/* $NetBSD: tr.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $ */ /* tr.c token ring interface support Contributed in May of 1999 by Andrew Chittenden */ /* * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996-2003 by Internet Software Consortium * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Internet Systems Consortium, Inc. * PO Box 360 * Newmarket, NH 03857 USA * * https://www.isc.org/ */ #include __RCSID("$NetBSD: tr.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $"); #include "dhcpd.h" #if defined (HAVE_TR_SUPPORT) && \ (defined (PACKET_ASSEMBLY) || defined (PACKET_DECODING)) #include "includes/netinet/ip.h" #include "includes/netinet/udp.h" #include "includes/netinet/if_ether.h" #include "netinet/if_tr.h" #include /* * token ring device handling subroutines. These are required as token-ring * does not have a simple on-the-wire header but requires the use of * source routing */ static int insert_source_routing (struct trh_hdr *trh, struct interface_info* interface); static void save_source_routing (struct trh_hdr *trh, struct interface_info* interface); static void expire_routes (void); /* * As we keep a list of interesting routing information only, a singly * linked list is all we need */ struct routing_entry { struct routing_entry *next; unsigned char addr[TR_ALEN]; unsigned char iface[5]; u_int16_t rcf; /* route control field */ u_int16_t rseg[8]; /* routing registers */ unsigned long access_time; /* time we last used this entry */ }; static struct routing_entry *routing_info = NULL; static int routing_timeout = 10; static struct timeval routing_timer; void assemble_tr_header (interface, buf, bufix, to) struct interface_info *interface; unsigned char *buf; unsigned *bufix; struct hardware *to; { struct trh_hdr *trh; int hdr_len; struct trllc *llc; /* set up the token header */ trh = (struct trh_hdr *) &buf[*bufix]; if (interface -> hw_address.hlen - 1 == sizeof (trh->saddr)) memcpy (trh->saddr, &interface -> hw_address.hbuf [1], sizeof (trh->saddr)); else memset (trh->saddr, 0x00, sizeof (trh->saddr)); if (to && to -> hlen == 7) /* XXX */ memcpy (trh->daddr, &to -> hbuf [1], sizeof trh->daddr); else memset (trh->daddr, 0xff, sizeof (trh->daddr)); hdr_len = insert_source_routing (trh, interface); trh->ac = AC; trh->fc = LLC_FRAME; /* set up the llc header for snap encoding after the tr header */ llc = (struct trllc *)(buf + *bufix + hdr_len); llc->dsap = EXTENDED_SAP; llc->ssap = EXTENDED_SAP; llc->llc = UI_CMD; llc->protid[0] = 0; llc->protid[1] = 0; llc->protid[2] = 0; llc->ethertype = htons(ETHERTYPE_IP); hdr_len += sizeof(struct trllc); *bufix += hdr_len; } static unsigned char tr_broadcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; /* * decoding the token header is a bit complex as you can see here. It is * further complicated by the linux kernel stripping off some valuable * information (see comment below) even though we've asked for the raw * packets. */ ssize_t decode_tr_header (interface, buf, bufix, from) struct interface_info *interface; unsigned char *buf; unsigned bufix; struct hardware *from; { struct trh_hdr *trh = (struct trh_hdr *) buf + bufix; struct trllc *llc; struct ip *ip; struct udphdr *udp; unsigned int route_len = 0; ssize_t hdr_len; struct timeval now; /* see whether any source routing information has expired */ gettimeofday(&now, NULL); if (routing_timer.tv_sec == 0) routing_timer.tv_sec = now.tv_sec + routing_timeout; else if ((now.tv_sec - routing_timer.tv_sec) > 0) expire_routes(); /* the kernel might have stripped off the source * routing bit. We try a heuristic to determine whether * this is the case and put it back on if so */ route_len = (ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8; llc = (struct trllc *)(buf + bufix + sizeof(struct trh_hdr)-TR_MAXRIFLEN+route_len); if (llc->dsap == EXTENDED_SAP && llc->ssap == EXTENDED_SAP && llc->llc == UI_CMD && llc->protid[0] == 0 && llc->protid[1] == 0 && llc->protid[2] == 0) { /* say there is source routing information present */ trh->saddr[0] |= TR_RII; } if (trh->saddr[0] & TR_RII) route_len = (ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8; else route_len = 0; hdr_len = sizeof (struct trh_hdr) - TR_MAXRIFLEN + route_len; /* now