/* Unix/Cygwin network code for Xconq kernel.
   Copyright (C) 1996, 1997, 1999 Stanley T. Shebs.

Xconq 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, or (at your option)
any later version.  See the file COPYING.  */

/* Note that this file does not include all Xconq .h files, since
   it may be used with auxiliary programs. */

#include "config.h"
#include "misc.h"
#include "dir.h"
#include "lisp.h"
#include "module.h"
#include "system.h"

#include <sys/stat.h>
#include <signal.h>
#include <unistd.h>
#include <pwd.h>
#include <sys/time.h>
#include <errno.h>
#include <fcntl.h>

#include <sys/file.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>
#ifndef __CYGWIN32__
# include <netinet/tcp.h>
#endif
#include <sys/ioctl.h>

static int accept_remote_connection(void);
static int wait_for(int timeout);

/* The file descriptor that a host makes available for other programs
   to connect into. */

int public_fd;

/* Flag indicating whether the public file descriptor is currently
   valid. */

int public_fd_valid;

/* The next id for a remote program. 0 means invalid, 1 is reserved for
   the first host of a game, so we start at 2. */

int nextrid = 2;

/* Array of file descriptors used with connections to remote programs,
   indexed by the remote programs' ids. */

int remote_fd[100];

int fd_valid[100];

/* Given a specification of how to open a remote connection (such as a
   hostname:port), and a host/join flag, set up a connection.  Return
   a number for the method being used, or 0 for failure. */

int
open_remote_connection(char *methodname, int willhost)
{
    int port, i, tmp_fd, tmp;
    char *port_str, hostname[100];
    struct hostent *hostent;
    struct sockaddr_in sockaddr;
    struct protoent *protoent;

    if (!strchr(methodname, ':')) {
	/* Try opening a serial port. */
#if 0
	struct sgttyb sg;
#endif
	remote_fd[2] = open(methodname, O_RDWR);
	fd_valid[2] = TRUE;
	if (remote_fd[2] < 0)
	  init_warning("Could not open remote device");

#if 0
	ioctl(remote_fd[2], TIOCGETP, &sg);
	sg.sg_flags = RAW;
	ioctl(remote_fd[2], TIOCSETP, &sg);
#endif
    } else {
	/* Using TCP; extract the port number. */
	port_str = strchr(methodname, ':');
	port = atoi(port_str + 1);

	tmp_fd = socket(PF_INET, SOCK_STREAM, 0);
	if (tmp_fd < 0)
	  init_warning("Can't open socket");

	/* Allow rapid reuse of this port. */
	tmp = 1;
	setsockopt (tmp_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
		    sizeof(tmp));

	if (willhost) {
	    sockaddr.sin_family = PF_INET;
	    sockaddr.sin_port = htons(port);
	    sockaddr.sin_addr.s_addr = INADDR_ANY;

	    public_fd = tmp_fd;
	    public_fd_valid = TRUE;

	    if (bind(public_fd, (struct sockaddr *) &sockaddr,
		     sizeof(sockaddr)))
	      init_warning("Can't bind address");

	    if (listen (public_fd, 1))
	      init_warning("Can't listen");

	    /* Our public socket is now available to receive
	       connection attempts.  These will appear as input on
	       public_fd, and then accept_remote_connection will
	       finish making the link. */

	    return 1;
	} else {
	    /* We're trying to join an existing game. */
	    tmp = min (port_str - methodname, (int) sizeof hostname - 1);
	    strncpy (hostname, methodname, tmp);
	    hostname[tmp] = '\0';
	    hostent = gethostbyname (hostname);
	    if (!hostent) {
		init_warning("%s: unknown host\n", hostname);
		return 0;
	    }
	    /* Try making the connection several times. */
	    for (i = 1; i <= 5; i++) {
		tmp_fd = socket(PF_INET, SOCK_STREAM, 0);
		if (tmp_fd < 0) {
		    init_warning("can't create a socket");
		    return 0;
		}

		/* Allow rapid reuse of this port. */
		tmp = 1;
		setsockopt(tmp_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
			   sizeof(tmp));

		/* Enable TCP keep alive process. */
		tmp = 1;
		setsockopt(tmp_fd, SOL_SOCKET, SO_KEEPALIVE, (char *) &tmp,
			   sizeof(tmp));

		sockaddr.sin_family = PF_INET;
		sockaddr.sin_port = htons(port);
		memcpy(&sockaddr.sin_addr.s_addr, hostent->h_addr,
		       sizeof (struct in_addr));

		if (connect(tmp_fd, (struct sockaddr *) &sockaddr,
			    sizeof(sockaddr)) == 0)
		  /* Success! Break out of the retry loop. */
		  break;

		close(tmp_fd);
		tmp_fd = -1;

		/* We retry for ECONNREFUSED because that is often a
		   temporary condition, which happens when the server
		   is being restarted.  */
		if (errno != ECONNREFUSED)
		  return 0;
		/* Wait a moment before trying again. */
		/* (should mention to the user) */
		sleep(1);
	    }

	    /* We know the host will be rid 1. */
	    remote_fd[1] = tmp_fd;
	    fd_valid[1] = TRUE;

	    protoent = getprotobyname ("tcp");
	    if (!protoent)
	      return 0;

	    tmp = 1;
	    if (setsockopt(remote_fd[1], protoent->p_proto, TCP_NODELAY,
			   (char *) &tmp, sizeof(tmp)))
	      return 0;

	    signal(SIGPIPE, SIG_IGN);

