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

   1 /* -*-c-*-
   2  *
   3  * $Id: chan.c,v 1.4 1999/08/31 17:42:49 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 1.4  1999/08/31 17:42:49  mdw
  33  * Use `sel_force' to avoid a `select' call between reads and writes.
  34  *
  35  * Revision 1.3  1999/07/27 18:30:53  mdw
  36  * Various minor portability fixes.
  37  *
  38  * Revision 1.2  1999/07/26 23:27:52  mdw
  39  * Minor modifications for new design.
  40  *
  41  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  42  * Initial revision.
  43  *
  44  */
  45
  46 /*----- Header files ------------------------------------------------------*/
  47
  48 #include "config.h"
  49
  50 #include <errno.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54
  55 #include <sys/types.h>
  56 #include <sys/time.h>
  57 #include <unistd.h>
  58 #include <sys/uio.h>
  59
  60 #include <mLib/alloc.h>
  61 #include <mLib/conn.h>
  62 #include <mLib/sel.h>
  63
  64 #include "chan.h"
  65 #include "fw.h"
  66
  67 /*----- Main code ---------------------------------------------------------*/
  68
  69 /* --- @writechan@ --- *
  70  *
  71  * Arguments:   @int fd@ = file descriptor to write to
  72  *              @unsigned mode@ = what the descriptor is ready for
  73  *              @void *vp@ = pointer to channel block
  74  *
  75  * Returns:     ---
  76  *
  77  * Use:         Writes to a channel.
  78  */
  79
  80 static void writechan(int fd, unsigned mode, void *vp)
  81 {
  82   chan *c = vp;
  83   int w;
  84   unsigned base = c->base;
  85   unsigned len = c->len;
  86
  87   /* --- Write data from my buffer --- */
  88
  89   if (len) {
  90
  91     /* --- Do the write --- */
  92
  93     if (base + len <= CHAN_BUFSZ)
  94       w = write(fd, c->buf + base, len);
  95     else {
  96       struct iovec iov[2];
  97       iov[0].iov_base = c->buf + base;
  98       iov[0].iov_len = CHAN_BUFSZ - base;
  99       iov[1].iov_base = c->buf;
 100       iov[1].iov_len = len - iov[0].iov_len;
 101       w = writev(fd, iov, 2);
 102     }
 103
 104     /* --- Sift through the results --- */
 105
 106     if (w < 0) {
 107       if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
 108         return;
 109       goto close;
 110     }
 111     else if (w == 0)
 112       goto close;
 113     else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE))
 114       sel_addfile(&c->r);
 115     c->len -= w;
 116   }
 117   if (c->len == 0)
 118     sel_rmfile(&c->w);
 119
 120   /* --- Close the output end if necessary --- */
 121
 122   if (c->len == 0 && (c->f & CHANF_CLOSE))
 123     c->func(c->p);
 124   return;
 125
 126   /* --- Force a close if an error occurred --- */
 127
 128 close:
 129   chan_close(c);
 130   c->func(c->p);
 131 }
 132
 133 /* --- @readchan@ --- *
 134  *
 135  * Arguments:   @int fd@ = file descriptor to read from
 136  *              @unsigned mode@ = what the descriptor is ready for
 137  *              @void *vp@ = pointer to channel block
 138  *
 139  * Returns:     ---
 140  *
 141  * Use:         Reads from a channel.
 142  */
 143
 144 static void readchan(int fd, unsigned mode, void *vp)
 145 {
 146   chan *c = vp;
 147   int r;
 148   unsigned base = (c->base + c->len) & (CHAN_BUFSZ - 1);
 149   unsigned len = CHAN_BUFSZ - c->len;
 150
 151   /* --- Do the read --- */
 152
 153   if (base + len <= CHAN_BUFSZ)
 154     r = read(fd, c->buf + base, len);
 155   else {
 156     struct iovec iov[2];
 157     iov[0].iov_base = c->buf + base;
 158     iov[0].iov_len = CHAN_BUFSZ - base;
 159     iov[1].iov_base = c->buf;
 160     iov[1].iov_len = len - iov[0].iov_len;
 161     r = readv(fd, iov, 2);
 162   }
 163
 164   /* --- Sift through the results --- */
 165
 166   if (r < 0) {
 167     if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
 168       return;
 169     goto close;
 170   }
 171   else if (r == 0)
 172     goto close;
 173   else if (c->len == 0 && (c->f & CHANF_READY)) {
 174     sel_addfile(&c->w);
 175     sel_force(&c->w);
 176   }
 177   c->len += r;
 178   if (c->len == CHAN_BUFSZ)
 179     sel_rmfile(&c->r);
 180   return;
 181
 182   /* --- Close the read end of the channel --- */
 183
 184 close:
 185   c->f |= CHANF_CLOSE;
 186   if (!c->len && (c->f & CHANF_READY)) {
 187     sel_addfile(&c->w);
 188     sel_force(&c->w);
 189   }
 190   sel_rmfile(&c->r);
 191 }
 192
 193 /* --- @chan_close@ --- *
 194  *
 195  * Arguments:   @chan *c@ = pointer to channel
 196  *
 197  * Returns:     ---
 198  *
 199  * Use:         Closes down a channel prematurely.
 200  */
 201
 202 void chan_close(chan *c)
 203 {
 204   if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ)
 205     sel_rmfile(&c->r);
 206   if ((c->f & CHANF_READY) && c->len != 0)
 207     sel_rmfile(&c->w);
 208 }
 209
 210 /* --- @chan_dest@ --- *
 211  *
 212  * Arguments:   @chan *c@ = pointer to channel
 213  *              @int fd@ = destination file descriptor for channel
 214  *
 215  * Returns:     ---
 216  *
 217  * Use:         Sets the channel's destination so it knows where to put
 218  *              data.
 219  */
 220
 221 void chan_dest(chan *c, int fd)
 222 {
 223   if (c->f & CHANF_READY)
 224     return;
 225   sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c);
 226   if (c->len || (c->f & CHANF_CLOSE)) {
 227     sel_addfile(&c->w);
 228     sel_force(&c->w);
 229   }
 230   c->f |= CHANF_READY;
 231 }
 232
 233 /* --- @chan_open@ --- *
 234  *
 235  * Arguments:   @chan *c@ = pointer to channel to open
 236  *              @int from, to@ = source and destination file descriptors
 237  *              @void (*func)(void *p)@ = function to call on closure
 238  *              @void *p@ = argument to pass to function
 239  *
 240  * Returns:     ---
 241  *
 242  * Use:         Opens a channel.  Data is copied from the source to the
 243  *              destination.  The @to@ argument may be @-1@ if the file
 244  *              descriptor isn't known yet.
 245  */
 246
 247 void chan_open(chan *c, int from, int to,
 248                void (*func)(void */*p*/), void *p)
 249 {
 250   c->func = func;
 251   c->p = p;
 252
 253   c->base = 0;
 254   c->len = 0;
 255   c->f = 0;
 256
 257   sel_initfile(sel, &c->r, from, SEL_READ, readchan, c);
 258   sel_addfile(&c->r);
 259
 260   if (to != -1)
 261     chan_dest(c, to);
 262 }
 263
 264 /*----- That's all, folks -------------------------------------------------*/