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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: chan.c,v 1.5 2000/07/19 17:55:43 mdw Exp $ |
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4 | * |
5 | * Channel management |
6 | * |
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7 | * (c) 1999 Straylight/Edgeware |
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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 $ |
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32 | * Revision 1.5 2000/07/19 17:55:43 mdw |
33 | * (writechan): Pointless tweak: when the buffer is empty, reset the start |
34 | * pointer to the beginning. This saves doing slightly trickier |
35 | * @writev(2)@ calls when loading is light. |
36 | * |
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37 | * Revision 1.4 1999/08/31 17:42:49 mdw |
38 | * Use `sel_force' to avoid a `select' call between reads and writes. |
39 | * |
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40 | * Revision 1.3 1999/07/27 18:30:53 mdw |
41 | * Various minor portability fixes. |
42 | * |
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43 | * Revision 1.2 1999/07/26 23:27:52 mdw |
44 | * Minor modifications for new design. |
45 | * |
46 | * Revision 1.1.1.1 1999/07/01 08:56:23 mdw |
47 | * Initial revision. |
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48 | * |
49 | */ |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
53 | #include "config.h" |
54 | |
55 | #include <errno.h> |
56 | #include <stdio.h> |
57 | #include <stdlib.h> |
58 | #include <string.h> |
59 | |
60 | #include <sys/types.h> |
61 | #include <sys/time.h> |
62 | #include <unistd.h> |
63 | #include <sys/uio.h> |
64 | |
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65 | #include <mLib/alloc.h> |
66 | #include <mLib/conn.h> |
67 | #include <mLib/sel.h> |
68 | |
69 | #include "chan.h" |
70 | #include "fw.h" |
71 | |
72 | /*----- Main code ---------------------------------------------------------*/ |
73 | |
74 | /* --- @writechan@ --- * |
75 | * |
76 | * Arguments: @int fd@ = file descriptor to write to |
77 | * @unsigned mode@ = what the descriptor is ready for |
78 | * @void *vp@ = pointer to channel block |
79 | * |
80 | * Returns: --- |
81 | * |
82 | * Use: Writes to a channel. |
83 | */ |
84 | |
85 | static void writechan(int fd, unsigned mode, void *vp) |
86 | { |
87 | chan *c = vp; |
88 | int w; |
89 | unsigned base = c->base; |
90 | unsigned len = c->len; |
91 | |
92 | /* --- Write data from my buffer --- */ |
93 | |
94 | if (len) { |
95 | |
96 | /* --- Do the write --- */ |
97 | |
98 | if (base + len <= CHAN_BUFSZ) |
99 | w = write(fd, c->buf + base, len); |
100 | else { |
101 | struct iovec iov[2]; |
102 | iov[0].iov_base = c->buf + base; |
103 | iov[0].iov_len = CHAN_BUFSZ - base; |
104 | iov[1].iov_base = c->buf; |
105 | iov[1].iov_len = len - iov[0].iov_len; |
106 | w = writev(fd, iov, 2); |
107 | } |
108 | |
109 | /* --- Sift through the results --- */ |
110 | |
111 | if (w < 0) { |
112 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
113 | return; |
114 | goto close; |
115 | } |
116 | else if (w == 0) |
117 | goto close; |
118 | else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE)) |
119 | sel_addfile(&c->r); |
120 | c->len -= w; |
121 | } |
122 | if (c->len == 0) |
123 | sel_rmfile(&c->w); |
124 | |
125 | /* --- Close the output end if necessary --- */ |
126 | |
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127 | if (c->len == 0) { |
128 | c->base = 0; |
129 | if (c->f & CHANF_CLOSE) |
130 | c->func(c->p); |
131 | } |
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132 | return; |
133 | |
134 | /* --- Force a close if an error occurred --- */ |
135 | |
136 | close: |
137 | chan_close(c); |
138 | c->func(c->p); |
139 | } |
140 | |
141 | /* --- @readchan@ --- * |
142 | * |
143 | * Arguments: @int fd@ = file descriptor to read from |
144 | * @unsigned mode@ = what the descriptor is ready for |
145 | * @void *vp@ = pointer to channel block |
146 | * |
147 | * Returns: --- |
148 | * |
149 | * Use: Reads from a channel. |
