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

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