eigrpd/eigrp_hello.c

   1 /*
   2  * EIGRP Sending and Receiving EIGRP Hello Packets.
   3  * Copyright (C) 2013-2016
   4  * Authors:
   5  *   Donnie Savage
   6  *   Jan Janovic
   7  *   Matej Perina
   8  *   Peter Orsag
   9  *   Peter Paluch
  10  *   Frantisek Gazo
  11  *   Tomas Hvorkovy
  12  *   Martin Kontsek
  13  *   Lukas Koribsky
  14  *
  15  * This file is part of GNU Zebra.
  16  *
  17  * GNU Zebra is free software; you can redistribute it and/or modify it
  18  * under the terms of the GNU General Public License as published by the
  19  * Free Software Foundation; either version 2, or (at your option) any
  20  * later version.
  21  *
  22  * GNU Zebra is distributed in the hope that it will be useful, but
  23  * WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25  * General Public License for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License along
  28  * with this program; see the file COPYING; if not, write to the Free Software
  29  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  30  */
  31
  32 #include <zebra.h>
  33
  34 #include "thread.h"
  35 #include "memory.h"
  36 #include "linklist.h"
  37 #include "prefix.h"
  38 #include "if.h"
  39 #include "table.h"
  40 #include "sockunion.h"
  41 #include "stream.h"
  42 #include "log.h"
  43 #include "sockopt.h"
  44 #include "checksum.h"
  45 #include "vty.h"
  46 #include "md5.h"
  47
  48 #include "eigrpd/eigrp_structs.h"
  49 #include "eigrpd/eigrpd.h"
  50 #include "eigrpd/eigrp_interface.h"
  51 #include "eigrpd/eigrp_neighbor.h"
  52 #include "eigrpd/eigrp_packet.h"
  53 #include "eigrpd/eigrp_zebra.h"
  54 #include "eigrpd/eigrp_vty.h"
  55 #include "eigrpd/eigrp_dump.h"
  56 #include "eigrpd/eigrp_macros.h"
  57
  58 /* Packet Type String. */
  59 static const struct message eigrp_general_tlv_type_str[] = {
  60         {EIGRP_TLV_PARAMETER, "PARAMETER"},
  61         {EIGRP_TLV_AUTH, "AUTH"},
  62         {EIGRP_TLV_SEQ, "SEQ"},
  63         {EIGRP_TLV_SW_VERSION, "SW_VERSION"},
  64         {EIGRP_TLV_NEXT_MCAST_SEQ, "NEXT_MCAST_SEQ"},
  65         {EIGRP_TLV_PEER_TERMINATION, "PEER_TERMINATION"},
  66         {EIGRP_TLV_PEER_MTRLIST, "PEER_MTRLIST"},
  67         {EIGRP_TLV_PEER_TIDLIST, "PEER_TIDLIST"},
  68         {0}};
  69
  70
  71 /*
  72  * @fn eigrp_hello_timer
  73  *
  74  * @param[in]   thread  current execution thread timer is associated with
  75  *
  76  * @return int  always returns 0
  77  *
  78  * @par
  79  * Called once per "hello" time interval, default 5 seconds
  80  * Sends hello packet via multicast for all interfaces eigrp
  81  * is configured for
  82  */
  83 int eigrp_hello_timer(struct thread *thread)
  84 {
  85         struct eigrp_interface *ei;
  86
  87         ei = THREAD_ARG(thread);
  88         ei->t_hello = NULL;
  89
  90         if (IS_DEBUG_EIGRP(0, TIMERS))
  91                 zlog_debug("Start Hello Timer (%s) Expire [%u]", IF_NAME(ei),
  92                            EIGRP_IF_PARAM(ei, v_hello));
  93
  94         /* Sending hello packet. */
  95         eigrp_hello_send(ei, EIGRP_HELLO_NORMAL, NULL);
  96
  97         /* Hello timer set. */
  98         ei->t_hello = NULL;
  99         thread_add_timer(master, eigrp_hello_timer, ei,
 100                          EIGRP_IF_PARAM(ei, v_hello), &ei->t_hello);
 101
 102         return 0;
 103 }
 104
 105 /**
 106  * @fn eigrp_hello_parameter_decode
 107  *
 108  * @param[in]           nbr     neighbor the ACK should be sent to
 109  * @param[in]           param   pointer packet TLV is stored to
 110  *
 111  * @return u_int16_t    number of bytes added to packet stream
 112  *
 113  * @par
 114  * Encode Parameter TLV, used to convey metric weights and the hold time.
