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redsocks.c
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redsocks.c
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/* redsocks2 - transparent TCP/UDP-to-proxy redirector
* Copyright (C) 2013-2017 Zhuofei Wang <[email protected]>
*
* This code is based on redsocks project developed by Leonid Evdokimov.
* Licensed under the Apache License, Version 2.0 (the "License").
*
*
* Copyright (C) 2007-2011 Leonid Evdokimov <[email protected]>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy
* of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <errno.h>
#include <assert.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <event2/bufferevent_struct.h>
#include "list.h"
#include "parser.h"
#include "log.h"
#include "main.h"
#include "base.h"
#include "redsocks.h"
#include "utils.h"
#define REDSOCKS_RELAY_HALFBUFF 1024*16
#define REDSOCKS_AUDIT_INTERVAL 60*2
static void redsocks_relay_relayreadcb(struct bufferevent *from, void *_client);
static void redsocks_relay_relaywritecb(struct bufferevent *from, void *_client);
void redsocks_event_error(struct bufferevent *buffev, short what, void *_arg);
extern relay_subsys direct_connect_subsys;
extern relay_subsys http_connect_subsys;
#if defined(ENABLE_HTTPS_PROXY)
extern relay_subsys https_connect_subsys;
#endif
extern relay_subsys http_relay_subsys;
extern relay_subsys socks4_subsys;
extern relay_subsys socks5_subsys;
#if !defined(DISABLE_SHADOWSOCKS)
extern relay_subsys shadowsocks_subsys;
#endif
static relay_subsys *relay_subsystems[] =
{
&direct_connect_subsys,
&http_connect_subsys,
&http_relay_subsys,
&socks4_subsys,
&socks5_subsys,
#if !defined(DISABLE_SHADOWSOCKS)
&shadowsocks_subsys,
#endif
#if defined(ENABLE_HTTPS_PROXY)
&https_connect_subsys,
#endif
};
extern relay_subsys autoproxy_subsys;
static list_head instances = LIST_HEAD_INIT(instances);
static parser_entry redsocks_entries[] =
{
{ .key = "local_ip", .type = pt_in_addr },
{ .key = "local_port", .type = pt_uint16 },
{ .key = "interface", .type = pt_pchar },
{ .key = "relay", .type = pt_pchar },
{ .key = "type", .type = pt_pchar },
{ .key = "login", .type = pt_pchar },
{ .key = "password", .type = pt_pchar },
{ .key = "listenq", .type = pt_uint16 },
{ .key = "min_accept_backoff", .type = pt_uint16 },
{ .key = "max_accept_backoff", .type = pt_uint16 },
{ .key = "autoproxy", .type = pt_uint16 },
{ .key = "timeout", .type = pt_uint16 },
{ }
};
/* There is no way to get `EVLIST_INSERTED` event flag outside of libevent, so
* here are tracking functions. */
static void tracked_event_set(
struct tracked_event *tev, evutil_socket_t fd, short events,
void (*callback)(evutil_socket_t, short, void *), void *arg)
{
tev->ev = event_new(get_event_base(), fd, events, callback, arg);
timerclear(&tev->inserted);
}
static int tracked_event_add(struct tracked_event *tev, const struct timeval *tv)
{
int ret = event_add(tev->ev, tv);
if (ret == 0)
gettimeofday(&tev->inserted, NULL);
return ret;
}
static int tracked_event_del(struct tracked_event *tev)
{
int ret = -1;
if (tev->ev) {
ret = event_del(tev->ev);
if (ret == 0) {
timerclear(&tev->inserted);
}
}
return ret;
}
static void tracked_event_free(struct tracked_event *tev)
{
if (tev->ev) {
if (timerisset(&tev->inserted)) {
event_del(tev->ev);
timerclear(&tev->inserted);
}
event_free(tev->ev);
tev->ev = NULL;
}
}
static int redsocks_onenter(parser_section *section)
{
// FIXME: find proper way to calulate instance_payload_len
int instance_payload_len = 0;
relay_subsys **ss;
FOREACH(ss, relay_subsystems)
if (instance_payload_len < (*ss)->instance_payload_len)
instance_payload_len = (*ss)->instance_payload_len;
redsocks_instance *instance = calloc(1, sizeof(*instance) + instance_payload_len);
if (!instance) {
parser_error(section->context, "Not enough memory");
return -1;
}
INIT_LIST_HEAD(&instance->list);
INIT_LIST_HEAD(&instance->clients);
struct sockaddr_in * addr = (struct sockaddr_in *)&instance->config.bindaddr;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
/* Default value can be checked in run-time, but I doubt anyone needs that.
