libgtop/src/daemon/gnuserv.c

/* -*-C-*-
 Server code for handling requests from clients and forwarding them
 on to the GNU Emacs process.

 This file is part of GNU Emacs.

 Copying is permitted under those conditions described by the GNU
 General Public License.

 Copyright (C) 1989 Free Software Foundation, Inc.

 Author: Andy Norman (ange@hplb.hpl.hp.com), based on 'etc/server.c'
         from the 18.52 GNU Emacs distribution.

 Please mail bugs and suggestions to the author at the above address.
*/

/* HISTORY 
 * 11-Nov-1990		bristor@simba	
 *    Added EOT stuff.
 */

/*
 * This file incorporates new features added by Bob Weiner <weiner@mot.com>,
 * Darrell Kindred <dkindred@cmu.edu> and Arup Mukherjee <arup@cmu.edu>.
 * Please see the note at the end of the README file for details.
 *
 * (If gnuserv came bundled with your emacs, the README file is probably
 * ../etc/gnuserv.README relative to the directory containing this file)
 */

#if 0
static char rcsid [] = "!Header: gnuserv.c,v 2.1 95/02/16 11:58:27 arup alpha !";
#endif

#include <glibtop/gnuserv.h>

#ifdef AIX
#include <sys/select.h>
#endif

#if !defined(SYSV_IPC) && !defined(UNIX_DOMAIN_SOCKETS) && !defined(INTERNET_DOMAIN_SOCKETS)
main ()
{
  fprintf (stderr,"Sorry, the Emacs server is only supported on systems that have\n");
  fprintf (stderr,"Unix Domain sockets, Internet Domain sockets or System V IPC\n");
  exit (1);
} /* main */
#else /* SYSV_IPC || UNIX_DOMAIN_SOCKETS || INTERNET_DOMAIN_SOCKETS */

#ifdef SYSV_IPC

int ipc_qid = 0;		/* ipc message queue id */
int ipc_wpid = 0;		/* watchdog task pid */


/*
  ipc_exit -- clean up the queue id and queue, then kill the watchdog task
              if it exists. exit with the given status.
*/
void
ipc_exit (int stat)
{
  msgctl (ipc_qid,IPC_RMID,0);
  
  if  (ipc_wpid != 0)
    kill (ipc_wpid, SIGKILL);
  
  exit (stat);
} /* ipc_exit */


/*
  ipc_handle_signal -- catch the signal given and clean up.
*/
void
ipc_handle_signal(int sig)
{
  ipc_exit (0);
} /* ipc_handle_signal */


/* 
  ipc_spawn_watchdog -- spawn a watchdog task to clean up the message queue should the
			server process die.
*/
void
ipc_spawn_watchdog (void)
{
  if ((ipc_wpid = fork ()) == 0)
    { /* child process */
      int ppid = getppid ();	/* parent's process id */
      
      setpgrp();		/* gnu kills process group on exit */
      
      while (1)
	{
	  if (kill (ppid, 0) < 0) /* ppid is no longer valid, parent
				     may have died */
	    {
	      ipc_exit (0);
	    } /* if */
	  
	  sleep(10);		/* have another go later */
	} /* while */
    } /* if */
  
} /* ipc_spawn_watchdog */


/*
  ipc_init -- initialize server, setting the global msqid that can be listened on.
*/
void
ipc_init (struct msgbuf **msgpp)
{
  key_t key;			/* messge key */
  char buf[GSERV_BUFSZ];	/* pathname for key */

  sprintf (buf,"/tmp/lgtd%d",(int)geteuid ());
  creat (buf,0600);
  key = ftok (buf,1);

  if ((ipc_qid = msgget (key,0600|IPC_CREAT)) == -1)
	  glibtop_error_io ("unable to create msg queue");

  ipc_spawn_watchdog ();

  signal (SIGTERM,ipc_handle_signal);
  signal (SIGINT,ipc_handle_signal);

  if ((*msgpp = (struct msgbuf *)
       malloc (sizeof **msgpp + GSERV_BUFSZ)) == NULL)
    {
      glibtop_warn_io ("unable to allocate space for message buffer");
      ipc_exit(1);
    } /* if */
} /* ipc_init */


