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udprelay.c
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/*
* udprelay.c - Setup UDP relay for both client and server
*
* Copyright (C) 2013 - 2016, Max Lv <max.c.lv@gmail.com>
*
* This file is part of the shadowsocks-libev.
*
* shadowsocks-libev is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* shadowsocks-libev is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with shadowsocks-libev; see the file COPYING. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <locale.h>
#include <signal.h>
#include <string.h>
#include <strings.h>
#include <time.h>
#include <unistd.h>
#ifndef __MINGW32__
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pthread.h>
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#if defined(HAVE_SYS_IOCTL_H) && defined(HAVE_NET_IF_H) && defined(__linux__)
#include <net/if.h>
#include <sys/ioctl.h>
#define SET_INTERFACE
#endif
#ifdef __MINGW32__
#include "win32.h"
#endif
#include <libcork/core.h>
#include <udns.h>
#include "utils.h"
#include "netutils.h"
#include "cache.h"
#include "udprelay.h"
#ifdef MODULE_REMOTE
#define MAX_UDP_CONN_NUM 512
#else
#define MAX_UDP_CONN_NUM 256
#endif
#ifdef MODULE_REMOTE
#ifdef MODULE_
#error "MODULE_REMOTE and MODULE_LOCAL should not be both defined"
#endif
#endif
#ifndef EAGAIN
#define EAGAIN EWOULDBLOCK
#endif
#ifndef EWOULDBLOCK
#define EWOULDBLOCK EAGAIN
#endif
static void server_recv_cb(EV_P_ ev_io *w, int revents);
static void remote_recv_cb(EV_P_ ev_io *w, int revents);
static void remote_timeout_cb(EV_P_ ev_timer *watcher, int revents);
static char *hash_key(const int af, const struct sockaddr_storage *addr);
#ifdef MODULE_REMOTE
static void query_resolve_cb(struct sockaddr *addr, void *data);
#endif
static void close_and_free_remote(EV_P_ remote_ctx_t *ctx);
static remote_ctx_t *new_remote(int fd, server_ctx_t *server_ctx);
#ifdef ANDROID
extern uint64_t tx;
extern uint64_t rx;
extern int vpn;
#endif
extern int verbose;
#ifdef MODULE_REMOTE
extern uint64_t tx;
extern uint64_t rx;
#endif
static int packet_size = DEFAULT_PACKET_SIZE;
static int buf_size = DEFAULT_PACKET_SIZE * 2;
static int server_num = 0;
static server_ctx_t *server_ctx_list[MAX_REMOTE_NUM] = { NULL };
#ifndef __MINGW32__
static int
setnonblocking(int fd)
{
int flags;
if (-1 == (flags = fcntl(fd, F_GETFL, 0))) {
flags = 0;
}
return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}
#endif
#if defined(MODULE_REMOTE) && defined(SO_BROADCAST)
static int
set_broadcast(int socket_fd)
{
int opt = 1;
return setsockopt(socket_fd, SOL_SOCKET, SO_BROADCAST, &opt, sizeof(opt));
}
#endif
#ifdef SO_NOSIGPIPE
static int
set_nosigpipe(int socket_fd)
{
int opt = 1;
return setsockopt(socket_fd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
}
#endif
#ifdef MODULE_REDIR
#ifndef IP_TRANSPARENT
#define IP_TRANSPARENT 19
#endif
#ifndef IP_RECVORIGDSTADDR
#define IP_RECVORIGDSTADDR 20
#endif
static int
get_dstaddr(struct msghdr *msg, struct sockaddr_storage *dstaddr)
{
struct cmsghdr *cmsg;
for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
if (cmsg->cmsg_level == SOL_IP && cmsg->cmsg_type == IP_RECVORIGDSTADDR) {
