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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: chan.c,v 1.7 2004/04/08 01:36:25 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 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include "config.h" |
32 | |
33 | #include <errno.h> |
34 | #include <stdio.h> |
35 | #include <stdlib.h> |
36 | #include <string.h> |
37 | |
38 | #include <sys/types.h> |
39 | #include <sys/time.h> |
40 | #include <unistd.h> |
41 | #include <sys/uio.h> |
42 | |
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43 | #include <mLib/alloc.h> |
44 | #include <mLib/conn.h> |
45 | #include <mLib/sel.h> |
46 | |
47 | #include "chan.h" |
48 | #include "fw.h" |
49 | |
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50 | #ifdef CHAN_DEBUG |
51 | # define D(x) x |
52 | #else |
53 | # define D(x) |
54 | #endif |
55 | |
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56 | /*----- Main code ---------------------------------------------------------*/ |
57 | |
58 | /* --- @writechan@ --- * |
59 | * |
60 | * Arguments: @int fd@ = file descriptor to write to |
61 | * @unsigned mode@ = what the descriptor is ready for |
62 | * @void *vp@ = pointer to channel block |
63 | * |
64 | * Returns: --- |
65 | * |
66 | * Use: Writes to a channel. |
67 | */ |
68 | |
69 | static void writechan(int fd, unsigned mode, void *vp) |
70 | { |
71 | chan *c = vp; |
72 | int w; |
73 | unsigned base = c->base; |
74 | unsigned len = c->len; |
75 | |
76 | /* --- Write data from my buffer --- */ |
77 | |
78 | if (len) { |
79 | |
80 | /* --- Do the write --- */ |
81 | |
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82 | D( printf("writechan %d: base = %u, len = %u; ", fd, base, len); ) |
83 | if (base + len <= CHAN_BUFSZ) { |
84 | D( printf("%u:%u", base, len); ) |
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85 | w = write(fd, c->buf + base, len); |
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86 | } else { |
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87 | struct iovec iov[2]; |
88 | iov[0].iov_base = c->buf + base; |
89 | iov[0].iov_len = CHAN_BUFSZ - base; |
90 | iov[1].iov_base = c->buf; |
91 | iov[1].iov_len = len - iov[0].iov_len; |
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92 | D( printf("%u:%u, %u:%u", |
93 | base, CHAN_BUFSZ - base, |
94 | 0, len + base - CHAN_BUFSZ); ) |
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95 | w = writev(fd, iov, 2); |
96 | } |
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97 | D( printf("; returned %d\n", w); ) |
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98 | |
99 | /* --- Sift through the results --- */ |
100 | |
101 | if (w < 0) { |
102 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
103 | return; |
104 | goto close; |
105 | } |
106 | else if (w == 0) |
107 | goto close; |
108 | else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE)) |
109 | sel_addfile(&c->r); |
110 | c->len -= w; |
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111 | c->base += w; |
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112 | } |
113 | if (c->len == 0) |
114 | sel_rmfile(&c->w); |
115 | |
116 | /* --- Close the output end if necessary --- */ |
117 | |
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118 | if (c->len == 0) { |
119 | c->base = 0; |
120 | if (c->f & CHANF_CLOSE) |
121 | c->func(c->p); |
122 | } |
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123 | return; |
124 | |
125 | /* --- Force a close if an error occurred --- */ |
126 | |
127 | close: |
128 | chan_close(c); |
129 | c->func(c->p); |
130 | } |
131 | |
132 | /* --- @readchan@ --- * |
133 | * |
134 | * Arguments: @int fd@ = file descriptor to read from |
135 | * @unsigned mode@ = what the descriptor is ready for |
136 | * @void *vp@ = pointer to channel block |
137 | * |
138 | * Returns: --- |
139 | * |
140 | * Use: Reads from a channel. |
141 | */ |
142 | |
143 | static void readchan(int fd, unsigned mode, void *vp) |
144 | { |
145 | chan *c = vp; |
146 | int r; |
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147 | unsigned base = c->base; |
148 | unsigned len = c->len; |
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149 | |
150 | /* --- Do the read --- */ |
151 | |
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152 | D( printf("readchan %d: base = %u, len = %u; ", fd, base, len); ) |
153 | if (base == 0) { |
154 | D( printf("%u:%u", len, CHAN_BUFSZ - len); ) |
155 | r = read(fd, c->buf + len, CHAN_BUFSZ - len); |
156 | } else if (base + len >= CHAN_BUFSZ) { |
157 | D( printf("%u:%u", base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); ) |
158 | r = read(fd, c->buf + base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); |
159 | } else { |
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160 | struct iovec iov[2]; |
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161 | iov[0].iov_base = c->buf + base + len; |
162 | iov[0].iov_len = CHAN_BUFSZ - base - len; |
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163 | iov[1].iov_base = c->buf; |
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164 | iov[1].iov_len = base; |
165 | D( printf("%u:%u, %u:%u", |
166 | base + len, CHAN_BUFSZ - base - len, |
167 | 0, base); ) |
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168 | r = readv(fd, iov, 2); |
169 | } |
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170 | D( printf("; returned %d\n", r); ) |
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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 -------------------------------------------------*/ |