/* * BIRD -- BGP Attributes * * (c) 2000 Martin Mares * * Can be freely distributed and used under the terms of the GNU GPL. */ #undef LOCAL_DEBUG #include #include "nest/bird.h" #include "nest/iface.h" #include "nest/protocol.h" #include "nest/route.h" #include "nest/attrs.h" #include "conf/conf.h" #include "lib/resource.h" #include "lib/string.h" #include "lib/unaligned.h" #include "bgp.h" /* * UPDATE message error handling * * All checks from RFC 4271 6.3 are done as specified with these exceptions: * - The semantic check of an IP address from NEXT_HOP attribute is missing. * - Checks of some optional attribute values are missing. * - Syntactic and semantic checks of NLRIs (done in DECODE_PREFIX()) * are probably inadequate. * * Loop detection based on AS_PATH causes updates to be withdrawn. RFC * 4271 does not explicitly specifiy the behavior in that case. * * Loop detection related to route reflection (based on ORIGINATOR_ID * and CLUSTER_LIST) causes updates to be withdrawn. RFC 4456 8 * specifies that such updates should be ignored, but that is generally * a bad idea. * * Error checking of optional transitive attributes is done according to * draft-ietf-idr-optional-transitive-03, but errors are handled always * as withdraws. * * Unexpected AS_CONFED_* segments in AS_PATH are logged and removed, * but unknown segments cause a session drop with Malformed AS_PATH * error (see validate_path()). The behavior in such case is not * explicitly specified by RFC 4271. RFC 5065 specifies that * inconsistent AS_CONFED_* segments should cause a session drop, but * implementations that pass invalid AS_CONFED_* segments are * widespread. * * Error handling of AS4_* attributes is done as specified by * draft-ietf-idr-rfc4893bis-03. There are several possible * inconsistencies between AGGREGATOR and AS4_AGGREGATOR that are not * handled by that draft, these are logged and ignored (see * bgp_reconstruct_4b_attrs()). */ static byte bgp_mandatory_attrs[] = { BA_ORIGIN, BA_AS_PATH #ifndef IPV6 ,BA_NEXT_HOP #endif }; struct attr_desc { char *name; int expected_length; int expected_flags; int type; int allow_in_ebgp; int (*validate)(struct bgp_proto *p, byte *attr, int len); void (*format)(eattr *ea, byte *buf, int buflen); }; #define IGNORE -1 #define WITHDRAW -2 static int bgp_check_origin(struct bgp_proto *p UNUSED, byte *a, int len UNUSED) { if (*a > 2) return 6; return 0; } static void bgp_format_origin(eattr *a, byte *buf, int buflen UNUSED) { static char *bgp_origin_names[] = { "IGP", "EGP", "Incomplete" }; bsprintf(buf, bgp_origin_names[a->u.data]); } static int path_segment_contains(byte *p, int bs, u32 asn) { int i; int len = p[1]; p += 2; for(i=0; ip.name, as_path ? "AS" : "AS4"); goto skip; } switch (a[0]) { case AS_PATH_SET: res++; break; case AS_PATH_SEQUENCE: res += a[1]; break; case AS_PATH_CONFED_SEQUENCE: case AS_PATH_CONFED_SET: if (as_path && path_segment_contains(a, bs, p->remote_as)) { log(L_WARN "%s: AS_CONFED_* segment with peer ASN found, misconfigured confederation?", p->p.name); return -1; } log(L_WARN "%s: %s_PATH attribute contains AS_CONFED_* segment, skipping segment", p->p.name, as_path ? "AS" : "AS4"); goto skip; default: return -1; } if (dst != a) memmove(dst, a, plen); dst += plen; skip: len -= plen; a += plen; } *ilength = dst - idata; return res; } static inline int validate_as_path(struct bgp_proto *p, byte *a, int *len) { return validate_path(p, 1, p->as4_session ? 