filter out unwanted packets: this is based on the packet * filter code in bpf.c */ llc = (struct trllc *)(buf + bufix + hdr_len); ip = (struct ip *) (llc + 1); udp = (struct udphdr *) ((unsigned char*) ip + IP_HL (ip)); /* make sure it is a snap encoded, IP, UDP, unfragmented packet sent * to our port */ if (llc->dsap != EXTENDED_SAP || ntohs(llc->ethertype) != ETHERTYPE_IP || ip->ip_p != IPPROTO_UDP || (ntohs (ip->ip_off) & IP_OFFMASK) != 0 || udp->uh_dport != *libdhcp_callbacks.local_port) return -1; /* only save source routing information for packets from valued hosts */ save_source_routing(trh, interface); return hdr_len + sizeof (struct trllc); } /* insert_source_routing inserts source route information into the token ring * header */ static int insert_source_routing (trh, interface) struct trh_hdr *trh; struct interface_info* interface; { struct routing_entry *rover; struct timeval now; unsigned int route_len = 0; gettimeofday(&now, NULL); /* single route broadcasts as per rfc 1042 */ if (memcmp(trh->daddr, tr_broadcast,TR_ALEN) == 0) { trh->saddr[0] |= TR_RII; trh->rcf = ((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK; trh->rcf |= (TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST); trh->rcf = htons(trh->rcf); } else { /* look for a routing entry */ for (rover = routing_info; rover != NULL; rover = rover->next) { if (memcmp(rover->addr, trh->daddr, TR_ALEN) == 0) break; } if (rover != NULL) { /* success: route that frame */ if ((rover->rcf & TR_RCF_LEN_MASK) >> 8) { u_int16_t rcf = rover->rcf; memcpy(trh->rseg,rover->rseg,sizeof(trh->rseg)); rcf ^= TR_RCF_DIR_BIT; rcf &= ~TR_RCF_BROADCAST_MASK; trh->rcf = htons(rcf); trh->saddr[0] |= TR_RII; } rover->access_time = now.tv_sec; } else { /* we don't have any routing information so send a * limited broadcast */ trh->saddr[0] |= TR_RII; trh->rcf = ((sizeof(trh->rcf)) << 8) & TR_RCF_LEN_MASK; trh->rcf |= (TR_RCF_FRAME2K | TR_RCF_LIMITED_BROADCAST); trh->rcf = htons(trh->rcf); } } /* return how much of the header we've actually used */ if (trh->saddr[0] & TR_RII) route_len = (ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8; else route_len = 0; return sizeof (struct trh_hdr) - TR_MAXRIFLEN + route_len; } /* * save any source routing information */ static void save_source_routing(trh, interface) struct trh_hdr *trh; struct interface_info *interface; { struct routing_entry *rover; struct timeval now; unsigned char saddr[TR_ALEN]; u_int16_t rcf = 0; gettimeofday(&now, NULL); memcpy(saddr, trh->saddr, sizeof(saddr)); saddr[0] &= 0x7f; /* strip off source routing present flag */ /* scan our table to see if we've got it */ for (rover = routing_info; rover != NULL; rover = rover->next) { if (memcmp(&rover->addr[0], &saddr[0], TR_ALEN) == 0) break; } /* found an entry so update it with fresh information */ if (rover != NULL) { if ((trh->saddr[0] & TR_RII) && ((ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8) > 2) { rcf = ntohs(trh->rcf); rcf &= ~TR_RCF_BROADCAST_MASK; memcpy(rover->rseg, trh->rseg, sizeof(rover->rseg)); } rover->rcf = rcf; rover->access_time = now.tv_sec; return; /* that's all folks */ } /* no entry found, so create one */ rover = dmalloc (sizeof (struct routing_entry), MDL); if (rover == NULL) { fprintf(stderr, "%s: unable to save source routing information\n", __FILE__); return; } memcpy(rover->addr, saddr, sizeof(rover->addr)); memcpy(rover->iface, interface->name, 5); rover->access_time = now.tv_sec; if (trh->saddr[0] & TR_RII) { if (((ntohs(trh->rcf) & TR_RCF_LEN_MASK) >> 8) > 2) { rcf = ntohs(trh->rcf); rcf &= ~TR_RCF_BROADCAST_MASK; memcpy(rover->rseg, trh->rseg, sizeof(rover->rseg)); } rover->rcf = rcf; } /* insert into list */ rover->next = routing_info; routing_info = rover; return; } /* * get rid of old routes */ static void expire_routes() { struct routing_entry *rover; struct routing_entry **prover = &routing_info; struct timeval now; gettimeofday(&now, NULL); while((rover = *prover) != NULL) { if ((now.tv_sec - rover->access_time) > routing_timeout) { *prover = rover->next; dfree (rover, MDL); } else prover = &rover->next; } /* Reset the timer */ routing_timer.tv_sec = now.tv_sec + routing_timeout; routing_timer.tv_usec = now.tv_usec; } #endif