 115  *
 116  * @usage
 117  * Note the addition of K6 for the new extended metrics, and does not apply to
 118  * older TLV packet formats.
 119  */
 120 static struct eigrp_neighbor *
 121 eigrp_hello_parameter_decode(struct eigrp_neighbor *nbr,
 122                              struct eigrp_tlv_hdr_type *tlv)
 123 {
 124         struct eigrp *eigrp = nbr->ei->eigrp;
 125         struct TLV_Parameter_Type *param = (struct TLV_Parameter_Type *)tlv;
 126
 127         /* copy over the values passed in by the neighbor */
 128         nbr->K1 = param->K1;
 129         nbr->K2 = param->K2;
 130         nbr->K3 = param->K3;
 131         nbr->K4 = param->K4;
 132         nbr->K5 = param->K5;
 133         nbr->K6 = param->K6;
 134         nbr->v_holddown = ntohs(param->hold_time);
 135
 136         /*
 137          * Check K1-K5 have the correct values to be able to become neighbors
 138          * K6 does not have to match
 139          */
 140         if ((eigrp->k_values[0] == nbr->K1) && (eigrp->k_values[1] == nbr->K2)
 141             && (eigrp->k_values[2] == nbr->K3)
 142             && (eigrp->k_values[3] == nbr->K4)
 143             && (eigrp->k_values[4] == nbr->K5)) {
 144
 145                 if (eigrp_nbr_state_get(nbr) == EIGRP_NEIGHBOR_DOWN) {
 146                         zlog_info("Neighbor %s (%s) is pending: new adjacency",
 147                                   inet_ntoa(nbr->src),
 148                                   ifindex2ifname(nbr->ei->ifp->ifindex,
 149                                                  VRF_DEFAULT));
 150
 151                         /* Expedited hello sent */
 152                         eigrp_hello_send(nbr->ei, EIGRP_HELLO_NORMAL, NULL);
 153
 154                         //     if(ntohl(nbr->ei->address->u.prefix4.s_addr) >
 155                         //     ntohl(nbr->src.s_addr))
 156                         eigrp_update_send_init(nbr);
 157
 158                         eigrp_nbr_state_set(nbr, EIGRP_NEIGHBOR_PENDING);
 159                 }
 160         } else {
 161                 if (eigrp_nbr_state_get(nbr) != EIGRP_NEIGHBOR_DOWN) {
 162                         if ((param->K1 & param->K2 & param->K3 & param->K4
 163                              & param->K5)
 164                             == 255) {
 165                                 zlog_info(
 166                                         "Neighbor %s (%s) is down: Interface PEER-TERMINATION received",
 167                                         inet_ntoa(nbr->src),
 168                                         ifindex2ifname(nbr->ei->ifp->ifindex,
 169                                                        VRF_DEFAULT));
 170                                 eigrp_nbr_delete(nbr);
 171                                 return NULL;
 172                         } else {
 173                                 zlog_info(
 174                                         "Neighbor %s (%s) going down: Kvalue mismatch",
 175                                         inet_ntoa(nbr->src),
 176                                         ifindex2ifname(nbr->ei->ifp->ifindex,
 177                                                        VRF_DEFAULT));
 178                                 eigrp_nbr_state_set(nbr, EIGRP_NEIGHBOR_DOWN);
 179                         }
 180                 }
 181         }
 182
 183         return nbr;
 184 }
 185
 186 static u_char
 187 eigrp_hello_authentication_decode(struct stream *s,
 188                                   struct eigrp_tlv_hdr_type *tlv_header,
 189                                   struct eigrp_neighbor *nbr)
 190 {
 191         struct TLV_MD5_Authentication_Type *md5;
 192
 193         md5 = (struct TLV_MD5_Authentication_Type *)tlv_header;
 194
 195         if (md5->auth_type == EIGRP_AUTH_TYPE_MD5)
 196                 return eigrp_check_md5_digest(s, md5, nbr,
 197                                               EIGRP_AUTH_BASIC_HELLO_FLAG);
 198         else if (md5->auth_type == EIGRP_AUTH_TYPE_SHA256)
 199                 return eigrp_check_sha256_digest(
 200                         s, (struct TLV_SHA256_Authentication_Type *)tlv_header,
 201                         nbr, EIGRP_AUTH_BASIC_HELLO_FLAG);
 202
 203         return 0;
 204 }
 205
 206 /**
 207  * @fn eigrp_sw_version_decode
 208  *
 209  * @param[in]           nbr     neighbor the ACK shoudl be sent to
 210  * @param[in]           param   pointer to TLV software version information
 211  *
 212  * @return void
 213  *
 214  * @par
 215  * Read the software version in the specified location.
