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SOCKS4.C
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C/C++ Source or Header
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1997-09-16
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4KB
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176 lines
char *socks4_rcs = "$Id: socks4.c,v 1.8 1997/09/06 18:55:39 ACJC Exp $";
/* Written and copyright by the Anonymous Coders and Junkbusters Corporation.
* Will be made available under the GNU General Public License.
* This software comes with NO WARRANTY.
*/
#include <stdio.h>
#include <sys/types.h>
#include <errno.h>
#ifdef _WIN32
#include <io.h>
#include <windows.h>
#else
#include <unistd.h>
#include <netinet/in.h>
#endif
#ifdef REGEX
#include <gnu_regex.h>
#endif
#include "jcc.h"
#define SOCKS_REQUEST_GRANTED 90
#define SOCKS_REQUEST_REJECT 91
#define SOCKS_REQUEST_IDENT_FAILED 92
#define SOCKS_REQUEST_IDENT_CONFLICT 93
/* structure of a socks client operation */
struct socks_op {
unsigned char vn; /* socks version number */
unsigned char cd; /* command code */
unsigned char dstport[2]; /* destination port */
unsigned char dstip[4]; /* destination address */
unsigned char userid; /* first byte of userid */
/* more bytes of the userid follow, terminated by a NULL */
};
/* structure of a socks server reply */
struct socks_reply {
unsigned char vn; /* socks version number */
unsigned char cd; /* command code */
unsigned char dstport[2]; /* destination port */
unsigned char dstip[4]; /* destination address */
};
static char socks_userid[] = "anonymous";
int
socks4_connect(struct gateway *gw, struct http_request *http)
{
unsigned char cbuf[BUFSIZ];
unsigned char sbuf[BUFSIZ];
struct socks_op *c = (struct socks_op *)cbuf;
struct socks_reply *s = (struct socks_reply *)sbuf;
int web_server_addr;
int n, csiz, sfd, target_port;
int err = 0;
char *errstr, *target_host;
if((gw->gateway_host == NULL) || (*gw->gateway_host == '\0')) {
if(DEBUG(CON)) fprintf(logfp,
" socks4_connect: NULL gateway host specified\n");
err = 1;
}
if(gw->gateway_port <= 0) {
if(DEBUG(CON)) fprintf(logfp,
" socks4_connect: invalid gateway port specified\n");
err = 1;
}
if(err) {
errno = EINVAL;
return(-1);
}
if(gw->forward_host) {
target_host = gw->forward_host;
target_port = gw->forward_port;
} else {
target_host = http->host;
target_port = http->port;
}
/* build a socks request for connection to the web server */
strcpy((char *)&(c->userid), socks_userid);
csiz = sizeof(*c) + sizeof(socks_userid) - 1;
switch(gw->type) {
case SOCKS_4:
web_server_addr = htonl(atoip(target_host));
break;
case SOCKS_4A:
web_server_addr = 0x00000001;
n = csiz + strlen(target_host) + 1;
if(n > sizeof(cbuf)) {
errno = EINVAL;
return(-1);
}
strcpy(((char *)cbuf) + csiz, http->host);
csiz = n;
break;
}
c->vn = 4;
c->cd = 1;
c->dstport[0] = (target_port >> 8) & 0xff;
c->dstport[1] = (target_port ) & 0xff;
c->dstip[0] = (web_server_addr >> 24) & 0xff;
c->dstip[1] = (web_server_addr >> 16) & 0xff;
c->dstip[2] = (web_server_addr >> 8) & 0xff;
c->dstip[3] = (web_server_addr ) & 0xff;
/* pass the request to the socks server */
sfd = connect_to(gw->gateway_host, gw->gateway_port);
if(sfd < 0) {
return(-1);
}
if((n = write_socket(sfd, c, csiz)) != csiz) {
if(DEBUG(CON)) {
fprintf(logfp, "SOCKS4 negotiation write failed...");
}
close_socket(sfd);
return(-1);
}
if((n = read_socket(sfd, sbuf, sizeof(sbuf))) != sizeof(*s)) {
if(DEBUG(CON)) {
fprintf(logfp, "SOCKS4 negotiation read failed...");
}
close_socket(sfd);
return(-1);
}
switch(s->cd) {
case SOCKS_REQUEST_GRANTED:
return(sfd);
break;
case SOCKS_REQUEST_REJECT:
errstr = "SOCKS request rejected or failed";
errno = EINVAL;
break;
case SOCKS_REQUEST_IDENT_FAILED:
errstr = "SOCKS request rejected because "
"SOCKS server cannot connect to identd on the client";
errno = EACCES;
break;
case SOCKS_REQUEST_IDENT_CONFLICT:
errstr = "SOCKS request rejected because "
"the client program and identd report "
"different user-ids";
errno = EACCES;
break;
default:
errstr = (char *) cbuf;
errno = ENOENT;
sprintf(errstr,
"SOCKS request rejected for reason code %d\n", s->cd);
}
if(DEBUG(CON)) {
fprintf(logfp, " socks4_connect: %s ...", errstr);
}
close_socket(sfd);
return(-1);
}