4 : 2, a, len); } static inline int validate_as4_path(struct bgp_proto *p, struct adata *path) { return validate_path(p, 0, 4, path->data, &path->length); } static int bgp_check_next_hop(struct bgp_proto *p UNUSED, byte *a UNUSED6, int len UNUSED6) { #ifdef IPV6 return IGNORE; #else ip_addr addr; memcpy(&addr, a, len); ipa_ntoh(addr); if (ipa_classify(addr) & IADDR_HOST) return 0; else return 8; #endif } static void bgp_format_next_hop(eattr *a, byte *buf, int buflen UNUSED) { ip_addr *ipp = (ip_addr *) a->u.ptr->data; #ifdef IPV6 /* in IPv6, we might have two addresses in NEXT HOP */ if ((a->u.ptr->length == NEXT_HOP_LENGTH) && ipa_nonzero(ipp[1])) { bsprintf(buf, "%I %I", ipp[0], ipp[1]); return; } #endif bsprintf(buf, "%I", ipp[0]); } static int bgp_check_aggregator(struct bgp_proto *p, byte *a UNUSED, int len) { int exp_len = p->as4_session ? 8 : 6; return (len == exp_len) ? 0 : WITHDRAW; } static void bgp_format_aggregator(eattr *a, byte *buf, int buflen UNUSED) { struct adata *ad = a->u.ptr; byte *data = ad->data; u32 as; as = get_u32(data); data += 4; bsprintf(buf, "%d.%d.%d.%d AS%u", data[0], data[1], data[2], data[3], as); } static int bgp_check_community(struct bgp_proto *p UNUSED, byte *a UNUSED, int len) { return ((len % 4) == 0) ? 0 : WITHDRAW; } static int bgp_check_cluster_list(struct bgp_proto *p UNUSED, byte *a UNUSED, int len) { return ((len % 4) == 0) ? 0 : 5; } static void bgp_format_cluster_list(eattr *a, byte *buf, int buflen) { /* Truncates cluster lists larger than buflen, probably not a problem */ int_set_format(a->u.ptr, 0, -1, buf, buflen); } static int bgp_check_reach_nlri(struct bgp_proto *p UNUSED, byte *a UNUSED, int len UNUSED) { #ifdef IPV6 p->mp_reach_start = a; p->mp_reach_len = len; #endif return IGNORE; } static int bgp_check_unreach_nlri(struct bgp_proto *p UNUSED, byte *a UNUSED, int len UNUSED) { #ifdef IPV6 p->mp_unreach_start = a; p->mp_unreach_len = len; #endif return IGNORE; } static int bgp_check_ext_community(struct bgp_proto *p UNUSED, byte *a UNUSED, int len) { return ((len % 8) == 0) ? 0 : WITHDRAW; } static int bgp_check_large_community(struct bgp_proto *p UNUSED, byte *a UNUSED, int len) { return ((len % 12) == 0) ? 0 : WITHDRAW; } static struct attr_desc bgp_attr_table[] = { { NULL, -1, 0, 0, 0, /* Undefined */ NULL, NULL }, { "origin", 1, BAF_TRANSITIVE, EAF_TYPE_INT, 1, /* BA_ORIGIN */ bgp_check_origin, bgp_format_origin }, { "as_path", -1, BAF_TRANSITIVE, EAF_TYPE_AS_PATH, 1, /* BA_AS_PATH */ NULL, NULL }, /* is checked by validate_as_path() as a special case */ { "next_hop", 4, BAF_TRANSITIVE, EAF_TYPE_IP_ADDRESS, 1, /* BA_NEXT_HOP */ bgp_check_next_hop, bgp_format_next_hop }, { "med", 4, BAF_OPTIONAL, EAF_TYPE_INT, 1, /* BA_MULTI_EXIT_DISC */ NULL, NULL }, { "local_pref", 4, BAF_TRANSITIVE, EAF_TYPE_INT, 0, /* BA_LOCAL_PREF */ NULL, NULL }, { "atomic_aggr", 0, BAF_TRANSITIVE, EAF_TYPE_OPAQUE, 1, /* BA_ATOMIC_AGGR */ NULL, NULL }, { "aggregator", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_OPAQUE, 1, /* BA_AGGREGATOR */ bgp_check_aggregator, bgp_format_aggregator }, { "community", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_INT_SET, 1, /* BA_COMMUNITY */ bgp_check_community, NULL }, { "originator_id", 4, BAF_OPTIONAL, EAF_TYPE_ROUTER_ID, 0, /* BA_ORIGINATOR_ID */ NULL, NULL }, { "cluster_list", -1, BAF_OPTIONAL, EAF_TYPE_INT_SET, 0, /* BA_CLUSTER_LIST */ bgp_check_cluster_list, bgp_format_cluster_list }, { .name = NULL }, /* BA_DPA */ { .name = NULL }, /* BA_ADVERTISER */ { .name = NULL }, /* BA_RCID_PATH */ { "mp_reach_nlri", -1, BAF_OPTIONAL, EAF_TYPE_OPAQUE, 1, /* BA_MP_REACH_NLRI */ bgp_check_reach_nlri, NULL }, { "mp_unreach_nlri", -1, BAF_OPTIONAL, EAF_TYPE_OPAQUE, 1, /* BA_MP_UNREACH_NLRI */ bgp_check_unreach_nlri, NULL }, { "ext_community", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_EC_SET, 1, /* BA_EXT_COMMUNITY */ bgp_check_ext_community, NULL }, { "as4_path", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_OPAQUE, 1, /* BA_AS4_PATH */ NULL, NULL }, { "as4_aggregator", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_OPAQUE, 1, /* BA_AS4_PATH */ NULL, NULL }, [BA_LARGE_COMMUNITY] = { "large_community", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_LC_SET, 1, bgp_check_large_community, NULL } }; /* BA_AS4_PATH is type EAF_TYPE_OPAQUE and not type EAF_TYPE_AS_PATH. * It does not matter as this attribute does not appear on routes in the routing table. */ #define ATTR_KNOWN(code) ((code) < ARRAY_SIZE(bgp_attr_table) && bgp_attr_table[code].name) static inline struct adata * bgp_alloc_adata(struct linpool *pool, unsigned len) { struct adata *ad = lp_alloc(pool, sizeof(struct adata) + len); ad->length = len; return ad; } static void bgp_set_attr(eattr *e, unsigned attr, uintptr_t val) { ASSERT(ATTR_KNOWN(attr)); e->id = EA_CODE(EAP_BGP, attr); e->type = bgp_attr_table[attr].type; e->flags = bgp_attr_table[attr].expected_flags; if (e->type & EAF_EMBEDDED) e->u.data = val; else e->u.ptr = (struct adata *) val; } static byte * bgp_set_attr_wa(eattr *e, struct linpool *pool, unsigned attr, unsigned len) { struct adata *ad = bgp_alloc_adata(pool, len); bgp_set_attr(e, attr, (uintptr_t) ad); return ad->data; } void bgp_attach_attr(ea_list **to, struct linpool *pool, unsigned attr, uintptr_t val) { ea_list *a = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr)); a->next = *to; *to = a; a->flags = EALF_SORTED; a->count = 1; bgp_set_attr(a->attrs, attr, val); } byte * bgp_attach_attr_wa(ea_list **to, struct linpool *pool, unsigned attr, unsigned len) { struct adata *ad = bgp_alloc_adata(pool, len); bgp_attach_attr(to, pool, attr, (uintptr_t) ad); return ad->data; } static int bgp_encode_attr_hdr(byte *dst, uint flags, unsigned code, int len) { int wlen; DBG("\tAttribute %02x (%d bytes, flags %02x)\n", code, len, flags); if (len < 256) { *dst++ = flags; *dst++ = code; *dst++ = len; wlen = 3; } else { *dst++ = flags | BAF_EXT_LEN; *dst++ = code; put_u16(dst, len); wlen = 4; } return wlen; } static void aggregator_convert_to_old(struct adata *aggr, byte *dst, int *new_used) { byte *src = aggr->data; *new_used = 0; u32 as = get_u32(src); if (as > 0xFFFF) { as = AS_TRANS; *new_used = 1; } put_u16(dst, as); /* Copy IPv4 address */ memcpy(dst + 2, src + 4, 4); } static void aggregator_convert_to_new(struct adata *aggr, byte *dst) { byte *src = aggr->data; u32 as = get_u16(src); put_u32(dst, as); /* Copy IPv4 address */ memcpy(dst + 4, src + 2, 4); } static int bgp_get_attr_len(eattr *a) { int len; if (ATTR_KNOWN(EA_ID(a->id))) { int code = EA_ID(a->id); struct attr_desc *desc = &bgp_attr_table[code]; len = desc->expected_length; if (len < 0) { ASSERT(!(a->type & EAF_EMBEDDED)); len = a->u.ptr->length; } } else { ASSERT((a->type & EAF_TYPE_MASK) == EAF_TYPE_OPAQUE); len = a->u.ptr->length; } return len; } #define ADVANCE(w, r, l) do { r -= l; w += l; } while (0) /** * bgp_encode_attrs - encode BGP attributes * @p: BGP instance * @w: buffer * @attrs: a list of extended attributes * @remains: remaining space in the buffer * * The bgp_encode_attrs() function takes a list of extended attributes * and converts it to its BGP representation (a part of an Update message). * * Result: Length of the