* Linux: sysctl net.core.somaxconn
* FreeBSD: sysctl kern.ipc.somaxconn */
instance->config.listenq = SOMAXCONN;
instance->config.min_backoff_ms = 100;
instance->config.max_backoff_ms = 60000;
instance->config.autoproxy = 0;
instance->config.timeout = 0;
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr =
(strcmp(entry->key, "interface") == 0) ? (void*)&instance->config.interface :
(strcmp(entry->key, "bind") == 0) ? (void*)&instance->config.bind :
(strcmp(entry->key, "relay") == 0) ? (void*)&instance->config.relay :
(strcmp(entry->key, "type") == 0) ? (void*)&instance->config.type :
(strcmp(entry->key, "login") == 0) ? (void*)&instance->config.login :
(strcmp(entry->key, "password") == 0) ? (void*)&instance->config.password :
(strcmp(entry->key, "listenq") == 0) ? (void*)&instance->config.listenq :
(strcmp(entry->key, "min_accept_backoff") == 0) ? (void*)&instance->config.min_backoff_ms :
(strcmp(entry->key, "max_accept_backoff") == 0) ? (void*)&instance->config.max_backoff_ms :
(strcmp(entry->key, "autoproxy") == 0) ? (void*)&instance->config.autoproxy :
(strcmp(entry->key, "timeout") == 0) ? (void*)&instance->config.timeout:
NULL;
section->data = instance;
return 0;
}
static int redsocks_onexit(parser_section *section)
{
/* FIXME: Rewrite in bullet-proof style. There are memory leaks if config
* file is not correct, so correct on-the-fly config reloading is
* currently impossible.
*/
const char *err = NULL;
redsocks_instance *instance = section->data;
section->data = NULL;
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr = NULL;
// Parse and update bind address and relay address
if (instance->config.bind) {
struct sockaddr * addr = (struct sockaddr *)&instance->config.bindaddr;
int addr_size = sizeof(instance->config.bindaddr);
if (evutil_parse_sockaddr_port(instance->config.bind, addr, &addr_size))
err = "invalid bind address";
}
if (!err && instance->config.relay) {
struct sockaddr * addr = (struct sockaddr *)&instance->config.relayaddr;
int addr_size = sizeof(instance->config.relayaddr);
if (evutil_parse_sockaddr_port(instance->config.relay, addr, &addr_size))
err = "invalid relay address";
}
if (!err && instance->config.type) {
relay_subsys **ss;
FOREACH(ss, relay_subsystems) {
if (!strcmp((*ss)->name, instance->config.type)) {
instance->relay_ss = *ss;
list_add(&instance->list, &instances);
break;
}
}
if (!instance->relay_ss)
err = "invalid `type` for redsocks";
}
else {
err = "no `type` for redsocks";
}
if (!err && !instance->config.min_backoff_ms) {
err = "`min_accept_backoff` must be positive, 0 ms is too low";
}
if (!err && !instance->config.max_backoff_ms) {
err = "`max_accept_backoff` must be positive, 0 ms is too low";
}
if (!err && !(instance->config.min_backoff_ms < instance->config.max_backoff_ms)) {
err = "`min_accept_backoff` must be less than `max_accept_backoff`";
}
if (err)
parser_error(section->context, "%s", err);
if (instance->config.timeout == 0)
instance->config.timeout = DEFAULT_CONNECT_TIMEOUT;
return err ? -1 : 0;
}
static parser_section redsocks_conf_section =
{
.name = "redsocks",
.entries = redsocks_entries,
.onenter = redsocks_onenter,
.onexit = redsocks_onexit
};
void redsocks_log_write_plain(
const char *file, int line, const char *func, int do_errno,
const struct sockaddr_storage *clientaddr,
const struct sockaddr_storage *destaddr,
int priority, const char *orig_fmt, ...
