tor/src/tools/tor-resolve.c

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/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson
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* Copyright (c) 2007-2018, The Tor Project, Inc.
*/
/* See LICENSE for licensing information */
#include "orconfig.h"
#include "lib/arch/bytes.h"
#include "lib/log/log.h"
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#include "lib/malloc/malloc.h"
#include "lib/net/address.h"
#include "lib/net/resolve.h"
#include "lib/net/socket.h"
#include "lib/sandbox/sandbox.h"
#include "lib/string/util_string.h"
#include "lib/net/socks5_status.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h> /* Must be included before sys/stat.h for Ultrix */
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#endif
#define RESPONSE_LEN_4 8
#define log_sock_error(act, _s) \
STMT_BEGIN log_fn(LOG_ERR, LD_NET, "Error while %s: %s", act, \
tor_socket_strerror(tor_socket_errno(_s))); STMT_END
static void usage(void) ATTR_NORETURN;
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/** Set *<b>out</b> to a newly allocated SOCKS4a resolve request with
* <b>username</b> and <b>hostname</b> as provided. Return the number
* of bytes in the request. */
static ssize_t
build_socks_resolve_request(char **out,
const char *username,
const char *hostname,
int reverse,
int version)
{
size_t len = 0;
tor_assert(out);
tor_assert(username);
tor_assert(hostname);
if (version == 4) {
len = 8 + strlen(username) + 1 + strlen(hostname) + 1;
*out = tor_malloc(len);
(*out)[0] = 4; /* SOCKS version 4 */
(*out)[1] = '\xF0'; /* Command: resolve. */
set_uint16((*out)+2, htons(0)); /* port: 0. */
set_uint32((*out)+4, htonl(0x00000001u)); /* addr: 0.0.0.1 */
memcpy((*out)+8, username, strlen(username)+1);
memcpy((*out)+8+strlen(username)+1, hostname, strlen(hostname)+1);
} else if (version == 5) {
int is_ip_address;
tor_addr_t addr;
size_t addrlen;
int ipv6;
is_ip_address = tor_addr_parse(&addr, hostname) != -1;
if (!is_ip_address && reverse) {
log_err(LD_GENERAL, "Tried to do a reverse lookup on a non-IP!");
return -1;
}
ipv6 = reverse && tor_addr_family(&addr) == AF_INET6;
addrlen = reverse ? (ipv6 ? 16 : 4) : 1 + strlen(hostname);
if (addrlen > UINT8_MAX) {
log_err(LD_GENERAL, "Hostname is too long!");
return -1;
}
len = 6 + addrlen;
*out = tor_malloc(len);
(*out)[0] = 5; /* SOCKS version 5 */
(*out)[1] = reverse ? '\xF1' : '\xF0'; /* RESOLVE_PTR or RESOLVE */
(*out)[2] = 0; /* reserved. */
if (reverse) {
(*out)[3] = ipv6 ? 4 : 1;
if (ipv6)
memcpy((*out)+4, tor_addr_to_in6_addr8(&addr), 16);
else
set_uint32((*out)+4, tor_addr_to_ipv4n(&addr));
} else {
(*out)[3] = 3;
(*out)[4] = (char)(uint8_t)(addrlen - 1);
memcpy((*out)+5, hostname, addrlen - 1);
}
set_uint16((*out)+4+addrlen, 0); /* port */
} else {
tor_assert(0);
}
return len;
}
static void
onion_warning(const char *hostname)
{
log_warn(LD_NET,
"%s is a hidden service; those don't have IP addresses. "
"You can use the AutomapHostsOnResolve option to have Tor return a "
"fake address for hidden services. Or you can have your "
"application send the address to Tor directly; we recommend an "
"application that uses SOCKS 5 with hostnames.",
hostname);
}
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/** Given a <b>len</b>-byte SOCKS4a response in <b>response</b>, set
* *<b>addr_out</b> to the address it contains (in host order).
* Return 0 on success, -1 on error.
