/* $OpenBSD: socks.c,v 1.24 2016/06/27 14:43:04 deraadt Exp $ */
/*
* Copyright (c) 1999 Niklas Hallqvist. All rights reserved.
* Copyright (c) 2004, 2005 Damien Miller. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: socks.c,v 1.3 2017/02/09 20:37:58 joerg Exp $");
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <resolv.h>
#ifdef __OpenBSD__
#include <readpassphrase.h>
#endif
#include "atomicio.h"
#define SOCKS_PORT "1080"
#define HTTP_PROXY_PORT "3128"
#define HTTP_MAXHDRS 64
#define SOCKS_V5 5
#define SOCKS_V4 4
#define SOCKS_NOAUTH 0
#define SOCKS_NOMETHOD 0xff
#define SOCKS_CONNECT 1
#define SOCKS_IPV4 1
#define SOCKS_DOMAIN 3
#define SOCKS_IPV6 4
int remote_connect(const char *, const char *, struct addrinfo);
int socks_connect(const char *, const char *, struct addrinfo,
const char *, const char *, struct addrinfo, int,
const char *);
static int
decode_addrport(const char *h, const char *p, struct sockaddr *addr,
socklen_t addrlen, int v4only, int numeric)
{
int r;
struct addrinfo hints, *res;
bzero(&hints, sizeof(hints));
hints.ai_family = v4only ? PF_INET : PF_UNSPEC;
hints.ai_flags = numeric ? AI_NUMERICHOST : 0;
hints.ai_socktype = SOCK_STREAM;
r = getaddrinfo(h, p, &hints, &res);
/* Don't fatal when attempting to convert a numeric address */
if (r != 0) {
if (!numeric) {
errx(1, "getaddrinfo(\"%.64s\", \"%.64s\"): %s", h, p,
gai_strerror(r));
}
return (-1);
}
if (addrlen < res->ai_addrlen) {
freeaddrinfo(res);
errx(1, "internal error: addrlen < res->ai_addrlen");
}
memcpy(addr, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);
return (0);
}
static int
proxy_read_line(int fd, char *buf, size_t bufsz)
{
size_t off;
for(off = 0;;) {
if (off >= bufsz)
errx(1, "proxy read too long");
if (atomicio(read, fd, buf + off, 1) != 1)
err(1, "proxy read");
/* Skip CR */
if (buf[off] == '\r')
continue;
if (buf[off] == '\n') {
buf[off] = '\0';
break;
}
off++;
}
return (off);
}
static const char *
getproxypass(const char *proxyuser, const char *proxyhost)
{
char prompt[512];
static char pw[256];
snprintf(prompt, sizeof(prompt), "Proxy password for %s@%s: ",
proxyuser, proxyhost);
#ifdef __NetBSD__
if (getpassfd(prompt, pw, sizeof(pw), NULL, GETPASS_NEED_TTY, 0)
== NULL)
#else
if (readpassphrase(prompt, pw, sizeof(pw), RPP_REQUIRE_TTY) == NULL)
#endif
err(1, "Unable to read proxy passphrase");
return (pw);
}
/*
* Error strings adapted from the generally accepted SOCKSv4 spec:
*
*
http://ftp.icm.edu.pl/packages/socks/socks4/SOCKS4.protocol
*/
static const char *
socks4_strerror(int e)
{
switch (e) {
case 90:
return "Succeeded";
case 91:
return "Request rejected or failed";
case 92:
return "SOCKS server cannot connect to identd on the client";
case 93:
return "Client program and identd report different user-ids";
default:
return "Unknown error";
}
}
/*
* Error strings taken almost directly from RFC 1928.
