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/* io.c
 *
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 *
 *
 * $Id$ */

/* lsh, an implementation of the ssh protocol
 *
 * Copyright (C) 1998 Niels Mller
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
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 */

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#include <assert.h>
#include <string.h>

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#include <unistd.h>
#include <poll.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
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#include <arpa/inet.h>
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#include "io.h"
#include "werror.h"
#include "write_buffer.h"
#include "xalloc.h"

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/* A little more than an hour */
#define MAX_TIMEOUT 4000

struct fd_read
{
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  struct abstract_read super;
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  int fd;
};

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static int do_read(struct abstract_read **r, UINT32 length, UINT8 *buffer)
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{
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  struct fd_read *closure
    = (struct fd_read *) *r;

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  while(1)
    {
      int res = read(closure->fd, buffer, length);
      if (!res)
	return A_EOF;
      if (res > 0)
	return res;
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      switch(errno)
	{
	case EINTR:
	  continue;
	case EWOULDBLOCK:  /* aka EAGAIN */
	  return 0;
	default:
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	  werror("io.c: do_read: read() failed (errno %d), %s\n",
		 errno, strerror(errno));
	  debug("  fd = %d, buffer = %p, length = %ud\n",
		closure->fd, buffer, length);
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	  return A_FAIL;
	}
    }
}
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#define FOR_FDS(type, fd, list, extra)				\
{								\
  type **(_fd);							\
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  type *(fd);							\
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  for(_fd = &(list); ((fd) = *_fd); (extra)) {
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#define END_FOR_FDS _fd = &(*_fd)->next; } }

/* UNLINK_FD must be followed by a continue, to avoid updating _fd */
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#define UNLINK_FD (*_fd = (*_fd)->next)
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void io_run(struct io_backend *b)
{
  while(1)
    {
      struct pollfd *fds;
      int i;
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      unsigned long nfds; /* FIXME: Should be nfds_t if that type is defined */
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      int timeout;
      int res;
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      nfds = b->nio + b->nlisten + b->nconnect;
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      if (b->callouts)
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	 {
	   time_t now = time(NULL);
	   if (now >= b->callouts->when)
	     timeout = 0;
	   else
	     {
	       if (b->callouts->when > now + MAX_TIMEOUT)
		 timeout = MAX_TIMEOUT * 1000;
	       else
		 timeout = (b->callouts->when - now) * 1000;
	     }
	 }
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      else
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	 {
	   if (!nfds)
	     /* All done */
	     break;
	   timeout = -1;
	 }

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      fds = alloca(sizeof(struct pollfd) * nfds);

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      /* Handle fds in order: write, read, accept, connect. */
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      i = 0;
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      FOR_FDS(struct io_fd, fd, b->io, i++)
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	 {
	   fds[i].fd = fd->on_hold ? -1 : fd->fd;
	   fds[i].events = 0;
	   if (!fd->on_hold)
	     fds[i].events |= POLLIN;

	   /* pre_write returns 0 if the buffer is empty */
	   if (write_buffer_pre_write(fd->buffer))
	     fds[i].events |= POLLOUT;
	 }
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      END_FOR_FDS;

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      FOR_FDS(struct listen_fd, fd, b->listen, i++)
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	 {
	   fds[i].fd = fd->fd;
	   fds[i].events = POLLIN;
	 }
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      END_FOR_FDS;

      FOR_FDS(struct connect_fd, fd, b->connect, i++)
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	 {
	   fds[i].fd = fd->fd;
	   fds[i].events = POLLOUT;
	 }
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      END_FOR_FDS;

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      res = poll(fds, nfds, timeout);

      if (!res)
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	 {
	   /* Timeout. Run the callout */
	   struct callout *f = b->callouts;

	   if (!CALLBACK(f->callout))
	     fatal("What now?");
	   b->callouts = f->next;
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	   lsh_free(f);
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	 }
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      if (res<0)
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	 {
	   switch(errno)
	     {
	     case EAGAIN:
	     case EINTR:
	       continue;
	     default:
	       fatal("io_run:poll failed: %s", strerror(errno));
	     }
	 }
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      else
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	 { /* Process files */
	   i = 0;