*/
static int
parse_socks4a_resolve_response(const char *hostname,
const char *response, size_t len,
tor_addr_t *addr_out)
{
uint8_t status;
tor_assert(response);
tor_assert(addr_out);
if (len < RESPONSE_LEN_4) {
log_warn(LD_PROTOCOL,"Truncated socks response.");
return -1;
}
if (((uint8_t)response[0])!=0) { /* version: 0 */
log_warn(LD_PROTOCOL,"Nonzero version in socks response: bad format.");
return -1;
}
status = (uint8_t)response[1];
if (get_uint16(response+2)!=0) { /* port: 0 */
log_warn(LD_PROTOCOL,"Nonzero port in socks response: bad format.");
return -1;
}
if (status != 90) {
log_warn(LD_NET,"Got status response '%d': socks request failed.", status);
if (!strcasecmpend(hostname, ".onion")) {
onion_warning(hostname);
return -1;
}
return -1;
}
tor_addr_from_ipv4n(addr_out, get_uint32(response+4));
return 0;
}
/* It would be nice to let someone know what SOCKS5 issue a user may have */
static const char *
socks5_reason_to_string(char reason)
{
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switch (reason) {
case SOCKS5_SUCCEEDED:
return "succeeded";
case SOCKS5_GENERAL_ERROR:
return "general error";
case SOCKS5_NOT_ALLOWED:
return "not allowed";
case SOCKS5_NET_UNREACHABLE:
return "network is unreachable";
case SOCKS5_HOST_UNREACHABLE:
return "host is unreachable";
case SOCKS5_CONNECTION_REFUSED:
return "connection refused";
case SOCKS5_TTL_EXPIRED:
return "ttl expired";
case SOCKS5_COMMAND_NOT_SUPPORTED:
return "command not supported";
case SOCKS5_ADDRESS_TYPE_NOT_SUPPORTED:
return "address type not supported";
default:
return "unknown SOCKS5 code";
}
}
/** Send a resolve request for <b>hostname</b> to the Tor listening on
* <b>sockshost</b>:<b>socksport</b>. Store the resulting IPv4
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* address (in host order) into *<b>result_addr</b>.
*/
static int
do_resolve(const char *hostname,
const tor_addr_t *sockshost, uint16_t socksport,
int reverse, int version,
tor_addr_t *result_addr, char **result_hostname)
{
int s = -1;
struct sockaddr_storage ss;
socklen_t socklen;
char *req = NULL;
ssize_t len = 0;
tor_assert(hostname);
tor_assert(result_addr);
tor_assert(version == 4 || version == 5);
tor_addr_make_unspec(result_addr);
*result_hostname = NULL;
s = tor_open_socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
if (s<0) {
log_sock_error("creating_socket", -1);
return -1;
}
socklen = tor_addr_to_sockaddr(sockshost, socksport,
(struct sockaddr *)&ss, sizeof(ss));
if (connect(s, (struct sockaddr*)&ss, socklen)) {
log_sock_error("connecting to SOCKS host", s);
goto err;
}
if (version == 5) {
char method_buf[2];
if (write_all_to_socket(s, "\x05\x01\x00", 3) != 3) {
log_err(LD_NET, "Error sending SOCKS5 method list.");
goto err;
}
if (read_all_from_socket(s, method_buf, 2) != 2) {
log_err(LD_NET, "Error reading SOCKS5 methods.");
goto err;
}
if (method_buf[0] != '\x05') {
log_err(LD_NET, "Unrecognized socks version: %u",
(unsigned)method_buf[0]);
goto err;
}
if (method_buf[1] != '\x00') {
log_err(LD_NET, "Unrecognized socks authentication method: %u",
(unsigned)method_buf[1]);
goto err;
}
}
if ((len = build_socks_resolve_request(&req, "", hostname, reverse,
version))<0) {
log_err(LD_BUG,"Error generating SOCKS request");
tor_assert(!req);
goto err;
}
if (write_all_to_socket(s, req, len) != len) {
log_sock_error("sending SOCKS request", s);
tor_free(req);
goto err;
}
tor_free(req);
if (version == 4) {
char reply_buf[RESPONSE_LEN_4];
if (read_all_from_socket(s, reply_buf, RESPONSE_LEN_4) != RESPONSE_LEN_4) {
log_err(LD_NET, "Error reading SOCKS4 response.");
goto err;
}
if (parse_socks4a_resolve_response(hostname,
reply_buf, RESPONSE_LEN_4,
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result_addr)<0) {
goto err;
}
} else {
char reply_buf[16];
if (read_all_from_socket(s, reply_buf, 4) != 4) {
log_err(LD_NET, "Error reading SOCKS5 response.");
goto err;
}
if (reply_buf[0] != 5) {
log_err(LD_NET, "Bad SOCKS5 reply version.");
goto err;
}
/* Give a user some useful feedback about SOCKS5 errors */