) {
int saved_errno = errno;
va_list ap;
char clientaddr_str[RED_INET_ADDRSTRLEN], destaddr_str[RED_INET_ADDRSTRLEN];
char fmt[MAX_LOG_LENGTH+1];
if (!log_level_enabled(priority))
return;
snprintf(fmt, sizeof(fmt), "[%s->%s]: %s",
red_inet_ntop(clientaddr, clientaddr_str, sizeof(clientaddr_str)),
red_inet_ntop(destaddr, destaddr_str, sizeof(destaddr_str)),
orig_fmt);
va_start(ap, orig_fmt);
errno = saved_errno;
_log_vwrite(file, line, func, do_errno, priority, &fmt[0], ap);
va_end(ap);
}
void redsocks_touch_client(redsocks_client *client)
{
redsocks_time(&client->last_event);
}
static inline const char* bufname(redsocks_client *client, struct bufferevent *buf)
{
assert(buf == client->client || buf == client->relay);
return buf == client->client ? "client" : "relay";
}
static void redsocks_relay_readcb(redsocks_client *client, struct bufferevent *from, struct bufferevent *to)
{
redsocks_log_error(client, LOG_DEBUG, "RCB %s, in: %zu", from == client->client?"client":"relay",
evbuffer_get_length(bufferevent_get_input(from)));
if (evbuffer_get_length(bufferevent_get_output(to)) < get_write_hwm(to)) {
if (bufferevent_write_buffer(to, bufferevent_get_input(from)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (bufferevent_enable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
else {
if (bufferevent_disable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_disable");
}
}
int process_shutdown_on_write_(redsocks_client *client, struct bufferevent *from, struct bufferevent *to)
{
assert(from == client->client || from == client->relay);
unsigned short from_evshut = from == client->client ? client->client_evshut : client->relay_evshut;
unsigned short to_evshut = to == client->client ? client->client_evshut : client->relay_evshut;
redsocks_log_error(client, LOG_DEBUG, "WCB %s, fs: %u, ts: %u, fin: %zu, fout: %zu, tin: %zu",
to == client->client?"client":"relay",
from_evshut,
to_evshut,
evbuffer_get_length(bufferevent_get_input(from)),
evbuffer_get_length(bufferevent_get_output(from)),
evbuffer_get_length(bufferevent_get_input(to)));
if ((from_evshut & EV_READ) && !(to_evshut & EV_WRITE)
&& evbuffer_get_length(bufferevent_get_input(from)) == 0) {
redsocks_shutdown(client, to, SHUT_WR, 0);
return 1;
}
return 0;
}
static void redsocks_relay_writecb(redsocks_client *client, struct bufferevent *from, struct bufferevent *to)
{
assert(from == client->client || from == client->relay);
unsigned short from_evshut = from == client->client ? client->client_evshut : client->relay_evshut;
if (process_shutdown_on_write_(client, from, to))
return;
if (evbuffer_get_length(bufferevent_get_output(to)) < get_write_hwm(to)) {
if (bufferevent_write_buffer(to, bufferevent_get_input(from)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (!(from_evshut & EV_READ) && bufferevent_enable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
}
static void redsocks_relay_relayreadcb(struct bufferevent *from, void *_client)
{
redsocks_client *client = _client;
redsocks_touch_client(client);
redsocks_relay_readcb(client, client->relay, client->client);
}
static void redsocks_relay_relaywritecb(struct bufferevent *to, void *_client)
{
redsocks_client *client = _client;
redsocks_touch_client(client);
redsocks_relay_writecb(client, client->client, client->relay);
}
static void redsocks_relay_clientreadcb(struct bufferevent *from, void *_client)
{
redsocks_client *client = _client;
redsocks_touch_client(client);
redsocks_relay_readcb(client, client->client, client->relay);
}
