec = 1000000;
nanosleep(&tv);
// print_split_msg(msg);
if (rand() % LOSS_RATE_TRANS == 0) {
printf("dropping packet on write\n");
} else {
printf("tun_write\n");
tun_write(sock, msg);
}
}
size_t pack_header(uint8_t *buf, size_t size, const char *cmd, const void *payload, size_t payload_size)
{
size_t len;
size_t off;
uint32_t cksum;
len = off = 0;
PACKLE32(HDR_MAGIC);
strncpy((char *)buf + 4, cmd, 12);
size_t cmd_len = strlen(cmd);
if (cmd_len < 12) {
memset(buf + 4 + cmd_len, 0, 12 - cmd_len);
}
len += 12;
off += 12;
PACKLE32(payload_size);
cksum = msg_cksum(payload, payload_size);
PACKLE32(cksum);
return HDR_SIZE;
}
