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/* redsocks - transparent TCP-to-proxy redirector
* Copyright (C) 2007-2011 Leonid Evdokimov <leon@darkk.net.ru>
*
* 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 <stdlib.h>
#include <string.h>
#include <assert.h>
#include "log.h"
#include "redsocks.h"
typedef enum socks4_state_t {
socks4_new,
socks4_request_sent,
socks4_reply_came,
socks4_MAX,
} socks4_state;
typedef struct socks4_req_t {
uint8_t ver;
uint8_t cmd;
uint16_t port;
uint32_t addr;
char login[1]; // we need at least zero-byte
} PACKED socks4_req;
const int socks4_ver = 4;
const int socks4_cmd_connect = 1;
const int socks4_cmd_bind = 2;
typedef struct socks4_reply_t {
uint8_t ver;
uint8_t status;
uint16_t port;
uint32_t addr;
} PACKED socks4_reply;
const int socks4_status_ok = 90;
const int socks4_status_fail = 91;
const int socks4_status_no_ident = 92;
const int socks4_status_fake_ident = 93;
static void socks4_instance_init(redsocks_instance *instance)
{
if (instance->config.password)
log_error(LOG_WARNING, "password <%s> is ignored for socks4 connections", instance->config.password);
}
static void socks4_client_init(redsocks_client *client)
{
client->state = socks4_new;
}
static void socks4_read_cb(struct bufferevent *buffev, void *_arg)
{
redsocks_client *client = _arg;
assert(client->state >= socks4_request_sent);
redsocks_touch_client(client);
if (client->state == socks4_request_sent) {
socks4_reply reply;
if (redsocks_read_expected(client, buffev->input, &reply, sizes_greater_equal, sizeof(reply)) < 0)
return;
client->state = socks4_reply_came;
if (reply.ver != 0) {
redsocks_log_error(client, LOG_NOTICE, "Socks4 server reported unexpected reply version...");
redsocks_drop_client(client);
}
else if (reply.status == socks4_status_ok)
redsocks_start_relay(client);
else {
redsocks_log_error(client, LOG_NOTICE, "Socks4 server status: %s (%i)",
reply.status == socks4_status_fail ? "fail" :
reply.status == socks4_status_no_ident ? "no ident" :
reply.status == socks4_status_fake_ident ? "fake ident" : "?",
reply.status);
redsocks_drop_client(client);
}
}
}
static struct evbuffer *socks4_mkconnect(redsocks_client *client)
{
const redsocks_config *config = &client->instance->config;
const char *username = config->login ? config->login : "";
// space for \0 comes from socks4_req->login
size_t username_len = strlen(username);
size_t len = sizeof(socks4_req) + username_len;
socks4_req *req = calloc(1, len);
req->ver = socks4_ver;
req->cmd = socks4_cmd_connect;
req->port = client->destaddr.sin_port;
req->addr = client->destaddr.sin_addr.s_addr;
memcpy(req->login, username, username_len + 1);
struct evbuffer *ret = mkevbuffer(req, len);
free(req);
return ret;
}
static void socks4_write_cb(struct bufferevent *buffev, void *_arg)
{
redsocks_client *client = _arg;
redsocks_touch_client(client);
if (client->state == socks4_new) {
redsocks_write_helper(
buffev, client,
socks4_mkconnect, socks4_request_sent, sizeof(socks4_reply)
);
}
else if (client->state >= socks4_request_sent) {
bufferevent_disable(buffev, EV_WRITE);
}
}
relay_subsys socks4_subsys =
{
.name = "socks4",
.payload_len = 0,
.instance_payload_len = 0,
.readcb = socks4_read_cb,
.writecb = socks4_write_cb,
.init = socks4_client_init,
.instance_init = socks4_instance_init,
};
/* vim:set tabstop=4 softtabstop=4 shiftwidth=4: */
/* vim:set foldmethod=marker foldlevel=32 foldmarker={,}: */
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