Greg Hartman | 76d05dc | 2016-11-23 15:51:27 -0800 | [diff] [blame] | 1 | /** |
| 2 | * @file |
| 3 | * This is the IPv4 packet segmentation and reassembly implementation. |
| 4 | * |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science. |
| 9 | * All rights reserved. |
| 10 | * |
| 11 | * Redistribution and use in source and binary forms, with or without modification, |
| 12 | * are permitted provided that the following conditions are met: |
| 13 | * |
| 14 | * 1. Redistributions of source code must retain the above copyright notice, |
| 15 | * this list of conditions and the following disclaimer. |
| 16 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 17 | * this list of conditions and the following disclaimer in the documentation |
| 18 | * and/or other materials provided with the distribution. |
| 19 | * 3. The name of the author may not be used to endorse or promote products |
| 20 | * derived from this software without specific prior written permission. |
| 21 | * |
| 22 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 23 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 24 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
| 25 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 26 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 27 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| 30 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
| 31 | * OF SUCH DAMAGE. |
| 32 | * |
| 33 | * This file is part of the lwIP TCP/IP stack. |
| 34 | * |
| 35 | * Author: Jani Monoses <jani@iv.ro> |
| 36 | * Simon Goldschmidt |
| 37 | * original reassembly code by Adam Dunkels <adam@sics.se> |
| 38 | * |
| 39 | */ |
| 40 | |
| 41 | #include "lwip/opt.h" |
| 42 | #include "lwip/ip_frag.h" |
| 43 | #include "lwip/def.h" |
| 44 | #include "lwip/inet_chksum.h" |
| 45 | #include "lwip/netif.h" |
| 46 | #include "lwip/snmp.h" |
| 47 | #include "lwip/stats.h" |
| 48 | #include "lwip/icmp.h" |
| 49 | |
| 50 | #include <string.h> |
| 51 | |
| 52 | #if IP_REASSEMBLY |
| 53 | /** |
| 54 | * The IP reassembly code currently has the following limitations: |
| 55 | * - IP header options are not supported |
| 56 | * - fragments must not overlap (e.g. due to different routes), |
| 57 | * currently, overlapping or duplicate fragments are thrown away |
| 58 | * if IP_REASS_CHECK_OVERLAP=1 (the default)! |
| 59 | * |
| 60 | * @todo: work with IP header options |
| 61 | */ |
| 62 | |
| 63 | /** Setting this to 0, you can turn off checking the fragments for overlapping |
| 64 | * regions. The code gets a little smaller. Only use this if you know that |
| 65 | * overlapping won't occur on your network! */ |
| 66 | #ifndef IP_REASS_CHECK_OVERLAP |
| 67 | #define IP_REASS_CHECK_OVERLAP 1 |
| 68 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 69 | |
| 70 | /** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is |
| 71 | * full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller. |
| 72 | * Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA |
| 73 | * is set to 1, so one datagram can be reassembled at a time, only. */ |
| 74 | #ifndef IP_REASS_FREE_OLDEST |
| 75 | #define IP_REASS_FREE_OLDEST 1 |
| 76 | #endif /* IP_REASS_FREE_OLDEST */ |
| 77 | |
| 78 | #define IP_REASS_FLAG_LASTFRAG 0x01 |
| 79 | |
| 80 | /** This is a helper struct which holds the starting |
| 81 | * offset and the ending offset of this fragment to |
| 82 | * easily chain the fragments. |
| 83 | * It has the same packing requirements as the IP header, since it replaces |
| 84 | * the IP header in memory in incoming fragments (after copying it) to keep |
| 85 | * track of the various fragments. (-> If the IP header doesn't need packing, |
| 86 | * this struct doesn't need packing, too.) |
| 87 | */ |
| 88 | #ifdef PACK_STRUCT_USE_INCLUDES |
| 89 | # include "arch/bpstruct.h" |
| 90 | #endif |
| 91 | PACK_STRUCT_BEGIN |
| 92 | struct ip_reass_helper { |
| 93 | PACK_STRUCT_FIELD(struct pbuf *next_pbuf); |
| 94 | PACK_STRUCT_FIELD(u16_t start); |
| 95 | PACK_STRUCT_FIELD(u16_t end); |
| 96 | } PACK_STRUCT_STRUCT; |
| 97 | PACK_STRUCT_END |
| 98 | #ifdef PACK_STRUCT_USE_INCLUDES |
| 99 | # include "arch/epstruct.h" |
| 100 | #endif |
| 101 | |
| 102 | #define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \ |
| 103 | (ip_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \ |
| 104 | ip_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \ |
| 105 | IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0 |
| 106 | |
| 107 | /* global variables */ |
| 108 | static struct ip_reassdata *reassdatagrams; |
| 109 | static u16_t ip_reass_pbufcount; |
| 110 | |
| 111 | /* function prototypes */ |
| 112 | static void ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev); |
| 113 | static int ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev); |
| 114 | |
| 115 | /** |
| 116 | * Reassembly timer base function |
| 117 | * for both NO_SYS == 0 and 1 (!). |
| 118 | * |
| 119 | * Should be called every 1000 msec (defined by IP_TMR_INTERVAL). |
| 120 | */ |
| 121 | void |
| 122 | ip_reass_tmr(void) |
| 123 | { |
| 124 | struct ip_reassdata *r, *prev = NULL; |
| 125 | |
| 126 | r = reassdatagrams; |
| 127 | while (r != NULL) { |
| 128 | /* Decrement the timer. Once it reaches 0, |
| 129 | * clean up the incomplete fragment assembly */ |
| 130 | if (r->timer > 0) { |
| 131 | r->timer--; |
| 132 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)r->timer)); |
| 133 | prev = r; |
| 134 | r = r->next; |
| 135 | } else { |
| 136 | /* reassembly timed out */ |
| 137 | struct ip_reassdata *tmp; |
| 138 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n")); |
| 139 | tmp = r; |
| 140 | /* get the next pointer before freeing */ |
| 141 | r = r->next; |
| 142 | /* free the helper struct and all enqueued pbufs */ |
| 143 | ip_reass_free_complete_datagram(tmp, prev); |
| 144 | } |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * Free a datagram (struct ip_reassdata) and all its pbufs. |
| 150 | * Updates the total count of enqueued pbufs (ip_reass_pbufcount), |
| 151 | * SNMP counters and sends an ICMP time exceeded packet. |
| 152 | * |
| 153 | * @param ipr datagram to free |
| 154 | * @param prev the previous datagram in the linked list |
| 155 | * @return the number of pbufs freed |
| 156 | */ |
| 157 | static int |
| 158 | ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev) |
| 159 | { |
| 160 | u16_t pbufs_freed = 0; |
| 161 | u8_t clen; |
| 162 | struct pbuf *p; |
| 163 | struct ip_reass_helper *iprh; |
| 164 | |
| 165 | LWIP_ASSERT("prev != ipr", prev != ipr); |
| 166 | if (prev != NULL) { |
| 167 | LWIP_ASSERT("prev->next == ipr", prev->next == ipr); |
| 168 | } |
| 169 | |
| 170 | snmp_inc_ipreasmfails(); |
| 171 | #if LWIP_ICMP |
| 172 | iprh = (struct ip_reass_helper *)ipr->p->payload; |
| 173 | if (iprh->start == 0) { |
| 174 | /* The first fragment was received, send ICMP time exceeded. */ |
| 175 | /* First, de-queue the first pbuf from r->p. */ |
| 176 | p = ipr->p; |
| 177 | ipr->p = iprh->next_pbuf; |
| 178 | /* Then, copy the original header into it. */ |
| 179 | SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN); |
| 180 | icmp_time_exceeded(p, ICMP_TE_FRAG); |
| 181 | clen = pbuf_clen(p); |
| 182 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff); |
| 183 | pbufs_freed += clen; |
| 184 | pbuf_free(p); |
| 185 | } |
| 186 | #endif /* LWIP_ICMP */ |
| 187 | |
| 188 | /* First, free all received pbufs. The individual pbufs need to be released |
| 189 | separately as they have not yet been chained */ |
| 190 | p = ipr->p; |
| 191 | while (p != NULL) { |
| 192 | struct pbuf *pcur; |
| 193 | iprh = (struct ip_reass_helper *)p->payload; |
| 194 | pcur = p; |
| 195 | /* get the next pointer before freeing */ |
| 196 | p = iprh->next_pbuf; |
| 197 | clen = pbuf_clen(pcur); |
| 198 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff); |
| 199 | pbufs_freed += clen; |
| 200 | pbuf_free(pcur); |
| 201 | } |
| 202 | /* Then, unchain the struct ip_reassdata from the list and free it. */ |
| 203 | ip_reass_dequeue_datagram(ipr, prev); |
| 204 | LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= pbufs_freed); |
| 205 | ip_reass_pbufcount -= pbufs_freed; |
| 206 | |
| 207 | return pbufs_freed; |
| 208 | } |
| 209 | |
| 210 | #if IP_REASS_FREE_OLDEST |
| 211 | /** |
| 212 | * Free the oldest datagram to make room for enqueueing new fragments. |
| 213 | * The datagram 'fraghdr' belongs to is not freed! |
| 214 | * |
| 215 | * @param fraghdr IP header of the current fragment |