 216  * This consists of two bytes of OS version, and two bytes of EIGRP
 217  * revision number.
 218  */
 219 static void eigrp_sw_version_decode(struct eigrp_neighbor *nbr,
 220                                     struct eigrp_tlv_hdr_type *tlv)
 221 {
 222         struct TLV_Software_Type *version = (struct TLV_Software_Type *)tlv;
 223
 224         nbr->os_rel_major = version->vender_major;
 225         nbr->os_rel_minor = version->vender_minor;
 226         nbr->tlv_rel_major = version->eigrp_major;
 227         nbr->tlv_rel_minor = version->eigrp_minor;
 228         return;
 229 }
 230
 231 /**
 232  * @fn eigrp_peer_termination_decode
 233  *
 234  * @param[in]           nbr     neighbor the ACK shoudl be sent to
 235  * @param[in]           tlv     pointer to TLV software version information
 236  *
 237  * @return void
 238  *
 239  * @par
 240  * Read the address in the TLV and match to out address. If
 241  * a match is found, move the sending neighbor to the down state. If
 242  * out address is not in the TLV, then ignore the peer termination
 243  */
 244 static void eigrp_peer_termination_decode(struct eigrp_neighbor *nbr,
 245                                           struct eigrp_tlv_hdr_type *tlv)
 246 {
 247         struct TLV_Peer_Termination_type *param =
 248                 (struct TLV_Peer_Termination_type *)tlv;
 249
 250         uint32_t my_ip = nbr->ei->address->u.prefix4.s_addr;
 251         uint32_t received_ip = param->neighbor_ip;
 252
 253         if (my_ip == received_ip) {
 254                 zlog_info("Neighbor %s (%s) is down: Peer Termination received",
 255                           inet_ntoa(nbr->src),
 256                           ifindex2ifname(nbr->ei->ifp->ifindex, VRF_DEFAULT));
 257                 /* set neighbor to DOWN */
 258                 nbr->state = EIGRP_NEIGHBOR_DOWN;
 259                 /* delete neighbor */
 260                 eigrp_nbr_delete(nbr);
 261         }
 262 }
 263
 264 /**
 265  * @fn eigrp_peer_termination_encode
 266  *
 267  * @param[in,out]   s             packet stream TLV is stored to
 268  * @param[in]           nbr_addr  pointer to neighbor address for Peer
 269  * Termination TLV
 270  *
 271  * @return u_int16_t    number of bytes added to packet stream
 272  *
 273  * @par
 274  * Function used to encode Peer Termination TLV to Hello packet.