	}
	return 1;
    }
    return 0;
}

/* If a program has attempted to connect to our published socket, accept
   the connection and add the program to our merry little band. */

static int
accept_remote_connection(void)
{
    struct hostent *hostent;
    struct sockaddr_in sockaddr;
    int tmp;
    char hostname[100];
    struct protoent *protoent;
    int new_fd;
    int rid;

    tmp = sizeof (sockaddr);
    new_fd = accept(public_fd, (struct sockaddr *) &sockaddr, &tmp);
    if (new_fd == -1) {
	init_warning("Accept failed");
	return 0;
    }
    /* Record the new file descriptor as a valid remote program. */
    rid = nextrid++;
    remote_fd[rid] = new_fd;
    fd_valid[rid] = TRUE;

    hostent = gethostbyaddr((char*)&sockaddr.sin_addr,
			    sizeof(sizeof(sockaddr.sin_addr)), 
			    AF_INET);
    if (hostent) {
	memcpy(hostname, hostent->h_name, hostent->h_length);
	hostname[hostent->h_length] = '\0';
    } else {
	strcpy(hostname, "unknown");
    }

    protoent = getprotobyname("tcp");
    if (!protoent)
      init_warning("getprotobyname");

    /* Enable TCP keep alive process. */
    tmp = 1;
    setsockopt(remote_fd[rid], SOL_SOCKET, SO_KEEPALIVE,
	       (char *) &tmp, sizeof(tmp));

    /* Tell TCP not to delay small packets.  This greatly speeds up
       interactive response. */
    tmp = 1;
    setsockopt(remote_fd[rid], protoent->p_proto, TCP_NODELAY,
	       (char *) &tmp, sizeof(tmp));

    /* If we don't do this, then program simply exits when the remote
       side dies.  */
    signal(SIGPIPE, SIG_IGN);
#if defined(FASYNC)
    fcntl(remote_fd[rid], F_SETFL, FASYNC);
#endif

    Dprintf("Remote connection from %s (#%d)\n", hostname, rid);
    return 1;
}

/* Send a given string out to a given program.  Return when the whole
   string has been delivered. */

void
low_send(int rid, char *buf)
{
    int fd, len, cc;

    fd = (rid > 0 ? remote_fd[rid] : remote_fd[1]);
    Dprintf("low_send %d (fd %d) \"%s\"\n", rid, fd, buf);
    len = strlen(buf);
    while (len > 0) {
	cc = write(fd, buf, len);

	if (cc < 0)
	  return;
	len -= cc;
	buf += cc;
    }
}

/* Wait for input, for a given period of time.  Return an rid or a
   special code (negative values). */

static int
wait_for(int timeout)
{
    int rid, numfds, maxfd;
    struct timeval tv;
    fd_set readfds, exceptfds;

    {
	static int counter = 0;
	if (timeout > 0) {
	    Dprintf("Waiting %d secs for input\n", timeout);
	} else {
	    counter = (++counter) % 1000;
#if 0 /* too much output */
	    if (counter == 999)
	      Dprintf("Checking for input 999 times\n");
#endif
	}
    }
    FD_ZERO (&readfds);
    FD_ZERO (&exceptfds);

    tv.tv_sec = timeout;
    tv.tv_usec = 0;

    maxfd = -2;
    if (public_fd_valid) {
	FD_SET(public_fd, &readfds);
	maxfd = max(public_fd, maxfd);
    }
    for (rid = 1; rid < nextrid; ++rid) {
	if (fd_valid[rid]) {
	    FD_SET(remote_fd[rid], &readfds);
	    FD_SET(remote_fd[rid], &exceptfds);
	    maxfd = max(remote_fd[rid], maxfd);
	}
    }
    /* (should test if maxfd < 0 still) */

    while (1) {
	numfds = select(maxfd+1, &readfds, 0, &exceptfds,
			(timeout >= 0 ? &tv : 0));

	if (numfds <= 0) {
	    if (numfds == 0)
	      return -1;
	    else if (errno == EINTR)
	      continue;
	    else
	      return -2;	/* Got an error from select or poll */
	}
	if (public_fd_valid) {
	    if (FD_ISSET(public_fd, &readfds)) {
		return 0;
	    }
	}
	for (rid = 1; rid < nextrid; ++rid) {
	    if (fd_valid[rid]) {
		if (FD_ISSET(remote_fd[rid], &readfds)) {
		    return rid;
		}
	    }
	}
	/* (should never happen) */
	return -1;
    }
}

/* For a given amount of time, listen for any data from our other
   programs. */

int
low_receive(int *ridp, char *buf, int maxchars, int timeout)
{
    int status, rid, fd, n;
    /* time_t */ unsigned long start_time, now;

    time(&start_time);

    while (1) {
	status = wait_for(timeout);
	if (status < 0) {
	    return FALSE;
	} else if (status == 0) {
	    accept_remote_connection();
	    continue;
	}
	/* We have data from one of the other programs. */
	rid = status;
	fd = remote_fd[rid] ;
	n = read(fd, buf, maxchars);
	if (n > 0) {
	    /* Make a string out of the received data. */
	    buf[n] = '\0';
	    *ridp = rid;
	    return TRUE;
	} else if (timeout == 0) {
	    /* We were just sniffing for anything laying around, and
	       there wasn't anything, so return emptyhanded. */
	    return FALSE;
	} else if (timeout == -1) {
	    /* Go around again. */
	} else {
	    time(&now);
	    if (now > start_time + timeout) {
		Dprintf("%ul > %ul + %d\n", now, start_time, timeout);
		return FALSE /* timed out */;
	    }
	}
    }
}

void
close_remote_connection(int rid)
{
    /* If we're closing before rids assigned, assume that an arg of 0
       means we were trying to join and failed. */
    if (rid == 0)
      rid = 1;

    if (!fd_valid[rid])
      return;

    close(remote_fd[rid]);
    fd_valid[rid] = FALSE;
}