static void redsocks_relay_clientwritecb(struct bufferevent *to, void *_client)
{
redsocks_client *client = _client;
redsocks_touch_client(client);
redsocks_relay_writecb(client, client->relay, client->client);
}
int redsocks_start_relay(redsocks_client *client)
{
int error;
bufferevent_event_cb event_cb;
bufferevent_setwatermark(client->client, EV_READ|EV_WRITE, 0, REDSOCKS_RELAY_HALFBUFF);
bufferevent_setwatermark(client->relay, EV_READ|EV_WRITE, 0, REDSOCKS_RELAY_HALFBUFF);
#if LIBEVENT_VERSION_NUMBER >= 0x02010100
bufferevent_getcb(client->client, NULL, NULL, &event_cb, NULL);
#else
event_cb = client->client->errorcb;
#endif
bufferevent_setcb(client->client, redsocks_relay_clientreadcb,
redsocks_relay_clientwritecb,
event_cb,
client);
#if LIBEVENT_VERSION_NUMBER >= 0x02010100
bufferevent_getcb(client->relay, NULL, NULL, &event_cb, NULL);
#else
event_cb = client->relay->errorcb;
#endif
bufferevent_setcb(client->relay, redsocks_relay_relayreadcb,
redsocks_relay_relaywritecb,
event_cb,
client);
error = bufferevent_enable(client->client,
client->client_evshut == EV_READ ? EV_WRITE :
client->client_evshut == EV_WRITE ? EV_READ :
client->client_evshut == (EV_READ|EV_WRITE) ? 0 : EV_READ | EV_WRITE);
if (!error)
error = bufferevent_enable(client->relay, EV_READ | EV_WRITE);
if (!error) {
redsocks_log_error(client, LOG_DEBUG, "data relaying started");
}
else {
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
redsocks_drop_client(client);
}
return error;
}
void redsocks_drop_client(redsocks_client *client)
{
int fd;
redsocks_log_error(client, LOG_DEBUG, "dropping client @ state: %d", client->state);
if (client->instance->config.autoproxy && autoproxy_subsys.fini)
autoproxy_subsys.fini(client);
if (client->instance->relay_ss->fini)
client->instance->relay_ss->fini(client);
if (client->client) {
fd = bufferevent_getfd(client->client);
bufferevent_disable(client->client, EV_READ|EV_WRITE);
bufferevent_free(client->client);
redsocks_close(fd);
}
if (client->relay) {
fd = bufferevent_getfd(client->relay);
bufferevent_disable(client->relay, EV_READ|EV_WRITE);
bufferevent_free(client->relay);
redsocks_close(fd);
}
list_del(&client->list);
free(client);
}
void redsocks_shutdown(redsocks_client *client, struct bufferevent *buffev, int how, int pseudo)
{
short evhow = 0;
char *strev, *strhow = NULL, *strevhow = NULL;
unsigned short *pevshut;
assert(how == SHUT_RD || how == SHUT_WR || how == SHUT_RDWR);
assert(buffev == client->client || buffev == client->relay);
if (how == SHUT_RD) {
strhow = "SHUT_RD";
evhow = EV_READ;
strevhow = "EV_READ";
}
else if (how == SHUT_WR) {
strhow = "SHUT_WR";
evhow = EV_WRITE;
strevhow = "EV_WRITE";
}
else if (how == SHUT_RDWR) {
strhow = "SHUT_RDWR";
evhow = EV_READ|EV_WRITE;
strevhow = "EV_READ|EV_WRITE";
}
assert(strhow && strevhow);
strev = buffev == client->client ? "client" : "relay";
pevshut = buffev == client->client ? &client->client_evshut : &client->relay_evshut;
if (bufferevent_disable(buffev, evhow) != 0)
redsocks_log_errno(client, LOG_ERR, "bufferevent_disable(%s, %s)", strev, strevhow);
// if EV_WRITE is already shut and we're going to shutdown read then
// we're either going to abort data flow (bad behaviour) or confirm EOF
// and in this case socket is already SHUT_RD'ed
if (!pseudo)
if ( !(how == SHUT_RD && (*pevshut & EV_WRITE)) )
if (shutdown(bufferevent_getfd(buffev), how) != 0) {
redsocks_log_errno(client, LOG_ERR, "shutdown(%s, %s)", strev, strhow);
// In case of 'Transport endpoint is not connected', shutdown as SHUT_RDWR.