 275  */
 276 static u_int16_t eigrp_peer_termination_encode(struct stream *s,
 277                                                struct in_addr *nbr_addr)
 278 {
 279         u_int16_t length = EIGRP_TLV_PEER_TERMINATION_LEN;
 280
 281         /* fill in type and length */
 282         stream_putw(s, EIGRP_TLV_PEER_TERMINATION);
 283         stream_putw(s, length);
 284
 285         /* fill in unknown field 0x04 */
 286         stream_putc(s, 0x04);
 287
 288         /* finally neighbor IP address */
 289         stream_put_ipv4(s, nbr_addr->s_addr);
 290
 291         return (length);
 292 }
 293
 294 /*
 295  * @fn eigrp_hello_receive
 296  *
 297  * @param[in]   eigrp           eigrp routing process
 298  * @param[in]   iph             pointer to ip header
 299  * @param[in]   eigrph          pointer to eigrp header
 300  * @param[in]   s               input ip stream
 301  * @param[in]   ei              eigrp interface packet arrived on
 302  * @param[in]   size            size of eigrp packet
 303  *
 304  * @return void
 305  *
 306  * @par
 307  * This is the main worker function for processing hello packets. It
 308  * will validate the peer associated with the src ip address of the ip
 309  * header, and then decode each of the general TLVs which the packet
 310  * may contain.
 311  *
 312  * @usage
 313  * Not all TLVs are current decoder.  This is a work in progress..
 314  */
 315 void eigrp_hello_receive(struct eigrp *eigrp, struct ip *iph,
 316                          struct eigrp_header *eigrph, struct stream *s,
 317                          struct eigrp_interface *ei, int size)
 318 {
 319         struct eigrp_tlv_hdr_type *tlv_header;
 320         struct eigrp_neighbor *nbr;
 321         uint16_t type;
 322         uint16_t length;
 323
 324         /* get neighbor struct */
 325         nbr = eigrp_nbr_get(ei, eigrph, iph);
 326
 327         /* neighbor must be valid, eigrp_nbr_get creates if none existed */
 328         assert(nbr);
 329
 330         if (IS_DEBUG_EIGRP_PACKET(eigrph->opcode - 1, RECV))
 331                 zlog_debug("Processing Hello size[%u] int(%s) nbr(%s)", size,
 332                            ifindex2ifname(nbr->ei->ifp->ifindex, VRF_DEFAULT),
 333                            inet_ntoa(nbr->src));
 334
 335         size -= EIGRP_HEADER_LEN;
 336         if (size < 0)
 337                 return;
 338
 339         tlv_header = (struct eigrp_tlv_hdr_type *)eigrph->tlv;
 340
 341         do {
 342                 type = ntohs(tlv_header->type);
 343                 length = ntohs(tlv_header->length);
 344
 345                 if ((length > 0) && (length <= size)) {
 346                         if (IS_DEBUG_EIGRP_PACKET(0, RECV))
 347                                 zlog_debug(
 348                                         "  General TLV(%s)",
 349                                         lookup_msg(eigrp_general_tlv_type_str,
 350                                                    type, NULL));
 351
 352                         // determine what General TLV is being processed
 353                         switch (type) {
 354                         case EIGRP_TLV_PARAMETER:
 355                                 nbr = eigrp_hello_parameter_decode(nbr,
 356                                                                    tlv_header);
 357                                 if (!nbr)
 358                                         return;
 359                                 break;
 360                         case EIGRP_TLV_AUTH: {
 361                                 if (eigrp_hello_authentication_decode(
 362                                             s, tlv_header, nbr)
 363                                     == 0)
 364                                         return;
 365                                 else
 366                                         break;
 367                                 break;
 368                         }
 369                         case EIGRP_TLV_SEQ:
 370                                 break;
 371                         case EIGRP_TLV_SW_VERSION:
