proxytunnel/http.c

/* Proxytunnel - (C) 2001-2020 Jos Visser / Mark Janssen    */
/* Contact:                  josv@osp.nl / maniac@maniac.nl */

/*
 * 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
 */

/* http.c */

#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>

#include "proxytunnel.h"
#include "io.h"
#include "basicauth.h"
#include "ntlm.h"

/*
 * Analyze the proxy's HTTP response. This must be a HTTP/1.? 200 OK type
 * header
 */
void analyze_HTTP(PTSTREAM *pts) {
	char *p;

	/* Strip html error pages for faulty proxies (Stephane Engel <steph[at]macchiati.org>) */
	do {
		if (readline(pts) <= 0) {
			message( "analyze_HTTP: readline failed: Connection closed by remote host\n" );
			exit(2);
		}
		p = strtok( buf, " \t");
	} while (strncmp( p, "HTTP/", 5) != 0 );

	if (strcmp( p, "HTTP/1.0" ) != 0 && strcmp( p, "HTTP/1.1" ) != 0) {
		message( "Unsupported HTTP version number %s\n", p );
		exit( 1 );
	}

	p = strtok( NULL, " ");

	if( strcmp( p, "200" ) != 0 ) {
		if( ! args_info.quiet_flag )
			message( "HTTP return code: %s ", p );

		p += strlen( p ) + 1;

		if( ! args_info.quiet_flag )
			message( "%s", p );

		if (!ntlm_challenge && strcmp( p, "407") != 0) {
			do {
				readline(pts);
				if (strncmp( buf, "Proxy-Authenticate: NTLM ", 25) == 0) {
					if (parse_type2((unsigned char *)&buf[25]) < 0)
						exit(1);
				}
			} while ( strcmp( buf, "\r\n" ) != 0 );
		}

		if (ntlm_challenge == 1) {
			proxy_protocol(pts);
			return;
		}
		exit( 1 );
	}
}

/*
 * Prints lines from a buffer prepended with a prefix
 */
void print_line_prefix(char *buf, char *prefix) {
	buf = strdup(buf);
	char *cur = strtok(buf, "\r\n");
	while ( cur != NULL) {
		message( "%s%s\n", prefix, cur );
		cur = strtok(NULL, "\r\n");
	}
//	message( "%s: '%s\n", prefix, buf );
}

/*
 * Execute the basic proxy protocol of CONNECT and response, until the
 * last line of the response has been read. The tunnel is then open.
 */
void proxy_protocol(PTSTREAM *pts) {
	/* Create the proxy CONNECT command into buf */
	if (args_info.remproxy_given ) {
		if( args_info.verbose_flag )
			message( "\nTunneling to %s (remote proxy)\n", args_info.remproxy_arg );
		sprintf( buf, "CONNECT %s HTTP/1.1\r\nHost: %s\r\n", args_info.remproxy_arg, args_info.host_arg ? args_info.host_arg : args_info.remproxy_arg );
	} else {
		if( args_info.verbose_flag )
			message( "\nTunneling to %s (destination)\n", args_info.dest_arg );
		sprintf( buf, "CONNECT %s HTTP/1.1\r\nHost: %s\r\n", args_info.dest_arg, args_info.host_arg ? args_info.host_arg : args_info.proxyhost_arg );
	}
	
	if ( args_info.user_given && args_info.pass_given ) {
		/* Create connect string including the authorization part */
		if (args_info.ntlm_flag) {
			if (ntlm_challenge == 1) {
				build_type3_response();
				ntlm_challenge = 2;
				strzcat( buf, "Proxy-Authorization: NTLM %s\r\n", ntlm_type3_buf );
			} else if (ntlm_challenge == 0) {
				strzcat( buf, "Proxy-Authorization: NTLM %s\r\n", ntlm_type1_buf );
			}
		} else {
			strzcat( buf, "Proxy-Authorization: Basic %s\r\n", basicauth(args_info.user_arg, args_info.pass_arg ) );
		}
	}

	strzcat( buf, "Proxy-Connection: Keep-Alive\r\n");
	/* Add extra header(s), headers are already \r\n terminated */
	if ( args_info.header_given )
		strzcat( buf, "%s", args_info.header_arg );

	strzcat( buf, "\r\n" );


	/* Print the CONNECT instruction before sending to proxy */
	if( args_info.verbose_flag ) {
		message( "Communication with local proxy:\n");
		print_line_prefix(buf, " -> ");
	}

	/* Send the CONNECT instruction to the proxy */
	if( stream_write( pts, buf, strlen( buf )) < 0 ) {
		my_perror( "Socket write error" );
		exit( 1 );
	}

//	if( args_info.verbose_flag )
//		message( "Data received from local proxy:\n");

	if( args_info.wa_bug_29744_flag && !args_info.encryptremproxy_flag && pts->ssl ) {
		message( "Switching to non-SSL communication (local proxy)\n");
		pts->ssl = 0;
	}

	/* Read the first line of the response and analyze it */
	analyze_HTTP(pts);

	if (ntlm_challenge < 3 && args_info.remproxy_given ) {
		/* Clean buffer for next analysis */
		while ( strcmp( buf, "\r\n" ) != 0 )
			readline(pts);

		/* If --encrypt-remproxy is specified, connect to the remote proxy using SSL */
		if ( args_info.encryptremproxy_flag )
			stream_enable_ssl(stunnel, args_info.remproxy_arg);

		if( args_info.verbose_flag )
			message( "\nTunneling to %s (destination)\n", args_info.dest_arg );
		sprintf( buf, "CONNECT %s HTTP/1.1\r\nHost: %s\r\n", args_info.dest_arg, args_info.host_arg ? args_info.host_arg : args_info.dest_arg);

		if ( args_info.remuser_given && args_info.rempass_given )
			strzcat( buf, "Proxy-Authorization: Basic %s\r\n", basicauth(args_info.remuser_arg, args_info.rempass_arg ));

		strzcat( buf, "Proxy-Connection: Keep-Alive\r\n");

		/* Add extra header(s), headers are already \r\n terminated */
		if ( args_info.header_given )
			strzcat( buf, "%s", args_info.header_arg );

		strzcat( buf, "\r\n" );

		/* Print the CONNECT instruction before sending to proxy */
		if( args_info.verbose_flag ) {
			message( "Communication with remote proxy:\n");
			print_line_prefix(buf, " -> ");
		}

		/* Send the CONNECT instruction to the proxy */
		if( stream_write( pts, buf, strlen( buf )) < 0 ) {
			my_perror( "Socket write error" );
			exit( 1 );
		}
	
//		if( args_info.verbose_flag )
//			message( "Received from remote proxy:\n");

		if( args_info.wa_bug_29744_flag && pts->ssl ) {
			message( "Switching to non-SSL communication (remote proxy)\n");
			pts->ssl = 0;
		}

		/* Read the first line of the response and analyze it */
		analyze_HTTP(pts);
	}

	/*
	 * Then, repeat reading lines of the responses until a blank line
	 * (which signifies the end of the response) is encountered.
	 */
	if (ntlm_challenge == 2) {
		ntlm_challenge = 3;
	} else {
		do {
			readline(pts);
		} while ( strcmp( buf, "\r\n" ) != 0 );
	}
}

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