/*
  handle_ipc_request -- accept a request from a client, pass the request on
  			to the GNU Emacs process, then wait for its reply and
			pass that on to the client.
*/
void
handle_ipc_request (struct msgbuf *msgp)
{
  struct msqid_ds msg_st;	/* message status */
  char buf[GSERV_BUFSZ];
  int len;			/* length of message / read */
  int s, result_len;            /* tag fields on the response from emacs */
  int offset = 0;
  int total = 1;                /* # bytes that will actually be sent off */

  if ((len = msgrcv (ipc_qid, msgp, GSERV_BUFSZ - 1, 1, 0)) < 0)
    {
      glibtop_warn_io ("msgrcv");
      ipc_exit (1);
    } /* if */

  msgctl (ipc_qid, IPC_STAT, &msg_st);
  strncpy (buf, msgp->mtext, len);
  buf[len] = '\0';		/* terminate */
  
  printf ("%d %s", ipc_qid, buf);
  fflush (stdout);

  /* now for the response from gnu */
  msgp->mtext[0] = '\0';

#if 0
  if ((len = read(0,buf,GSERV_BUFSZ-1)) < 0)
    {
      glibtop_warn_io ("read");
      ipc_exit (1);
  } /* if */

  sscanf (buf, "%d:%[^\n]\n", &junk, msgp->mtext);
#else

  /* read in "n/m:" (n=client fd, m=message length) */

  while (offset < (GSERV_BUFSZ-1) && 
	 ((len = read (0, buf + offset, 1)) > 0) &&
	 buf[offset] != ':')
    {
      offset += len;
    }

  if (len < 0)
    glibtop_error_io ("read");

  /* parse the response from emacs, getting client fd & result length */
  buf[offset] = '\0';
  sscanf (buf, "%d/%d", &s, &result_len);

  while (result_len > 0)
    {
      if ((len = read(0, buf, min2 (result_len, GSERV_BUFSZ - 1))) < 0)
	glibtop_error_io ("read");

      /* Send this string off, but only if we have enough space */ 

      if (GSERV_BUFSZ > total)
	{
	  if (total + len <= GSERV_BUFSZ)
	    buf[len] = 0;
	  else
	    buf[GSERV_BUFSZ - total] = 0;

	  send_string(s,buf);
	  total += strlen(buf);
	}

      result_len -= len;
    }

  /* eat the newline */
  while ((len = read (0,buf,1)) == 0)
    ;
  if (len < 0)
    glibtop_error_io ("read");

  if (buf[0] != '\n')
    glibtop_error ("garbage after result [%c]", buf[0]);
#endif

  /* Send a response back to the client. */

  msgp->mtype = msg_st.msg_lspid;
  if (msgsnd (ipc_qid,msgp,strlen(msgp->mtext)+1,0) < 0)
    glibtop_warn_io ("msgsend(gnuserv)");

} /* handle_ipc_request */
#endif /* SYSV_IPC */


#if defined(INTERNET_DOMAIN_SOCKETS) || defined(UNIX_DOMAIN_SOCKETS)
/*
  echo_request -- read request from a given socket descriptor, and send the information
                  to stdout (the gnu process).
*/
static void
echo_request (int s)
{
  char buf[GSERV_BUFSZ];
  int len;

  printf("%d ",s);
  
  /* read until we get a newline or no characters */
  while ((len = recv(s,buf,GSERV_BUFSZ-1,0)) > 0) {
    buf[len] = '\0';
    printf("%s",buf);

    if (buf[len-1] == EOT_CHR) {
      fflush(stdout);
      break;			/* end of message */
    }

  } /* while */

  if (len < 0)
    glibtop_error_io ("recv");
  