if (errno == ENOTCONN)
evhow = EV_READ|EV_WRITE;
}
*pevshut |= evhow;
if (client->relay_evshut == (EV_READ|EV_WRITE) && client->client_evshut == (EV_READ|EV_WRITE)) {
redsocks_log_error(client, LOG_DEBUG, "both client and server disconnected");
redsocks_drop_client(client);
}
}
// I assume that -1 is invalid errno value
static int redsocks_socket_geterrno(redsocks_client *client, struct bufferevent *buffev)
{
int pseudo_errno = red_socket_geterrno(buffev);
if (pseudo_errno == -1) {
redsocks_log_errno(client, LOG_ERR, "red_socket_geterrno");
return -1;
}
return pseudo_errno;
}
void redsocks_event_error(struct bufferevent *buffev, short what, void *_arg)
{
redsocks_client *client = _arg;
assert(buffev == client->relay || buffev == client->client);
redsocks_touch_client(client);
if (!(what & BEV_EVENT_ERROR))
errno = redsocks_socket_geterrno(client, buffev);
redsocks_log_errno(client, LOG_DEBUG, "%s, what: " event_fmt_str,
buffev == client->client?"client":"relay",
event_fmt(what));
if (what == (BEV_EVENT_READING|BEV_EVENT_EOF)) {
redsocks_shutdown(client, buffev, SHUT_RD, 1);
// Ensure the other party could send remaining data and SHUT_WR also
if (buffev == client->client)
{
if (!(client->relay_evshut & EV_WRITE) && client->relay_connected)
bufferevent_enable(client->relay, EV_WRITE);
}
else
{
if (!(client->client_evshut & EV_WRITE))
bufferevent_enable(client->client, EV_WRITE);
}
}
else {
redsocks_drop_client(client);
}
}
int sizes_equal(size_t a, size_t b)
{
return a == b;
}
int sizes_greater_equal(size_t a, size_t b)
{
return a >= b;
}
int redsocks_read_expected(redsocks_client *client, struct evbuffer *input, void *data, size_comparator comparator, size_t expected)
{
size_t len = evbuffer_get_length(input);
if (comparator(len, expected)) {
int read = evbuffer_remove(input, data, expected);
UNUSED(read);
assert(read == expected);
return 0;
}
else {
redsocks_log_error(client, LOG_NOTICE, "Can't get expected amount of data");
redsocks_drop_client(client);
return -1;
}
}
struct evbuffer *mkevbuffer(void *data, size_t len)
{
struct evbuffer *buff = NULL, *retval = NULL;
buff = evbuffer_new();
if (!buff) {
log_errno(LOG_ERR, "evbuffer_new");
goto fail;
}
if (evbuffer_add(buff, data, len) < 0) {
log_errno(LOG_ERR, "evbuffer_add");
goto fail;
}
retval = buff;
buff = NULL;
fail:
if (buff)
evbuffer_free(buff);
return retval;
}
int redsocks_write_helper_ex(
struct bufferevent *buffev, redsocks_client *client,
redsocks_message_maker mkmessage, int state, size_t wm_low, size_t wm_high)
{
assert(client);
return redsocks_write_helper_ex_plain(buffev, client, (redsocks_message_maker_plain)mkmessage,
client, state, wm_low, wm_high);
}
int redsocks_write_helper_ex_plain(
struct bufferevent *buffev, redsocks_client *client,
redsocks_message_maker_plain mkmessage, void *p, int state, size_t wm_low, size_t wm_high)
{
int len;
struct evbuffer *buff = NULL;
int drop = 1;
if (mkmessage) {
buff = mkmessage(p);
if (!buff)
goto fail;
assert(!client || buffev == client->relay);
len = bufferevent_write_buffer(buffev, buff);
if (len < 0) {
if (client)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
else
log_errno(LOG_ERR, "bufferevent_write_buffer");
goto fail;
}
}
if (client)
client->state = state;
bufferevent_setwatermark(buffev, EV_READ, wm_low, wm_high);
bufferevent_enable(buffev, EV_READ);
drop = 0;
fail:
if (buff)
evbuffer_free(buff);
if (drop && client)
redsocks_drop_client(client);
return drop ? -1 : 0;
}
int redsocks_write_helper(
struct bufferevent *buffev, redsocks_client *client,
redsocks_message_maker mkmessage, int state, size_t wm_only)
{
assert(client);
return redsocks_write_helper_ex(buffev, client, mkmessage, state, wm_only, wm_only);
}
void redsocks_relay_connected(struct bufferevent *buffev, void *_arg)
{
redsocks_client *client = _arg;
assert(buffev == client->relay);
redsocks_touch_client(client);
if (!red_is_socket_connected_ok(buffev)) {
redsocks_log_errno(client, LOG_NOTICE, "red_is_socket_connected_ok");
goto fail;
}
client->relay_connected = 1;
/* We do not need to detect timeouts any more.