| 216 | * @param pbufs_needed number of pbufs needed to enqueue |
| 217 | * (used for freeing other datagrams if not enough space) |
| 218 | * @return the number of pbufs freed |
| 219 | */ |
| 220 | static int |
| 221 | ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed) |
| 222 | { |
| 223 | /* @todo Can't we simply remove the last datagram in the |
| 224 | * linked list behind reassdatagrams? |
| 225 | */ |
| 226 | struct ip_reassdata *r, *oldest, *prev; |
| 227 | int pbufs_freed = 0, pbufs_freed_current; |
| 228 | int other_datagrams; |
| 229 | |
| 230 | /* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs, |
| 231 | * but don't free the datagram that 'fraghdr' belongs to! */ |
| 232 | do { |
| 233 | oldest = NULL; |
| 234 | prev = NULL; |
| 235 | other_datagrams = 0; |
| 236 | r = reassdatagrams; |
| 237 | while (r != NULL) { |
| 238 | if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) { |
| 239 | /* Not the same datagram as fraghdr */ |
| 240 | other_datagrams++; |
| 241 | if (oldest == NULL) { |
| 242 | oldest = r; |
| 243 | } else if (r->timer <= oldest->timer) { |
| 244 | /* older than the previous oldest */ |
| 245 | oldest = r; |
| 246 | } |
| 247 | } |
| 248 | if (r->next != NULL) { |
| 249 | prev = r; |
| 250 | } |
| 251 | r = r->next; |
| 252 | } |
| 253 | if (oldest != NULL) { |
| 254 | pbufs_freed_current = ip_reass_free_complete_datagram(oldest, prev); |
| 255 | pbufs_freed += pbufs_freed_current; |
| 256 | } |
| 257 | } while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1)); |
| 258 | return pbufs_freed; |
| 259 | } |
| 260 | #endif /* IP_REASS_FREE_OLDEST */ |
| 261 | |
| 262 | /** |
| 263 | * Enqueues a new fragment into the fragment queue |
| 264 | * @param fraghdr points to the new fragments IP hdr |
| 265 | * @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space) |
| 266 | * @return A pointer to the queue location into which the fragment was enqueued |
| 267 | */ |
| 268 | static struct ip_reassdata* |
| 269 | ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen) |
| 270 | { |
| 271 | struct ip_reassdata* ipr; |
| 272 | /* No matching previous fragment found, allocate a new reassdata struct */ |
| 273 | ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA); |
| 274 | if (ipr == NULL) { |
| 275 | #if IP_REASS_FREE_OLDEST |
| 276 | if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) { |
| 277 | ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA); |
| 278 | } |
| 279 | if (ipr == NULL) |
| 280 | #endif /* IP_REASS_FREE_OLDEST */ |
| 281 | { |
| 282 | IPFRAG_STATS_INC(ip_frag.memerr); |
| 283 | LWIP_DEBUGF(IP_REASS_DEBUG,("Failed to alloc reassdata struct\n")); |
| 284 | return NULL; |
| 285 | } |
| 286 | } |
| 287 | memset(ipr, 0, sizeof(struct ip_reassdata)); |
| 288 | ipr->timer = IP_REASS_MAXAGE; |
| 289 | |
| 290 | /* enqueue the new structure to the front of the list */ |
| 291 | ipr->next = reassdatagrams; |
| 292 | reassdatagrams = ipr; |
| 293 | /* copy the ip header for later tests and input */ |
| 294 | /* @todo: no ip options supported? */ |
| 295 | SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN); |
| 296 | return ipr; |
| 297 | } |
| 298 | |
| 299 | /** |
| 300 | * Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs. |
| 301 | * @param ipr points to the queue entry to dequeue |
| 302 | */ |
| 303 | static void |
| 304 | ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev) |
| 305 | { |
| 306 | |
| 307 | /* dequeue the reass struct */ |
| 308 | if (reassdatagrams == ipr) { |
| 309 | /* it was the first in the list */ |
| 310 | reassdatagrams = ipr->next; |
| 311 | } else { |
| 312 | /* it wasn't the first, so it must have a valid 'prev' */ |
| 313 | LWIP_ASSERT("sanity check linked list", prev != NULL); |
| 314 | prev->next = ipr->next; |
| 315 | } |
| 316 | |
| 317 | /* now we can free the ip_reass struct */ |
| 318 | memp_free(MEMP_REASSDATA, ipr); |
| 319 | } |
| 320 | |
| 321 | /** |
| 322 | * Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list |
| 323 | * will grow over time as new pbufs are rx. |
| 324 | * Also checks that the datagram passes basic continuity checks (if the last |
| 325 | * fragment was received at least once). |
| 326 | * @param root_p points to the 'root' pbuf for the current datagram being assembled. |