} /* echo_request */


/*
  handle_response -- accept a response from stdin (the gnu process) and pass the
                     information on to the relevant client.
*/
static void
handle_response (void)
{
#if 0
  char buf[GSERV_BUFSZ+1];
  int offset=0;
  int s;
  int len;
  int result_len;

  /* read in "n/m:" (n=client fd, m=message length) */
  while (offset < GSERV_BUFSZ && 
	 ((len = read(0,buf+offset,1)) > 0) &&
	 buf[offset] != ':') {
    offset += len;
  }

  if (len < 0)
    glibtop_error_io ("read");
      
  /* parse the response from emacs, getting client fd & result length */
  buf[offset] = '\0';
  sscanf(buf,"%d/%d", &s, &result_len);

  while (result_len > 0) {
    if ((len = read(0,buf,min2(result_len,GSERV_BUFSZ))) < 0)
      glibtop_error_io ("read");

    buf[len] = '\0';
    send_string(s,buf);
    result_len -= len;
  }

  /* eat the newline */
  while ((len = read(0,buf,1)) == 0)
    ;
  if (len < 0)
    glibtop_error_io ("read");

  if (buf[0] != '\n')
    glibtop_error ("garbage after result");

  /* send the newline */
  buf[1] = '\0';
  send_string(s,buf);
  close(s); 
#else
  glibtop_error ("handle_response (): Function not implemented");
#endif

} /* handle_response */
#endif /* INTERNET_DOMAIN_SOCKETS || UNIX_DOMAIN_SOCKETS */


#ifdef INTERNET_DOMAIN_SOCKETS
struct entry {
  u_long host_addr;
  struct entry *next;
};

struct entry *permitted_hosts[TABLE_SIZE];

#ifdef AUTH_MAGIC_COOKIE
# include <X11/X.h>
# include <X11/Xauth.h>

static Xauth *server_xauth = NULL;
#endif 

static int 
timed_read (int fd, char *buf, int max, int timeout, int one_line)
{
  fd_set rmask;
  struct timeval tv; /* = {timeout, 0}; */
  char c = 0;
  int nbytes = 0;
  int r;
  
  tv.tv_sec = timeout;
  tv.tv_usec = 0;

  FD_ZERO(&rmask);
  FD_SET(fd, &rmask);
  
  do
    {
      r = select(fd + 1, &rmask, NULL, NULL, &tv);

      if (r > 0)
	{
	  if (read (fd, &c, 1) == 1 )
	    {
	      *buf++ = c;
	      ++nbytes;
	    }
	  else
	    {
	      glibtop_warn_io ("read error on socket");
	      return -1;
	    }
	}
      else if (r == 0)
	{
	  glibtop_warn ("read timed out");
	  return -1;
	}
      else
	{
	  glibtop_warn_io ("error in select");
	  return -1;
	}
    } while ((nbytes < max) &&  !(one_line && (c == '\n')));

  --buf;
  if (one_line && *buf == '\n')
    {
      *buf = 0;
    }

  return nbytes;
}
	
	

/*
  permitted -- return whether a given host is allowed to connect to the server.
*/
static int
permitted (u_long host_addr, int fd)
{
  int key;
  struct entry *entry;

  char auth_protocol[128]; 
  char buf[1024];
  int  auth_data_len;

  if (fd > 0)
    {
      /* we are checking permission on a real connection */

      /* Read auth protocol name */
  
      if (timed_read(fd, auth_protocol, AUTH_NAMESZ, AUTH_TIMEOUT, 1) <= 0)
	return FALSE;

      if (strcmp (auth_protocol, DEFAUTH_NAME) &&
	  strcmp (auth_protocol, MCOOKIE_NAME))
	{
	  glibtop_warn ("Authentication protocol from client is invalid", auth_protocol);
	  
	  return FALSE;
	}

      if (!strcmp(auth_protocol, MCOOKIE_NAME))
	{

	  /*
	   * doing magic cookie auth
	   */

	  if (timed_read(fd, buf, 10, AUTH_TIMEOUT, 1) <= 0)
	    return FALSE;

	  auth_data_len = atoi(buf);

	  if (timed_read(fd, buf, auth_data_len, AUTH_TIMEOUT, 0) != auth_data_len)
	    return FALSE;
      