memcpy(dstaddr, CMSG_DATA(cmsg), sizeof(struct sockaddr_in));
dstaddr->ss_family = AF_INET;
return 0;
} else if (cmsg->cmsg_level == SOL_IPV6 && cmsg->cmsg_type == IP_RECVORIGDSTADDR) {
memcpy(dstaddr, CMSG_DATA(cmsg), sizeof(struct sockaddr_in6));
dstaddr->ss_family = AF_INET6;
return 0;
}
}
return 1;
}
#endif
#define HASH_KEY_LEN sizeof(struct sockaddr_storage) + sizeof(int)
static char *
hash_key(const int af, const struct sockaddr_storage *addr)
{
size_t addr_len = sizeof(struct sockaddr_storage);
static char key[HASH_KEY_LEN];
memset(key, 0, HASH_KEY_LEN);
memcpy(key, &af, sizeof(int));
memcpy(key + sizeof(int), (const uint8_t *)addr, addr_len);
return key;
}
#if defined(MODULE_REDIR) || defined(MODULE_REMOTE)
static int
construct_udprealy_header(const struct sockaddr_storage *in_addr,
char *addr_header)
{
int addr_header_len = 0;
if (in_addr->ss_family == AF_INET) {
struct sockaddr_in *addr = (struct sockaddr_in *)in_addr;
size_t addr_len = sizeof(struct in_addr);
addr_header[addr_header_len++] = 1;
memcpy(addr_header + addr_header_len, &addr->sin_addr, addr_len);
addr_header_len += addr_len;
memcpy(addr_header + addr_header_len, &addr->sin_port, 2);
addr_header_len += 2;
} else if (in_addr->ss_family == AF_INET6) {
struct sockaddr_in6 *addr = (struct sockaddr_in6 *)in_addr;
size_t addr_len = sizeof(struct in6_addr);
addr_header[addr_header_len++] = 4;
memcpy(addr_header + addr_header_len, &addr->sin6_addr, addr_len);
addr_header_len += addr_len;
memcpy(addr_header + addr_header_len, &addr->sin6_port, 2);
addr_header_len += 2;
} else {
return 0;
}
return addr_header_len;
}
#endif
static int
parse_udprealy_header(const char *buf, const size_t buf_len,
char *host, char *port, struct sockaddr_storage *storage)
{
const uint8_t atyp = *(uint8_t *)buf;
int offset = 1;
// get remote addr and port
if ((atyp & ADDRTYPE_MASK) == 1) {
// IP V4
size_t in_addr_len = sizeof(struct in_addr);
if (buf_len >= in_addr_len + 3) {
if (storage != NULL) {
struct sockaddr_in *addr = (struct sockaddr_in *)storage;
addr->sin_family = AF_INET;
addr->sin_addr = *(struct in_addr *)(buf + offset);
addr->sin_port = *(uint16_t *)(buf + offset + in_addr_len);
}
if (host != NULL) {
dns_ntop(AF_INET, (const void *)(buf + offset),
host, INET_ADDRSTRLEN);
}
offset += in_addr_len;
}
} else if ((atyp & ADDRTYPE_MASK) == 3) {
// Domain name
uint8_t name_len = *(uint8_t *)(buf + offset);
if (name_len + 4 <= buf_len) {
if (storage != NULL) {
char tmp[257] = { 0 };
struct cork_ip ip;
memcpy(tmp, buf + offset + 1, name_len);
if (cork_ip_init(&ip, tmp) != -1) {
if (ip.version == 4) {
struct sockaddr_in *addr = (struct sockaddr_in *)storage;
dns_pton(AF_INET, tmp, &(addr->sin_addr));
addr->sin_port = *(uint16_t *)(buf + offset + 1 + name_len);
addr->sin_family = AF_INET;
} else if (ip.version == 6) {
struct sockaddr_in6 *addr = (struct sockaddr_in6 *)storage;
dns_pton(AF_INET, tmp, &(addr->sin6_addr));
addr->sin6_port = *(uint16_t *)(buf + offset + 1 + name_len);
addr->sin6_family = AF_INET6;
}
}
}
if (host != NULL) {
memcpy(host, buf + offset + 1, name_len);
}
offset += 1 + name_len;
}
} else if ((atyp & ADDRTYPE_MASK) == 4) {