| 327 | * @param new_p points to the pbuf for the current fragment |
| 328 | * @return 0 if invalid, >0 otherwise |
| 329 | */ |
| 330 | static int |
| 331 | ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p) |
| 332 | { |
| 333 | struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL; |
| 334 | struct pbuf *q; |
| 335 | u16_t offset,len; |
| 336 | struct ip_hdr *fraghdr; |
| 337 | int valid = 1; |
| 338 | |
| 339 | /* Extract length and fragment offset from current fragment */ |
| 340 | fraghdr = (struct ip_hdr*)new_p->payload; |
| 341 | len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4; |
| 342 | offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8; |
| 343 | |
| 344 | /* overwrite the fragment's ip header from the pbuf with our helper struct, |
| 345 | * and setup the embedded helper structure. */ |
| 346 | /* make sure the struct ip_reass_helper fits into the IP header */ |
| 347 | LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN", |
| 348 | sizeof(struct ip_reass_helper) <= IP_HLEN); |
| 349 | iprh = (struct ip_reass_helper*)new_p->payload; |
| 350 | iprh->next_pbuf = NULL; |
| 351 | iprh->start = offset; |
| 352 | iprh->end = offset + len; |
| 353 | |
| 354 | /* Iterate through until we either get to the end of the list (append), |
| 355 | * or we find on with a larger offset (insert). */ |
| 356 | for (q = ipr->p; q != NULL;) { |
| 357 | iprh_tmp = (struct ip_reass_helper*)q->payload; |
| 358 | if (iprh->start < iprh_tmp->start) { |
| 359 | /* the new pbuf should be inserted before this */ |
| 360 | iprh->next_pbuf = q; |
| 361 | if (iprh_prev != NULL) { |
| 362 | /* not the fragment with the lowest offset */ |
| 363 | #if IP_REASS_CHECK_OVERLAP |
| 364 | if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) { |
| 365 | /* fragment overlaps with previous or following, throw away */ |
| 366 | goto freepbuf; |
| 367 | } |
| 368 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 369 | iprh_prev->next_pbuf = new_p; |
| 370 | } else { |
| 371 | /* fragment with the lowest offset */ |
| 372 | ipr->p = new_p; |
| 373 | } |
| 374 | break; |
| 375 | } else if(iprh->start == iprh_tmp->start) { |
| 376 | /* received the same datagram twice: no need to keep the datagram */ |
| 377 | goto freepbuf; |
| 378 | #if IP_REASS_CHECK_OVERLAP |
| 379 | } else if(iprh->start < iprh_tmp->end) { |
| 380 | /* overlap: no need to keep the new datagram */ |
| 381 | goto freepbuf; |
| 382 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 383 | } else { |
| 384 | /* Check if the fragments received so far have no wholes. */ |
| 385 | if (iprh_prev != NULL) { |
| 386 | if (iprh_prev->end != iprh_tmp->start) { |
| 387 | /* There is a fragment missing between the current |
| 388 | * and the previous fragment */ |
| 389 | valid = 0; |
| 390 | } |
| 391 | } |
| 392 | } |
| 393 | q = iprh_tmp->next_pbuf; |
| 394 | iprh_prev = iprh_tmp; |
| 395 | } |
| 396 | |
| 397 | /* If q is NULL, then we made it to the end of the list. Determine what to do now */ |
| 398 | if (q == NULL) { |
| 399 | if (iprh_prev != NULL) { |
| 400 | /* this is (for now), the fragment with the highest offset: |
| 401 | * chain it to the last fragment */ |
| 402 | #if IP_REASS_CHECK_OVERLAP |
| 403 | LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start); |
| 404 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 405 | iprh_prev->next_pbuf = new_p; |
| 406 | if (iprh_prev->end != iprh->start) { |
| 407 | valid = 0; |
| 408 | } |
| 409 | } else { |
| 410 | #if IP_REASS_CHECK_OVERLAP |
| 411 | LWIP_ASSERT("no previous fragment, this must be the first fragment!", |
| 412 | ipr->p == NULL); |
| 413 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 414 | /* this is the first fragment we ever received for this ip datagram */ |
| 415 | ipr->p = new_p; |
| 416 | } |
| 417 | } |
| 418 | |
| 419 | /* At this point, the validation part begins: */ |
| 420 | /* If we already received the last fragment */ |
| 421 | if ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0) { |
| 422 | /* and had no wholes so far */ |
| 423 | if (valid) { |
| 424 | /* then check if the rest of the fragments is here */ |
| 425 | /* Check if the queue starts with the first datagram */ |
| 426 | if (((struct ip_reass_helper*)ipr->p->payload)->start != 0) { |
