/*	libdrcom - Library for communicating with DrCOM 2133 Broadband Access Server	Copyright (C) 2005 William Poetra Yoga Hadisoeseno <williampoetra@yahoo.com>	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 <stdio.h>#include <stdlib.h>#include <string.h>#include <errno.h>#include <sys/types.h>#include <sys/socket.h>#include <pthread.h>#include "md5.h"#include "drcomd.h"#include "daemon_server.h"#include "log.h"static uint16_t _prepare_folded(struct drcom_info *info, struct drcom_host_msg *keepalive_skel){	unsigned char buf[16 + 16], digest[16];	int password_len, i;	uint16_t folded;	password_len = strlen(info->password);	memcpy(digest, keepalive_skel->msg, 16);	memcpy(buf, digest, 16);	strncpy((char *) (buf + 16), info->password, 16);	MD5(buf, 16 + password_len, digest);	folded = 0;	for (i = 0; i < 16; i += 2)		folded += *((uint16_t *) (digest + i));	return folded;}static int _respond(struct drcom_socks *socks, uint16_t folded, 		struct drcom_host_msg *keepalive_skel, uint8_t *question){	struct drcom_host_msg ans, *answer = &ans;	struct sockaddr_in servaddr_in;	unsigned char digest[16];	uint16_t x;	int r;	memcpy(answer, keepalive_skel, sizeof(*answer));	memcpy(&servaddr_in, &socks->servaddr_in, sizeof(servaddr_in));	x = folded ^ *((uint16_t *) question);	answer->msg[0] = (x & 0x00ff) + ((x & 0xff00) >> 1);	answer->msg[1] = 0x01;	answer->msg[2] = 0x14;	answer->msg[3] = 0x00;	answer->msg[4] = 0x07;	answer->msg[5] = 0x0b;	answer->msg[6] = question[0];	answer->msg[7] = question[1];	MD5((unsigned char *) answer, 1 + 1 + 1 + 4 + 2, digest);	memcpy(answer->msg + 2, digest, 16);	answer->msg[18] = 0xff;	r = sendto(socks->sockfd, answer, sizeof(*answer), 0,			 (struct sockaddr *) &servaddr_in,			 sizeof(struct sockaddr));	if (r != sizeof(*answer))		return -1; /* error */	return 0;}static int drcom_watchport(struct drcom_handle *h){	struct drcom_socks *socks = (struct drcom_socks *) h->socks;	struct drcom_info *info = (struct drcom_info *) h->info;	struct drcom_host_msg *keepalive_skel = (struct drcom_host_msg *) h->response;	struct drcom_serv_msg s_msg, *serv_msg = &s_msg;	uint16_t folded;	int r;	struct sockaddr_in servaddr_in;	socklen_t fromlen;	if(serv_msg == NULL)		goto err;	folded = _prepare_folded(info, keepalive_skel);	memcpy(&servaddr_in, &socks->servaddr_in, sizeof(servaddr_in));	fromlen = sizeof(servaddr_in);	while (1) {		/* cleanup the buffer first */		memset(serv_msg, 0, sizeof(struct drcom_serv_msg));		r = recvfrom(socks->sockfd, serv_msg, sizeof(struct drcom_serv_msg), 0,				 (struct sockaddr *) &servaddr_in, &fromlen);		if (r < 0)		{			logerr("watchport: recvfrom: %s", strerror(errno));			goto err;		}		else if (r == 0)		{			loginfo("watchport: received nothing\n");			continue; /* ignore r == 0 cases for now */		}		if (serv_msg->m != 'M')		{			loginfo("Unknown server packet(serv_msg->m==%u)\n", serv_msg->m);			continue;		}		switch (serv_msg->mt)		{			case '8': 				loginfo("%s\n", (char *) serv_msg->msg); 				break;			case '&': 				r = _respond(socks, folded, keepalive_skel, serv_msg->msg);				if (r < 0)					goto err;				break;			default: 				loginfo("Unknown message type.\n"); 				break;		}	}err:	return -1;}void *daemon_watchport(void *arg){	block_sigusr1();	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);	pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);	drcom_watchport((struct drcom_handle *) arg);	loginfo("watchport returns\n");	return NULL;}