 372                                 eigrp_sw_version_decode(nbr, tlv_header);
 373                                 break;
 374                         case EIGRP_TLV_NEXT_MCAST_SEQ:
 375                                 break;
 376                         case EIGRP_TLV_PEER_TERMINATION:
 377                                 eigrp_peer_termination_decode(nbr, tlv_header);
 378                                 return;
 379                                 break;
 380                         case EIGRP_TLV_PEER_MTRLIST:
 381                         case EIGRP_TLV_PEER_TIDLIST:
 382                                 break;
 383                         default:
 384                                 break;
 385                         }
 386                 }
 387
 388                 tlv_header = (struct eigrp_tlv_hdr_type *)(((char *)tlv_header)
 389                                                            + length);
 390                 size -= length;
 391
 392         } while (size > 0);
 393
 394
 395         /*If received packet is hello with Parameter TLV*/
 396         if (ntohl(eigrph->ack) == 0) {
 397                 /* increment statistics. */
 398                 ei->hello_in++;
 399                 if (nbr)
 400                         eigrp_nbr_state_update(nbr);
 401         }
 402
 403         if (IS_DEBUG_EIGRP_PACKET(0, RECV))
 404                 zlog_debug("Hello Packet received from %s",
 405                            inet_ntoa(nbr->src));
 406 }
 407
 408 u_int32_t FRR_MAJOR;
 409 u_int32_t FRR_MINOR;
 410
 411 void eigrp_sw_version_initialize(void)
 412 {
 413         char ver_string[] = VERSION;
 414         char *dash = strstr(ver_string, "-");
 415         int ret;
 416
 417         if (dash)
 418                 dash[0] = '\0';
 419
 420         ret = sscanf(ver_string, "%d.%d", &FRR_MAJOR, &FRR_MINOR);
 421         if (ret != 2)
 422                 zlog_err("Did not Properly parse %s, please fix VERSION string",
 423                          VERSION);
 424 }
 425
 426 /**
 427  * @fn eigrp_sw_version_encode
 428  *
 429  * @param[in,out]       s       packet stream TLV is stored to
 430  *
 431  * @return u_int16_t    number of bytes added to packet stream
 432  *
 433  * @par
 434  * Store the software version in the specified location.
 435  * This consists of two bytes of OS version, and two bytes of EIGRP
 436  * revision number.
 437  */
 438 static u_int16_t eigrp_sw_version_encode(struct stream *s)
 439 {
 440         u_int16_t length = EIGRP_TLV_SW_VERSION_LEN;
 441
 442         // setup the tlv fields
 443         stream_putw(s, EIGRP_TLV_SW_VERSION);
 444         stream_putw(s, length);
 445
 446         stream_putc(s, FRR_MAJOR);  //!< major os version
 447         stream_putc(s, FRR_MINOR); //!< minor os version
 448
 449         /* and the core eigrp version */
 450         stream_putc(s, EIGRP_MAJOR_VERSION);
 451         stream_putc(s, EIGRP_MINOR_VERSION);
 452
 453         return (length);
 454 }
 455
 456 /**
 457  * @fn eigrp_tidlist_encode
 458  *
 459  * @param[in,out]       s       packet stream TLV is stored to
 460  *
 461  * @return void
 462  *
 463  * @par
 464  * If doing mutli-topology, then store the supported TID list.
 465  * This is currently a place holder function
 466  */
 467 static u_int16_t eigrp_tidlist_encode(struct stream *s)
 468 {
 469         // u_int16_t length = EIGRP_TLV_SW_VERSION_LEN;
 470         return 0;
 471 }
 472
 473 /**
 474  * @fn eigrp_sequence_encode
 475  *
 476  * @param[in,out]       s       packet stream TLV is stored to
 477  *
 478  * @return u_int16_t    number of bytes added to packet stream
 479  *
 480  * @par
 481  * Part of conditional receive process
 482  *
 483  */
 484 static u_int16_t eigrp_sequence_encode(struct stream *s)
 485 {
 486         u_int16_t length = EIGRP_TLV_SEQ_BASE_LEN;
 487         struct eigrp *eigrp;
 488         struct eigrp_interface *ei;
 489         struct listnode *node, *node2, *nnode2;
 490         struct eigrp_neighbor *nbr;