| 427 | valid = 0; |
| 428 | } else { |
| 429 | /* and check that there are no wholes after this datagram */ |
| 430 | iprh_prev = iprh; |
| 431 | q = iprh->next_pbuf; |
| 432 | while (q != NULL) { |
| 433 | iprh = (struct ip_reass_helper*)q->payload; |
| 434 | if (iprh_prev->end != iprh->start) { |
| 435 | valid = 0; |
| 436 | break; |
| 437 | } |
| 438 | iprh_prev = iprh; |
| 439 | q = iprh->next_pbuf; |
| 440 | } |
| 441 | /* if still valid, all fragments are received |
| 442 | * (because to the MF==0 already arrived */ |
| 443 | if (valid) { |
| 444 | LWIP_ASSERT("sanity check", ipr->p != NULL); |
| 445 | LWIP_ASSERT("sanity check", |
| 446 | ((struct ip_reass_helper*)ipr->p->payload) != iprh); |
| 447 | LWIP_ASSERT("validate_datagram:next_pbuf!=NULL", |
| 448 | iprh->next_pbuf == NULL); |
| 449 | LWIP_ASSERT("validate_datagram:datagram end!=datagram len", |
| 450 | iprh->end == ipr->datagram_len); |
| 451 | } |
| 452 | } |
| 453 | } |
| 454 | /* If valid is 0 here, there are some fragments missing in the middle |
| 455 | * (since MF == 0 has already arrived). Such datagrams simply time out if |
| 456 | * no more fragments are received... */ |
| 457 | return valid; |
| 458 | } |
| 459 | /* If we come here, not all fragments were received, yet! */ |
| 460 | return 0; /* not yet valid! */ |
| 461 | #if IP_REASS_CHECK_OVERLAP |
| 462 | freepbuf: |
| 463 | ip_reass_pbufcount -= pbuf_clen(new_p); |
| 464 | pbuf_free(new_p); |
| 465 | return 0; |
| 466 | #endif /* IP_REASS_CHECK_OVERLAP */ |
| 467 | } |
| 468 | |
| 469 | /** |
| 470 | * Reassembles incoming IP fragments into an IP datagram. |
| 471 | * |
| 472 | * @param p points to a pbuf chain of the fragment |
| 473 | * @return NULL if reassembly is incomplete, ? otherwise |
| 474 | */ |
| 475 | struct pbuf * |
| 476 | ip_reass(struct pbuf *p) |
| 477 | { |
| 478 | struct pbuf *r; |
| 479 | struct ip_hdr *fraghdr; |
| 480 | struct ip_reassdata *ipr; |
| 481 | struct ip_reass_helper *iprh; |
| 482 | u16_t offset, len; |
| 483 | u8_t clen; |
| 484 | struct ip_reassdata *ipr_prev = NULL; |
| 485 | |
| 486 | IPFRAG_STATS_INC(ip_frag.recv); |
| 487 | snmp_inc_ipreasmreqds(); |
| 488 | |
| 489 | fraghdr = (struct ip_hdr*)p->payload; |
| 490 | |
| 491 | if ((IPH_HL(fraghdr) * 4) != IP_HLEN) { |
| 492 | LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: IP options currently not supported!\n")); |
| 493 | IPFRAG_STATS_INC(ip_frag.err); |
| 494 | goto nullreturn; |
| 495 | } |
| 496 | |
| 497 | offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8; |
| 498 | len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4; |
| 499 | |
| 500 | /* Check if we are allowed to enqueue more datagrams. */ |
| 501 | clen = pbuf_clen(p); |
| 502 | if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) { |
| 503 | #if IP_REASS_FREE_OLDEST |
| 504 | if (!ip_reass_remove_oldest_datagram(fraghdr, clen) || |
| 505 | ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS)) |
| 506 | #endif /* IP_REASS_FREE_OLDEST */ |
| 507 | { |
| 508 | /* No datagram could be freed and still too many pbufs enqueued */ |
| 509 | LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n", |
| 510 | ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS)); |
| 511 | IPFRAG_STATS_INC(ip_frag.memerr); |
| 512 | /* @todo: send ICMP time exceeded here? */ |
| 513 | /* drop this pbuf */ |
| 514 | goto nullreturn; |
| 515 | } |
| 516 | } |
| 517 | |
| 518 | /* Look for the datagram the fragment belongs to in the current datagram queue, |
| 519 | * remembering the previous in the queue for later dequeueing. */ |
| 520 | for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) { |
| 521 | /* Check if the incoming fragment matches the one currently present |
| 522 | in the reassembly buffer. If so, we proceed with copying the |
| 523 | fragment into the buffer. */ |
| 524 | if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) { |
| 525 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass: matching previous fragment ID=%"X16_F"\n", |
| 526 | ntohs(IPH_ID(fraghdr)))); |
| 527 | IPFRAG_STATS_INC(ip_frag.cachehit); |
| 528 | break; |
| 529 | } |
| 530 | ipr_prev = ipr; |
| 531 | } |
| 532 | |
| 533 | if (ipr == NULL) { |
| 534 | /* Enqueue a new datagram into the datagram queue */ |
