}
#endif
-#define PACKET_READ_OFFS (20-16)
+struct pkt_hdr {
+ // Note that ordering of the first three uint16_ts must match the wire!
+ uint16_t len;
+ uint16_t id;
+ uint16_t frag_flags: 3,
+ offset : 13;
+ uint8_t proto;
+ uint8_t padding;
+};
+static_assert(sizeof(struct pkt_hdr) == 8);
+
+// Have to leave room to add a TCP header plus above header (after dropping IP header)
+#define PACKET_READ_OFFS sizeof(pkt_hdr)
#define PACKET_READ_SIZE (1500 - PACKET_READ_OFFS)
static int tun_alloc(char *dev, const char* local_ip, const char* remote_ip, int queues, int *fds)
fds[i] = fd;
}
- sprintf(buf, "ip link set %s mtu %d", dev, PACKET_READ_SIZE);
+ sprintf(buf, "ip link set dev %s mtu %ld", dev, PACKET_READ_SIZE - 20);
err = system(buf);
if (err) goto err;
return err;
}
-static int check_ip_header(const unsigned char* buf, ssize_t buf_len, uint8_t expected_type) {
+static int check_ip_header(const unsigned char* buf, ssize_t buf_len, int16_t expected_type, struct pkt_hdr *gen_hdr) {
if (buf_len < 20) {
// < size than IPv4?
return -1;
return -1;
}
- if ((((uint16_t)buf[2]) << 8 | buf[3]) != buf_len) {
+ /*if ((((uint16_t)buf[2]) << 8 | buf[3]) != buf_len) {
//fprintf(stderr, "Packet len %u != %ld\n", ((uint16_t)buf[2]) << 8 | buf[3], buf_len);
return -1;
- }
+ }*/
- if (buf[9] != expected_type) {
+ if (expected_type > 0 && buf[9] != expected_type) {
fprintf(stderr, "Packet type %u, not %u\n", buf[9], expected_type);
return -1;
}
- return header_size;
-}
-
-#define UDP_PORTS 4242
-static int check_udp_header(const unsigned char* buf, ssize_t buf_len) {
- if (buf_len < 8) {
- return -1;
+ if (gen_hdr) {
+ memcpy(gen_hdr, buf + 2, 6); // len, id, frag offset
+ gen_hdr->proto = buf[9];
+ gen_hdr->padding = 0;
}
- if (((((uint16_t)buf[0]) << 8) | (buf[1])) != UDP_PORTS) {
- return -1;
- }
- if (((((uint16_t)buf[2]) << 8) | (buf[3])) != UDP_PORTS) {
- return -1;
- }
- return 8;
+
+ return header_size;
}
void print_packet(const unsigned char* buf, ssize_t buf_len) {
buf[17] = checksum >> 8; // Checksum
}
-// len is data length, not including headers!
-static void build_ip_header(unsigned char* buf, uint16_t len, uint8_t proto, const in_addr_t& src_addr, const in_addr_t& dest_addr) {
+static void build_ip_header(unsigned char* buf, struct pkt_hdr hdr, const in_addr_t& src_addr, const in_addr_t& dest_addr) {
buf[0 ] = (4 << 4) | 5; // IPv4 + IHL of 5 (20 bytes)
buf[1 ] = 0; // DSCP 0 + ECN 0
- buf[2 ] = (len + 20) >> 8; // Length
- buf[3 ] = (len + 20); // Length
- memset(buf + 4, 0, 4); // Identification and Fragment 0s
- buf[6 ] = 1 << 6; // DF bit
+ memcpy(buf + 2, &hdr, 6); // length, identification, flags, and offset
buf[8 ] = 255; // TTL
- buf[9 ] = proto; // Protocol Number
+ buf[9 ] = hdr.proto; // Protocol Number
buf[10] = 0; // Checksum
buf[11] = 0; // Checksum
buf[11] = checksum >> 8;
}
-// length is data length, not including headers
-static void build_udp_header(unsigned char* buf, uint16_t len) {
- buf[0] = UDP_PORTS >> 8;
- buf[1] = UDP_PORTS & 0xff;
- buf[2] = UDP_PORTS >> 8;
- buf[3] = UDP_PORTS & 0xff;
- buf[4] = (len + 8) >> 8;
- buf[5] = (len + 8);
-
- // Checksum 0 for now
- buf[6] = 0;
- buf[7] = 0;
-}
-
-
const signed char p_util_hexdigit[256] =
{ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
static in_addr_t src, tun_src, tun_dest;
static uint64_t tcp_init_magic;
