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xK/common.c

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/*
* common.c: common functionality
*
* Copyright (c) 2014, Přemysl Janouch <p.janouch@gmail.com>
* All rights reserved.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#define LIBERTY_WANT_SSL
#define LIBERTY_WANT_POLLER
#define LIBERTY_WANT_PROTO_IRC
#ifdef WANT_SYSLOG_LOGGING
#define print_fatal_data ((void *) LOG_ERR)
#define print_error_data ((void *) LOG_ERR)
#define print_warning_data ((void *) LOG_WARNING)
#define print_status_data ((void *) LOG_INFO)
#define print_debug_data ((void *) LOG_DEBUG)
#endif // WANT_SYSLOG_LOGGING
#include "liberty/liberty.c"
#include <arpa/inet.h>
// --- Logging -----------------------------------------------------------------
static void
log_message_syslog (void *user_data, const char *quote, const char *fmt,
va_list ap)
{
int prio = (int) (intptr_t) user_data;
va_list va;
va_copy (va, ap);
int size = vsnprintf (NULL, 0, fmt, va);
va_end (va);
if (size < 0)
return;
char buf[size + 1];
if (vsnprintf (buf, sizeof buf, fmt, ap) >= 0)
syslog (prio, "%s%s", quote, buf);
}
// --- SOCKS 5/4a (blocking implementation) ------------------------------------
// These are awkward protocols. Note that the `username' is used differently
// in SOCKS 4a and 5. In the former version, it is the username that you can
// get ident'ed against. In the latter version, it forms a pair with the
// password field and doesn't need to be an actual user on your machine.
// TODO: make a non-blocking poller-based version of this;
// either use c-ares or (even better) start another thread to do resolution
struct socks_addr
{
enum socks_addr_type
{
SOCKS_IPV4 = 1, ///< IPv4 address
SOCKS_DOMAIN = 3, ///< Domain name to be resolved
SOCKS_IPV6 = 4 ///< IPv6 address
}
type; ///< The type of this address
union
{
uint8_t ipv4[4]; ///< IPv4 address, network octet order
const char *domain; ///< Domain name
uint8_t ipv6[16]; ///< IPv6 address, network octet order
}
data; ///< The address itself
};
struct socks_data
{
struct socks_addr address; ///< Target address
uint16_t port; ///< Target port
const char *username; ///< Authentication username
const char *password; ///< Authentication password
struct socks_addr bound_address; ///< Bound address at the server
uint16_t bound_port; ///< Bound port at the server
};
static bool
socks_get_socket (struct addrinfo *addresses, int *fd, struct error **e)
{
int sockfd;
for (; addresses; addresses = addresses->ai_next)
{
sockfd = socket (addresses->ai_family,
addresses->ai_socktype, addresses->ai_protocol);
if (sockfd == -1)
continue;
set_cloexec (sockfd);
int yes = 1;
soft_assert (setsockopt (sockfd, SOL_SOCKET, SO_KEEPALIVE,
&yes, sizeof yes) != -1);
if (!connect (sockfd, addresses->ai_addr, addresses->ai_addrlen))
break;
xclose (sockfd);
}
if (!addresses)
{
error_set (e, "couldn't connect to the SOCKS server");
return false;
}
*fd = sockfd;
return true;
}
#define SOCKS_FAIL(...) \
BLOCK_START \
error_set (e, __VA_ARGS__); \
goto fail; \
BLOCK_END
#define SOCKS_RECV(buf, len) \
BLOCK_START \
if ((n = recv (sockfd, (buf), (len), 0)) == -1) \
SOCKS_FAIL ("%s: %s", "recv", strerror (errno)); \
if (n != (len)) \
SOCKS_FAIL ("%s: %s", "protocol error", "unexpected EOF"); \
BLOCK_END
static bool
socks_4a_connect (struct addrinfo *addresses, struct socks_data *data,
int *fd, struct error **e)
{
int sockfd;
if (!socks_get_socket (addresses, &sockfd, e))
return false;
const void *dest_ipv4 = "\x00\x00\x00\x01";
const char *dest_domain = NULL;