| 535 | ipr = ip_reass_enqueue_new_datagram(fraghdr, clen); |
| 536 | /* Bail if unable to enqueue */ |
| 537 | if(ipr == NULL) { |
| 538 | goto nullreturn; |
| 539 | } |
| 540 | } else { |
| 541 | if (((ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) && |
| 542 | ((ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) { |
| 543 | /* ipr->iphdr is not the header from the first fragment, but fraghdr is |
| 544 | * -> copy fraghdr into ipr->iphdr since we want to have the header |
| 545 | * of the first fragment (for ICMP time exceeded and later, for copying |
| 546 | * all options, if supported)*/ |
| 547 | SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN); |
| 548 | } |
| 549 | } |
| 550 | /* Track the current number of pbufs current 'in-flight', in order to limit |
| 551 | the number of fragments that may be enqueued at any one time */ |
| 552 | ip_reass_pbufcount += clen; |
| 553 | |
| 554 | /* At this point, we have either created a new entry or pointing |
| 555 | * to an existing one */ |
| 556 | |
| 557 | /* check for 'no more fragments', and update queue entry*/ |
| 558 | if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) { |
| 559 | ipr->flags |= IP_REASS_FLAG_LASTFRAG; |
| 560 | ipr->datagram_len = offset + len; |
| 561 | LWIP_DEBUGF(IP_REASS_DEBUG, |
| 562 | ("ip_reass: last fragment seen, total len %"S16_F"\n", |
| 563 | ipr->datagram_len)); |
| 564 | } |
| 565 | /* find the right place to insert this pbuf */ |
| 566 | /* @todo: trim pbufs if fragments are overlapping */ |
| 567 | if (ip_reass_chain_frag_into_datagram_and_validate(ipr, p)) { |
| 568 | /* the totally last fragment (flag more fragments = 0) was received at least |
| 569 | * once AND all fragments are received */ |
| 570 | ipr->datagram_len += IP_HLEN; |
| 571 | |
| 572 | /* save the second pbuf before copying the header over the pointer */ |
| 573 | r = ((struct ip_reass_helper*)ipr->p->payload)->next_pbuf; |
| 574 | |
| 575 | /* copy the original ip header back to the first pbuf */ |
| 576 | fraghdr = (struct ip_hdr*)(ipr->p->payload); |
| 577 | SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN); |
| 578 | IPH_LEN_SET(fraghdr, htons(ipr->datagram_len)); |
| 579 | IPH_OFFSET_SET(fraghdr, 0); |
| 580 | IPH_CHKSUM_SET(fraghdr, 0); |
| 581 | /* @todo: do we need to set calculate the correct checksum? */ |
| 582 | IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN)); |
| 583 | |
| 584 | p = ipr->p; |
| 585 | |
| 586 | /* chain together the pbufs contained within the reass_data list. */ |
| 587 | while(r != NULL) { |
| 588 | iprh = (struct ip_reass_helper*)r->payload; |
| 589 | |
| 590 | /* hide the ip header for every succeding fragment */ |
| 591 | pbuf_header(r, -IP_HLEN); |
| 592 | pbuf_cat(p, r); |
| 593 | r = iprh->next_pbuf; |
| 594 | } |
| 595 | /* release the sources allocate for the fragment queue entry */ |
| 596 | ip_reass_dequeue_datagram(ipr, ipr_prev); |
| 597 | |
| 598 | /* and adjust the number of pbufs currently queued for reassembly. */ |
| 599 | ip_reass_pbufcount -= pbuf_clen(p); |
| 600 | |
| 601 | /* Return the pbuf chain */ |
| 602 | return p; |
| 603 | } |
| 604 | /* the datagram is not (yet?) reassembled completely */ |
| 605 | LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount)); |
| 606 | return NULL; |
| 607 | |
| 608 | nullreturn: |
| 609 | LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: nullreturn\n")); |
| 610 | IPFRAG_STATS_INC(ip_frag.drop); |
| 611 | pbuf_free(p); |
| 612 | return NULL; |
| 613 | } |
| 614 | #endif /* IP_REASSEMBLY */ |
| 615 | |
| 616 | #if IP_FRAG |
| 617 | #if IP_FRAG_USES_STATIC_BUF |
| 618 | static u8_t buf[LWIP_MEM_ALIGN_SIZE(IP_FRAG_MAX_MTU + MEM_ALIGNMENT - 1)]; |
| 619 | #else /* IP_FRAG_USES_STATIC_BUF */ |
| 620 | |
| 621 | #if !LWIP_NETIF_TX_SINGLE_PBUF |
| 622 | /** Allocate a new struct pbuf_custom_ref */ |
| 623 | static struct pbuf_custom_ref* |
| 624 | ip_frag_alloc_pbuf_custom_ref(void) |
| 625 | { |
| 626 | return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF); |
| 627 | } |
| 628 | |
| 629 | /** Free a struct pbuf_custom_ref */ |
| 630 | static void |
| 631 | ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref* p) |
| 632 | { |
| 633 | LWIP_ASSERT("p != NULL", p != NULL); |
