static void server_recv_cb (EV_P_ ev_io *w, int revents)
{
struct server_ctx *server_recv_ctx = (struct server_ctx *)w;
struct server *server = server_recv_ctx->server;
struct remote *remote = NULL;
int len = server->buf_len;
char **buf = &server->buf;
ev_timer_again(EV_A_ &server->recv_ctx->watcher);
if (server->stage != 0)
{
remote = server->remote;
buf = &remote->buf;
len = 0;
}
ssize_t r = recv(server->fd, *buf + len, BUF_SIZE - len, 0);
if (r == 0)
{
// connection closed
if (verbose)
{
LOGD("server_recv close the connection");
}
close_and_free_remote(EV_A_ remote);
close_and_free_server(EV_A_ server);
return;
}
else if (r == -1)
{
if (errno == EAGAIN || errno == EWOULDBLOCK)
{
// no data
// continue to wait for recv
return;
}
else
{
ERROR("server recv");
close_and_free_remote(EV_A_ remote);
close_and_free_server(EV_A_ server);
return;
}
}
// handle incomplete header
if (server->stage == 0)
{
r += server->buf_len;
if (r <= enc_get_iv_len())
{
// wait for more
if (verbose)
{
LOGD("imcomplete header: %zu", r);
}
server->buf_len = r;
return;
}
else
{
server->buf_len = 0;
}
}
*buf = ss_decrypt(BUF_SIZE, *buf, &r, server->d_ctx);
if (*buf == NULL)
{
LOGE("invalid password or cipher");
close_and_free_remote(EV_A_ remote);
close_and_free_server(EV_A_ server);
return;
}
// handshake and transmit data
if (server->stage == 5)
{
int s = send(remote->fd, remote->buf, r, 0);
if (s == -1)
{
if (errno == EAGAIN || errno == EWOULDBLOCK)
{
// no data, wait for send
remote->buf_len = r;
remote->buf_idx = 0;
ev_io_stop(EV_A_ &server_recv_ctx->io);
ev_io_start(EV_A_ &remote->send_ctx->io);
}
else
{
ERROR("server_recv_send");
close_and_free_remote(EV_A_ remote);
close_and_free_server(EV_A_ server);
}
}
else if (s < r)
{
remote->buf_len = r - s;
remote->buf_idx = s;
ev_io_stop(EV_A_ &server_recv_ctx->io);
ev_io_start(EV_A_ &remote->send_ctx->io);
}
return;
}
else if (server->stage == 0)
{
/*
* Shadowsocks Protocol:
*
* +------+----------+----------+
* | ATYP | DST.ADDR | DST.PORT |
* +------+----------+----------+
* | 1 | Variable | 2 |
* +------+----------+----------+
*/
int offset = 0;
char atyp = server->buf[offset++];
char host[256] = {0};
char port[64] = {0};
// get remote addr and port
if (atyp == 1)
{
// IP V4
size_t in_addr_len = sizeof(struct in_addr);
if (r > in_addr_len)
{
inet_ntop(AF_INET, (const void *)(server->buf + offset),
host, INET_ADDRSTRLEN);
offset += in_addr_len;
}
}
else if (atyp == 3)
{
// Domain name
uint8_t name_len = *(uint8_t *)(server->buf + offset);
if (name_len < r && name_len < 255 && name_len > 0)
{
memcpy(host, server->buf + offset + 1, name_len);
offset += name_len + 1;
}
}
else if (atyp == 4)
{
// IP V6
size_t in6_addr_len = sizeof(struct in6_addr);
if (r > in6_addr_len)
{
inet_ntop(AF_INET6, (const void*)(server->buf + offset),
host, INET6_ADDRSTRLEN);
offset += in6_addr_len;
}
}
if (offset == 1)
{
LOGE("invalid header with addr type %d", atyp);
close_and_free_server(EV_A_ server);
return;
}
sprintf(port, "%d",
ntohs(*(uint16_t *)(server->buf + offset)));
offset += 2;
if (verbose)
{
LOGD("connect to: %s:%s", host, port);
}
struct addrinfo hints;
asyncns_query_t *query;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
query = asyncns_getaddrinfo(server->listen_ctx->asyncns,
host, port, &hints);
if (query == NULL)
{
ERROR("asyncns_getaddrinfo");
close_and_free_server(EV_A_ server);
return;
}