 491         size_t backup_end, size_end;
 492         int found;
 493
 494         eigrp = eigrp_lookup();
 495         if (eigrp == NULL) {
 496                 return 0;
 497         }
 498
 499         // add in the parameters TLV
 500         backup_end = stream_get_endp(s);
 501         stream_putw(s, EIGRP_TLV_SEQ);
 502         size_end = s->endp;
 503         stream_putw(s, 0x0000);
 504         stream_putc(s, IPV4_MAX_BYTELEN);
 505
 506         found = 0;
 507         for (ALL_LIST_ELEMENTS_RO(eigrp->eiflist, node, ei)) {
 508                 for (ALL_LIST_ELEMENTS(ei->nbrs, node2, nnode2, nbr)) {
 509                         if (nbr->multicast_queue->count > 0) {
 510                                 length += (u_int16_t)stream_put_ipv4(
 511                                         s, nbr->src.s_addr);
 512                                 found = 1;
 513                         }
 514                 }
 515         }
 516
 517         if (found == 0) {
 518                 stream_set_endp(s, backup_end);
 519                 return 0;
 520         }
 521
 522         backup_end = stream_get_endp(s);
 523         stream_set_endp(s, size_end);
 524         stream_putw(s, length);
 525         stream_set_endp(s, backup_end);
 526
 527         return length;
 528 }
 529
 530 /**
 531  * @fn eigrp_sequence_encode
 532  *
 533  * @param[in,out]       s       packet stream TLV is stored to
 534  *
 535  * @return u_int16_t    number of bytes added to packet stream
 536  *
 537  * @par
 538  * Part of conditional receive process
 539  *
 540  */
 541 static u_int16_t eigrp_next_sequence_encode(struct stream *s)
 542 {
 543         u_int16_t length = EIGRP_NEXT_SEQUENCE_TLV_SIZE;
 544         struct eigrp *eigrp;
 545
 546         eigrp = eigrp_lookup();
 547         if (eigrp == NULL) {
 548                 return 0;
 549         }
 550
 551         // add in the parameters TLV
 552         stream_putw(s, EIGRP_TLV_NEXT_MCAST_SEQ);
 553         stream_putw(s, EIGRP_NEXT_SEQUENCE_TLV_SIZE);
 554         stream_putl(s, eigrp->sequence_number + 1);
 555
 556         return length;
 557 }
 558
 559 /**
 560  * @fn eigrp_hello_parameter_encode
 561  *
 562  * @param[in]           ei      pointer to interface hello packet came in on
 563  * @param[in,out]       s       packet stream TLV is stored to
 564  *
 565  * @return u_int16_t    number of bytes added to packet stream
 566  *
 567  * @par
 568  * Encode Parameter TLV, used to convey metric weights and the hold time.
 569  *
 570  * @usage
 571  * Note the addition of K6 for the new extended metrics, and does not apply to
 572  * older TLV packet formats.
 573  */
 574 static u_int16_t eigrp_hello_parameter_encode(struct eigrp_interface *ei,
 575                                               struct stream *s, u_char flags)
 576 {
 577         u_int16_t length = EIGRP_TLV_PARAMETER_LEN;
 578
 579         // add in the parameters TLV
 580         stream_putw(s, EIGRP_TLV_PARAMETER);
 581         stream_putw(s, EIGRP_TLV_PARAMETER_LEN);
 582
 583         // if graceful shutdown is needed to be announced, send all 255 in K
 584         // values
 585         if (flags & EIGRP_HELLO_GRACEFUL_SHUTDOWN) {
 586                 stream_putc(s, 0xff); /* K1 */
 587                 stream_putc(s, 0xff); /* K2 */
 588                 stream_putc(s, 0xff); /* K3 */
 589                 stream_putc(s, 0xff); /* K4 */
 590                 stream_putc(s, 0xff); /* K5 */
 591                 stream_putc(s, 0xff); /* K6 */
 592         } else                        // set k values
 593         {
 594                 stream_putc(s, ei->eigrp->k_values[0]); /* K1 */
 595                 stream_putc(s, ei->eigrp->k_values[1]); /* K2 */
 596                 stream_putc(s, ei->eigrp->k_values[2]); /* K3 */
 597                 stream_putc(s, ei->eigrp->k_values[3]); /* K4 */
 598                 stream_putc(s, ei->eigrp->k_values[4]); /* K5 */
 599                 stream_putc(s, ei->eigrp->k_values[5]); /* K6 */
 600         }
 601
 602         // and set hold time value..