	   /* Handle writing first */
	   FOR_FDS(struct io_fd, fd, b->io, i++)
	     {
	       if (fds[i].revents & POLLOUT)
		 {
		   UINT32 size = MIN(fd->buffer->end - fd->buffer->start,
				     fd->buffer->block_size);
		   int res = write(fd->fd,
				   fd->buffer->buffer + fd->buffer->start,
				   size);
		   if (!res)
		     fatal("Closed?");
		   if (res < 0)
		     switch(errno)
		       {
		       case EINTR:
		       case EAGAIN:
			 break;
		       default:
			 werror("io.c: write failed, %s\n", strerror(errno));
			 CALLBACK(fd->close_callback);

			 fd->please_close = 1;

			 break;
		       }
		   else if (!res)
		     fatal("What now?");
		   else
		     fd->buffer->start += res;
		 }
	     }
	   END_FOR_FDS;

	   /* Handle reading */
	   i = 0; /* Start over */
	   FOR_FDS(struct io_fd, fd, b->io, i++)
	     {
	       if (!fd->please_close
		   && (fds[i].revents & POLLIN))
		 {
		   struct fd_read r =
		   { { do_read }, fd->fd };

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		   /* The handler function may install a new handler */
		   if (!READ_HANDLER(fd->handler,
				     &r.super))
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		     {
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		       /* FIXME: Perhaps we should not close yet, but
			* stop reading and close as soon as the write
			* buffer is flushed? But in that case, we
			* probably also want to set some flag on the
			* write buffer so that no more data can be
			* written into it. */
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		       fd->please_close = 1;
		     }
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		}
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	      if (fd->please_close)
		{
		  /* FIXME: Cleanup properly...
		   *
		   * After a write error, read state must be freed,
		   * and vice versa. */
		  UNLINK_FD;
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		  b->nio--;
		  if (fd->handler)
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		    lsh_free(fd->handler);
		  lsh_free(fd->buffer);
		  lsh_free(fd);
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		  continue;
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		}
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	    }
	  END_FOR_FDS;

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	  FOR_FDS(struct listen_fd, fd, b->listen, i++)
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	    {
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	      if (fds[i].revents & POLLIN)
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		{
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		  /* FIXME: Do something with the peer address? */
		  struct sockaddr_in peer;
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		  size_t addr_len = sizeof(peer);
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		  int conn = accept(fd->fd,
				    (struct sockaddr *) &peer, &addr_len);
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		  if (conn < 0)
		    {
		      werror("io.c: accept() failed, %s", strerror(errno));
		      continue;
		    }
		  if (!FD_CALLBACK(fd->callback, conn))
		    {
		      /* FIXME: Should fd be closed here? */
		      UNLINK_FD;
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		      lsh_free(fd);
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		      continue;
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		    }
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		}
	    }
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	  END_FOR_FDS;
	  
	  FOR_FDS(struct connect_fd, fd, b->connect, i++)
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	    {
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	      if (fds[i].revents & POLLOUT)
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		{
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		  if (!FD_CALLBACK(fd->callback, fd->fd))
		    fatal("What now?");
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		  b->nconnect--;
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		  UNLINK_FD;
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		  lsh_free(fd);
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		  continue;
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		}
	    }
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	  END_FOR_FDS;
	}
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   }
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}

/*
 * Fill in ADDR from HOST, SERVICE and PROTOCOL.
 * Supplying a null pointer for HOST means use INADDR_ANY.
 * Otherwise HOST is an numbers-and-dits ip-number or a dns name.
 *
 * PROTOCOL can be tcp or udp.
 *
 * Supplying a null pointer for SERVICE, means use port 0, i.e. no port.
 * 
 * Returns zero on errors, 1 if everything is ok.
 */
int
get_inaddr(struct sockaddr_in	* addr,
	   const char		* host,
	   const char		* service,
	   const char		* protocol)
{
  memset(addr, 0, sizeof *addr);
  addr->sin_family = AF_INET;