| 634 | memp_free(MEMP_FRAG_PBUF, p); |
| 635 | } |
| 636 | |
| 637 | /** Free-callback function to free a 'struct pbuf_custom_ref', called by |
| 638 | * pbuf_free. */ |
| 639 | static void |
| 640 | ipfrag_free_pbuf_custom(struct pbuf *p) |
| 641 | { |
| 642 | struct pbuf_custom_ref *pcr = (struct pbuf_custom_ref*)p; |
| 643 | LWIP_ASSERT("pcr != NULL", pcr != NULL); |
| 644 | LWIP_ASSERT("pcr == p", (void*)pcr == (void*)p); |
| 645 | if (pcr->original != NULL) { |
| 646 | pbuf_free(pcr->original); |
| 647 | } |
| 648 | ip_frag_free_pbuf_custom_ref(pcr); |
| 649 | } |
| 650 | #endif /* !LWIP_NETIF_TX_SINGLE_PBUF */ |
| 651 | #endif /* IP_FRAG_USES_STATIC_BUF */ |
| 652 | |
| 653 | /** |
| 654 | * Fragment an IP datagram if too large for the netif. |
| 655 | * |
| 656 | * Chop the datagram in MTU sized chunks and send them in order |
| 657 | * by using a fixed size static memory buffer (PBUF_REF) or |
| 658 | * point PBUF_REFs into p (depending on IP_FRAG_USES_STATIC_BUF). |
| 659 | * |
| 660 | * @param p ip packet to send |
| 661 | * @param netif the netif on which to send |
| 662 | * @param dest destination ip address to which to send |
| 663 | * |
| 664 | * @return ERR_OK if sent successfully, err_t otherwise |
| 665 | */ |
| 666 | err_t |
| 667 | ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest) |
| 668 | { |
| 669 | struct pbuf *rambuf; |
| 670 | #if IP_FRAG_USES_STATIC_BUF |
| 671 | struct pbuf *header; |
| 672 | #else |
| 673 | #if !LWIP_NETIF_TX_SINGLE_PBUF |
| 674 | struct pbuf *newpbuf; |
| 675 | #endif |
| 676 | struct ip_hdr *original_iphdr; |
| 677 | #endif |
| 678 | struct ip_hdr *iphdr; |
| 679 | u16_t nfb; |
| 680 | u16_t left, cop; |
| 681 | u16_t mtu = netif->mtu; |
| 682 | u16_t ofo, omf; |
| 683 | u16_t last; |
| 684 | u16_t poff = IP_HLEN; |
| 685 | u16_t tmp; |
| 686 | #if !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF |
| 687 | u16_t newpbuflen = 0; |
| 688 | u16_t left_to_copy; |
| 689 | #endif |
| 690 | |
| 691 | /* Get a RAM based MTU sized pbuf */ |
| 692 | #if IP_FRAG_USES_STATIC_BUF |
| 693 | /* When using a static buffer, we use a PBUF_REF, which we will |
| 694 | * use to reference the packet (without link header). |
| 695 | * Layer and length is irrelevant. |
| 696 | */ |
| 697 | rambuf = pbuf_alloc(PBUF_LINK, 0, PBUF_REF); |
| 698 | if (rambuf == NULL) { |
| 699 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc(PBUF_LINK, 0, PBUF_REF) failed\n")); |
| 700 | return ERR_MEM; |
| 701 | } |
| 702 | rambuf->tot_len = rambuf->len = mtu; |
| 703 | rambuf->payload = LWIP_MEM_ALIGN((void *)buf); |
| 704 | |
| 705 | /* Copy the IP header in it */ |
| 706 | iphdr = (struct ip_hdr *)rambuf->payload; |
| 707 | SMEMCPY(iphdr, p->payload, IP_HLEN); |
| 708 | #else /* IP_FRAG_USES_STATIC_BUF */ |
| 709 | original_iphdr = (struct ip_hdr *)p->payload; |
| 710 | iphdr = original_iphdr; |
| 711 | #endif /* IP_FRAG_USES_STATIC_BUF */ |
| 712 | |
| 713 | /* Save original offset */ |
| 714 | tmp = ntohs(IPH_OFFSET(iphdr)); |
| 715 | ofo = tmp & IP_OFFMASK; |
| 716 | omf = tmp & IP_MF; |
| 717 | |
| 718 | left = p->tot_len - IP_HLEN; |
| 719 | |
| 720 | nfb = (mtu - IP_HLEN) / 8; |
| 721 | |
| 722 | while (left) { |
| 723 | last = (left <= mtu - IP_HLEN); |
| 724 | |
| 725 | /* Set new offset and MF flag */ |
| 726 | tmp = omf | (IP_OFFMASK & (ofo)); |
| 727 | if (!last) { |
| 728 | tmp = tmp | IP_MF; |
| 729 | } |
| 730 | |
| 731 | /* Fill this fragment */ |
| 732 | cop = last ? left : nfb * 8; |
| 733 | |
| 734 | #if IP_FRAG_USES_STATIC_BUF |
| 735 | poff += pbuf_copy_partial(p, (u8_t*)iphdr + IP_HLEN, cop, poff); |
| 736 | #else /* IP_FRAG_USES_STATIC_BUF */ |
| 737 | #if LWIP_NETIF_TX_SINGLE_PBUF |
| 738 | rambuf = pbuf_alloc(PBUF_IP, cop, PBUF_RAM); |
| 739 | if (rambuf == NULL) { |
| 740 | return ERR_MEM; |
| 741 | } |
| 742 | LWIP_ASSERT("this needs a pbuf in one piece!", |
| 743 | (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL)); |
| 744 | poff += pbuf_copy_partial(p, rambuf->payload, cop, poff); |
| 745 | /* make room for the IP header */ |
| 746 | if(pbuf_header(rambuf, IP_HLEN)) { |
| 747 | pbuf_free(rambuf); |
| 748 | return ERR_MEM; |
| 749 | } |
| 750 | /* fill in the IP header */ |
| 751 | SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN); |
