mdw@git.distorted.org.uk Git - fwd/blob - chan.c

   1 /* -*-c-*-
   2  *
   3  * $Id: chan.c,v 1.2 1999/07/26 23:27:52 mdw Exp $
   4  *
   5  * Channel management
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: chan.c,v $
  32  * Revision 1.2  1999/07/26 23:27:52  mdw
  33  * Minor modifications for new design.
  34  *
  35  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  36  * Initial revision.
  37  *
  38  */
  39
  40 /*----- Header files ------------------------------------------------------*/
  41
  42 #include "config.h"
  43
  44 #include <errno.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <sys/types.h>
  50 #include <sys/time.h>
  51 #include <unistd.h>
  52 #include <sys/uio.h>
  53
  54 #include <sys/socket.h>
  55 #include <netinet/in.h>
  56 #include <arpa/inet.h>
  57
  58 #include <mLib/alloc.h>
  59 #include <mLib/conn.h>
  60 #include <mLib/sel.h>
  61
  62 #include "chan.h"
  63 #include "fw.h"
  64
  65 /*----- Main code ---------------------------------------------------------*/
  66
  67 /* --- @writechan@ --- *
  68  *
  69  * Arguments:   @int fd@ = file descriptor to write to
  70  *              @unsigned mode@ = what the descriptor is ready for
  71  *              @void *vp@ = pointer to channel block
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Writes to a channel.
  76  */
  77
  78 static void writechan(int fd, unsigned mode, void *vp)
  79 {
  80   chan *c = vp;
  81   int w;
  82   unsigned base = c->base;
  83   unsigned len = c->len;
  84
  85   /* --- Write data from my buffer --- */
  86
  87   if (len) {
  88
  89     /* --- Do the write --- */
  90
  91     if (base + len <= CHAN_BUFSZ)
  92       w = write(fd, c->buf + base, len);
  93     else {
  94       struct iovec iov[2];
  95       iov[0].iov_base = c->buf + base;
  96       iov[0].iov_len = CHAN_BUFSZ - base;
  97       iov[1].iov_base = c->buf;
  98       iov[1].iov_len = len - iov[0].iov_len;
  99       w = writev(fd, iov, 2);
 100     }
 101
 102     /* --- Sift through the results --- */
 103
 104     if (w < 0) {
 105       if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
 106         return;
 107       goto close;
 108     }
 109     else if (w == 0)
 110       goto close;
 111     else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE))
 112       sel_addfile(&c->r);
 113     c->len -= w;
 114   }
 115   if (c->len == 0)
 116     sel_rmfile(&c->w);
 117
 118   /* --- Close the output end if necessary --- */
 119
 120   if (c->len == 0 && (c->f & CHANF_CLOSE))
 121     c->func(c->p);
 122   return;
 123
 124   /* --- Force a close if an error occurred --- */
 125
 126 close:
 127   chan_close(c);
 128   c->func(c->p);
 129 }
 130
 131 /* --- @readchan@ --- *
 132  *
 133  * Arguments:   @int fd@ = file descriptor to read from
 134  *              @unsigned mode@ = what the descriptor is ready for
 135  *              @void *vp@ = pointer to channel block
 136  *
 137  * Returns:     ---
 138  *
 139  * Use:         Reads from a channel.
 140  */
 141
 142 static void readchan(int fd, unsigned mode, void *vp)
 143 {
 144   chan *c = vp;
 145   int r;
 146   unsigned base = (c->base + c->len) & (CHAN_BUFSZ - 1);
 147   unsigned len = CHAN_BUFSZ - c->len;
 148
 149   /* --- Do the read --- */
 150
 151   if (base + len <= CHAN_BUFSZ)
 152     r = read(fd, c->buf + base, len);
 153   else {
 154     struct iovec iov[2];
 155     iov[0].iov_base = c->buf + base;
 156     iov[0].iov_len = CHAN_BUFSZ - base;
 157     iov[1].iov_base = c->buf;
 158     iov[1].iov_len = len - iov[0].iov_len;
 159     r = readv(fd, iov, 2);
 160   }
 161
 162   /* --- Sift through the results --- */
 163
 164   if (r < 0) {
 165     if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
 166       return;
 167     goto close;
 168   }
 169   else if (r == 0)
 170     goto close;
 171   else if (c->len == 0 && (c->f & CHANF_READY))
 172     sel_addfile(&c->w);
 173   c->len += r;
 174   if (c->len == CHAN_BUFSZ)
 175     sel_rmfile(&c->r);
 176   return;
 177
 178   /* --- Close the read end of the channel --- */
 179
 180 close:
 181   c->f |= CHANF_CLOSE;
 182   if (!c->len && (c->f & CHANF_READY))
 183     sel_addfile(&c->w);
 184   sel_rmfile(&c->r);
 185 }
 186
 187 /* --- @chan_close@ --- *
 188  *
 189  * Arguments:   @chan *c@ = pointer to channel
 190  *
 191  * Returns:     ---
 192  *
 193  * Use:         Closes down a channel prematurely.
 194  */
 195
 196 void chan_close(chan *c)
 197 {
 198   if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ)
 199     sel_rmfile(&c->r);
 200   if ((c->f & CHANF_READY) && c->len != 0)
 201     sel_rmfile(&c->w);
 202 }
 203
 204 /* --- @chan_dest@ --- *
 205  *
 206  * Arguments:   @chan *c@ = pointer to channel
 207  *              @int fd@ = destination file descriptor for channel
 208  *
 209  * Returns:     ---
 210  *
 211  * Use:         Sets the channel's destination so it knows where to put
 212  *              data.
 213  */
 214
 215 void chan_dest(chan *c, int fd)
 216 {
 217   if (c->f & CHANF_READY)
 218     return;
 219   sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c);
 220   if (c->len || (c->f & CHANF_CLOSE))
 221     sel_addfile(&c->w);
 222   c->f |= CHANF_READY;
 223 }
 224
 225 /* --- @chan_open@ --- *
 226  *
 227  * Arguments:   @chan *c@ = pointer to channel to open
 228  *              @int from, to@ = source and destination file descriptors
 229  *              @void (*func)(void *p)@ = function to call on closure
 230  *              @void *p@ = argument to pass to function
 231  *
 232  * Returns:     ---
 233  *
 234  * Use:         Opens a channel.  Data is copied from the source to the
 235  *              destination.  The @to@ argument may be @-1@ if the file
 236  *              descriptor isn't known yet.
 237  */
 238
 239 void chan_open(chan *c, int from, int to,
 240                void (*func)(void */*p*/), void *p)
 241 {
 242   c->func = func;
 243   c->p = p;
 244
 245   c->base = 0;
 246   c->len = 0;
 247   c->f = 0;
 248
 249   sel_initfile(sel, &c->r, from, SEL_READ, readchan, c);
 250   sel_addfile(&c->r);
 251
 252   if (to != -1)
 253     chan_dest(c, to);
 254 }
 255
 256 /*----- That's all, folks -------------------------------------------------*/