char buf[INET6_ADDRSTRLEN];
switch (data->address.type)
{
case SOCKS_IPV4:
dest_ipv4 = data->address.data.ipv4;
break;
case SOCKS_IPV6:
// About the best thing we can do, not sure if it works anywhere at all
if (!inet_ntop (AF_INET6, &data->address.data.ipv6, buf, sizeof buf))
SOCKS_FAIL ("%s: %s", "inet_ntop", strerror (errno));
dest_domain = buf;
break;
case SOCKS_DOMAIN:
dest_domain = data->address.data.domain;
}
struct str req;
str_init (&req);
str_append_c (&req, 4); // version
str_append_c (&req, 1); // connect
str_append_c (&req, data->port >> 8); // higher bits of port
str_append_c (&req, data->port); // lower bits of port
str_append_data (&req, dest_ipv4, 4); // destination address
if (data->username)
str_append (&req, data->username);
str_append_c (&req, '\0');
if (dest_domain)
{
str_append (&req, dest_domain);
str_append_c (&req, '\0');
}
ssize_t n = send (sockfd, req.str, req.len, 0);
str_free (&req);
if (n == -1)
SOCKS_FAIL ("%s: %s", "send", strerror (errno));
uint8_t resp[8];
SOCKS_RECV (resp, sizeof resp);
if (resp[0] != 0)
SOCKS_FAIL ("protocol error");
switch (resp[1])
{
case 90:
break;
case 91:
SOCKS_FAIL ("request rejected or failed");
case 92:
SOCKS_FAIL ("%s: %s", "request rejected",
"SOCKS server cannot connect to identd on the client");
case 93:
SOCKS_FAIL ("%s: %s", "request rejected",
"identd reports different user-id");
default:
SOCKS_FAIL ("protocol error");
}
*fd = sockfd;
return true;
fail:
xclose (sockfd);
return false;
}
#undef SOCKS_FAIL
#define SOCKS_FAIL(...) \
BLOCK_START \
error_set (e, __VA_ARGS__); \
return false; \
BLOCK_END
static bool
socks_5_userpass_auth (int sockfd, struct socks_data *data, struct error **e)
{
size_t ulen = strlen (data->username);
if (ulen > 255)
ulen = 255;
size_t plen = strlen (data->password);
if (plen > 255)
plen = 255;
uint8_t req[3 + ulen + plen], *p = req;
*p++ = 0x01; // version
*p++ = ulen; // username length
memcpy (p, data->username, ulen);
p += ulen;
*p++ = plen; // password length
memcpy (p, data->password, plen);
p += plen;
ssize_t n = send (sockfd, req, p - req, 0);
if (n == -1)
SOCKS_FAIL ("%s: %s", "send", strerror (errno));
uint8_t resp[2];
SOCKS_RECV (resp, sizeof resp);
if (resp[0] != 0x01)
SOCKS_FAIL ("protocol error");
if (resp[1] != 0x00)
SOCKS_FAIL ("authentication failure");
return true;
}
static bool
socks_5_auth (int sockfd, struct socks_data *data, struct error **e)
{
bool can_auth = data->username && data->password;
uint8_t hello[4];
hello[0] = 0x05; // version
hello[1] = 1 + can_auth; // number of authentication methods
hello[2] = 0x00; // no authentication required
hello[3] = 0x02; // username/password
ssize_t n = send (sockfd, hello, 3 + can_auth, 0);
if (n == -1)
SOCKS_FAIL ("%s: %s", "send", strerror (errno));
uint8_t resp[2];
SOCKS_RECV (resp, sizeof resp);
if (resp[0] != 0x05)
SOCKS_FAIL ("protocol error");
switch (resp[1])
{
case 0x02:
if (!can_auth)
SOCKS_FAIL ("protocol error");
if (!socks_5_userpass_auth (sockfd, data, e))
return false;
case 0x00:
break;
case 0xFF:
SOCKS_FAIL ("no acceptable authentication methods");
default:
SOCKS_FAIL ("protocol error");
}
return true;
}
static bool
socks_5_send_req (int sockfd, struct socks_data *data, struct error **e)
{
uint8_t req[4 + 256 + 2], *p = req;
*p++ = 0x05; // version
*p++ = 0x01; // connect
*p++ = 0x00; // reserved
*p++ = data->address.type;
switch (data->address.type)
{
case SOCKS_IPV4:
memcpy (p, data->address.data.ipv4, sizeof data->address.data.ipv4);
p += sizeof data->address.data.ipv4;
break;
case SOCKS_DOMAIN:
{