attribute block generated or -1 if not enough space. */ uint bgp_encode_attrs(struct bgp_proto *p, byte *w, ea_list *attrs, int remains) { uint i, code, type, flags; byte *start = w; int len, rv; for(i=0; icount; i++) { eattr *a = &attrs->attrs[i]; ASSERT(EA_PROTO(a->id) == EAP_BGP); code = EA_ID(a->id); #ifdef IPV6 /* When talking multiprotocol BGP, the NEXT_HOP attributes are used only temporarily. */ if (code == BA_NEXT_HOP) continue; #endif /* When AS4-aware BGP speaker is talking to non-AS4-aware BGP speaker, * we have to convert our 4B AS_PATH to 2B AS_PATH and send our AS_PATH * as optional AS4_PATH attribute. */ if ((code == BA_AS_PATH) && (! p->as4_session)) { len = a->u.ptr->length; if (remains < (len + 4)) goto err_no_buffer; /* Using temporary buffer because don't know a length of created attr * and therefore a length of a header. Perhaps i should better always * use BAF_EXT_LEN. */ byte buf[len]; int new_used; int nl = as_path_convert_to_old(a->u.ptr, buf, &new_used); DBG("BGP: Encoding old AS_PATH\n"); rv = bgp_encode_attr_hdr(w, BAF_TRANSITIVE, BA_AS_PATH, nl); ADVANCE(w, remains, rv); memcpy(w, buf, nl); ADVANCE(w, remains, nl); if (! new_used) continue; if (remains < (len + 4)) goto err_no_buffer; /* We should discard AS_CONFED_SEQUENCE or AS_CONFED_SET path segments * here but we don't support confederations and such paths we already * discarded in bgp_check_as_path(). */ DBG("BGP: Encoding AS4_PATH\n"); rv = bgp_encode_attr_hdr(w, BAF_OPTIONAL | BAF_TRANSITIVE, BA_AS4_PATH, len); ADVANCE(w, remains, rv); memcpy(w, a->u.ptr->data, len); ADVANCE(w, remains, len); continue; } /* The same issue with AGGREGATOR attribute */ if ((code == BA_AGGREGATOR) && (! p->as4_session)) { int new_used; len = 6; if (remains < (len + 3)) goto err_no_buffer; rv = bgp_encode_attr_hdr(w, BAF_OPTIONAL | BAF_TRANSITIVE, BA_AGGREGATOR, len); ADVANCE(w, remains, rv); aggregator_convert_to_old(a->u.ptr, w, &new_used); ADVANCE(w, remains, len); if (! new_used) continue; len = 8; if (remains < (len + 3)) goto err_no_buffer; rv = bgp_encode_attr_hdr(w, BAF_OPTIONAL | BAF_TRANSITIVE, BA_AS4_AGGREGATOR, len); ADVANCE(w, remains, rv); memcpy(w, a->u.ptr->data, len); ADVANCE(w, remains, len); continue; } /* Standard path continues here ... */ type = a->type & EAF_TYPE_MASK; flags = a->flags & (BAF_OPTIONAL | BAF_TRANSITIVE | BAF_PARTIAL); len = bgp_get_attr_len(a); /* Skip empty sets */ if (((type == EAF_TYPE_INT_SET) || (type == EAF_TYPE_EC_SET) || (type == EAF_TYPE_LC_SET)) && (len == 0)) continue; if (remains < len + 4) goto err_no_buffer; rv = bgp_encode_attr_hdr(w, flags, code, len); ADVANCE(w, remains, rv); switch (type) { case EAF_TYPE_INT: case EAF_TYPE_ROUTER_ID: if (len == 4) put_u32(w, a->u.data); else *w = a->u.data; break; case EAF_TYPE_IP_ADDRESS: { ip_addr ip = *(ip_addr *)a->u.ptr->data; ipa_hton(ip); memcpy(w, &ip, len); break; } case EAF_TYPE_INT_SET: case EAF_TYPE_LC_SET: case EAF_TYPE_EC_SET: { u32 *z = int_set_get_data(a->u.ptr); int i; for(i=0; iu.ptr->data, len); break; default: bug("bgp_encode_attrs: unknown attribute type %02x", a->type); } ADVANCE(w, remains, len); } return w - start; err_no_buffer: return -1; } /* static void bgp_init_prefix(struct fib_node *N) { struct bgp_prefix *p = (struct bgp_prefix *) N; p->bucket_node.next = NULL; } */ static int bgp_compare_u32(const u32 *x, const u32 *y) { return (*x < *y) ? -1 : (*x > *y) ? 