// IP V6
size_t in6_addr_len = sizeof(struct in6_addr);
if (buf_len >= in6_addr_len + 3) {
if (storage != NULL) {
struct sockaddr_in6 *addr = (struct sockaddr_in6 *)storage;
addr->sin6_family = AF_INET6;
addr->sin6_addr = *(struct in6_addr *)(buf + offset);
addr->sin6_port = *(uint16_t *)(buf + offset + in6_addr_len);
}
if (host != NULL) {
dns_ntop(AF_INET6, (const void *)(buf + offset),
host, INET6_ADDRSTRLEN);
}
offset += in6_addr_len;
}
}
if (offset == 1) {
LOGE("[udp] invalid header with addr type %d", atyp);
return 0;
}
if (port != NULL) {
sprintf(port, "%d", ntohs(*(uint16_t *)(buf + offset)));
}
offset += 2;
return offset;
}
static char *
get_addr_str(const struct sockaddr *sa)
{
static char s[SS_ADDRSTRLEN];
memset(s, 0, SS_ADDRSTRLEN);
char addr[INET6_ADDRSTRLEN] = { 0 };
char port[PORTSTRLEN] = { 0 };
uint16_t p;
switch (sa->sa_family) {
case AF_INET:
dns_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr),
addr, INET_ADDRSTRLEN);
p = ntohs(((struct sockaddr_in *)sa)->sin_port);
sprintf(port, "%d", p);
break;
case AF_INET6:
dns_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr),
addr, INET6_ADDRSTRLEN);
p = ntohs(((struct sockaddr_in *)sa)->sin_port);
sprintf(port, "%d", p);
break;
default:
strncpy(s, "Unknown AF", SS_ADDRSTRLEN);
}
int addr_len = strlen(addr);
int port_len = strlen(port);
memcpy(s, addr, addr_len);
memcpy(s + addr_len + 1, port, port_len);
s[addr_len] = ':';
return s;
}
int
create_remote_socket(int ipv6)
{
int remote_sock;
if (ipv6) {
// Try to bind IPv6 first
struct sockaddr_in6 addr;
memset(&addr, 0, sizeof(struct sockaddr_in6));
addr.sin6_family = AF_INET6;
addr.sin6_addr = in6addr_any;
addr.sin6_port = 0;
remote_sock = socket(AF_INET6, SOCK_DGRAM, 0);
if (remote_sock == -1) {
ERROR("[udp] cannot create socket");
return -1;
}
if (bind(remote_sock, (struct sockaddr *)&addr, sizeof(addr)) != 0) {
FATAL("[udp] cannot bind remote");
return -1;
}
} else {
// Or else bind to IPv4
struct sockaddr_in addr;
memset(&addr, 0, sizeof(struct sockaddr_in));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = INADDR_ANY;
addr.sin_port = 0;
remote_sock = socket(AF_INET, SOCK_DGRAM, 0);
if (remote_sock == -1) {
ERROR("[udp] cannot create socket");
return -1;
}
if (bind(remote_sock, (struct sockaddr *)&addr, sizeof(addr)) != 0) {
FATAL("[udp] cannot bind remote");
return -1;
}
}
return remote_sock;
}
int
create_server_socket(const char *host, const char *port)
{
struct addrinfo hints;
struct addrinfo *result, *rp, *ipv4v6bindall;
int s, server_sock;
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 */
hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG; /* For wildcard IP address */
hints.ai_protocol = IPPROTO_UDP;
s = getaddrinfo(host, port, &hints, &result);
if (s != 0) {
LOGE("[udp] getaddrinfo: %s", gai_strerror(s));
return -1;
}
rp = result;
/*
* On Linux, with net.ipv6.bindv6only = 0 (the default), getaddrinfo(NULL) with
* AI_PASSIVE returns 0.0.0.0 and :: (in this order). AI_PASSIVE was meant to
* return a list of addresses to listen on, but it is impossible to listen on
* 0.0.0.0 and :: at the same time, if :: implies dualstack mode.
