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189935b1 | 1 | /* |
2 | * IRC - Internet Relay Chat, common/dbuf.c | |
3 | * Copyright (C) 1990 Markku Savela | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 1, or (at your option) | |
8 | * any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
18 | */ | |
19 | /** @file | |
20 | * @brief Implementation of functions dealing with data buffers. | |
21 | * @version $Id: dbuf.c,v 1.12 2004/12/11 05:13:44 klmitch Exp $ | |
22 | */ | |
23 | #include "config.h" | |
24 | ||
25 | #include "dbuf.h" | |
26 | #include "ircd_alloc.h" | |
27 | #include "ircd_chattr.h" | |
28 | #include "ircd_features.h" | |
29 | #include "ircd_log.h" | |
30 | #include "send.h" | |
31 | #include "sys.h" /* MIN */ | |
32 | ||
33 | /* #include <assert.h> -- Now using assert in ircd_log.h */ | |
34 | #include <string.h> | |
35 | ||
36 | /* | |
37 | * dbuf is a collection of functions which can be used to | |
38 | * maintain a dynamic buffering of a byte stream. | |
39 | * Functions allocate and release memory dynamically as | |
40 | * required [Actually, there is nothing that prevents | |
41 | * this package maintaining the buffer on disk, either] | |
42 | */ | |
43 | ||
44 | /** Number of dbufs allocated. | |
45 | * This should only be modified by dbuf.c. | |
46 | */ | |
47 | int DBufAllocCount = 0; | |
48 | /** Number of dbufs in use. | |
49 | * This should only be modified by dbuf.c. | |
50 | */ | |
51 | int DBufUsedCount = 0; | |
52 | ||
53 | /** List of allocated but unused DBuf structures. */ | |
54 | static struct DBufBuffer *dbufFreeList = 0; | |
55 | ||
56 | /** Size of data for a single DBufBuffer. */ | |
57 | #define DBUF_SIZE 2048 | |
58 | ||
59 | /** Single data buffer in a DBuf. */ | |
60 | struct DBufBuffer { | |
61 | struct DBufBuffer *next; /**< Next data buffer, NULL if last */ | |
62 | char *start; /**< data starts here */ | |
63 | char *end; /**< data ends here */ | |
64 | char data[DBUF_SIZE]; /**< Actual data stored here */ | |
65 | }; | |
66 | ||
67 | /** Return memory used by allocated data buffers. | |
68 | * @param[out] allocated Receives number of bytes allocated to DBufs. | |
69 | * @param[out] used Receives number of bytes for currently used DBufs. | |
70 | */ | |
71 | void dbuf_count_memory(size_t *allocated, size_t *used) | |
72 | { | |
73 | assert(0 != allocated); | |
74 | assert(0 != used); | |
75 | *allocated = DBufAllocCount * sizeof(struct DBufBuffer); | |
76 | *used = DBufUsedCount * sizeof(struct DBufBuffer); | |
77 | } | |
78 | ||
79 | /** Allocate a new DBufBuffer. | |
80 | * If #dbufFreeList != NULL, use the head of that list; otherwise, | |
81 | * allocate a new buffer. | |
82 | * @return Newly allocated buffer list. | |
83 | */ | |
84 | static struct DBufBuffer *dbuf_alloc(void) | |
85 | { | |
86 | struct DBufBuffer* db = dbufFreeList; | |
87 | ||
88 | if (db) { | |
89 | dbufFreeList = db->next; | |
90 | ++DBufUsedCount; | |
91 | } | |
92 | else if (DBufAllocCount * DBUF_SIZE < feature_int(FEAT_BUFFERPOOL)) { | |
93 | db = (struct DBufBuffer*) MyMalloc(sizeof(struct DBufBuffer)); | |
94 | assert(0 != db); | |
95 | ++DBufAllocCount; | |
96 | ++DBufUsedCount; | |
97 | } | |
98 | return db; | |
99 | } | |
100 | ||
101 | /** Release a DBufBuffer back to the free list. | |
102 | * @param[in] db Data buffer to release. | |
103 | */ | |
104 | static void dbuf_free(struct DBufBuffer *db) | |
105 | { | |
106 | assert(0 != db); | |
107 | --DBufUsedCount; | |
108 | db->next = dbufFreeList; | |
109 | dbufFreeList = db; | |
110 | } | |
111 | ||
112 | /** Handle a memory allocation error on a DBuf. | |
113 | * This frees all the buffers owned by the DBuf, since we have to | |
114 | * close the associated connection. | |
115 | * @param[in] dyn DBuf to clean out. | |
116 | * @return Zero. | |
117 | */ | |
118 | static int dbuf_malloc_error(struct DBuf *dyn) | |
119 | { | |
120 | struct DBufBuffer *db; | |
121 | struct DBufBuffer *next; | |
122 | ||
123 | for (db = dyn->head; db; db = next) | |