*/
static const char *
socks5_strerror(int e)
{
switch (e) {
case 0:
return "Succeeded";
case 1:
return "General SOCKS server failure";
case 2:
return "Connection not allowed by ruleset";
case 3:
return "Network unreachable";
case 4:
return "Host unreachable";
case 5:
return "Connection refused";
case 6:
return "TTL expired";
case 7:
return "Command not supported";
case 8:
return "Address type not supported";
default:
return "Unknown error";
}
}
int
socks_connect(const char *host, const char *port,
struct addrinfo hints __unused,
const char *proxyhost, const char *proxyport, struct addrinfo proxyhints,
int socksv, const char *proxyuser)
{
int proxyfd, r, authretry = 0;
size_t hlen, wlen;
unsigned char buf[1024];
char *cbuf = (char *)buf;
size_t cnt;
struct sockaddr_storage addr;
struct sockaddr_in *in4 = (struct sockaddr_in *)&addr;
struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&addr;
in_port_t serverport;
const char *proxypass = NULL;
if (proxyport == NULL)
proxyport = (socksv == -1) ? HTTP_PROXY_PORT : SOCKS_PORT;
/* Abuse API to lookup port */
if (decode_addrport("0.0.0.0", port, (struct sockaddr *)&addr,
sizeof(addr), 1, 1) == -1)
errx(1, "unknown port \"%.64s\"", port);
serverport = in4->sin_port;
again:
if (authretry++ > 3)
errx(1, "Too many authentication failures");
proxyfd = remote_connect(proxyhost, proxyport, proxyhints);
if (proxyfd < 0)
return (-1);
if (socksv == 5) {
if (decode_addrport(host, port, (struct sockaddr *)&addr,
sizeof(addr), 0, 1) == -1)
addr.ss_family = 0; /* used in switch below */
/* Version 5, one method: no authentication */
buf[0] = SOCKS_V5;
buf[1] = 1;
buf[2] = SOCKS_NOAUTH;
cnt = atomicio(vwrite, proxyfd, buf, 3);
if (cnt != 3)
err(1, "write failed (%zu/3)", cnt);
cnt = atomicio(read, proxyfd, buf, 2);
if (cnt != 2)
err(1, "read failed (%zu/3)", cnt);
if (buf[1] == SOCKS_NOMETHOD)
errx(1, "authentication method negotiation failed");
switch (addr.ss_family) {
case 0:
/* Version 5, connect: domain name */
/* Max domain name length is 255 bytes */
hlen = strlen(host);
if (hlen > 255)
errx(1, "host name too long for SOCKS5");
buf[0] = SOCKS_V5;
buf[1] = SOCKS_CONNECT;
buf[2] = 0;
buf[3] = SOCKS_DOMAIN;
buf[4] = hlen;
memcpy(buf + 5, host, hlen);
memcpy(buf + 5 + hlen, &serverport, sizeof serverport);
wlen = 7 + hlen;
break;
case AF_INET:
/* Version 5, connect: IPv4 address */
buf[0] = SOCKS_V5;
buf[1] = SOCKS_CONNECT;
buf[2] = 0;
buf[3] = SOCKS_IPV4;
memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr);
memcpy(buf + 8, &in4->sin_port, sizeof in4->sin_port);
wlen = 10;
break;
case AF_INET6:
/* Version 5, connect: IPv6 address */
buf[0] = SOCKS_V5;
buf[1] = SOCKS_CONNECT;
buf[2] = 0;
buf[3] = SOCKS_IPV6;
memcpy(buf + 4, &in6->sin6_addr, sizeof in6->sin6_addr);
memcpy(buf + 20, &in6->sin6_port,
sizeof in6->sin6_port);
wlen = 22;
break;
default:
errx(1, "internal error: silly AF");
}
cnt = atomicio(vwrite, proxyfd, buf, wlen);
if (cnt != wlen)
err(1, "write failed (%zu/%zu)", cnt, wlen);
cnt = atomicio(read, proxyfd, buf, 4);
if (cnt != 4)
err(1, "read failed (%zu/4)", cnt);
