DeforaNetworks/fwknop
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fwknop/client/http_resolve_host.c

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/*
*****************************************************************************
*
* 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 2009-2013 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
struct url
{
char port[MAX_PORT_STR_LEN+1];
char host[MAX_URL_HOST_LEN+1];
char path[MAX_URL_PATH_LEN+1];
};
static int
try_url(struct url *url, fko_cli_options_t *options)
{
int sock, res, error, http_buf_len, i;
int bytes_read = 0, position = 0;
int o1, o2, o3, o4;
struct addrinfo *result, *rp, hints;
char http_buf[HTTP_MAX_REQUEST_LEN] = {0};
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 )
{
log_msg(LOG_VERBOSITY_ERROR, "Winsock initialization error %d", 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: close\r\n\r\n",
url->path,
options->http_user_agent,
url->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(url->host, url->port, &hints, &result);
if (error != 0)
{
log_msg(LOG_VERBOSITY_ERROR, "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) {
log_msg(LOG_VERBOSITY_ERROR, "resolve_ip_http: Could not create socket: ", strerror(errno));
return(-1);
}
freeaddrinfo(result);
log_msg(LOG_VERBOSITY_DEBUG, "\nHTTP request: %s", http_buf);
res = send(sock, http_buf, http_buf_len, 0);
if(res < 0)
{
log_msg(LOG_VERBOSITY_ERROR, "resolve_ip_http: write error: ", strerror(errno));
}
else if(res != http_buf_len)
{
log_msg(LOG_VERBOSITY_WARNING,
"[#] Warning: bytes sent (%i) not spa data length (%i).",
res, http_buf_len
);
}
do
{
memset(http_buf, 0x0, sizeof(http_buf));
bytes_read = recv(sock, http_buf, sizeof(http_buf), 0);
if ( bytes_read > 0 ) {
if(position + bytes_read >= HTTP_MAX_RESPONSE_LEN)
break;
memcpy(&http_response[position], http_buf, bytes_read);
position += bytes_read;
}
}
while ( bytes_read > 0 );
http_response[HTTP_MAX_RESPONSE_LEN-1] = '\0';
#ifdef WIN32
closesocket(sock);
#else
close(sock);
#endif
log_msg(LOG_VERBOSITY_DEBUG, "\nHTTP response: %s", http_response);
/* 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)
{
log_msg(LOG_VERBOSITY_ERROR, "Did not find the end of HTTP header.");
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_IPV4_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, sizeof(options->allow_ip_str));
log_msg(LOG_VERBOSITY_INFO,
"\n[+] Resolved external IP (via http://%s%s) as: %s",
url->host,
url->path,
options->allow_ip_str);
return(1);
}
else
{
log_msg(LOG_VERBOSITY_ERROR,
"[-] From http://%s%s\n Invalid IP (%s) in HTTP response:\n\n%s",
url->host, url->path, ndx, http_response);
return(-1);
}
}
static int
parse_url(char *res_url, struct url* url)
{
char *s_ndx, *e_ndx;
int tlen, tlen_offset, port, is_err;
/* https is not supported.
*/
if(strncasecmp(res_url, "https", 5) == 0)
{
log_msg(LOG_VERBOSITY_ERROR, "[*] https is not yet supported for http-resolve-ip.");
return(-1);
}
/* Strip off http:// portion if necessary
*/
if(strncasecmp(res_url, "http://", 7) == 0)
s_ndx = res_url + 7;
else
s_ndx = res_url;
/* Look for a colon in case an alternate port was specified.
*/
e_ndx = strchr(s_ndx, ':');
if(e_ndx != NULL)
{
port = strtol_wrapper(e_ndx+1, 1, MAX_PORT, NO_EXIT_UPON_ERR, &is_err);
if(is_err != FKO_SUCCESS)
{
log_msg(LOG_VERBOSITY_ERROR,
"[*] resolve-url port value is invalid, must be in [%d-%d]",
1, MAX_PORT);
return(-1);
}
snprintf(url->port, sizeof(url->port)-1, "%u", port);
/* Get the offset we need to skip the port portion when we
* extract the hostname part.
*/
tlen_offset = strlen(url->port)+1;
}
else
{
strlcpy(url->port, "80", sizeof(url->port));
tlen_offset = 0;
}
/* Get rid of any trailing slash
*/
if(res_url[strlen(res_url)-1] == '/')
res_url[strlen(res_url)-1] = '\0';
e_ndx = strchr(s_ndx, '/');
if(e_ndx == NULL)
tlen = strlen(s_ndx)+1;
else
tlen = (e_ndx-s_ndx)+1;
tlen -= tlen_offset;
if(tlen > MAX_URL_HOST_LEN)
{
log_msg(LOG_VERBOSITY_ERROR, "resolve-url hostname portion is too large.");
return(-1);
}
strlcpy(url->host, s_ndx, tlen);
if(e_ndx != NULL)
{
if(strlen(e_ndx) > MAX_URL_PATH_LEN)
{
log_msg(LOG_VERBOSITY_ERROR, "resolve-url path portion is too large.");
return(-1);
}
strlcpy(url->path, e_ndx, sizeof(url->path));
}
else
{
/* default to "GET /" if there isn't a more specific URL
*/
strlcpy(url->path, "/", sizeof(url->path));
}
return(0);
}
int
resolve_ip_http(fko_cli_options_t *options)
{
int res;
struct url url;
memset(&url, 0, sizeof(url));
if(options->resolve_url != NULL)
{
if(parse_url(options->resolve_url, &url) < 0)
{
log_msg(LOG_VERBOSITY_ERROR, "Error parsing resolve-url");
return(-1);
}
res = try_url(&url, options);
} else {
strlcpy(url.port, "80", sizeof(url.port));
strlcpy(url.host, HTTP_RESOLVE_HOST, sizeof(url.host));
strlcpy(url.path, HTTP_RESOLVE_URL, sizeof(url.path));
res = try_url(&url, options);
if(res != 1)
{
/* try the backup url (just switches the host to cipherdyne.com)
*/
strlcpy(url.host, HTTP_BACKUP_RESOLVE_HOST, sizeof(url.host));
#ifndef WIN32
sleep(2);
#endif
res = try_url(&url, options);
}
}
return(res);
}
/***EOF***/
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