| 752 | iphdr = rambuf->payload; |
| 753 | #else /* LWIP_NETIF_TX_SINGLE_PBUF */ |
| 754 | /* When not using a static buffer, create a chain of pbufs. |
| 755 | * The first will be a PBUF_RAM holding the link and IP header. |
| 756 | * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged, |
| 757 | * but limited to the size of an mtu. |
| 758 | */ |
| 759 | rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM); |
| 760 | if (rambuf == NULL) { |
| 761 | return ERR_MEM; |
| 762 | } |
| 763 | LWIP_ASSERT("this needs a pbuf in one piece!", |
| 764 | (p->len >= (IP_HLEN))); |
| 765 | SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN); |
| 766 | iphdr = (struct ip_hdr *)rambuf->payload; |
| 767 | |
| 768 | /* Can just adjust p directly for needed offset. */ |
| 769 | p->payload = (u8_t *)p->payload + poff; |
| 770 | p->len -= poff; |
| 771 | |
| 772 | left_to_copy = cop; |
| 773 | while (left_to_copy) { |
| 774 | struct pbuf_custom_ref *pcr; |
| 775 | newpbuflen = (left_to_copy < p->len) ? left_to_copy : p->len; |
| 776 | /* Is this pbuf already empty? */ |
| 777 | if (!newpbuflen) { |
| 778 | p = p->next; |
| 779 | continue; |
| 780 | } |
| 781 | pcr = ip_frag_alloc_pbuf_custom_ref(); |
| 782 | if (pcr == NULL) { |
| 783 | pbuf_free(rambuf); |
| 784 | return ERR_MEM; |
| 785 | } |
| 786 | /* Mirror this pbuf, although we might not need all of it. */ |
| 787 | newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, p->payload, newpbuflen); |
| 788 | if (newpbuf == NULL) { |
| 789 | ip_frag_free_pbuf_custom_ref(pcr); |
| 790 | pbuf_free(rambuf); |
| 791 | return ERR_MEM; |
| 792 | } |
| 793 | pbuf_ref(p); |
| 794 | pcr->original = p; |
| 795 | pcr->pc.custom_free_function = ipfrag_free_pbuf_custom; |
| 796 | |
| 797 | /* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain |
| 798 | * so that it is removed when pbuf_dechain is later called on rambuf. |
| 799 | */ |
| 800 | pbuf_cat(rambuf, newpbuf); |
| 801 | left_to_copy -= newpbuflen; |
| 802 | if (left_to_copy) { |
| 803 | p = p->next; |
| 804 | } |
| 805 | } |
| 806 | poff = newpbuflen; |
| 807 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */ |
| 808 | #endif /* IP_FRAG_USES_STATIC_BUF */ |
| 809 | |
| 810 | /* Correct header */ |
| 811 | IPH_OFFSET_SET(iphdr, htons(tmp)); |
| 812 | IPH_LEN_SET(iphdr, htons(cop + IP_HLEN)); |
| 813 | IPH_CHKSUM_SET(iphdr, 0); |
| 814 | IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN)); |
| 815 | |
| 816 | #if IP_FRAG_USES_STATIC_BUF |
| 817 | if (last) { |
| 818 | pbuf_realloc(rambuf, left + IP_HLEN); |
| 819 | } |
| 820 | |
| 821 | /* This part is ugly: we alloc a RAM based pbuf for |
| 822 | * the link level header for each chunk and then |
| 823 | * free it.A PBUF_ROM style pbuf for which pbuf_header |
| 824 | * worked would make things simpler. |
| 825 | */ |
| 826 | header = pbuf_alloc(PBUF_LINK, 0, PBUF_RAM); |
| 827 | if (header != NULL) { |
| 828 | pbuf_chain(header, rambuf); |
| 829 | netif->output(netif, header, dest); |
| 830 | IPFRAG_STATS_INC(ip_frag.xmit); |
| 831 | snmp_inc_ipfragcreates(); |
| 832 | pbuf_free(header); |
| 833 | } else { |
| 834 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc() for header failed\n")); |
| 835 | pbuf_free(rambuf); |
| 836 | return ERR_MEM; |
| 837 | } |
| 838 | #else /* IP_FRAG_USES_STATIC_BUF */ |
| 839 | /* No need for separate header pbuf - we allowed room for it in rambuf |
| 840 | * when allocated. |
| 841 | */ |
| 842 | netif->output(netif, rambuf, dest); |
| 843 | IPFRAG_STATS_INC(ip_frag.xmit); |
| 844 | |
| 845 | /* Unfortunately we can't reuse rambuf - the hardware may still be |
| 846 | * using the buffer. Instead we free it (and the ensuing chain) and |
| 847 | * recreate it next time round the loop. If we're lucky the hardware |
| 848 | * will have already sent the packet, the free will really free, and |
| 849 | * there will be zero memory penalty. |
| 850 | */ |
| 851 | |
| 852 | pbuf_free(rambuf); |
| 853 | #endif /* IP_FRAG_USES_STATIC_BUF */ |
| 854 | left -= cop; |
| 855 | ofo += nfb; |
| 856 | } |
| 857 | #if IP_FRAG_USES_STATIC_BUF |
| 858 | pbuf_free(rambuf); |
| 859 | #endif /* IP_FRAG_USES_STATIC_BUF */ |
| 860 | snmp_inc_ipfragoks(); |
| 861 | return ERR_OK; |
| 862 | } |
| 863 | #endif /* IP_FRAG */ |