1 : 0; } static inline void bgp_normalize_int_set(u32 *dest, u32 *src, unsigned cnt) { memcpy(dest, src, sizeof(u32) * cnt); qsort(dest, cnt, sizeof(u32), (int(*)(const void *, const void *)) bgp_compare_u32); } static int bgp_compare_ec(const u32 *xp, const u32 *yp) { u64 x = ec_get(xp, 0); u64 y = ec_get(yp, 0); return (x < y) ? -1 : (x > y) ? 1 : 0; } static inline void bgp_normalize_ec_set(struct adata *ad, u32 *src, int internal) { u32 *dst = int_set_get_data(ad); /* Remove non-transitive communities (EC_TBIT active) on external sessions */ if (! internal) { int len = int_set_get_size(ad); u32 *t = dst; int i; for (i=0; i < len; i += 2) { if (src[i] & EC_TBIT) continue; *t++ = src[i]; *t++ = src[i+1]; } ad->length = (t - dst) * 4; } else memcpy(dst, src, ad->length); qsort(dst, ad->length / 8, 8, (int(*)(const void *, const void *)) bgp_compare_ec); } static int bgp_compare_lc(const u32 *x, const u32 *y) { if (x[0] != y[0]) return (x[0] > y[0]) ? 1 : -1; if (x[1] != y[1]) return (x[1] > y[1]) ? 1 : -1; if (x[2] != y[2]) return (x[2] > y[2]) ? 1 : -1; return 0; } static inline void bgp_normalize_lc_set(u32 *dest, u32 *src, unsigned cnt) { memcpy(dest, src, LCOMM_LENGTH * cnt); qsort(dest, cnt, LCOMM_LENGTH, (int(*)(const void *, const void *)) bgp_compare_lc); } static void bgp_rehash_buckets(struct bgp_proto *p) { struct bgp_bucket **old = p->bucket_hash; struct bgp_bucket **new; unsigned oldn = p->hash_size; unsigned i, e, mask; struct bgp_bucket *b; p->hash_size = p->hash_limit; DBG("BGP: Rehashing bucket table from %d to %d\n", oldn, p->hash_size); p->hash_limit *= 4; if (p->hash_limit >= 65536) p->hash_limit = ~0; new = p->bucket_hash = mb_allocz(p->p.pool, p->hash_size * sizeof(struct bgp_bucket *)); mask = p->hash_size - 1; for (i=0; ihash_next; e = b->hash & mask; b->hash_next = new[e]; if (b->hash_next) b->hash_next->hash_prev = b; b->hash_prev = NULL; new[e] = b; } mb_free(old); } static struct bgp_bucket * bgp_new_bucket(struct bgp_proto *p, ea_list *new, unsigned hash) { struct bgp_bucket *b; unsigned ea_size = sizeof(ea_list) + new->count * sizeof(eattr); unsigned ea_size_aligned = BIRD_ALIGN(ea_size, CPU_STRUCT_ALIGN); unsigned size = sizeof(struct bgp_bucket) + ea_size_aligned; unsigned i; byte *dest; unsigned index = hash & (p->hash_size - 1); /* Gather total size of non-inline attributes */ for (i=0; icount; i++) { eattr *a = &new->attrs[i]; if (!(a->type & EAF_EMBEDDED)) size += BIRD_ALIGN(sizeof(struct adata) + a->u.ptr->length, CPU_STRUCT_ALIGN); } /* Create the bucket and hash it */ b = mb_alloc(p->p.pool, size); b->hash_next = p->bucket_hash[index]; if (b->hash_next) b->hash_next->hash_prev = b; p->bucket_hash[index] = b; b->hash_prev = NULL; b->hash = hash; add_tail(&p->bucket_queue, &b->send_node); init_list(&b->prefixes); memcpy(b->eattrs, new, ea_size); dest = ((byte *)b->eattrs) + ea_size_aligned; /* Copy values of non-inline attributes */ for (i=0; icount; i++) { eattr *a = &b->eattrs->attrs[i]; if (!(a->type & EAF_EMBEDDED)) { struct adata *oa = a->u.ptr; struct adata *na = (struct adata *) dest; memcpy(na, oa, sizeof(struct adata) + oa->length); a->u.ptr = na; dest += BIRD_ALIGN(sizeof(struct adata) + na->length, CPU_STRUCT_ALIGN); } } /* If needed, rehash */ p->hash_count++; if (p->hash_count > p->hash_limit) bgp_rehash_buckets(p); return b; } static struct bgp_bucket * bgp_get_bucket(struct bgp_proto *p, net *n, ea_list *attrs, int originate) { ea_list *new; unsigned i, cnt, hash, code; eattr *a, *d; u32 seen = 0; struct bgp_bucket *b; /* Merge the attribute list */ new = alloca(ea_scan(attrs)); ea_merge(attrs, new); ea_sort(new); /* Normalize attributes */ d = new->attrs; cnt = new->count; new->count = 0; for(i=0; iattrs[i]; if (EA_PROTO(a->id) != EAP_BGP) continue; code = EA_ID(a->id); if (ATTR_KNOWN(code)) { if (!bgp_attr_table[code].allow_in_ebgp && !p->is_internal) continue; /* The flags might have been zero if the attr was added by filters */ a->flags = (a->flags & BAF_PARTIAL) | bgp_attr_table[code].expected_flags; if (code < 32) seen |= 1 << code; } else { /* Don't re-export unknown non-transitive attributes */ if (!