asyncns_setuserdata(server->listen_ctx->asyncns, query, server);
// XXX: should handle buffer carefully
if (r > offset)
{
server->buf_len = r - offset;
server->buf_idx = offset;
}
server->stage = 4;
server->query = query;
ev_io_stop(EV_A_ &server_recv_ctx->io);
return;
}
// should not reach here
FATAL("server context error.");
}
static void server_recv_cb(EV_P_ ev_io *w, int revents)
{
struct server_ctx *server_ctx = (struct server_ctx *)w;
struct sockaddr_storage src_addr;
char *buf = malloc(BUF_SIZE);
socklen_t src_addr_len = sizeof(struct sockaddr_storage);
unsigned int offset = 0;
ssize_t buf_len =
recvfrom(server_ctx->fd, buf, BUF_SIZE, 0, (struct sockaddr *)&src_addr,
&src_addr_len);
if (buf_len == -1) {
// error on recv
// simply drop that packet
if (verbose) {
ERROR("[udp] server_recvfrom");
}
goto CLEAN_UP;
}
if (verbose) {
LOGD("[udp] server receive a packet.");
}
#ifdef UDPRELAY_REMOTE
buf = ss_decrypt_all(BUF_SIZE, buf, &buf_len, server_ctx->method);
if (buf == NULL) {
if (verbose) {
ERROR("[udp] server_ss_decrypt_all");
}
goto CLEAN_UP;
}
#endif
#ifdef UDPRELAY_LOCAL
#ifndef UDPRELAY_TUNNEL
uint8_t frag = *(uint8_t *)(buf + 2);
offset += 3;
#endif
#endif
/*
*
* SOCKS5 UDP Request
* +----+------+------+----------+----------+----------+
* |RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA |
* +----+------+------+----------+----------+----------+
* | 2 | 1 | 1 | Variable | 2 | Variable |
* +----+------+------+----------+----------+----------+
*
* SOCKS5 UDP Response
* +----+------+------+----------+----------+----------+
* |RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA |
* +----+------+------+----------+----------+----------+
* | 2 | 1 | 1 | Variable | 2 | Variable |
* +----+------+------+----------+----------+----------+
*
* shadowsocks UDP Request (before encrypted)
* +------+----------+----------+----------+
* | ATYP | DST.ADDR | DST.PORT | DATA |
* +------+----------+----------+----------+
* | 1 | Variable | 2 | Variable |
* +------+----------+----------+----------+
*
* shadowsocks UDP Response (before encrypted)
* +------+----------+----------+----------+
* | ATYP | DST.ADDR | DST.PORT | DATA |
* +------+----------+----------+----------+
* | 1 | Variable | 2 | Variable |
* +------+----------+----------+----------+
*
* shadowsocks UDP Request and Response (after encrypted)
* +-------+--------------+
* | IV | PAYLOAD |
* +-------+--------------+
* | Fixed | Variable |
* +-------+--------------+
*
*/
#ifdef UDPRELAY_TUNNEL
char addr_header[256] = { 0 };
char * host = server_ctx->tunnel_addr.host;
char * port = server_ctx->tunnel_addr.port;
int host_len = strlen(host);
uint16_t port_num = (uint16_t)atoi(port);
uint16_t port_net_num = htons(port_num);
int addr_header_len = 2 + host_len + 2;
// initialize the addr header
addr_header[0] = 3;
addr_header[1] = host_len;
memcpy(addr_header + 2, host, host_len);
memcpy(addr_header + 2 + host_len, &port_net_num, 2);
// reconstruct the buffer
char *tmp = malloc(buf_len + addr_header_len);
memcpy(tmp, addr_header, addr_header_len);
memcpy(tmp + addr_header_len, buf, buf_len);
free(buf);
buf = tmp;
buf_len += addr_header_len;
#else
char host[256] = { 0 };
char port[64] = { 0 };
int addr_header_len = parse_udprealy_header(buf + offset,
buf_len - offset, host, port);
if (addr_header_len == 0) {
// error in parse header
goto CLEAN_UP;
}
char *addr_header = buf + offset;
#endif
char *key = hash_key(addr_header, addr_header_len, &src_addr);