150 | */ |
151 | |
152 | static void readchan(int fd, unsigned mode, void *vp) |
153 | { |
154 | chan *c = vp; |
155 | int r; |
156 | unsigned base = (c->base + c->len) & (CHAN_BUFSZ - 1); |
157 | unsigned len = CHAN_BUFSZ - c->len; |
158 | |
159 | /* --- Do the read --- */ |
160 | |
161 | if (base + len <= CHAN_BUFSZ) |
162 | r = read(fd, c->buf + base, len); |
163 | else { |
164 | struct iovec iov[2]; |
165 | iov[0].iov_base = c->buf + base; |
166 | iov[0].iov_len = CHAN_BUFSZ - base; |
167 | iov[1].iov_base = c->buf; |
168 | iov[1].iov_len = len - iov[0].iov_len; |
169 | r = readv(fd, iov, 2); |
170 | } |
171 | |
172 | /* --- Sift through the results --- */ |
173 | |
174 | if (r < 0) { |
175 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
176 | return; |
177 | goto close; |
178 | } |
179 | else if (r == 0) |
180 | goto close; |
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181 | else if (c->len == 0 && (c->f & CHANF_READY)) { |
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182 | sel_addfile(&c->w); |
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183 | sel_force(&c->w); |
184 | } |
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185 | c->len += r; |
186 | if (c->len == CHAN_BUFSZ) |
187 | sel_rmfile(&c->r); |
188 | return; |
189 | |
190 | /* --- Close the read end of the channel --- */ |
191 | |
192 | close: |
193 | c->f |= CHANF_CLOSE; |
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194 | if (!c->len && (c->f & CHANF_READY)) { |
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195 | sel_addfile(&c->w); |
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196 | sel_force(&c->w); |
197 | } |
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198 | sel_rmfile(&c->r); |
199 | } |
200 | |
201 | /* --- @chan_close@ --- * |
202 | * |
203 | * Arguments: @chan *c@ = pointer to channel |
204 | * |
205 | * Returns: --- |
206 | * |
207 | * Use: Closes down a channel prematurely. |
208 | */ |
209 | |
210 | void chan_close(chan *c) |
211 | { |
212 | if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ) |
213 | sel_rmfile(&c->r); |
214 | if ((c->f & CHANF_READY) && c->len != 0) |
215 | sel_rmfile(&c->w); |
216 | } |
217 | |
218 | /* --- @chan_dest@ --- * |
219 | * |
220 | * Arguments: @chan *c@ = pointer to channel |
221 | * @int fd@ = destination file descriptor for channel |
222 | * |
223 | * Returns: --- |
224 | * |
225 | * Use: Sets the channel's destination so it knows where to put |
226 | * data. |
227 | */ |
228 | |
229 | void chan_dest(chan *c, int fd) |
230 | { |
231 | if (c->f & CHANF_READY) |
232 | return; |
233 | sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c); |
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234 | if (c->len || (c->f & CHANF_CLOSE)) { |
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235 | sel_addfile(&c->w); |
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236 | sel_force(&c->w); |
237 | } |
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238 | c->f |= CHANF_READY; |
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239 | } |
240 | |
241 | /* --- @chan_open@ --- * |
242 | * |
243 | * Arguments: @chan *c@ = pointer to channel to open |
244 | * @int from, to@ = source and destination file descriptors |
245 | * @void (*func)(void *p)@ = function to call on closure |
246 | * @void *p@ = argument to pass to function |
247 | * |
248 | * Returns: --- |
249 | * |
250 | * Use: Opens a channel. Data is copied from the source to the |
251 | * destination. The @to@ argument may be @-1@ if the file |
252 | * descriptor isn't known yet. |
253 | */ |
254 | |
255 | void chan_open(chan *c, int from, int to, |
256 | void (*func)(void */*p*/), void *p) |
257 | { |
258 | c->func = func; |
259 | c->p = p; |
260 | |
261 | c->base = 0; |
262 | c->len = 0; |
263 | c->f = 0; |
264 | |
265 | sel_initfile(sel, &c->r, from, SEL_READ, readchan, c); |
266 | sel_addfile(&c->r); |
267 | |
268 | if (to != -1) |
269 | chan_dest(c, to); |
270 | } |
271 | |
272 | /*----- That's all, folks -------------------------------------------------*/ |