The two peers will handle it. */
bufferevent_set_timeouts(client->relay, NULL, NULL);
bufferevent_setcb(client->relay, client->instance->relay_ss->readcb,
client->instance->relay_ss->writecb,
redsocks_event_error,
client);
#if LIBEVENT_VERSION_NUMBER >= 0x02010100
bufferevent_trigger(client->relay, EV_WRITE, 0);
#else
if (client->instance->relay_ss->writecb)
client->instance->relay_ss->writecb(client->relay, client);
#endif
return;
fail:
redsocks_drop_client(client);
}
int redsocks_connect_relay(redsocks_client *client)
{
char * interface = client->instance->config.interface;
struct timeval tv;
tv.tv_sec = client->instance->config.timeout;
tv.tv_usec = 0;
// Allowing binding relay socket to specified IP for outgoing connections
client->relay = red_connect_relay(interface,
&client->instance->config.relayaddr,
NULL,
redsocks_relay_connected,
redsocks_event_error, client, &tv);
if (!client->relay) {
redsocks_log_errno(client, LOG_ERR, "red_connect_relay failed!!!");
redsocks_drop_client(client);
return -1;
}
return 0;
}
static void redsocks_accept_backoff(int fd, short what, void *_arg)
{
redsocks_instance *self = _arg;
/* Isn't it already deleted? EV_PERSIST has nothing common with timeouts in
* old libevent... On the other hand libevent does not return any error. */
if (tracked_event_del(&self->accept_backoff) != 0)
log_errno(LOG_ERR, "event_del");
if (tracked_event_add(&self->listener, NULL) != 0)
log_errno(LOG_ERR, "event_add");
}
void redsocks_close_internal(int fd, const char* file, int line, const char *func)
{
if (close(fd) == 0) {
redsocks_instance *instance = NULL;
struct timeval now;
gettimeofday(&now, NULL);
list_for_each_entry(instance, &instances, list) {
if (timerisset(&instance->accept_backoff.inserted)) {
struct timeval min_accept_backoff = {
instance->config.min_backoff_ms / 1000,
(instance->config.min_backoff_ms % 1000) * 1000};
struct timeval time_passed;
timersub(&now, &instance->accept_backoff.inserted, &time_passed);
if (timercmp(&min_accept_backoff, &time_passed, <)) {
redsocks_accept_backoff(-1, 0, instance);
break;
}
}
}
}
else {
const int do_errno = 1;
_log_write(file, line, func, do_errno, LOG_WARNING, "close");
}
}
static void redsocks_accept_client(int fd, short what, void *_arg)
{
redsocks_instance *self = _arg;
redsocks_client *client = NULL;
struct sockaddr_storage clientaddr;
struct sockaddr_storage myaddr;
struct sockaddr_storage destaddr;
socklen_t addrlen = sizeof(clientaddr);
int client_fd = -1;
int error;
// working with client_fd
client_fd = accept(fd, (struct sockaddr*)&clientaddr, &addrlen);
if (client_fd == -1) {
/* Different systems use different `errno` value to signal different
* `lack of file descriptors` conditions. Here are most of them. */
if (errno == ENFILE || errno == EMFILE || errno == ENOBUFS || errno == ENOMEM) {
self->accept_backoff_ms = (self->accept_backoff_ms << 1) + 1;
clamp_value(self->accept_backoff_ms, self->config.min_backoff_ms, self->config.max_backoff_ms);
int delay = (red_randui32() % self->accept_backoff_ms) + 1;
log_errno(LOG_WARNING, "accept: out of file descriptors, backing off for %u ms", delay);
struct timeval tvdelay = { delay / 1000, (delay % 1000) * 1000 };
if (tracked_event_del(&self->listener) != 0)
log_errno(LOG_ERR, "event_del");
if (tracked_event_add(&self->accept_backoff, &tvdelay) != 0)
log_errno(LOG_ERR, "event_add");
}
else {
