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1 | /* -*-c-*- |
2 | * |
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3 | * Channel management |
4 | * |
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5 | * (c) 1999 Straylight/Edgeware |
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6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of the `fw' port forwarder. |
11 | * |
12 | * `fw' is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU General Public License as published by |
14 | * the Free Software Foundation; either version 2 of the License, or |
15 | * (at your option) any later version. |
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16 | * |
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17 | * `fw' is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU General Public License |
23 | * along with `fw'; if not, write to the Free Software Foundation, |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
25 | */ |
26 | |
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27 | /*----- Header files ------------------------------------------------------*/ |
28 | |
29 | #include "config.h" |
30 | |
31 | #include <errno.h> |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include <sys/types.h> |
37 | #include <sys/time.h> |
38 | #include <unistd.h> |
39 | #include <sys/uio.h> |
40 | |
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41 | #include <mLib/alloc.h> |
42 | #include <mLib/conn.h> |
43 | #include <mLib/sel.h> |
44 | |
45 | #include "chan.h" |
46 | #include "fw.h" |
47 | |
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48 | #ifdef CHAN_DEBUG |
49 | # define D(x) x |
50 | #else |
51 | # define D(x) |
52 | #endif |
53 | |
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54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @writechan@ --- * |
57 | * |
58 | * Arguments: @int fd@ = file descriptor to write to |
59 | * @unsigned mode@ = what the descriptor is ready for |
60 | * @void *vp@ = pointer to channel block |
61 | * |
62 | * Returns: --- |
63 | * |
64 | * Use: Writes to a channel. |
65 | */ |
66 | |
67 | static void writechan(int fd, unsigned mode, void *vp) |
68 | { |
69 | chan *c = vp; |
70 | int w; |
71 | unsigned base = c->base; |
72 | unsigned len = c->len; |
73 | |
74 | /* --- Write data from my buffer --- */ |
75 | |
76 | if (len) { |
77 | |
78 | /* --- Do the write --- */ |
79 | |
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80 | D( printf("writechan %d: base = %u, len = %u; ", fd, base, len); ) |
81 | if (base + len <= CHAN_BUFSZ) { |
82 | D( printf("%u:%u", base, len); ) |
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83 | w = write(fd, c->buf + base, len); |
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84 | } else { |
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85 | struct iovec iov[2]; |
86 | iov[0].iov_base = c->buf + base; |
87 | iov[0].iov_len = CHAN_BUFSZ - base; |
88 | iov[1].iov_base = c->buf; |
89 | iov[1].iov_len = len - iov[0].iov_len; |
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90 | D( printf("%u:%u, %u:%u", |
91 | base, CHAN_BUFSZ - base, |
92 | 0, len + base - CHAN_BUFSZ); ) |
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93 | w = writev(fd, iov, 2); |
94 | } |
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95 | D( printf("; returned %d\n", w); ) |
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96 | |
97 | /* --- Sift through the results --- */ |
98 | |
99 | if (w < 0) { |
100 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
101 | return; |
102 | goto close; |
103 | } |
104 | else if (w == 0) |
105 | goto close; |
106 | else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE)) |
107 | sel_addfile(&c->r); |
108 | c->len -= w; |
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109 | c->base += w; |
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110 | } |
111 | if (c->len == 0) |
112 | sel_rmfile(&c->w); |
113 | |
114 | /* --- Close the output end if necessary --- */ |
115 | |
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116 | if (c->len == 0) { |
117 | c->base = 0; |
118 | if (c->f & CHANF_CLOSE) |
119 | c->func(c->p); |
120 | } |
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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; |
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145 | unsigned base = c->base; |
146 | unsigned len = c->len; |
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147 | |
148 | /* --- Do the read --- */ |
149 | |
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150 | D( printf("readchan %d: base = %u, len = %u; ", fd, base, len); ) |