  /*
   *  Set host part of ADDR
   */
  if (host == NULL)
    addr->sin_addr.s_addr = INADDR_ANY;
  else
    {
      /* First check for numerical ip-number */
      addr->sin_addr.s_addr = inet_addr(host);
      if (addr->sin_addr.s_addr == (unsigned long)-1)
	{
	  struct hostent * hp;
	  
	  hp = gethostbyname(host);
	  if (hp == NULL)
	    return 0;
	  memcpy(&addr->sin_addr, hp->h_addr, hp->h_length);
	  addr->sin_family = hp->h_addrtype;
	}
    }

  /*
   *  Set port part of ADDR
   */
  if (service == NULL)
    addr->sin_port = htons(0);
  else
    {
      char		* end;
      long		  portno;

      portno = strtol(service, &end, 10);
      if (portno > 0  &&  portno <= 65535
	  &&  end != service  &&  *end == '\0')
	{
	  addr->sin_port = htons(portno);
	}
      else
	{
	  struct servent	* serv;

	  serv = getservbyname(service, "tcp");
	  if (serv == NULL)
	    return 0;
	  addr->sin_port = serv->s_port;
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	}
    }
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  return 1;
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}

void io_set_nonblocking(int fd)
{
  if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
    fatal("io_set_nonblocking: fcntl() failed, %s", strerror(errno));
}

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/* Some code is taken from bellman's tcputils. */
struct connect_fd *io_connect(struct io_backend *b,
			      struct sockaddr_in *remote,
			      struct sockaddr_in *local,
			      struct fd_callback *f)
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{
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  struct connect_fd *fd;
  int s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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  if (s<0)
    return NULL;
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  io_set_nonblocking(s);
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  if (local  &&  bind(s, (struct sockaddr *)local, sizeof *local) < 0)
    {
      int saved_errno = errno;
      close(s);
      errno = saved_errno;
      return NULL;
    }
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  if ( (connect(s, (struct sockaddr *)remote, sizeof *remote) < 0)
       && (errno != EINPROGRESS) )       
    {
      int saved_errno = errno;
      close(s);
      errno = saved_errno;
      return NULL;
    }
  
  fd = xalloc(sizeof(struct connect_fd));
  fd->fd = s;
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  fd->callback = f;
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  fd->next = b->connect;
  b->connect = fd;
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  b->nconnect++;
  
  return fd;
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}

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struct listen_fd *io_listen(struct io_backend *b,
			    struct sockaddr_in *local,
			    struct fd_callback *callback)
{
  struct listen_fd *fd;
  int s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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  if (s<0)
    return NULL;

  io_set_nonblocking(s);

  {
    int yes = 1;
    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char*)&yes, sizeof yes);
  }

  if (bind(s, (struct sockaddr *)local, sizeof *local) < 0)
    {
      close(s);
      return NULL;
    }

  if (listen(s, 256) < 0) 
    {
      close(s);
      return NULL;
    }

  fd = xalloc(sizeof(struct connect_fd));

  fd->fd = s;
  fd->callback = callback;

  fd->next = b->listen;
  b->listen = fd;
  b->nlisten++;
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  return fd;
}

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struct abstract_write *io_read_write(struct io_backend *b,
				     int fd,
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				     struct read_handler *read_callback,
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				     UINT32 block_size,
				     struct callback *close_callback)
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{
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  struct io_fd *f= xalloc(sizeof(struct io_fd));
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  struct write_buffer *buffer = write_buffer_alloc(block_size);
  
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  f->fd = fd;
  f->please_close = 0;
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  f->handler = read_callback;
  f->close_callback = close_callback;
  f->buffer = buffer;
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  f->next = b->io;
  b->io = f;
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  b->nio++;
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  return &buffer->super;
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}