log_errno(LOG_WARNING, "accept");
}
goto fail;
}
self->accept_backoff_ms = 0;
// socket is really bound now (it could be bound to 0.0.0.0)
addrlen = sizeof(myaddr);
error = getsockname(client_fd, (struct sockaddr*)&myaddr, &addrlen);
if (error) {
log_errno(LOG_WARNING, "getsockname");
goto fail;
}
error = getdestaddr(client_fd, &clientaddr, &myaddr, &destaddr);
if (error) {
goto fail;
}
error = evutil_make_socket_nonblocking(client_fd);
if (error) {
log_errno(LOG_ERR, "evutil_make_socket_nonblocking");
goto fail;
}
if (apply_tcp_keepalive(client_fd))
goto fail;
// everything seems to be ok, let's allocate some memory
if (self->config.autoproxy)
client = calloc(1, sizeof(redsocks_client) +
self->relay_ss->payload_len + autoproxy_subsys.payload_len
);
else
client = calloc(1, sizeof(redsocks_client) + self->relay_ss->payload_len);
if (!client) {
log_errno(LOG_ERR, "calloc");
goto fail;
}
client->instance = self;
memcpy(&client->clientaddr, &clientaddr, sizeof(clientaddr));
memcpy(&client->destaddr, &destaddr, sizeof(destaddr));
INIT_LIST_HEAD(&client->list);
self->relay_ss->init(client);
if (self->config.autoproxy)
autoproxy_subsys.init(client);
if (redsocks_time(&client->first_event) == ((time_t)-1))
goto fail;
redsocks_touch_client(client);
client->client = bufferevent_socket_new(get_event_base(), client_fd, 0);
if (!client->client) {
log_errno(LOG_ERR, "bufferevent_socket_new");
goto fail;
}
bufferevent_setcb(client->client, NULL, NULL, redsocks_event_error, client);
client_fd = -1;
// enable reading to handle EOF from client
if (bufferevent_enable(client->client, EV_READ) != 0) {
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
goto fail;
}
list_add(&client->list, &self->clients);
redsocks_log_error(client, LOG_DEBUG, "accepted");
if (self->config.autoproxy && autoproxy_subsys.connect_relay)
autoproxy_subsys.connect_relay(client);
else if (self->relay_ss->connect_relay)
self->relay_ss->connect_relay(client);
else
redsocks_connect_relay(client);
return;
fail:
if (client) {
redsocks_drop_client(client);
}
if (client_fd != -1)
redsocks_close(client_fd);
}
static const char *redsocks_evshut_str(unsigned short evshut)
{
return
evshut == EV_READ ? "SHUT_RD" :
evshut == EV_WRITE ? "SHUT_WR" :
evshut == (EV_READ|EV_WRITE) ? "SHUT_RDWR" :
evshut == 0 ? "" :
"???";
}
static const char *redsocks_event_str(unsigned short what)
{
return
what == EV_READ ? "R/-" :
what == EV_WRITE ? "-/W" :
what == (EV_READ|EV_WRITE) ? "R/W" :
what == 0 ? "-/-" :
"???";
}
void redsocks_dump_client(redsocks_client * client, int loglevel)
{
time_t now = redsocks_time(NULL);
const char *s_client_evshut = redsocks_evshut_str(client->client_evshut);
const char *s_relay_evshut = redsocks_evshut_str(client->relay_evshut);
redsocks_log_error(client, loglevel, "client(%i): (%s)%s%s input %zu output %zu, relay(%i): (%s)%s%s input %zu output %zu, age: %li sec, idle: %li sec.",
client->client ? bufferevent_getfd(client->client) : -1,
redsocks_event_str(client->client ? bufferevent_get_enabled(client->client) : 0),
s_client_evshut[0] ? " " : "", s_client_evshut,
client->client ? evbuffer_get_length(bufferevent_get_input(client->client)) : 0,
client->client ? evbuffer_get_length(bufferevent_get_output(client->client)) : 0,
client->relay ? bufferevent_getfd(client->relay) : -1,
redsocks_event_str(client->relay ? bufferevent_get_enabled(client->relay) : 0),