 603         stream_putw(s, IF_DEF_PARAMS(ei->ifp)->v_wait);
 604
 605         return length;
 606 }
 607
 608 /**
 609  * @fn eigrp_hello_encode
 610  *
 611  * @param[in]           ei      pointer to interface hello packet came in on
 612  * @param[in]           s       packet stream TLV is stored to
 613  * @param[in]           ack      if non-zero, neigbors sequence packet to ack
 614  * @param[in]           flags  type of hello packet
 615  * @param[in]           nbr_addr  pointer to neighbor address for Peer
 616  * Termination TLV
 617  *
 618  * @return eigrp_packet         pointer initialize hello packet
 619  *
 620  * @par
 621  * Allocate an EIGRP hello packet, and add in the the approperate TLVs
 622  *
 623  */
 624 static struct eigrp_packet *eigrp_hello_encode(struct eigrp_interface *ei,
 625                                                in_addr_t addr, u_int32_t ack,
 626                                                u_char flags,
 627                                                struct in_addr *nbr_addr)
 628 {
 629         struct eigrp_packet *ep;
 630         u_int16_t length = EIGRP_HEADER_LEN;
 631
 632         // allocate a new packet to be sent
 633         ep = eigrp_packet_new(ei->ifp->mtu, NULL);
 634
 635         if (ep) {
 636                 // encode common header feilds
 637                 eigrp_packet_header_init(EIGRP_OPC_HELLO, ei->eigrp, ep->s, 0, 0, ack);
 638
 639                 // encode Authentication TLV
 640                 if ((IF_DEF_PARAMS(ei->ifp)->auth_type == EIGRP_AUTH_TYPE_MD5)
 641                     && (IF_DEF_PARAMS(ei->ifp)->auth_keychain != NULL)) {
 642                         length += eigrp_add_authTLV_MD5_to_stream(ep->s, ei);
 643                 } else if ((IF_DEF_PARAMS(ei->ifp)->auth_type
 644                             == EIGRP_AUTH_TYPE_SHA256)
 645                            && (IF_DEF_PARAMS(ei->ifp)->auth_keychain != NULL)) {
 646                         length += eigrp_add_authTLV_SHA256_to_stream(ep->s, ei);
 647                 }
 648
 649                 /* encode appropriate parameters to Hello packet */
 650                 if (flags & EIGRP_HELLO_GRACEFUL_SHUTDOWN)
 651                         length += eigrp_hello_parameter_encode(
 652                                 ei, ep->s, EIGRP_HELLO_GRACEFUL_SHUTDOWN);
 653                 else
 654                         length += eigrp_hello_parameter_encode(
 655                                 ei, ep->s, EIGRP_HELLO_NORMAL);
 656
 657                 // figure out the version of code we're running
 658                 length += eigrp_sw_version_encode(ep->s);
 659
 660                 if (flags & EIGRP_HELLO_ADD_SEQUENCE) {
 661                         length += eigrp_sequence_encode(ep->s);
 662                         length += eigrp_next_sequence_encode(ep->s);
 663                 }
 664
 665                 // add in the TID list if doing multi-topology
 666                 length += eigrp_tidlist_encode(ep->s);
 667
 668                 /* encode Peer Termination TLV if needed */
 669                 if (flags & EIGRP_HELLO_GRACEFUL_SHUTDOWN_NBR)
 670                         length +=
 671                                 eigrp_peer_termination_encode(ep->s, nbr_addr);
 672
 673                 // Set packet length
 674                 ep->length = length;
 675
 676                 // set soruce address for the hello packet
 677                 ep->dst.s_addr = addr;
 678
 679                 if ((IF_DEF_PARAMS(ei->ifp)->auth_type == EIGRP_AUTH_TYPE_MD5)
 680                     && (IF_DEF_PARAMS(ei->ifp)->auth_keychain != NULL)) {
 681                         eigrp_make_md5_digest(ei, ep->s,
 682                                               EIGRP_AUTH_BASIC_HELLO_FLAG);
 683                 } else if ((IF_DEF_PARAMS(ei->ifp)->auth_type
 684                             == EIGRP_AUTH_TYPE_SHA256)
 685                            && (IF_DEF_PARAMS(ei->ifp)->auth_keychain != NULL)) {
 686                         eigrp_make_sha256_digest(ei, ep->s,
 687                                                  EIGRP_AUTH_BASIC_HELLO_FLAG);
 688                 }
 689