(a->flags & BAF_TRANSITIVE)) continue; } *d = *a; if ((d->type & EAF_ORIGINATED) && !originate && (d->flags & BAF_TRANSITIVE) && (d->flags & BAF_OPTIONAL)) d->flags |= BAF_PARTIAL; switch (d->type & EAF_TYPE_MASK) { case EAF_TYPE_INT_SET: { struct adata *z = alloca(sizeof(struct adata) + d->u.ptr->length); z->length = d->u.ptr->length; bgp_normalize_int_set((u32 *) z->data, (u32 *) d->u.ptr->data, z->length / 4); d->u.ptr = z; break; } case EAF_TYPE_EC_SET: { struct adata *z = alloca(sizeof(struct adata) + d->u.ptr->length); z->length = d->u.ptr->length; bgp_normalize_ec_set(z, (u32 *) d->u.ptr->data, p->is_internal); d->u.ptr = z; break; } case EAF_TYPE_LC_SET: { struct adata *z = alloca(sizeof(struct adata) + d->u.ptr->length); z->length = d->u.ptr->length; bgp_normalize_lc_set((u32 *) z->data, (u32 *) d->u.ptr->data, z->length / LCOMM_LENGTH); d->u.ptr = z; break; } default: ; } d++; new->count++; } /* Hash */ hash = ea_hash(new); for(b=p->bucket_hash[hash & (p->hash_size - 1)]; b; b=b->hash_next) if (b->hash == hash && ea_same(b->eattrs, new)) { DBG("Found bucket.\n"); return b; } /* Ensure that there are all mandatory attributes */ for(i=0; ip.name, bgp_attr_table[bgp_mandatory_attrs[i]].name, n->n.prefix, n->n.pxlen); return NULL; } /* Check if next hop is valid */ a = ea_find(new, EA_CODE(EAP_BGP, BA_NEXT_HOP)); if (!a || ipa_equal(p->cf->remote_ip, *(ip_addr *)a->u.ptr->data)) { log(L_ERR "%s: Invalid NEXT_HOP attribute in route %I/%d", p->p.name, n->n.prefix, n->n.pxlen); return NULL; } /* Create new bucket */ DBG("Creating bucket.\n"); return bgp_new_bucket(p, new, hash); } void bgp_free_bucket(struct bgp_proto *p, struct bgp_bucket *buck) { if (buck->hash_next) buck->hash_next->hash_prev = buck->hash_prev; if (buck->hash_prev) buck->hash_prev->hash_next = buck->hash_next; else p->bucket_hash[buck->hash & (p->hash_size-1)] = buck->hash_next; mb_free(buck); } /* Prefix hash table */ #define PXH_KEY(n1) n1->n.prefix, n1->n.pxlen, n1->path_id #define PXH_NEXT(n) n->next #define PXH_EQ(p1,l1,i1,p2,l2,i2) ipa_equal(p1, p2) && l1 == l2 && i1 == i2 #define PXH_FN(p,l,i) ipa_hash32(p) ^ u32_hash((l << 16) ^ i) #define PXH_REHASH bgp_pxh_rehash #define PXH_PARAMS /8, *2, 2, 2, 8, 20 HASH_DEFINE_REHASH_FN(PXH, struct bgp_prefix) void bgp_init_prefix_table(struct bgp_proto *p, u32 order) { HASH_INIT(p->prefix_hash, p->p.pool, order); p->prefix_slab = sl_new(p->p.pool, sizeof(struct bgp_prefix)); } static struct bgp_prefix * bgp_get_prefix(struct bgp_proto *p, ip_addr prefix, int pxlen, u32 path_id) { struct bgp_prefix *bp = HASH_FIND(p->prefix_hash, PXH, prefix, pxlen, path_id); if (bp) return bp; bp = sl_alloc(p->prefix_slab); bp->n.prefix = prefix; bp->n.pxlen = pxlen; bp->path_id = path_id; bp->bucket_node.next = NULL; HASH_INSERT2(p->prefix_hash, PXH, p->p.pool, bp); return bp; } void bgp_free_prefix(struct bgp_proto *p, struct bgp_prefix *bp) { HASH_REMOVE2(p->prefix_hash, PXH, p->p.pool, bp); sl_free(p->prefix_slab, bp); } void bgp_rt_notify(struct proto *P, rtable *tbl UNUSED, net *n, rte *new, rte *old UNUSED, ea_list *attrs) { struct bgp_proto *p = (struct bgp_proto *) P; struct bgp_bucket *buck; struct bgp_prefix *px; rte *key; u32 path_id; DBG("BGP: Got route %I/%d %s\n", n->n.prefix, n->n.pxlen, new ? "up" : "down"); if (new) { key = new; buck = bgp_get_bucket(p, n, attrs, new->attrs->source != RTS_BGP); if (!buck) /* Inconsistent attribute list */ return; } else { key = old; if (!