8c384020b3
reimplementation of the famous tool that can do arbitrary TCP and UDP connections and listens. This gaves sysadm the same tool the crackers have, so that they may learn what the network is about and protect it better. For developers, this is an invaluable debugging tool, and a good build block of scripts. Discussed on: freebsd-hackers@
236 lines
6.2 KiB
C
236 lines
6.2 KiB
C
/* $OpenBSD: socks.c,v 1.9 2004/10/17 03:13:55 djm Exp $ */
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/*
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* Copyright (c) 1999 Niklas Hallqvist. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <err.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define SOCKS_PORT "1080"
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#define HTTP_PROXY_PORT "3128"
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#define HTTP_MAXHDRS 64
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#define SOCKS_V5 5
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#define SOCKS_V4 4
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#define SOCKS_NOAUTH 0
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#define SOCKS_NOMETHOD 0xff
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#define SOCKS_CONNECT 1
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#define SOCKS_IPV4 1
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int remote_connect(char *, char *, struct addrinfo);
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int socks_connect(char *host, char *port, struct addrinfo hints,
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char *proxyhost, char *proxyport, struct addrinfo proxyhints,
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int socksv);
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static in_addr_t
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decode_addr(const char *s)
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{
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struct hostent *hp = gethostbyname (s);
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struct in_addr retval;
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if (hp)
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return *(in_addr_t *)hp->h_addr_list[0];
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if (inet_aton (s, &retval))
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return retval.s_addr;
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errx (1, "cannot decode address \"%s\"", s);
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}
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static in_port_t
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decode_port(const char *s)
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{
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struct servent *sp;
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in_port_t port;
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char *p;
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port = strtol (s, &p, 10);
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if (s == p) {
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sp = getservbyname (s, "tcp");
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if (sp)
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return sp->s_port;
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}
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if (*s != '\0' && *p == '\0')
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return htons (port);
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errx (1, "cannot decode port \"%s\"", s);
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}
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static int
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proxy_read_line(int fd, char *buf, int bufsz)
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{
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int r, off;
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for(off = 0;;) {
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if (off >= bufsz)
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errx(1, "proxy read too long");
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if ((r = read(fd, buf + off, 1)) <= 0) {
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if (r == -1 && errno == EINTR)
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continue;
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err(1, "proxy read");
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}
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/* Skip CR */
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if (buf[off] == '\r')
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continue;
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if (buf[off] == '\n') {
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buf[off] = '\0';
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break;
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}
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off++;
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}
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return (off);
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}
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int
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socks_connect(char *host, char *port, struct addrinfo hints,
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char *proxyhost, char *proxyport, struct addrinfo proxyhints,
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int socksv)
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{
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int proxyfd, r;
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unsigned char buf[1024];
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ssize_t cnt;
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in_addr_t serveraddr;
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in_port_t serverport;
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if (proxyport == NULL)
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proxyport = (socksv == -1) ? HTTP_PROXY_PORT : SOCKS_PORT;
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proxyfd = remote_connect(proxyhost, proxyport, proxyhints);
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if (proxyfd < 0)
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return -1;
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serveraddr = decode_addr (host);
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serverport = decode_port (port);
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if (socksv == 5) {
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/* Version 5, one method: no authentication */
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buf[0] = SOCKS_V5;
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buf[1] = 1;
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buf[2] = SOCKS_NOAUTH;
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cnt = write (proxyfd, buf, 3);
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if (cnt == -1)
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err (1, "write failed");
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if (cnt != 3)
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errx (1, "short write, %d (expected 3)", cnt);
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read (proxyfd, buf, 2);
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if (buf[1] == SOCKS_NOMETHOD)
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errx (1, "authentication method negotiation failed");
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/* Version 5, connect: IPv4 address */
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buf[0] = SOCKS_V5;
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buf[1] = SOCKS_CONNECT;
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buf[2] = 0;
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buf[3] = SOCKS_IPV4;
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memcpy (buf + 4, &serveraddr, sizeof serveraddr);
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memcpy (buf + 8, &serverport, sizeof serverport);
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/* XXX Handle short writes better */
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cnt = write (proxyfd, buf, 10);
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if (cnt == -1)
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err (1, "write failed");
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if (cnt != 10)
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errx (1, "short write, %d (expected 10)", cnt);
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/* XXX Handle short reads better */
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cnt = read (proxyfd, buf, sizeof buf);
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if (cnt == -1)
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err (1, "read failed");
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if (cnt != 10)
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errx (1, "unexpected reply size %d (expected 10)", cnt);
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if (buf[1] != 0)
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errx (1, "connection failed, SOCKS error %d", buf[1]);
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} else if (socksv == 4) {
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/* Version 4 */
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buf[0] = SOCKS_V4;
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buf[1] = SOCKS_CONNECT; /* connect */
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memcpy (buf + 2, &serverport, sizeof serverport);
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memcpy (buf + 4, &serveraddr, sizeof serveraddr);
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buf[8] = 0; /* empty username */
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cnt = write (proxyfd, buf, 9);
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if (cnt == -1)
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err (1, "write failed");
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if (cnt != 9)
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errx (1, "short write, %d (expected 9)", cnt);
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/* XXX Handle short reads better */
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cnt = read (proxyfd, buf, 8);
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if (cnt == -1)
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err (1, "read failed");
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if (cnt != 8)
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errx (1, "unexpected reply size %d (expected 8)", cnt);
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if (buf[1] != 90)
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errx (1, "connection failed, SOCKS error %d", buf[1]);
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} else if (socksv == -1) {
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/* HTTP proxy CONNECT */
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/* Disallow bad chars in hostname */
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if (strcspn(host, "\r\n\t []:") != strlen(host))
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errx (1, "Invalid hostname");
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/* Try to be sane about numeric IPv6 addresses */
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if (strchr(host, ':') != NULL) {
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r = snprintf(buf, sizeof(buf),
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"CONNECT [%s]:%d HTTP/1.0\r\n\r\n",
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host, ntohs(serverport));
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} else {
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r = snprintf(buf, sizeof(buf),
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"CONNECT %s:%d HTTP/1.0\r\n\r\n",
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host, ntohs(serverport));
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}
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if (r == -1 || r >= sizeof(buf))
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errx (1, "hostname too long");
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r = strlen(buf);
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/* XXX atomicio */
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cnt = write (proxyfd, buf, r);
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if (cnt == -1)
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err (1, "write failed");
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if (cnt != r)
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errx (1, "short write, %d (expected %d)", cnt, r);
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/* Read reply */
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for (r = 0; r < HTTP_MAXHDRS; r++) {
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proxy_read_line(proxyfd, buf, sizeof(buf));
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if (r == 0 && strncmp(buf, "HTTP/1.0 200 ", 12) != 0)
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errx (1, "Proxy error: \"%s\"", buf);
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/* Discard headers until we hit an empty line */
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if (*buf == '\0')
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break;
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}
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} else
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errx (1, "Unknown proxy protocol %d", socksv);
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return proxyfd;
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}
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