*/
if (!host) {
ipv4v6bindall = result;
/* Loop over all address infos found until a IPV6 address is found. */
while (ipv4v6bindall) {
if (ipv4v6bindall->ai_family == AF_INET6) {
rp = ipv4v6bindall; /* Take first IPV6 address available */
break;
}
ipv4v6bindall = ipv4v6bindall->ai_next; /* Get next address info, if any */
}
}
for (/*rp = result*/; rp != NULL; rp = rp->ai_next) {
server_sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
if (server_sock == -1) {
continue;
}
if (rp->ai_family == AF_INET6) {
int ipv6only = host ? 1 : 0;
setsockopt(server_sock, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6only, sizeof(ipv6only));
}
int opt = 1;
setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
#ifdef SO_NOSIGPIPE
set_nosigpipe(server_sock);
#endif
int err = set_reuseport(server_sock);
if (err == 0) {
LOGI("udp port reuse enabled");
}
#ifdef IP_TOS
// Set QoS flag
int tos = 46;
setsockopt(server_sock, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
#endif
#ifdef MODULE_REDIR
if (setsockopt(server_sock, SOL_IP, IP_TRANSPARENT, &opt, sizeof(opt))) {
ERROR("[udp] setsockopt IP_TRANSPARENT");
exit(EXIT_FAILURE);
}
if (setsockopt(server_sock, IPPROTO_IP, IP_RECVORIGDSTADDR, &opt, sizeof(opt))) {
FATAL("[udp] setsockopt IP_RECVORIGDSTADDR");
}
#endif
s = bind(server_sock, rp->ai_addr, rp->ai_addrlen);
if (s == 0) {
/* We managed to bind successfully! */
break;
} else {
ERROR("[udp] bind");
}
close(server_sock);
}
if (rp == NULL) {
LOGE("[udp] cannot bind");
return -1;
}
freeaddrinfo(result);
return server_sock;
}
remote_ctx_t *
new_remote(int fd, server_ctx_t *server_ctx)
{
remote_ctx_t *ctx = ss_malloc(sizeof(remote_ctx_t));
memset(ctx, 0, sizeof(remote_ctx_t));
ctx->fd = fd;
ctx->server_ctx = server_ctx;
ev_io_init(&ctx->io, remote_recv_cb, fd, EV_READ);
ev_timer_init(&ctx->watcher, remote_timeout_cb, server_ctx->timeout,
server_ctx->timeout);
return ctx;
}
server_ctx_t *
new_server_ctx(int fd)
{
server_ctx_t *ctx = ss_malloc(sizeof(server_ctx_t));
memset(ctx, 0, sizeof(server_ctx_t));
ctx->fd = fd;
ev_io_init(&ctx->io, server_recv_cb, fd, EV_READ);
return ctx;
}
#ifdef MODULE_REMOTE
struct query_ctx *
new_query_ctx(char *buf, size_t len)
{
struct query_ctx *ctx = ss_malloc(sizeof(struct query_ctx));
memset(ctx, 0, sizeof(struct query_ctx));
ctx->buf = ss_malloc(sizeof(buffer_t));
balloc(ctx->buf, len);
memcpy(ctx->buf->array, buf, len);
ctx->buf->len = len;
return ctx;
}
void
close_and_free_query(EV_P_ struct query_ctx *ctx)
{
if (ctx != NULL) {
if (ctx->query != NULL) {
resolv_cancel(ctx->query);
ctx->query = NULL;
}
if (ctx->buf != NULL) {
bfree(ctx->buf);
ss_free(ctx->buf);
}
ss_free(ctx);
}
}
#endif
void
close_and_free_remote(EV_P_ remote_ctx_t *ctx)
{
if (ctx != NULL) {
ev_timer_stop(EV_A_ & ctx->watcher);
ev_io_stop(EV_A_ & ctx->io);
close(ctx->fd);
ss_free(ctx);
}
}
static void
remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
{
remote_ctx_t *remote_ctx
= cork_container_of(watcher, remote_ctx_t, watcher);
if (verbose) {
LOGI("[udp] connection timeout");
}
char *key = hash_key(remote_ctx->af, &remote_ctx->src_addr);
cache_remove(remote_ctx->server_ctx->conn_cache, key, HASH_KEY_LEN);
}
#ifdef MODULE_REMOTE
static void
query_resolve_cb(struct sockaddr *addr, void *data)
{