(buck = p->withdraw_bucket)) { buck = p->withdraw_bucket = mb_alloc(P->pool, sizeof(struct bgp_bucket)); init_list(&buck->prefixes); } } path_id = p->add_path_tx ? key->attrs->src->global_id : 0; px = bgp_get_prefix(p, n->n.prefix, n->n.pxlen, path_id); if (px->bucket_node.next) { DBG("\tRemoving old entry.\n"); rem_node(&px->bucket_node); } add_tail(&buck->prefixes, &px->bucket_node); bgp_schedule_packet(p->conn, PKT_UPDATE); } static int bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *pool) { ea_list *ea = lp_alloc(pool, sizeof(ea_list) + 4*sizeof(eattr)); rta *rta = e->attrs; byte *z; ea->next = *attrs; *attrs = ea; ea->flags = EALF_SORTED; ea->count = 4; bgp_set_attr(ea->attrs, BA_ORIGIN, ((rta->source == RTS_OSPF_EXT1) || (rta->source == RTS_OSPF_EXT2)) ? ORIGIN_INCOMPLETE : ORIGIN_IGP); if (p->is_internal) bgp_set_attr_wa(ea->attrs+1, pool, BA_AS_PATH, 0); else { z = bgp_set_attr_wa(ea->attrs+1, pool, BA_AS_PATH, 6); z[0] = AS_PATH_SEQUENCE; z[1] = 1; /* 1 AS */ put_u32(z+2, p->local_as); } /* iBGP -> use gw, eBGP multi-hop -> use source_addr, eBGP single-hop -> use gw if on the same iface */ z = bgp_set_attr_wa(ea->attrs+2, pool, BA_NEXT_HOP, NEXT_HOP_LENGTH); if (p->cf->next_hop_self || rta->dest != RTD_ROUTER || ipa_equal(rta->gw, IPA_NONE) || ipa_is_link_local(rta->gw) || (!p->is_internal && !p->cf->next_hop_keep && (!p->neigh || (rta->iface != p->neigh->iface)))) set_next_hop(z, p->source_addr); else set_next_hop(z, rta->gw); bgp_set_attr(ea->attrs+3, BA_LOCAL_PREF, p->cf->default_local_pref); return 0; /* Leave decision to the filters */ } static inline int bgp_as_path_loopy(struct bgp_proto *p, rta *a) { int num = p->cf->allow_local_as + 1; eattr *e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); return (e && (num > 0) && as_path_contains(e->u.ptr, p->local_as, num)); } static inline int bgp_originator_id_loopy(struct bgp_proto *p, rta *a) { eattr *e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_ORIGINATOR_ID)); return (e && (e->u.data == p->local_id)); } static inline int bgp_cluster_list_loopy(struct bgp_proto *p, rta *a) { eattr *e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_CLUSTER_LIST)); return (e && p->rr_client && int_set_contains(e->u.ptr, p->rr_cluster_id)); } static inline void bgp_path_prepend(rte *e, ea_list **attrs, struct linpool *pool, u32 as) { eattr *a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); bgp_attach_attr(attrs, pool, BA_AS_PATH, (uintptr_t) as_path_prepend(pool, a->u.ptr, as)); } static inline void bgp_cluster_list_prepend(rte *e, ea_list **attrs, struct linpool *pool, u32 cid) { eattr *a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_CLUSTER_LIST)); bgp_attach_attr(attrs, pool, BA_CLUSTER_LIST, (uintptr_t) int_set_prepend(pool, a ? a->u.ptr : NULL, cid)); } static int bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *pool, int rr) { eattr *a; if (!p->is_internal && !p->rs_client) { bgp_path_prepend(e, attrs, pool, p->local_as); /* The MULTI_EXIT_DISC attribute received from a neighboring AS MUST NOT be * propagated to other neighboring ASes. * Perhaps it would be better to undefine it. */ a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); if (a) bgp_attach_attr(attrs, pool, BA_MULTI_EXIT_DISC, 