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/* $Id: http_resolve_host.c 268 2010-07-18 01:56:19Z dstuart $
*****************************************************************************
*
* File: http_resolve_host.c
*
* Author: Damien S. Stuart
*
* Purpose: Routine for using an http request to obtain a client's IP
* address as seen from the outside world.
*
* Copyright 2009-2010 Damien Stuart (dstuart@dstuart.org)
*
* License (GNU Public License):
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*****************************************************************************
*/
#include "fwknop_common.h"
#include "utils.h"
#include <errno.h>
#ifdef WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#else
#if HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#include <netdb.h>
#endif
int
resolve_ip_http(fko_cli_options_t *options)
{
int sock, res, error, http_buf_len, i;
int o1, o2, o3, o4;
struct addrinfo *result, *rp, hints;
char http_buf[HTTP_MAX_REQUEST_LEN];
char http_response[HTTP_MAX_RESPONSE_LEN] = {0};
char *ndx;
#ifdef WIN32
WSADATA wsa_data;
/* Winsock needs to be initialized...
*/
res = WSAStartup( MAKEWORD(1,1), &wsa_data );
if( res != 0 )
{
fprintf(stderr, "Winsock initialization error %d\n", res );
return(-1);
}
#endif
/* Build our HTTP request to resolve the external IP (this is similar to
* to contacting whatismyip.org, but using a different URL).
*/
snprintf(http_buf, HTTP_MAX_REQUEST_LEN,
"GET %s HTTP/1.0\r\nUser-Agent: %s\r\nAccept: */*\r\n"
"Host: %s\r\nConnection: Keep-Alive\r\n\r\n",
HTTP_RESOLVE_URL, options->http_user_agent, HTTP_RESOLVE_HOST
);
http_buf_len = strlen(http_buf);
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
error = getaddrinfo(HTTP_RESOLVE_HOST, "80", &hints, &result);
if (error != 0)
{
fprintf(stderr, "error in getaddrinfo: %s\n", gai_strerror(error));
return(-1);
}
for (rp = result; rp != NULL; rp = rp->ai_next) {
sock = socket(rp->ai_family, rp->ai_socktype,
rp->ai_protocol);
if (sock < 0)
continue;
if ((error = (connect(sock, rp->ai_addr, rp->ai_addrlen) != -1)))
break; /* made it */
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
}
if (rp == NULL) {
perror("resolve_ip_http: Could not create socket: ");
return(-1);
}
freeaddrinfo(result);
res = send(sock, http_buf, http_buf_len, 0);
if(res < 0)
{
perror("resolve_ip_http: write error: ");
}
else if(res != http_buf_len)
{
fprintf(stderr,
"[#] Warning: bytes sent (%i) not spa data length (%i).\n",
res, http_buf_len
);
}
res = recv(sock, http_response, HTTP_MAX_RESPONSE_LEN, 0);
http_response[HTTP_MAX_RESPONSE_LEN-1] = '\0';
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
/* Move to the end of the HTTP header and to the start of the content.
*/
ndx = strstr(http_response, "\r\n\r\n");
if(ndx == NULL)
{
fprintf(stderr, "Did not find the end of HTTP header.\n");
return(-1);
}
ndx += 4;
/* Walk along the content to try to find the end of the IP address.
* Note: We are expecting the content to be just an IP address
* (possibly followed by whitespace or other not-digit value).
*/
for(i=0; i<MAX_IP_STR_LEN; i++) {
if(! isdigit(*(ndx+i)) && *(ndx+i) != '.')
break;
}
/* Terminate at the first non-digit and non-dot.
*/
*(ndx+i) = '\0';
/* Now that we have what we think is an IP address string. We make
* sure the format and values are sane.
*/
if((sscanf(ndx, "%u.%u.%u.%u", &o1, &o2, &o3, &o4)) == 4
&& o1 >= 0 && o1 <= 255
&& o2 >= 0 && o2 <= 255
&& o3 >= 0 && o3 <= 255
&& o4 >= 0 && o4 <= 255)
{
strlcpy(options->allow_ip_str, ndx, MAX_IP_STR_LEN);
if(options->verbose)
printf("Resolved external IP (via http://%s%s) as: %s\n",
HTTP_RESOLVE_HOST, HTTP_RESOLVE_URL, options->allow_ip_str);
return(0);
}
else
{
fprintf(stderr, "Invalid IP (%s) in HTTP response.\n", ndx);
return(-1);
}
}
/***EOF***/
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