struct query_ctx *query_ctx = (struct query_ctx *)data;
struct ev_loop *loop = query_ctx->server_ctx->loop;
if (verbose) {
LOGI("[udp] udns resolved");
}
query_ctx->query = NULL;
if (addr == NULL) {
LOGE("[udp] udns returned an error");
} else {
remote_ctx_t *remote_ctx = query_ctx->remote_ctx;
int cache_hit = 0;
// Lookup in the conn cache
if (remote_ctx == NULL) {
char *key = hash_key(AF_UNSPEC, &query_ctx->src_addr);
cache_lookup(query_ctx->server_ctx->conn_cache, key, HASH_KEY_LEN, (void *)&remote_ctx);
}
if (remote_ctx == NULL) {
int remotefd = create_remote_socket(addr->sa_family == AF_INET6);
if (remotefd != -1) {
setnonblocking(remotefd);
#ifdef SO_BROADCAST
set_broadcast(remotefd);
#endif
#ifdef SO_NOSIGPIPE
set_nosigpipe(remotefd);
#endif
#ifdef IP_TOS
// Set QoS flag
int tos = 46;
setsockopt(remotefd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
#endif
#ifdef SET_INTERFACE
if (query_ctx->server_ctx->iface) {
if (setinterface(remotefd, query_ctx->server_ctx->iface) == -1)
ERROR("setinterface");
}
#endif
remote_ctx = new_remote(remotefd, query_ctx->server_ctx);
remote_ctx->src_addr = query_ctx->src_addr;
remote_ctx->server_ctx = query_ctx->server_ctx;
remote_ctx->addr_header_len = query_ctx->addr_header_len;
memcpy(remote_ctx->addr_header, query_ctx->addr_header,
query_ctx->addr_header_len);
} else {
ERROR("[udp] bind() error");
}
} else {
cache_hit = 1;
}
if (remote_ctx != NULL) {
memcpy(&remote_ctx->dst_addr, addr, sizeof(struct sockaddr_storage));
size_t addr_len = get_sockaddr_len(addr);
int s = sendto(remote_ctx->fd, query_ctx->buf->array, query_ctx->buf->len,
0, addr, addr_len);
if (s == -1) {
ERROR("[udp] sendto_remote");
if (!cache_hit) {
close_and_free_remote(EV_A_ remote_ctx);
}
} else {
if (!cache_hit) {
// Add to conn cache
char *key = hash_key(AF_UNSPEC, &remote_ctx->src_addr);
cache_insert(query_ctx->server_ctx->conn_cache, key, HASH_KEY_LEN, (void *)remote_ctx);
ev_io_start(EV_A_ & remote_ctx->io);
ev_timer_start(EV_A_ & remote_ctx->watcher);
}
}
}
}
// clean up
close_and_free_query(EV_A_ query_ctx);
}
#endif
static void
remote_recv_cb(EV_P_ ev_io *w, int revents)
{
ssize_t r;
remote_ctx_t *remote_ctx = (remote_ctx_t *)w;
server_ctx_t *server_ctx = remote_ctx->server_ctx;
// server has been closed
if (server_ctx == NULL) {
LOGE("[udp] invalid server");
close_and_free_remote(EV_A_ remote_ctx);
return;
}
struct sockaddr_storage src_addr;
socklen_t src_addr_len = sizeof(struct sockaddr_storage);
memset(&src_addr, 0, src_addr_len);
buffer_t *buf = ss_malloc(sizeof(buffer_t));
balloc(buf, buf_size);
// recv
r = recvfrom(remote_ctx->fd, buf->array, buf_size, 0, (struct sockaddr *)&src_addr, &src_addr_len);
if (r == -1) {
// error on recv
// simply drop that packet
ERROR("[udp] remote_recv_recvfrom");
goto CLEAN_UP;
} else if (r > packet_size) {
LOGE("[udp] remote_recv_recvfrom fragmentation");
goto CLEAN_UP;
}
buf->len = r;
#ifdef MODULE_LOCAL
int err = ss_decrypt_all(buf, server_ctx->method, 0, buf_size);
if (err) {
// drop the packet silently
goto CLEAN_UP;
}
//SSR beg
if (server_ctx->protocol_plugin) {
obfs_class *protocol_plugin = server_ctx->protocol_plugin;
if (protocol_plugin->client_udp_post_decrypt) {
buf->len = protocol_plugin->client_udp_post_decrypt(server_ctx->protocol, &buf->array, buf->len, &buf->capacity);