124 | { | |
125 | next = db->next; | |
126 | dbuf_free(db); | |
127 | } | |
128 | dyn->tail = dyn->head = 0; | |
129 | dyn->length = 0; | |
130 | return 0; | |
131 | } | |
132 | ||
133 | /** Append bytes to a data buffer. | |
134 | * @param[in] dyn Buffer to append to. | |
135 | * @param[in] buf Data to append. | |
136 | * @param[in] length Number of bytes to append. | |
137 | * @return Non-zero on success, or zero on failure. | |
138 | */ | |
139 | int dbuf_put(struct DBuf *dyn, const char *buf, unsigned int length) | |
140 | { | |
141 | struct DBufBuffer** h; | |
142 | struct DBufBuffer* db; | |
143 | unsigned int chunk; | |
144 | ||
145 | assert(0 != dyn); | |
146 | assert(0 != buf); | |
147 | /* | |
148 | * Locate the last non-empty buffer. If the last buffer is full, | |
149 | * the loop will terminate with 'db==NULL'. | |
150 | * This loop assumes that the 'dyn->length' field is correctly | |
151 | * maintained, as it should--no other check really needed. | |
152 | */ | |
153 | if (!dyn->length) | |
154 | h = &(dyn->head); | |
155 | else | |
156 | h = &(dyn->tail); | |
157 | /* | |
158 | * Append users data to buffer, allocating buffers as needed | |
159 | */ | |
160 | dyn->length += length; | |
161 | ||
162 | for (; length > 0; h = &(db->next)) { | |
163 | if (0 == (db = *h)) { | |
164 | if (0 == (db = dbuf_alloc())) { | |
165 | if (feature_bool(FEAT_HAS_FERGUSON_FLUSHER)) { | |
166 | /* | |
167 | * from "Married With Children" episode were Al bought a REAL toilet | |
168 | * on the black market because he was tired of the wimpy water | |
169 | * conserving toilets they make these days --Bleep | |
170 | */ | |
171 | /* | |
172 | * Apparently this doesn't work, the server _has_ to | |
173 | * dump a few clients to handle the load. A fully loaded | |
174 | * server cannot handle a net break without dumping some | |
175 | * clients. If we flush the connections here under a full | |
176 | * load we may end up starving the kernel for mbufs and | |
177 | * crash the machine | |
178 | */ | |
179 | /* | |
180 | * attempt to recover from buffer starvation before | |
181 | * bailing this may help servers running out of memory | |
182 | */ | |
183 | flush_connections(0); | |
184 | db = dbuf_alloc(); | |
185 | } | |
186 | ||
187 | if (0 == db) | |
188 | return dbuf_malloc_error(dyn); | |
189 | } | |
190 | dyn->tail = db; | |
191 | *h = db; | |
192 | db->next = 0; | |
193 | db->start = db->end = db->data; | |
194 | } | |
195 | chunk = (db->data + DBUF_SIZE) - db->end; | |
196 | if (chunk) { | |
197 | if (chunk > length) | |
198 | chunk = length; | |
199 | ||
200 | memcpy(db->end, buf, chunk); | |
201 | ||
202 | length -= chunk; | |
203 | buf += chunk; | |
204 | db->end += chunk; | |
205 | } | |
206 | } | |
207 | return 1; | |
208 | } | |
209 | ||
210 | /** Get the first contiguous block of data from a DBuf. | |
211 | * Generally a call to dbuf_map(dyn, &count) will be followed with a | |
212 | * call to dbuf_delete(dyn, count). | |
213 | * @param[in] dyn DBuf to retrieve data from. | |
214 | * @param[out] length Receives number of bytes in block. | |
215 | * @return Pointer to start of block (or NULL if the first block is empty). | |
216 | */ | |
217 | const char *dbuf_map(const struct DBuf* dyn, unsigned int* length) | |
218 | { | |
219 | assert(0 != dyn); | |
220 | assert(0 != length); | |
221 | ||
222 | if (0 == dyn->length) | |
223 | { | |
224 | *length = 0; | |
225 | return 0; | |
226 | } | |
227 | assert(0 != dyn->head); | |
228 | ||
229 | *length = dyn->head->end - dyn->head->start; | |
230 | return dyn->head->start; | |
231 | } | |
232 | ||
233 | /** Discard data from a DBuf. | |
234 | * @param[in,out] dyn DBuf to drop data from. | |
235 | * @param[in] length Number of bytes to discard. | |
236 | */ | |
237 | void dbuf_delete(struct DBuf *dyn, unsigned int length) | |
238 | { | |
239 | struct DBufBuffer *db; | |
240 | unsigned int chunk; | |
241 | ||
242 | if (length > dyn->length) | |
243 | length = dyn->length; | |