#ifdef AUTH_MAGIC_COOKIE
	  if (server_xauth && server_xauth->data &&
	      !memcmp(buf, server_xauth->data, auth_data_len))
	    {
	      return TRUE;
	    }
#else 
	  glibtop_warn ("client tried Xauth, but server is not compiled with Xauth");
#endif
      
      /*
       * auth failed, but allow this to fall through to the GNU_SECURE
       * protocol....
       */

	  glibtop_warn ("Xauth authentication failed, trying GNU_SECURE auth...");
	  
	}
    
      /* Other auth protocols go here, and should execute only if the
       * auth_protocol name matches.
       */

    }


  /* Now, try the old GNU_SECURE stuff... */
  
  /* First find the hash key */
  key = HASH(host_addr) % TABLE_SIZE;
  
  /* Now check the chain for that hash key */
  for(entry = permitted_hosts[key]; entry != NULL; entry=entry->next)
    if (host_addr == entry->host_addr) 
      return(TRUE);
  
  return(FALSE);

} /* permitted */


/* 
  add_host -- add the given host to the list of permitted hosts, provided it isn't
              already there.
*/	
static void
add_host (u_long host_addr)
{
  int key;
  struct entry *new_entry;
  
  if (!permitted (host_addr, -1))
    {
      if ((new_entry = (struct entry *) malloc(sizeof(struct entry))) == NULL)
	glibtop_error_io ("unable to malloc space for permitted host entry");

      new_entry->host_addr = host_addr;
      key = HASH(host_addr) % TABLE_SIZE;
      new_entry->next = permitted_hosts[key];
      permitted_hosts[key] = new_entry;
    } /* if */

} /* add_host */


/*
  setup_table -- initialise the table of hosts allowed to contact the server,
                 by reading from the file specified by the GNU_SECURE
		 environment variable
                 Put in the local machine, and, if a security file is specifed,
                 add each host that is named in the file.
		 Return the number of hosts added.
*/
static int
setup_table (void)
{
  FILE *host_file;
  char *file_name;
  char hostname[HOSTNAMSZ];
  u_int host_addr;
  int i, hosts=0;
  
  /* Make sure every entry is null */
  for (i = 0; i < TABLE_SIZE; i++)
    permitted_hosts [i] = NULL;

  gethostname (hostname, HOSTNAMSZ);

  if (((long) host_addr = glibtop_internet_addr (hostname)) == -1)
    glibtop_error ("unable to find %s in /etc/hosts or from YP", hostname);

#ifdef AUTH_MAGIC_COOKIE
  
  server_xauth = XauGetAuthByAddr (FamilyInternet, 
				   sizeof(host_addr), (char *)&host_addr,
				   strlen(MCOOKIE_SCREEN), MCOOKIE_SCREEN, 
				   strlen(MCOOKIE_X_NAME), MCOOKIE_X_NAME);
  hosts++;

#endif /* AUTH_MAGIC_COOKIE */
  

#if 0 /* Don't even want to allow access from the local host by default */
  add_host (host_addr);					/* add local host */
  hosts++;
#endif 

  if (((file_name = getenv ("GNU_SECURE")) != NULL &&    /* security file  */
       (host_file = fopen (file_name, "r")) != NULL))	/* opened ok */
    {
      while ((fscanf (host_file, "%s", hostname) != EOF))	/* find a host */
	if (((long) host_addr = glibtop_internet_addr (hostname)) != -1)/* get its addr */
	  {
	    add_host (host_addr);				/* add the addr */
	    hosts++;
	  }
      fclose (host_file);
    } /* if */

  return hosts;
} /* setup_table */


/*
  internet_init -- initialize server, returning an internet socket that can
                    be listened on.
*/
static int
internet_init (void)
{
  int ls;			/* socket descriptor */
  struct servent *sp;		/* pointer to service information */
  struct sockaddr_in server;	/* for local socket address */
  char *ptr;			/* ptr to return from getenv */

  if (setup_table() == 0) 
    return -1;