size_t dlen = strlen (data->address.data.domain);
if (dlen > 255)
dlen = 255;
*p++ = dlen;
memcpy (p, data->address.data.domain, dlen);
p += dlen;
break;
}
case SOCKS_IPV6:
memcpy (p, data->address.data.ipv6, sizeof data->address.data.ipv6);
p += sizeof data->address.data.ipv6;
break;
}
*p++ = data->port >> 8;
*p++ = data->port;
if (send (sockfd, req, p - req, 0) == -1)
SOCKS_FAIL ("%s: %s", "send", strerror (errno));
return true;
}
static bool
socks_5_process_resp (int sockfd, struct socks_data *data, struct error **e)
{
uint8_t resp_header[4];
ssize_t n;
SOCKS_RECV (resp_header, sizeof resp_header);
if (resp_header[0] != 0x05)
SOCKS_FAIL ("protocol error");
switch (resp_header[1])
{
case 0x00:
break;
case 0x01: SOCKS_FAIL ("general SOCKS server failure");
case 0x02: SOCKS_FAIL ("connection not allowed by ruleset");
case 0x03: SOCKS_FAIL ("network unreachable");
case 0x04: SOCKS_FAIL ("host unreachable");
case 0x05: SOCKS_FAIL ("connection refused");
case 0x06: SOCKS_FAIL ("TTL expired");
case 0x07: SOCKS_FAIL ("command not supported");
case 0x08: SOCKS_FAIL ("address type not supported");
default: SOCKS_FAIL ("protocol error");
}
switch ((data->bound_address.type = resp_header[3]))
{
case SOCKS_IPV4:
SOCKS_RECV (data->bound_address.data.ipv4,
sizeof data->bound_address.data.ipv4);
break;
case SOCKS_IPV6:
SOCKS_RECV (data->bound_address.data.ipv6,
sizeof data->bound_address.data.ipv6);
break;
case SOCKS_DOMAIN:
{
uint8_t len;
SOCKS_RECV (&len, sizeof len);
char domain[len + 1];
SOCKS_RECV (domain, len);
domain[len] = '\0';
data->bound_address.data.domain = xstrdup (domain);
break;
}
default:
SOCKS_FAIL ("protocol error");
}
uint16_t port;
SOCKS_RECV (&port, sizeof port);
data->bound_port = ntohs (port);
return true;
}
#undef SOCKS_FAIL
#undef SOCKS_RECV
static bool
socks_5_connect (struct addrinfo *addresses, struct socks_data *data,
int *fd, struct error **e)
{
int sockfd;
if (!socks_get_socket (addresses, &sockfd, e))
return false;
if (!socks_5_auth (sockfd, data, e)
|| !socks_5_send_req (sockfd, data, e)
|| !socks_5_process_resp (sockfd, data, e))
{
xclose (sockfd);
return false;
}
*fd = sockfd;
return true;
}
static int
socks_connect (const char *socks_host, const char *socks_port,
const char *host, const char *port,
const char *username, const char *password, struct error **e)
{
int result = -1;
struct addrinfo gai_hints, *gai_result;
memset (&gai_hints, 0, sizeof gai_hints);
gai_hints.ai_socktype = SOCK_STREAM;
unsigned long port_no;
const struct servent *serv;
if ((serv = getservbyname (port, "tcp")))
port_no = (uint16_t) ntohs (serv->s_port);
else if (!xstrtoul (&port_no, port, 10) || !port_no || port_no > UINT16_MAX)
{
error_set (e, "invalid port number");
goto fail;
}
int err = getaddrinfo (socks_host, socks_port, &gai_hints, &gai_result);
if (err)
{
error_set (e, "%s: %s", "getaddrinfo", gai_strerror (err));
goto fail;
}
struct socks_data data =
{ .username = username, .password = password, .port = port_no };
if (inet_pton (AF_INET, host, &data.address.data.ipv4) == 1)
data.address.type = SOCKS_IPV4;
else if (inet_pton (AF_INET6, host, &data.address.data.ipv6) == 1)
data.address.type = SOCKS_IPV6;
else
{
data.address.type = SOCKS_DOMAIN;
data.address.data.domain = host;
}
if (!socks_5_connect (gai_result, &data, &result, NULL))
socks_4a_connect (gai_result, &data, &result, e);
if (data.bound_address.type == SOCKS_DOMAIN)
free ((char *) data.bound_address.data.domain);
freeaddrinfo (gai_result);
fail:
return result;
}
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