244 | ||
245 | while (length > 0) | |
246 | { | |
247 | if (0 == (db = dyn->head)) | |
248 | break; | |
249 | chunk = db->end - db->start; | |
250 | if (chunk > length) | |
251 | chunk = length; | |
252 | ||
253 | length -= chunk; | |
254 | dyn->length -= chunk; | |
255 | db->start += chunk; | |
256 | ||
257 | if (db->start == db->end) | |
258 | { | |
259 | dyn->head = db->next; | |
260 | dbuf_free(db); | |
261 | } | |
262 | } | |
263 | if (0 == dyn->head) | |
264 | { | |
265 | dyn->length = 0; | |
266 | dyn->tail = 0; | |
267 | } | |
268 | } | |
269 | ||
270 | /** Copy data from a buffer and remove what was copied. | |
271 | * @param[in,out] dyn Buffer to copy from. | |
272 | * @param[out] buf Buffer to write to. | |
273 | * @param[in] length Maximum number of bytes to copy. | |
274 | * @return Number of bytes actually copied. | |
275 | */ | |
276 | unsigned int dbuf_get(struct DBuf *dyn, char *buf, unsigned int length) | |
277 | { | |
278 | unsigned int moved = 0; | |
279 | unsigned int chunk; | |
280 | const char *b; | |
281 | ||
282 | assert(0 != dyn); | |
283 | assert(0 != buf); | |
284 | ||
285 | while (length > 0 && (b = dbuf_map(dyn, &chunk)) != 0) | |
286 | { | |
287 | if (chunk > length) | |
288 | chunk = length; | |
289 | ||
290 | memcpy(buf, b, chunk); | |
291 | dbuf_delete(dyn, chunk); | |
292 | ||
293 | buf += chunk; | |
294 | length -= chunk; | |
295 | moved += chunk; | |
296 | } | |
297 | return moved; | |
298 | } | |
299 | ||
300 | /** Flush empty lines from a buffer. | |
301 | * @param[in,out] dyn Data buffer to flush. | |
302 | * @return Number of bytes in first available block (or zero if none). | |
303 | */ | |
304 | static unsigned int dbuf_flush(struct DBuf *dyn) | |
305 | { | |
306 | struct DBufBuffer *db = dyn->head; | |
307 | ||
308 | if (0 == db) | |
309 | return 0; | |
310 | ||
311 | assert(db->start < db->end); | |
312 | /* | |
313 | * flush extra line terms | |
314 | */ | |
315 | while (IsEol(*db->start)) | |
316 | { | |
317 | if (++db->start == db->end) | |
318 | { | |
319 | dyn->head = db->next; | |
320 | dbuf_free(db); | |
321 | if (0 == (db = dyn->head)) | |
322 | { | |
323 | dyn->tail = 0; | |
324 | dyn->length = 0; | |
325 | break; | |
326 | } | |
327 | } | |
328 | --dyn->length; | |
329 | } | |
330 | return dyn->length; | |
331 | } | |
332 | ||
333 | /** Copy a single line from a data buffer. | |
334 | * If the output buffer cannot hold the whole line, or if there is no | |
335 | * EOL in the buffer, return 0. | |
336 | * @param[in,out] dyn Data buffer to copy from. | |
337 | * @param[out] buf Buffer to copy to. | |
338 | * @param[in] length Maximum number of bytes to copy. | |
339 | * @return Number of bytes copied to \a buf. | |
340 | */ | |
341 | unsigned int dbuf_getmsg(struct DBuf *dyn, char *buf, unsigned int length) | |
342 | { | |
343 | struct DBufBuffer *db; | |
344 | char *start; | |
345 | char *end; | |
346 | unsigned int count; | |
347 | unsigned int copied = 0; | |
348 | ||
349 | assert(0 != dyn); | |
350 | assert(0 != buf); | |
351 | ||
352 | if (0 == dbuf_flush(dyn)) | |
353 | return 0; | |
354 | ||
355 | assert(0 != dyn->head); | |
356 | ||
357 | db = dyn->head; | |
358 | start = db->start; | |
359 | ||
360 | assert(start < db->end); | |
361 | ||
362 | if (length > dyn->length) | |
363 | length = dyn->length; | |
364 | /* | |
365 | * might as well copy it while we're here | |
366 | */ | |
367 | while (length > 0) | |
368 | { | |
369 | end = IRCD_MIN(db->end, (start + length)); | |
370 | while (start < end && !IsEol(*start)) | |
371 | *buf++ = *start++; | |
372 | ||
373 | count = start - db->start; | |
374 | if (start < end) | |
375 | { | |
376 | *buf = '\0'; | |
377 | copied += count; | |
378 | dbuf_delete(dyn, copied); | |
379 | dbuf_flush(dyn); | |
380 | return copied; | |
381 | } | |
382 | if (0 == (db = db->next)) | |
383 | break; | |
384 | copied += count; | |
385 | length -= count; | |
386 | start = db->start; | |
387 | } | |
388 | return 0; | |
389 | } |