struct cache *conn_cache = server_ctx->conn_cache;
struct remote_ctx *remote_ctx = NULL;
cache_lookup(conn_cache, key, (void *)&remote_ctx);
if (remote_ctx != NULL) {
if (memcmp(&src_addr, &remote_ctx->src_addr, sizeof(src_addr))
|| strcmp(addr_header, remote_ctx->addr_header) != 0) {
remote_ctx = NULL;
}
}
if (remote_ctx == NULL) {
if (verbose) {
LOGD("[udp] cache missed: %s:%s <-> %s", host, port,
get_addr_str((struct sockaddr *)&src_addr));
}
} else {
if (verbose) {
LOGD("[udp] cache hit: %s:%s <-> %s", host, port,
get_addr_str((struct sockaddr *)&src_addr));
}
}
#ifdef UDPRELAY_LOCAL
#ifndef UDPRELAY_TUNNEL
if (frag) {
LOGE("[udp] drop a message since frag is not 0, but %d", frag);
goto CLEAN_UP;
}
#endif
if (remote_ctx == NULL) {
struct addrinfo hints;
struct addrinfo *result;
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_UNSPEC; /* Return IPv4 and IPv6 choices */
hints.ai_socktype = SOCK_DGRAM; /* We want a UDP socket */
int s = getaddrinfo(server_ctx->remote_host, server_ctx->remote_port,
&hints, &result);
if (s != 0 || result == NULL) {
LOGE("[udp] getaddrinfo: %s", gai_strerror(s));
goto CLEAN_UP;
}
// Bind to any port
int remotefd = create_remote_socket(result->ai_family == AF_INET6);
if (remotefd < 0) {
ERROR("[udp] udprelay bind() error..");
// remember to free addrinfo
freeaddrinfo(result);
goto CLEAN_UP;
}
setnonblocking(remotefd);
#ifdef SO_NOSIGPIPE
set_nosigpipe(remotefd);
#endif
#ifdef SET_INTERFACE
if (server_ctx->iface) {
setinterface(remotefd, server_ctx->iface);
}
#endif
// Init remote_ctx
remote_ctx = new_remote(remotefd, server_ctx);
remote_ctx->src_addr = src_addr;
remote_ctx->dst_addr = *((struct sockaddr_storage *)result->ai_addr);
remote_ctx->addr_header_len = addr_header_len;
memcpy(remote_ctx->addr_header, addr_header, addr_header_len);
// Add to conn cache
cache_insert(conn_cache, key, (void *)remote_ctx);
// Start remote io
ev_io_start(EV_A_ & remote_ctx->io);
// clean up
freeaddrinfo(result);
}
if (offset > 0) {
buf_len -= offset;
memmove(buf, buf + offset, buf_len);
}
buf = ss_encrypt_all(BUF_SIZE, buf, &buf_len, server_ctx->method);
size_t addr_len = sizeof(struct sockaddr_in);
if (remote_ctx->dst_addr.ss_family == AF_INET6) {
addr_len = sizeof(struct sockaddr_in6);
}
int s = sendto(remote_ctx->fd, buf, buf_len, 0,
(struct sockaddr *)&remote_ctx->dst_addr, addr_len);
if (s == -1) {
ERROR("[udp] sendto_remote");
}
#else
if (remote_ctx == NULL) {
struct addrinfo hints;
asyncns_query_t *query;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
query = asyncns_getaddrinfo(server_ctx->asyncns,
host, port, &hints);
if (query == NULL) {
ERROR("[udp] asyncns_getaddrinfo");
goto CLEAN_UP;
}
struct query_ctx *query_ctx = new_query_ctx(query,
buf + addr_header_len,
buf_len - addr_header_len);
query_ctx->server_ctx = server_ctx;
query_ctx->addr_header_len = addr_header_len;
query_ctx->src_addr = src_addr;
memcpy(query_ctx->addr_header, addr_header, addr_header_len);
asyncns_setuserdata(server_ctx->asyncns, query, query_ctx);
} else {
size_t addr_len = sizeof(struct sockaddr_in);
if (remote_ctx->dst_addr.ss_family == AF_INET6) {
addr_len = sizeof(struct sockaddr_in6);
}
int s = sendto(remote_ctx->fd, buf + addr_header_len,
buf_len - addr_header_len, 0,
(struct sockaddr *)&remote_ctx->dst_addr, addr_len);
if (s == -1) {
ERROR("[udp] sendto_remote");
}
}
#endif
CLEAN_UP:
free(buf);
}