s_relay_evshut[0] ? " " : "", s_relay_evshut,
client->relay ? evbuffer_get_length(bufferevent_get_input(client->relay)) : 0,
client->relay ? evbuffer_get_length(bufferevent_get_output(client->relay)) : 0,
now - client->first_event,
now - client->last_event);
}
static void redsocks_dump_instance(redsocks_instance *instance)
{
redsocks_client *client = NULL;
char addr_str[RED_INET_ADDRSTRLEN];
log_error(LOG_INFO, "Dumping client list for instance (%s @ %s):",
instance->relay_ss->name,
red_inet_ntop(&instance->config.bindaddr, addr_str, sizeof(addr_str)));
list_for_each_entry(client, &instance->clients, list)
redsocks_dump_client(client, LOG_INFO);
log_error(LOG_INFO, "End of client list.");
}
static void redsocks_debug_dump()
{
redsocks_instance *instance = NULL;
list_for_each_entry(instance, &instances, list)
redsocks_dump_instance(instance);
}
/* Audit is required to clean up hung connections.
* Not all connections are closed gracefully by both ends. In any case that
* either far end of client or far end of relay does not close connection
* gracefully, we got hung connections.
*/
static void redsocks_audit_instance(redsocks_instance *instance)
{
redsocks_client *tmp, *client = NULL;
time_t now = redsocks_time(NULL);
int drop_it = 0;
char addr_str[RED_INET_ADDRSTRLEN];
log_error(LOG_DEBUG, "Audit client list for instance (%s @ %s):",
instance->relay_ss->name,
red_inet_ntop(&instance->config.bindaddr, addr_str, sizeof(addr_str)));
list_for_each_entry_safe(client, tmp, &instance->clients, list) {
drop_it = 0;
if (now - client->last_event >= REDSOCKS_AUDIT_INTERVAL){
/* Only take actions if no touch of the client for at least an audit cycle.*/
/* drop this client if either end disconnected */
if ((client->client_evshut == EV_WRITE && client->relay_evshut == EV_READ)
|| (client->client_evshut == EV_READ && client->relay_evshut == EV_WRITE)
|| (client->client_evshut == (EV_READ|EV_WRITE) && client->relay_evshut == EV_WRITE)
|| (client->client_evshut == EV_READ && client->relay == NULL))
drop_it = 1;
}
/* close long connections without activities */
if (now - client->last_event >= 3600 * 2)
drop_it = 1;
if (drop_it){
redsocks_dump_client(client, LOG_DEBUG);
redsocks_drop_client(client);
}
}
log_error(LOG_DEBUG, "End of auditing client list.");
}
static void redsocks_audit(int sig, short what, void *_arg)
{
redsocks_instance * tmp, *instance = NULL;
list_for_each_entry_safe(instance, tmp, &instances, list)
redsocks_audit_instance(instance);
}
static void redsocks_fini_instance(redsocks_instance *instance);
static int redsocks_init_instance(redsocks_instance *instance)
{
/* FIXME: redsocks_fini_instance is called in case of failure, this
* function will remove instance from instances list - result
* looks ugly.
*/
int error;
evutil_socket_t fd = -1;
if (instance->relay_ss->instance_init
&& instance->relay_ss->instance_init(instance)) {
log_errno(LOG_ERR, "Failed to init relay subsystem.");
goto fail;
}
fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (fd == -1) {
log_errno(LOG_ERR, "socket");
goto fail;
}
error = evutil_make_listen_socket_reuseable(fd);
if (error) {
log_errno(LOG_ERR, "evutil_make_listen_socket_reuseable");
goto fail;
}
// iptables TPROXY target does not send packets to non-transparent sockets
if (make_socket_transparent(fd))
log_error(LOG_WARNING, "Continue without TPROXY support");