/*
 * modem.c - Routines to setup the serial port and talk to the modem
 *
 * Copyright (C) 1997-2000 SpellCaster Telecommunications Inc.
 * $Id: modem.c,v 1.2 2004/04/05 03:20:48 bcrl Exp $
 * Released under the GNU Public License. See LICENSE file for details.
 */

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <syslog.h>
#include <libgen.h>
#include "ttyd.h"

extern struct linedef ttyconfig[MAXCONFIG];
extern struct optiondef options;
extern int chatpid;
/*
 * Routine to check if a lock file is valid
 * Returns 1 for a valid lockfile and 0 for a bad one or error
 */
int check_lock(char *lck_file,pid_t *pid) {
	char pid_str[12];
	int lck_fd,n;

	memset(pid_str, '\0', 12);
	/* Check for a stale lock */
	lck_fd = open(lck_file, O_RDONLY, 0);
	if(!lck_fd) {
		return(0);
	}

	n = read(lck_fd, &pid_str, 11);
	close(lck_fd);
	if(n < 0) {
		return(0);
	}

	/* See if the process still exists */
	
	sscanf(pid_str, " %d", pid);
/*	
	syslog(LOG_NOTICE,"PID.KILL.ERRNO: %d.%d.%d", *pid, kill(*pid,0),errno);

	if(pid == 0 || (kill(*pid, 0) < 0 && errno == ESRCH)) {
*/			
	if(pid == 0 || kill(*pid, 0) < 0 ) {
		/* Stale lock file */
	syslog(LOG_NOTICE,"Process still exists");
		return(1);
	} else {
		/* Valid lock file */
		return(0);
	}
}
/*
 * Routine to make up a lockfile for the port. It will break a stale
 * lockfile if it finds it or return -1 if there is already a lockfile
 */
int lock_port(struct slinedef *port) {
	int lck_fd;
	char lck_file[1024],*tmp;
	pid_t pid;
	char pid_str[12];

	memset(pid_str, '\0', 12);
	if (strchr(ttyconfig[port->confignum].linename,'/')!=NULL) {
			tmp = basename(ttyconfig[port->confignum].linename);
			sprintf(lck_file, "%s%s", LOCK_PREFIX, tmp);
	} else {
		sprintf(lck_file, "%s%s", LOCK_PREFIX, ttyconfig[port->confignum].linename);
	}
	syslog(LOG_NOTICE,"Lockfile name: %s", lck_file);
	while(1) {
		if ((lck_fd = open(lck_file, O_RDWR | O_EXCL | O_CREAT, 0644))<0) {
			if(errno == EEXIST) {
				if (check_lock(lck_file,&pid)) {
					syslog(LOG_NOTICE,"%s: Port locked by pid %d", ttyconfig[port->confignum].linename,pid);
					return(1);
				}
				else {
					/* Unlink the old lock */
					unlink(lck_file);
					syslog(LOG_NOTICE,"%s: Removed stale lock, pid %d",ttyconfig[port->confignum].linename, pid);
					continue;
				}
			}
			else {
				syslog(LOG_NOTICE,"%s: Failed to lock port: %s %s", ttyconfig[port->confignum].linename,lck_file,strerror(errno));
				return(1);
			}
		}
		
		/* Write our lock info */
		pid = getpid();
		sprintf(pid_str, "%010d\n", pid);
		write(lck_fd, pid_str, 11);

		close(lck_fd);
		return(0);
	}
}

/*
 * Routine to remove the lock file
 */
void unlock_port(struct slinedef *port) {
	char lck_file[1024],*tmp;
	
	if (strchr(ttyconfig[port->confignum].linename,'/')!=NULL) {
			tmp = basename(ttyconfig[port->confignum].linename);
			snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, tmp);
	} else {
		snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, ttyconfig[port->confignum].linename);
	}
	unlink(lck_file);
}

/*
 * Routine to open the serial port and get a lockfile on it
 */
int open_port(struct slinedef *port) {
	char tmp[1024];
	int fd, fl;

	/* Create a lock file is possible */
	if (lock_port(port)>0) {
		return(1);
	}

	/* Open the connection to the serial port */
	if (ttyconfig[port->confignum].linename[0]=='/') {
		strncpy(tmp,ttyconfig[port->confignum].linename,1023);
	} else {
		snprintf(tmp,1023,"/dev/%s",ttyconfig[port->confignum].linename);
	}
	if ((fd = open(tmp, O_RDWR | O_EXCL | O_NONBLOCK, 0))<0) {
		syslog(LOG_NOTICE,"Error opening serial port %s: %s",tmp,strerror(errno));
		return(1);
	}
	port->fd=fd;

	/* drain any characters waiting */
	while (read(fd, tmp, sizeof(tmp)) > 0)
		;

	/* put the fd back into blocking mode */
	fl = fcntl(port->fd, F_GETFL, 0);
	fl &= ~O_NONBLOCK;
	fcntl(port->fd, F_SETFL, fl);

	return(0);
}

/*
 * Routine to configure the serial port so we can talk to it
 */
int init_port(struct slinedef *port) {
	struct termios tios;

	/* Get the current line settings */
	if(tcgetattr(port->fd, &tios)) {
		syslog(LOG_NOTICE,"Unable to get port %s's setting: %s", ttyconfig[port->confignum].linename,strerror(errno));
		return -errno;
	}

