Elimar Riesebieter wrote in
<20200717154710.ngfefdhfx3o63...@toy.home.lxtec.de>:
|* Fadi Barbàra <m...@fadibarbara.it> [2020-07-17 12:43 +0200]:
|
|> Hi everybody,
|> I am trying to compile lynx with socks5 support (--with-socks
|> --with-socks5). Unfortunately I do not find how to install the library
|> needed for the job. I am on debian.
|>
|> Do you know where to look for an answer?
|
|AFAIK libsocks5 isn't available on Debian. Testet with
|
|$ apt-cache search libsocks
|
|Elimar
I never have seen such a library. So either you, Fadi, have to
use the lynx development version which has builtin SOCKS5 support,
or you could use the wrapper program below, from Gaetan Bisson of
ArchLinux.
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
/*
* Copyright (C) 2013, Gaetan Bisson <bis...@archlinux.org>.
*
* 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.
*/
/*
* USocks. Minimalistic SOCKS5 proxying library.
*
* USocks implements a connect() function (on top of the system one) which
* forwards connections through a prescribed SOCKS5 proxy; its design focuses
* are code clarity and conciseness.
*
* Compile with:
*
* cc -O2 -fPIC -ldl -shared -o usocks.so usocks.c
*
* Use by exporting:
*
* USOCKS_PORT=7772
* USOCKS_ADDR=127.0.0.1
* LD_PRELOAD=`pwd`/usocks.so
*/
/* ****************************************************************************
*
* HEADERS
*
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* ****************************************************************************
*
* INITIALIZE PROXY DATA AND LOCATE LIBC'S CONNECT()
*
*/
typedef int (*connect_t)(int, const struct sockaddr *, socklen_t);
connect_t r_connect;
struct sockaddr_in us_proxy;
int us_in = 1;
int us_init () {
char *port = getenv("USOCKS_PORT");
char *addr = getenv("USOCKS_ADDR");
if (!port || !addr) return 1;
memset(&us_proxy, 0, sizeof(us_proxy));
us_proxy.sin_family = AF_INET;
us_proxy.sin_port = htons(atoi(port));
us_proxy.sin_addr.s_addr = inet_addr(addr);
r_connect = (connect_t)(intptr_t)dlsym(RTLD_NEXT, "connect");
return 0;
}
/* ****************************************************************************
*
* LEAVE NO BYTES BEHIND
*
*/
int us_sendall (int socket, const char *buffer, size_t length, int flags) {
int r, off=0;
while(off<length) {
r = send(socket, buffer+off, length-off, flags);
if (r<0) return -1;
off += r;
}
return off;
}
int us_recvall (int socket, char *buffer, size_t length, int flags) {
int r, off=0;
while (off<length) {
r = recv(socket, buffer+off, length-off, flags);
if (r<0) return -1;
off += r;
}
return off;
}
/* ****************************************************************************
*
* REDEFINE CONNECT()
*
*/
const unsigned char l4[] = { 0x7f }; /* matches loopback IPv4 addresses */
const unsigned char l6[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }; /* matches loopback IPv6 address */
const unsigned char l64[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 0x7f }; /* matches loopback IPv6to4 addresses */
int connect (int sock, const struct sockaddr *addr, socklen_t len) {
int p, t, v, f=sizeof(t);
char b[256];
/* get proxy data */
if (us_in) us_in = us_init();
if (us_in) return -1;
/* let unix domain sockets and loopback traffic through */
switch (addr->sa_family) {
case AF_UNIX:
return r_connect(sock,addr,len);
case AF_INET6:
if (!memcmp(&(((struct sockaddr_in6 *)addr)->sin6_addr.s6_addr), l64, 13) ||
!memcmp(&(((struct sockaddr_in6 *)addr)->sin6_addr.s6_addr), l6, 16))
return r_connect(sock,addr,len);
v=16;
break;
case AF_INET:
if (!memcmp(&(((struct sockaddr_in *)addr)->sin_addr.s_addr), l4, 1))
return r_connect(sock,addr,len);
v=4;
break;
default:
return -1;
}
/* let non-TCP through */
getsockopt(sock, SOL_SOCKET, SO_TYPE, &t, (socklen_t *)&f);
if (t!=SOCK_STREAM) return r_connect(sock,addr,len);
/* open blocking connection to proxy */
f = fcntl(sock, F_GETFL);
p = socket(AF_INET, SOCK_STREAM, 0);
fcntl(p, F_SETFL, f & ~O_NONBLOCK);
if (r_connect(p,(struct sockaddr*)&us_proxy,sizeof(us_proxy))) return -1;
/* protocol version and authentication method */
b[0] = '\x05';
b[1] = '\x01';
b[2] = '\x00';
if (us_sendall(p,b,3,0)!=3) goto err;
if (us_recvall(p,b,2,0)!=2) goto err;
if (b[0]!='\x05') goto err;
if (b[1]!='\x00') goto err;
/* connection request */
b[0] = '\x05';
b[1] = '\x01';
b[2] = '\x00';
if (v==4) {
b[3] = '\x01';
memcpy(b+4, &(((struct sockaddr_in *)addr)->sin_addr.s_addr), 4);
memcpy(b+8, &(((struct sockaddr_in *)addr)->sin_port), 2);
} else {
b[3] = '\x04';
memcpy(b+4, &(((struct sockaddr_in6 *)addr)->sin6_addr.s6_addr), 16);
memcpy(b+20, &(((struct sockaddr_in6 *)addr)->sin6_port), 2);
}
if (us_sendall(p,b,v+6,0)!=v+6) goto err;
if (us_recvall(p,b,4,0)!=4) goto err;
if (b[0]!='\x05') goto err;
if (b[1]!='\x00') goto err;
if (b[2]!='\x00') goto err;
if (b[3]=='\x01') {
if (us_recvall(p,b,6,0)!=6) goto err;
} else {
if (us_recvall(p,b,18,0)!=18) goto err;
}
/* return proxy socket */
close(sock);
fcntl(p, F_SETFL, f);
fcntl(p, F_DUPFD, sock);
return 0;
err:
close(p);
return -1;
}
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