if (reply_buf[1] != 0) {
log_warn(LD_NET,"Got SOCKS5 status response '%u': %s",
(unsigned)reply_buf[1],
socks5_reason_to_string(reply_buf[1]));
if (reply_buf[1] == 4 && !strcasecmpend(hostname, ".onion")) {
onion_warning(hostname);
}
goto err;
}
if (reply_buf[3] == 1) {
/* IPv4 address */
if (read_all_from_socket(s, reply_buf, 4) != 4) {
log_err(LD_NET, "Error reading address in socks5 response.");
goto err;
}
tor_addr_from_ipv4n(result_addr, get_uint32(reply_buf));
} else if (reply_buf[3] == 4) {
/* IPv6 address */
if (read_all_from_socket(s, reply_buf, 16) != 16) {
log_err(LD_NET, "Error reading address in socks5 response.");
goto err;
}
tor_addr_from_ipv6_bytes(result_addr, reply_buf);
} else if (reply_buf[3] == 3) {
/* Domain name */
size_t result_len;
if (read_all_from_socket(s, reply_buf, 1) != 1) {
log_err(LD_NET, "Error reading address_length in socks5 response.");
goto err;
}
result_len = *(uint8_t*)(reply_buf);
*result_hostname = tor_malloc(result_len+1);
if (read_all_from_socket(s, *result_hostname, result_len)
!= (int) result_len) {
log_err(LD_NET, "Error reading hostname in socks5 response.");
goto err;
}
(*result_hostname)[result_len] = '\0';
}
}
tor_close_socket(s);
return 0;
err:
tor_close_socket(s);
return -1;
}
/** Print a usage message and exit. */
static void
usage(void)
{
puts("Syntax: tor-resolve [-4] [-5] [-v] [-x] [-p port] "
"hostname [sockshost[:socksport]]");
exit(1);
}
/** Entry point to tor-resolve */
int
main(int argc, char **argv)
{
tor_addr_t sockshost;
uint16_t socksport = 0, port_option = 0;
int isSocks4 = 0, isVerbose = 0, isReverse = 0;
char **arg;
int n_args;
tor_addr_t result;
char *result_hostname = NULL;
init_logging(1);
sandbox_disable_getaddrinfo_cache();
arg = &argv[1];
n_args = argc-1;
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if (!n_args)
usage();
if (!strcmp(arg[0],"--version")) {
printf("Tor version %s.\n",VERSION);
return 0;
}
while (n_args && *arg[0] == '-') {
if (!strcmp("-v", arg[0]))
isVerbose = 1;
else if (!strcmp("-4", arg[0]))
isSocks4 = 1;
else if (!strcmp("-5", arg[0]))
isSocks4 = 0;
else if (!strcmp("-x", arg[0]))
isReverse = 1;
else if (!strcmp("-p", arg[0])) {
int p;
if (n_args < 2) {
fprintf(stderr, "No arguments given to -p\n");
usage();
}
p = atoi(arg[1]);
if (p<1 || p > 65535) {
fprintf(stderr, "-p requires a number between 1 and 65535\n");
usage();
}
port_option = (uint16_t) p;
++arg; /* skip the port */
--n_args;
} else {
fprintf(stderr, "Unrecognized flag '%s'\n", arg[0]);
usage();
}
++arg;
--n_args;
}
if (isSocks4 && isReverse) {
fprintf(stderr, "Reverse lookups not supported with SOCKS4a\n");
usage();
}
log_severity_list_t *severities =
tor_malloc_zero(sizeof(log_severity_list_t));
if (isVerbose)
set_log_severity_config(LOG_DEBUG, LOG_ERR, severities);
else
set_log_severity_config(LOG_WARN, LOG_ERR, severities);
add_stream_log(severities, "<stderr>", fileno(stderr));
tor_free(severities);
if (n_args == 1) {
log_debug(LD_CONFIG, "defaulting to localhost");
tor_addr_from_ipv4h(&sockshost, 0x7f000001u); /* localhost */
if (port_option) {
log_debug(LD_CONFIG, "Using port %d", (int)port_option);
socksport = port_option;
} else {
log_debug(LD_CONFIG, "defaulting to port 9050");
socksport = 9050; /* 9050 */
}
} else if (n_args == 2) {
if (tor_addr_port_lookup(arg[1], &sockshost, &socksport)<0) {
fprintf(stderr, "Couldn't parse/resolve address %s", arg[1]);
return 1;
}
if (socksport && port_option && socksport != port_option) {
log_warn(LD_CONFIG, "Conflicting ports; using %d, not %d",
(int)socksport, (int)port_option);
} else if (port_option) {
socksport = port_option;
} else if (!socksport) {
log_debug(LD_CONFIG, "defaulting to port 9050");
socksport = 9050;
}
} else {
usage();
}
if (network_init()<0) {
log_err(LD_BUG,"Error initializing network; exiting.");
return 1;
}
if (do_resolve(arg[0], &sockshost, socksport, isReverse,
isSocks4 ? 4 : 5, &result,
&result_hostname))
return 1;
if (result_hostname) {
printf("%s\n", result_hostname);
} else {
printf("%s\n", fmt_addr(&result));
}
return 0;
}