  /* clear out address structure */
  memset((char *)&server, 0, sizeof (struct sockaddr_in));
  
  /* Set up address structure for the listen socket. */
  server.sin_family = AF_INET;
  server.sin_addr.s_addr = INADDR_ANY;

  /* Find the information for the gnu server
   * in order to get the needed port number.
   */
  if ((ptr = getenv ("GNU_PORT")) != NULL)
    server.sin_port = htons (atoi (ptr));
  else if ((sp = getservbyname ("gnuserv", "tcp")) == NULL)
    server.sin_port = htons (DEFAULT_PORT+getuid());
  else
    server.sin_port = sp->s_port;
  
  /* Create the listen socket. */
  if ((ls = socket (AF_INET,SOCK_STREAM, 0)) == -1)
    glibtop_error_io ("unable to create socket");
  
  /* Bind the listen address to the socket. */
  if (bind(ls,(struct sockaddr *) &server,sizeof(struct sockaddr_in)) == -1)
    glibtop_error_io ("bind");

  /* Initiate the listen on the socket so remote users
   * can connect. 
   */
  if (listen(ls,20) == -1)
    glibtop_error_io ("listen");

  return(ls);

} /* internet_init */


/*
  handle_internet_request -- accept a request from a client and send the information
                             to stdout (the gnu process).
*/
static void
handle_internet_request (int ls)
{
  int s;
  size_t addrlen = sizeof(struct sockaddr_in);
  struct sockaddr_in peer;	/* for peer socket address */

  memset((char *)&peer,0,sizeof(struct sockaddr_in));

  if ((s = accept(ls,(struct sockaddr *)&peer, (void *) &addrlen)) == -1)
    glibtop_error_io ("accept");
  
  /* Check that access is allowed - if not return crud to the client */
  if (!permitted(peer.sin_addr.s_addr, s))
    {
      close(s);
      glibtop_warn ("Refused connection from %s", inet_ntoa (peer.sin_addr));
      return;
    } /* if */

  echo_request(s);
  
} /* handle_internet_request */
#endif /* INTERNET_DOMAIN_SOCKETS */


#ifdef UNIX_DOMAIN_SOCKETS
/*
  unix_init -- initialize server, returning an unix-domain socket that can
               be listened on.
*/
static int
unix_init (void)
{
  int ls;			/* socket descriptor */
  struct sockaddr_un server; 	/* unix socket address */
  int bindlen;

  if ((ls = socket (AF_UNIX,SOCK_STREAM, 0)) < 0)
    glibtop_error_io ("unable to create socket");

  /* Set up address structure for the listen socket. */
#ifdef HIDE_UNIX_SOCKET
  sprintf (server.sun_path, "/tmp/lgtddir%d", (int)geteuid());
  if (mkdir (server.sun_path, 0700) < 0)
    {
      /* assume it already exists, and try to set perms */
      if (chmod (server.sun_path, 0700) < 0)
	glibtop_error_io ("Can't set permissions on %s", server.sun_path);
    }
  strcat(server.sun_path, "/lgtd");
  unlink(server.sun_path);	/* remove old file if it exists */
#else /* HIDE_UNIX_SOCKET */
  sprintf(server.sun_path, "/tmp/lgtd%d", (int)geteuid());
  unlink(server.sun_path);	/* remove old file if it exists */
#endif /* HIDE_UNIX_SOCKET */

  server.sun_family = AF_UNIX;
#ifdef HAVE_SOCKADDR_SUN_LEN
  /* See W. R. Stevens "Advanced Programming in the Unix Environment"
     p. 502 */
  bindlen = (sizeof (server.sun_len) + sizeof (server.sun_family)
	     + strlen (server.sun_path) + 1);
  server.sun_len = bindlen;
#else
  bindlen = strlen (server.sun_path) + sizeof (server.sun_family);
#endif
 
  if (bind (ls, (struct sockaddr *)&server, bindlen) < 0)
    glibtop_error_io ("bind");

  chmod(server.sun_path,0700);	/* only this user can send commands */

  if (listen(ls,20) < 0)
    glibtop_error_io ("listen");