if ((int)buf->len < 0) {
LOGE("client_udp_post_decrypt");
close_and_free_remote(EV_A_ remote_ctx);
return;
}
if ( buf->len == 0 )
return;
}
}
// SSR end
#ifdef MODULE_REDIR
struct sockaddr_storage dst_addr;
memset(&dst_addr, 0, sizeof(struct sockaddr_storage));
int len = parse_udprealy_header(buf->array, buf->len, NULL, NULL, &dst_addr);
if (dst_addr.ss_family != AF_INET && dst_addr.ss_family != AF_INET6) {
LOGI("[udp] ss-redir does not support domain name");
goto CLEAN_UP;
}
if (verbose) {
char src[SS_ADDRSTRLEN];
char dst[SS_ADDRSTRLEN];
strcpy(src, get_addr_str((struct sockaddr *)&src_addr));
strcpy(dst, get_addr_str((struct sockaddr *)&dst_addr));
LOGI("[udp] recv %s via %s", dst, src);
}
#else
int len = parse_udprealy_header(buf->array, buf->len, NULL, NULL, NULL);
#endif
if (len == 0) {
LOGI("[udp] error in parse header");
// error in parse header
goto CLEAN_UP;
}
// server may return using a different address type other than the type we
// have used during sending
#if defined(MODULE_TUNNEL) || defined(MODULE_REDIR)
// Construct packet
buf->len -= len;
memmove(buf->array, buf->array + len, buf->len);
#else
#ifdef ANDROID
rx += buf->len;
#endif
// Construct packet
brealloc(buf, buf->len + 3, buf_size);
memmove(buf->array + 3, buf->array, buf->len);
memset(buf->array, 0, 3);
buf->len += 3;
#endif
#endif
#ifdef MODULE_REMOTE
rx += buf->len;
char addr_header_buf[512];
char *addr_header = remote_ctx->addr_header;
int addr_header_len = remote_ctx->addr_header_len;
if (remote_ctx->af == AF_INET || remote_ctx->af == AF_INET6) {
addr_header_len = construct_udprealy_header(&src_addr, addr_header_buf);
addr_header = addr_header_buf;
}
// Construct packet
brealloc(buf, buf->len + addr_header_len, buf_size);
memmove(buf->array + addr_header_len, buf->array, buf->len);
memcpy(buf->array, addr_header, addr_header_len);
buf->len += addr_header_len;
int err = ss_encrypt_all(buf, server_ctx->method, 0, buf_size);
if (err) {
// drop the packet silently
goto CLEAN_UP;
}
#endif
if (buf->len > packet_size) {
LOGE("[udp] remote_recv_sendto fragmentation");
goto CLEAN_UP;
}
size_t remote_src_addr_len = get_sockaddr_len((struct sockaddr *)&remote_ctx->src_addr);
#ifdef MODULE_REDIR
size_t remote_dst_addr_len = get_sockaddr_len((struct sockaddr *)&dst_addr);
int src_fd = socket(remote_ctx->src_addr.ss_family, SOCK_DGRAM, 0);
if (src_fd < 0) {
ERROR("[udp] remote_recv_socket");
goto CLEAN_UP;
}
int opt = 1;
if (setsockopt(src_fd, SOL_IP, IP_TRANSPARENT, &opt, sizeof(opt))) {
ERROR("[udp] remote_recv_setsockopt");
close(src_fd);
goto CLEAN_UP;
}
if (setsockopt(src_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
ERROR("[udp] remote_recv_setsockopt");
close(src_fd);
goto CLEAN_UP;
}
#ifdef IP_TOS
// Set QoS flag
int tos = 46;
setsockopt(src_fd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
#endif
if (bind(src_fd, (struct sockaddr *)&dst_addr, remote_dst_addr_len) != 0) {
ERROR("[udp] remote_recv_bind");
close(src_fd);
goto CLEAN_UP;
}
int s = sendto(src_fd, buf->array, buf->len, 0,
(struct sockaddr *)&remote_ctx->src_addr, remote_src_addr_len);
if (s == -1) {
ERROR("[udp] remote_recv_sendto");
close(src_fd);
goto CLEAN_UP;
}
close(src_fd);
#else
int s = sendto(server_ctx->fd, buf->array, buf->len, 0,