-#define PENDING_MESSAGES_BUFF_SIZE (0x3000)
-#define PACKET_READ_OFFS (20-16)
-#define PACKET_READ_SIZE (1500 - PACKET_READ_OFFS)
+#define PENDING_MESSAGES_BUFF_SIZE (0x800)
#define THREAD_POLL_SLEEP_MICS 250
struct MessageQueue {
std::tuple<sockaddr_in, std::array<unsigned char, PACKET_READ_SIZE + PACKET_READ_OFFS>, ssize_t> messagesPendingRingBuff[PENDING_MESSAGES_BUFF_SIZE];
static std::chrono::steady_clock::time_point last_ack_recv;
static void tcp_to_tun() {
- unsigned char buf[1500];
+ unsigned char buf[PACKET_READ_SIZE + PACKET_READ_OFFS];
struct sockaddr_in pkt_src;
memset(&pkt_src, 0, sizeof(pkt_src));
unsigned char* buf = std::get<1>(msg).data();
ssize_t nread = std::get<2>(msg);
- int header_size = check_ip_header(buf, nread, 0x06); // Only support TCP
+ int header_size = check_ip_header(buf, nread, 0x06, NULL); // Only support TCP
if (header_size < 0)
continue;
fprintf(stderr, "Failed to send SYNACK with err %d (%s)\n", err, strerror(err));
}
} else if (!syn) {
- tcp_buf += tcp_header_size - 20 - 8; // IPv4 header is 20 bytes + UDP header is 8 bytes
+ if (nread < (ssize_t)(tcp_header_size + header_size + sizeof(struct pkt_hdr))) continue;
+ struct pkt_hdr hdr;
+ memcpy(&hdr, tcp_buf + tcp_header_size, sizeof(struct pkt_hdr));
+ tcp_buf += tcp_header_size + sizeof(struct pkt_hdr) - 20; // IPv4 header is 20 bytes
- // Replace TCP with IPv4 header
- build_udp_header(tcp_buf + 20, nread - tcp_header_size - header_size);
- build_ip_header(tcp_buf, nread - tcp_header_size - header_size + 8, 0x11, tun_dest, tun_src); // UDP
+ // Replace TCP + pkt_hdr with IPv4 header
+ build_ip_header(tcp_buf, hdr, tun_dest, tun_src);
write(fd[0], tcp_buf, nread - tcp_header_size - header_size + 20 + 8);
}
unsigned char* buf = std::get<1>(msg).data();
ssize_t nread = std::get<2>(msg);
- int header_size = check_ip_header(buf + PACKET_READ_OFFS, nread, 0x11); // Only support UDP
- if (header_size < 0)
+ struct pkt_hdr hdr;
+ int header_size = check_ip_header(buf + PACKET_READ_OFFS, nread, -1, &hdr); // Any paket type is okay
+ if (header_size < 20)
continue;
- if (header_size + 8 > nread) {
- fprintf(stderr, "Short UDP packet\n");
+ if (header_size > nread) {
+ fprintf(stderr, "Short packet\n");
continue;
}
- if (check_udp_header(buf + PACKET_READ_OFFS + header_size, nread - header_size) != 8) {
- fprintf(stderr, "Bad UDP header\n");
+ if ((size_t)nread > 1500 - 20 - sizeof(struct pkt_hdr)) { // Packets must fit in 1500 bytes with a TCP and packet hdr
+ fprintf(stderr, "Long packet\n");
continue;
}
- unsigned char* tcp_start = buf + PACKET_READ_OFFS + header_size + 8 - 20;
- build_tcp_header(tcp_start, nread - header_size - 8, 0, 0, src, dest.sin_addr.s_addr);
+ unsigned char* tcp_start = buf + PACKET_READ_OFFS + header_size - 20 - sizeof(struct pkt_hdr);
+ memcpy(tcp_start + 20, &hdr, sizeof(struct pkt_hdr));
+ build_tcp_header(tcp_start, nread - header_size + sizeof(struct pkt_hdr), 0, 0, src, dest.sin_addr.s_addr);
- ssize_t res = sendto(fdr, tcp_start, nread + 20 - 8 - header_size, 0, (struct sockaddr*)&dest, sizeof(dest));
+ ssize_t res = sendto(fdr, tcp_start, nread + 20 + sizeof(struct pkt_hdr) - header_size, 0, (struct sockaddr*)&dest, sizeof(dest));
if (res < 0) {
int err = errno;
fprintf(stderr, "Failed to send with err %d (%s)\n", err, strerror(err));
projects / tunudptotcp / commitdiff