  /* #### there are also better ways of dealing with this when
     sigvec() is present. */
#if  defined (HAVE_SIGPROCMASK)
  {						
  sigset_t _mask;
  sigemptyset (&_mask);
  sigaddset (&_mask, SIGPIPE);
  sigprocmask (SIG_BLOCK, &_mask, NULL);
  }
#else
  signal (SIGPIPE, SIG_IGN);	/* in case user kills client */
#endif

  return (ls);

} /* unix_init */


/*
  handle_unix_request -- accept a request from a client and send the information
                         to stdout (the gnu process).
*/
static void
handle_unix_request (int ls)
{
  int s;
  size_t len = sizeof(struct sockaddr_un);
  struct sockaddr_un server; 	/* for unix socket address */

  server.sun_family = AF_UNIX;

  if ((s = accept (ls, (struct sockaddr *)&server, (void *)&len)) < 0)
    glibtop_error_io ("accept");

  echo_request(s);
  
} /* handle_unix_request */
#endif /* UNIX_DOMAIN_SOCKETS */


int
main(argc,argv)
     int argc;
     char *argv[];
{
  int chan;			/* temporary channel number */
  int ils = -1;			/* internet domain listen socket */
  int uls = -1;			/* unix domain listen socket */
#ifdef SYSV_IPC
  struct msgbuf *msgp;		/* message buffer */
#endif /* SYSV_IPC */

  glibtop_init ();

  for(chan=3; chan < _NFILE; close(chan++)) /* close unwanted channels */
    ;

#ifdef SYSV_IPC
  ipc_init(&msgp);		/* get a msqid to listen on, and a message buffer */
#endif /* SYSV_IPC */

#ifdef INTERNET_DOMAIN_SOCKETS
  ils = internet_init();	/* get a internet domain socket to listen on */
#endif /* INTERNET_DOMAIN_SOCKETS */

#ifdef UNIX_DOMAIN_SOCKETS
  uls = unix_init();		/* get a unix domain socket to listen on */
#endif /* UNIX_DOMAIN_SOCKETS */

  while (1) {
#ifdef SYSV_IPC
    handle_ipc_request(msgp);
#else /* NOT SYSV_IPC */
    fd_set rmask;
    FD_ZERO(&rmask);
    FD_SET(fileno(stdin), &rmask);
    if (uls >= 0)
      FD_SET(uls, &rmask);
    if (ils >= 0)
      FD_SET(ils, &rmask);
    
    if (select(max2(fileno(stdin),max2(uls,ils)) + 1, &rmask, 
	       (fd_set *)NULL, (fd_set *)NULL, (struct timeval *)NULL) < 0)
      glibtop_error_io ("select");

#ifdef UNIX_DOMAIN_SOCKETS
    if (uls > 0 && FD_ISSET(uls, &rmask))
      handle_unix_request(uls);
#endif

#ifdef INTERNET_DOMAIN_SOCKETS
    if (ils > 0 && FD_ISSET(ils, &rmask))
      handle_internet_request(ils);
#endif /* INTERNET_DOMAIN_SOCKETS */

    if (FD_ISSET(fileno(stdin), &rmask))      /* from stdin (gnu process) */
      handle_response();
#endif /* NOT SYSV_IPC */
  } /* while */

  return 0;
} /* main */

#endif /* SYSV_IPC || UNIX_DOMAIN_SOCKETS || INTERNET_DOMAIN_SOCKETS */