if (buf[1] != 0) {
errx(1, "connection failed, SOCKSv5 error: %s",
socks5_strerror(buf[1]));
}
switch (buf[3]) {
case SOCKS_IPV4:
cnt = atomicio(read, proxyfd, buf + 4, 6);
if (cnt != 6)
err(1, "read failed (%zu/6)", cnt);
break;
case SOCKS_IPV6:
cnt = atomicio(read, proxyfd, buf + 4, 18);
if (cnt != 18)
err(1, "read failed (%zu/18)", cnt);
break;
default:
errx(1, "connection failed, unsupported address type");
}
} else if (socksv == 4) {
/* This will exit on lookup failure */
decode_addrport(host, port, (struct sockaddr *)&addr,
sizeof(addr), 1, 0);
/* Version 4 */
buf[0] = SOCKS_V4;
buf[1] = SOCKS_CONNECT; /* connect */
memcpy(buf + 2, &in4->sin_port, sizeof in4->sin_port);
memcpy(buf + 4, &in4->sin_addr, sizeof in4->sin_addr);
buf[8] = 0; /* empty username */
wlen = 9;
cnt = atomicio(vwrite, proxyfd, buf, wlen);
if (cnt != wlen)
err(1, "write failed (%zu/%zu)", cnt, wlen);
cnt = atomicio(read, proxyfd, buf, 8);
if (cnt != 8)
err(1, "read failed (%zu/8)", cnt);
if (buf[1] != 90) {
errx(1, "connection failed, SOCKSv4 error: %s",
socks4_strerror(buf[1]));
}
} else if (socksv == -1) {
/* HTTP proxy CONNECT */
/* Disallow bad chars in hostname */
if (strcspn(host, "\r\n\t []:") != strlen(host))
errx(1, "Invalid hostname");
/* Try to be sane about numeric IPv6 addresses */
if (strchr(host, ':') != NULL) {
r = snprintf(cbuf, sizeof(buf),
"CONNECT [%s]:%d HTTP/1.0\r\n",
host, ntohs(serverport));
} else {
r = snprintf(cbuf, sizeof(buf),
"CONNECT %s:%d HTTP/1.0\r\n",
host, ntohs(serverport));
}
if (r == -1 || (size_t)r >= sizeof(buf))
errx(1, "hostname too long");
r = strlen(cbuf);
cnt = atomicio(vwrite, proxyfd, buf, r);
if (cnt != (size_t)r)
err(1, "write failed (%zu/%d)", cnt, r);
if (authretry > 1) {
char resp[1024];
proxypass = getproxypass(proxyuser, proxyhost);
r = snprintf(cbuf, sizeof(buf), "%s:%s",
proxyuser, proxypass);
if (r == -1 || (size_t)r >= sizeof(buf) ||
b64_ntop(buf, strlen(cbuf), resp,
sizeof(resp)) == -1)
errx(1, "Proxy username/password too long");
r = snprintf(cbuf, sizeof(buf), "Proxy-Authorization: "
"Basic %s\r\n", resp);
if (r == -1 || (size_t)r >= sizeof(buf))
errx(1, "Proxy auth response too long");
r = strlen(cbuf);
if ((ssize_t)(cnt = atomicio(vwrite, proxyfd, buf, r)) != r)
err(1, "write failed (%zu/%d)", cnt, r);
}
/* Terminate headers */
if ((cnt = atomicio(vwrite, proxyfd, __UNCONST("\r\n"), 2)) != 2)
err(1, "write failed (%zu/2)", cnt);
/* Read status reply */
proxy_read_line(proxyfd, cbuf, sizeof(buf));
if (proxyuser != NULL &&
strncmp(cbuf, "HTTP/1.0 407 ", 12) == 0) {
if (authretry > 1) {
fprintf(stderr, "Proxy authentication "
"failed\n");
}
close(proxyfd);
goto again;
} else if (strncmp(cbuf, "HTTP/1.0 200 ", 12) != 0 &&
strncmp(cbuf, "HTTP/1.1 200 ", 12) != 0)
errx(1, "Proxy error: \"%s\"", buf);
/* Headers continue until we hit an empty line */
for (r = 0; r < HTTP_MAXHDRS; r++) {
proxy_read_line(proxyfd, cbuf, sizeof(buf));
if (*buf == '\0')
break;
}
if (*buf != '\0')
errx(1, "Too many proxy headers received");
} else
errx(1, "Unknown proxy protocol %d", socksv);
return (proxyfd);
}