151 | if (base == 0) { |
152 | D( printf("%u:%u", len, CHAN_BUFSZ - len); ) |
153 | r = read(fd, c->buf + len, CHAN_BUFSZ - len); |
154 | } else if (base + len >= CHAN_BUFSZ) { |
155 | D( printf("%u:%u", base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); ) |
156 | r = read(fd, c->buf + base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); |
157 | } else { |
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158 | struct iovec iov[2]; |
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159 | iov[0].iov_base = c->buf + base + len; |
160 | iov[0].iov_len = CHAN_BUFSZ - base - len; |
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161 | iov[1].iov_base = c->buf; |
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162 | iov[1].iov_len = base; |
163 | D( printf("%u:%u, %u:%u", |
164 | base + len, CHAN_BUFSZ - base - len, |
165 | 0, base); ) |
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166 | r = readv(fd, iov, 2); |
167 | } |
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168 | D( printf("; returned %d\n", r); ) |
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169 | |
170 | /* --- Sift through the results --- */ |
171 | |
172 | if (r < 0) { |
173 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
174 | return; |
175 | goto close; |
176 | } |
177 | else if (r == 0) |
178 | goto close; |
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179 | else if (c->len == 0 && (c->f & CHANF_READY)) { |
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180 | sel_addfile(&c->w); |
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181 | sel_force(&c->w); |
182 | } |
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183 | c->len += r; |
184 | if (c->len == CHAN_BUFSZ) |
185 | sel_rmfile(&c->r); |
186 | return; |
187 | |
188 | /* --- Close the read end of the channel --- */ |
189 | |
190 | close: |
191 | c->f |= CHANF_CLOSE; |
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192 | if (!c->len && (c->f & CHANF_READY)) { |
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193 | sel_addfile(&c->w); |
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194 | sel_force(&c->w); |
195 | } |
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196 | sel_rmfile(&c->r); |
197 | } |
198 | |
199 | /* --- @chan_close@ --- * |
200 | * |
201 | * Arguments: @chan *c@ = pointer to channel |
202 | * |
203 | * Returns: --- |
204 | * |
205 | * Use: Closes down a channel prematurely. |
206 | */ |
207 | |
208 | void chan_close(chan *c) |
209 | { |
210 | if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ) |
211 | sel_rmfile(&c->r); |
212 | if ((c->f & CHANF_READY) && c->len != 0) |
213 | sel_rmfile(&c->w); |
214 | } |
215 | |
216 | /* --- @chan_dest@ --- * |
217 | * |
218 | * Arguments: @chan *c@ = pointer to channel |
219 | * @int fd@ = destination file descriptor for channel |
220 | * |
221 | * Returns: --- |
222 | * |
223 | * Use: Sets the channel's destination so it knows where to put |
224 | * data. |
225 | */ |
226 | |
227 | void chan_dest(chan *c, int fd) |
228 | { |
229 | if (c->f & CHANF_READY) |
230 | return; |
231 | sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c); |
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232 | if (c->len || (c->f & CHANF_CLOSE)) { |
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233 | sel_addfile(&c->w); |
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234 | sel_force(&c->w); |
235 | } |
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236 | c->f |= CHANF_READY; |
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237 | } |
238 | |
239 | /* --- @chan_open@ --- * |
240 | * |
241 | * Arguments: @chan *c@ = pointer to channel to open |
242 | * @int from, to@ = source and destination file descriptors |
243 | * @void (*func)(void *p)@ = function to call on closure |
244 | * @void *p@ = argument to pass to function |
245 | * |
246 | * Returns: --- |
247 | * |
248 | * Use: Opens a channel. Data is copied from the source to the |
249 | * destination. The @to@ argument may be @-1@ if the file |
250 | * descriptor isn't known yet. |
251 | */ |
252 | |
253 | void chan_open(chan *c, int from, int to, |
254 | void (*func)(void */*p*/), void *p) |
255 | { |
256 | c->func = func; |
257 | c->p = p; |
258 | |
259 | c->base = 0; |
260 | c->len = 0; |
261 | c->f = 0; |
262 | |
263 | sel_initfile(sel, &c->r, from, SEL_READ, readchan, c); |
264 | sel_addfile(&c->r); |
265 | |
266 | if (to != -1) |
267 | chan_dest(c, to); |
268 | } |
269 | |
270 | /*----- That's all, folks -------------------------------------------------*/ |