	/* Modify for PPP */
	tios.c_cflag &= ~(CSIZE | CSTOPB | PARENB | CLOCAL);
	tios.c_cflag |= CS8 | CREAD | HUPCL;
	tios.c_iflag = IGNBRK | IGNPAR;
	tios.c_oflag = 0;
	tios.c_lflag = 0;
	tios.c_cc[VMIN] = 1;
	tios.c_cc[VTIME] = 0;

	/* Remove modem control if direct */
	if(ttyconfig[port->confignum].type == TYPE_LOCAL) {
		tios.c_cflag ^= (CLOCAL | HUPCL);
		syslog(LOG_NOTICE,"Port %s set to local mode", ttyconfig[port->confignum].linename);
	}		

	/* Set flow control */
	if(ttyconfig[port->confignum].flow == FLOW_RTS) {
		tios.c_cflag |= CRTSCTS;
		syslog(LOG_NOTICE,"Port %s set to RTSCTS", ttyconfig[port->confignum].linename);
	} else {
		tios.c_iflag |= IXOFF;
		tios.c_cc[VSTOP]  = 0x13;
		tios.c_cc[VSTART] = 0x11;
		syslog(LOG_NOTICE,"Port %s set to XONOFF", ttyconfig[port->confignum].linename);
	}

	/* Set the speed */
	if (cfsetospeed (&tios, ttyconfig[port->confignum].speed)<0) {
		syslog(LOG_NOTICE,"Can't set out baudrate: %s",strerror(errno));
	}
	if (cfsetispeed (&tios, ttyconfig[port->confignum].speed)<0) {
		syslog(LOG_NOTICE,"Can't set in baudrate: %s",strerror(errno));
	}

	/* Set the attributes */
	if(tcsetattr(port->fd, TCSAFLUSH, &tios) < 0) {
		syslog(LOG_NOTICE,"Configuring of port %s failed: %s", ttyconfig[port->confignum].linename,strerror(errno));
		return(errno);
	}
	return(0);
}

/*
 * Routine to execute chat and open a connection to the remove site with the wonderous
 * AT commands. This should be replaced with a routine to talk to the serial port directly
 * as this would be 100 times more efficient.
 */
int do_chat(struct slinedef *port,char *connect) {
	int status;
	int efd;
	pid_t pid;
	char command[1024];

	/* Make up our command to pass to /bin/sh */
	sprintf(command,"%s %s %s",options.chatprog, options.chatparams, connect);
	/* fork and chat */
#ifdef DEBUG
	syslog(LOG_NOTICE,"Running: %s",command);
#endif

#ifndef NOFORK
	pid = fork();
	
	if(pid < 0) {
		syslog(LOG_NOTICE,"%s: fork", ttyconfig[port->confignum].linename);
		return(errno);
	}

	if(pid == 0) {
#endif
		/* Make the serial port stdin and stdout */
		dup2(port->fd, 0);
		dup2(port->fd, 1);

		/* Make stderr the log file */
		efd = open("/dev/null", O_RDWR);
		dup2(efd, 2);

		/* run chat - should be fixed not to run sh! */
		execlp("/bin/sh","/bin/sh","-c",command,(char *)0);
		/* We only get here on error */
		exit(-errno);
#ifndef NOFORK
	}
	chatpid=pid;
	while(waitpid(pid, &status, 0) < 0) {
		if(errno == EINTR)
			continue;
	}
	if (status==0) {
		syslog(LOG_NOTICE,"Chat on port %s completed sucessfully\n", ttyconfig[port->confignum].linename);
	} else {
		syslog(LOG_NOTICE,"Chat on port %s failed. Exit code %d\n", ttyconfig[port->confignum].linename,WEXITSTATUS(status));
	}
#endif
	return(status);
}

/*
 * Routine to find the first available serial port to dial out on. Returns the
 * config item number if an available port is found, otherwise it returns -1
 */
int findserial(int portnum) {
	int i, t;
	char lck_file[1024],*tmp;
	pid_t pid;
		
	/* Check if the port number in the config file has an available serial port */
	/* This allows the user to select the port to dial out on */
	if (portnum<MAXCONFIG) {
		if (strchr(ttyconfig[portnum].linename,'/')!=NULL) {
				tmp = basename(ttyconfig[portnum].linename);
				snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, tmp);
		} else {
			snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, ttyconfig[portnum].linename);
		}
		/* Check for a lock file and if the lock file is invalid */
		if (access(lck_file,F_OK)==0) {
			/* Check if existing lockfile is valid */
			if (!check_lock(lck_file,&pid)) {
				/* Found an unused port */
				return(portnum);
			}
		}
	}
	/* Well, specific port not avaiable, so pick on */
	/* Loop until the end or we get to the end */
	for (i=0;((i<MAXCONFIG) && (ttyconfig[i].linename[0]!=(char)0));i++) {
		if (strchr(ttyconfig[i].linename,'/')!=NULL) {
				tmp = basename(ttyconfig[i].linename);
				snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, tmp);
		} else {
			snprintf(lck_file, 1024, "%s%s", LOCK_PREFIX, ttyconfig[i].linename);
		}
		/* Check for a lock file and if the lock file is invalid */
		if (access(lck_file,F_OK)==0) {
			/* Check if existing lockfile is valid */
			t = check_lock(lck_file,&pid);
			if ( t != 0 ) {
				/* Found an unused port */
				return(i);
			}
		} else {
			return(i);
		}
	}
	return(-1);
}