 690                 // EIGRP Checksum
 691                 eigrp_packet_checksum(ei, ep->s, length);
 692         }
 693
 694         return (ep);
 695 }
 696
 697 /**
 698  * @fn eigrp_hello_send
 699  *
 700  * @param[in]           nbr     neighbor the ACK should be sent to
 701  *
 702  * @return void
 703  *
 704  * @par
 705  *  Send (unicast) a hello packet with the destination address
 706  *  associated with the neighbor.  The eigrp header ACK feild will be
 707  *  updated to the neighbor's sequence number to acknolodge any
 708  *  outstanding packets
 709  */
 710 void eigrp_hello_send_ack(struct eigrp_neighbor *nbr)
 711 {
 712         struct eigrp_packet *ep;
 713
 714         /* if packet succesfully created, add it to the interface queue */
 715         ep = eigrp_hello_encode(nbr->ei, nbr->src.s_addr,
 716                                 nbr->recv_sequence_number, EIGRP_HELLO_NORMAL,
 717                                 NULL);
 718
 719         if (ep) {
 720                 if (IS_DEBUG_EIGRP_PACKET(0, SEND))
 721                         zlog_debug("Queueing [Hello] Ack Seq [%u] nbr [%s]",
 722                                    nbr->recv_sequence_number,
 723                                    inet_ntoa(nbr->src));
 724
 725                 /* Add packet to the top of the interface output queue*/
 726                 eigrp_fifo_push(nbr->ei->obuf, ep);
 727
 728                 /* Hook thread to write packet. */
 729                 if (nbr->ei->on_write_q == 0) {
 730                         listnode_add(nbr->ei->eigrp->oi_write_q, nbr->ei);
 731                         nbr->ei->on_write_q = 1;
 732                 }
 733                 thread_add_write(master, eigrp_write, nbr->ei->eigrp,
 734                                  nbr->ei->eigrp->fd, &nbr->ei->eigrp->t_write);
 735         }
 736 }
 737
 738 /**
 739  * @fn eigrp_hello_send
 740  *
 741  * @param[in]           ei      pointer to interface hello should be sent
 742  * @param[in]           flags type of hello packet
 743  * @param[in]           nbr_addr  pointer to neighbor address for Peer
 744  * Termination TLV
 745  *
 746  * @return void
 747  *
 748  * @par
 749  * Build and enqueue a generic (multicast) periodic hello packet for
 750  * sending.  If no packets are currently queues, the packet will be
 751  * sent immadiatly
 752  */
 753 void eigrp_hello_send(struct eigrp_interface *ei, u_char flags,
 754                       struct in_addr *nbr_addr)
 755 {
 756         struct eigrp_packet *ep = NULL;
 757
 758         /* If this is passive interface, do not send EIGRP Hello.
 759            if ((EIGRP_IF_PASSIVE_STATUS (ei) == EIGRP_IF_PASSIVE) ||
 760            (ei->type != EIGRP_IFTYPE_NBMA))
 761            return;
 762         */
 763
 764         if (IS_DEBUG_EIGRP_PACKET(0, SEND))
 765                 zlog_debug("Queueing [Hello] Interface(%s)", IF_NAME(ei));
 766
 767         /* if packet was succesfully created, then add it to the interface queue
 768          */
 769         ep = eigrp_hello_encode(ei, htonl(EIGRP_MULTICAST_ADDRESS), 0, flags,
 770                                 nbr_addr);
 771
 772         if (ep) {
 773                 // Add packet to the top of the interface output queue
 774                 eigrp_fifo_push(ei->obuf, ep);
 775
 776                 /* Hook thread to write packet. */
 777                 if (ei->on_write_q == 0) {
 778                         listnode_add(ei->eigrp->oi_write_q, ei);
 779                         ei->on_write_q = 1;
 780                 }
 781
 782                 if (ei->eigrp->t_write == NULL) {
 783                         if (flags & EIGRP_HELLO_GRACEFUL_SHUTDOWN) {
 784                                 thread_execute(master, eigrp_write, ei->eigrp,
 785                                                ei->eigrp->fd);
 786                         } else {
 787                                 thread_add_write(master, eigrp_write, ei->eigrp,
 788                                                  ei->eigrp->fd,
 789                                                  &ei->eigrp->t_write);
 790                         }
 791                 }
 792         }
 793 }