(struct sockaddr *)&remote_ctx->src_addr, remote_src_addr_len);
if (s == -1) {
ERROR("[udp] remote_recv_sendto");
goto CLEAN_UP;
}
#endif
// handle the UDP packet successfully,
// triger the timer
ev_timer_again(EV_A_ & remote_ctx->watcher);
CLEAN_UP:
bfree(buf);
ss_free(buf);
}
static void
server_recv_cb(EV_P_ ev_io *w, int revents)
{
server_ctx_t *server_ctx = (server_ctx_t *)w;
struct sockaddr_storage src_addr;
memset(&src_addr, 0, sizeof(struct sockaddr_storage));
buffer_t *buf = ss_malloc(sizeof(buffer_t));
balloc(buf, buf_size);
socklen_t src_addr_len = sizeof(struct sockaddr_storage);
unsigned int offset = 0;
#ifdef MODULE_REDIR
char control_buffer[64] = { 0 };
struct msghdr msg;
memset(&msg, 0, sizeof(struct msghdr));
struct iovec iov[1];
struct sockaddr_storage dst_addr;
memset(&dst_addr, 0, sizeof(struct sockaddr_storage));
msg.msg_name = &src_addr;
msg.msg_namelen = src_addr_len;
msg.msg_control = control_buffer;
msg.msg_controllen = sizeof(control_buffer);
iov[0].iov_base = buf->array;
iov[0].iov_len = buf_size;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
buf->len = recvmsg(server_ctx->fd, &msg, 0);
if (buf->len == -1) {
ERROR("[udp] server_recvmsg");
goto CLEAN_UP;
} else if (buf->len > packet_size) {
ERROR("[udp] UDP server_recv_recvmsg fragmentation");
goto CLEAN_UP;
}
if (get_dstaddr(&msg, &dst_addr)) {
LOGE("[udp] unable to get dest addr");
goto CLEAN_UP;
}
src_addr_len = msg.msg_namelen;
#else
ssize_t r;
r = recvfrom(server_ctx->fd, buf->array, buf_size,
0, (struct sockaddr *)&src_addr, &src_addr_len);
if (r == -1) {
// error on recv
// simply drop that packet
ERROR("[udp] server_recv_recvfrom");
goto CLEAN_UP;
} else if (r > packet_size) {
ERROR("[udp] server_recv_recvfrom fragmentation");
goto CLEAN_UP;
}
buf->len = r;
#endif
#ifdef MODULE_REMOTE
tx += buf->len;
int err = ss_decrypt_all(buf, server_ctx->method, server_ctx->auth, buf_size);
if (err) {
// drop the packet silently
goto CLEAN_UP;
}
#endif
#ifdef MODULE_LOCAL
#if !defined(MODULE_TUNNEL) && !defined(MODULE_REDIR)
#ifdef ANDROID
tx += buf->len;
#endif
uint8_t frag = *(uint8_t *)(buf->array + 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 | HMAC-SHA1 |
* +------+----------+----------+----------+-------------+
* | 1 | Variable | 2 | Variable | 10 |
* +------+----------+----------+----------+-------------+
*
* If ATYP & ONETIMEAUTH_FLAG(0x10) != 0, Authentication (HMAC-SHA1) is enabled.
*
* The key of HMAC-SHA1 is (IV + KEY) and the input is the whole packet.
* The output of HMAC-SHA is truncated to 10 bytes (leftmost bits).
*
* 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 MODULE_REDIR
if (verbose) {
char src[SS_ADDRSTRLEN];
char dst[SS_ADDRSTRLEN];
strcpy(src, get_addr_str((struct sockaddr *)&src_addr));
strcpy(dst, get_addr_str((struct sockaddr *)&dst_addr));
LOGI("[udp] redir to %s from %s", dst, src);
}
char addr_header[512] = { 0 };
int addr_header_len = construct_udprealy_header(&dst_addr, addr_header);
if (addr_header_len == 0) {
LOGE("[udp] failed to parse tproxy addr");
goto CLEAN_UP;
}
// reconstruct the buffer
brealloc(buf, buf->len + addr_header_len, buf_size);
memmove(buf->array + addr_header_len, buf->array, buf->len);
memcpy(buf->array, addr_header, addr_header_len);