0); } /* iBGP -> keep next_hop, eBGP multi-hop -> use source_addr, * eBGP single-hop -> keep next_hop if on the same iface. * If the next_hop is zero (i.e. link-local), keep only if on the same iface. * * Note that same-iface-check uses iface from route, which is based on gw. */ a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP)); if (a && !p->cf->next_hop_self && (p->cf->next_hop_keep || (p->is_internal && ipa_nonzero(*((ip_addr *) a->u.ptr->data))) || (p->neigh && (e->attrs->iface == p->neigh->iface)))) { /* Leave the original next hop attribute, will check later where does it point */ } else { /* Need to create new one */ byte *b = bgp_attach_attr_wa(attrs, pool, BA_NEXT_HOP, NEXT_HOP_LENGTH); set_next_hop(b, p->source_addr); } if (rr) { /* Handling route reflection, RFC 4456 */ struct bgp_proto *src = (struct bgp_proto *) e->attrs->src->proto; a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGINATOR_ID)); if (!a) bgp_attach_attr(attrs, pool, BA_ORIGINATOR_ID, src->remote_id); /* We attach proper cluster ID according to whether the route is entering or leaving the cluster */ bgp_cluster_list_prepend(e, attrs, pool, src->rr_client ? src->rr_cluster_id : p->rr_cluster_id); /* Two RR clients with different cluster ID, hmmm */ if (src->rr_client && p->rr_client && (src->rr_cluster_id != p->rr_cluster_id)) bgp_cluster_list_prepend(e, attrs, pool, p->rr_cluster_id); } return 0; /* Leave decision to the filters */ } static int bgp_community_filter(struct bgp_proto *p, rte *e) { eattr *a; struct adata *d; /* Check if we aren't forbidden to export the route by communities */ a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_COMMUNITY)); if (a) { d = a->u.ptr; if (int_set_contains(d, BGP_COMM_NO_ADVERTISE)) { DBG("\tNO_ADVERTISE\n"); return 1; } if (!p->is_internal && (int_set_contains(d, BGP_COMM_NO_EXPORT) || int_set_contains(d, BGP_COMM_NO_EXPORT_SUBCONFED))) { DBG("\tNO_EXPORT\n"); return 1; } } return 0; } int bgp_import_control(struct proto *P, rte **new, ea_list **attrs, struct linpool *pool) { rte *e = *new; struct bgp_proto *p = (struct bgp_proto *) P; struct bgp_proto *new_bgp = (e->attrs->src->proto->proto == &proto_bgp) ? (struct bgp_proto *) e->attrs->src->proto : NULL; if (p == new_bgp) /* Poison reverse updates */ return -1; if (new_bgp) { /* We should check here for cluster list loop, because the receiving BGP instance might have different cluster ID */ if (bgp_cluster_list_loopy(p, e->attrs)) return -1; if (p->cf->interpret_communities && bgp_community_filter(p, e)) return -1; if (p->local_as == new_bgp->local_as && p->is_internal && new_bgp->is_internal) { /* Redistribution of internal routes with IBGP */ if (p->rr_client || new_bgp->rr_client) /* Route reflection, RFC 4456 */ return bgp_update_attrs(p, e, attrs, pool, 1); else return -1; } else return bgp_update_attrs(p, e, attrs, pool, 0); } else return bgp_create_attrs(p, e, attrs, pool); } static inline u32 bgp_get_neighbor(rte *r) { eattr *e = ea_find(r->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); u32 as; if (e && as_path_get_first(e->u.ptr, &as)) return as; else return ((struct bgp_proto *) r->attrs->src->proto)->remote_as; } static inline int rte_resolvable(rte *rt) { int rd = rt->attrs->dest; return (rd == RTD_ROUTER) || (rd == RTD_DEVICE) || (rd == RTD_MULTIPATH); } int bgp_rte_better(rte *new, rte *old) { struct bgp_proto *new_bgp = (struct bgp_proto *) new->attrs->src->proto; struct bgp_proto *old_bgp = (struct bgp_proto *) old->attrs->src->proto; eattr *x, *y; u32 n, o; /* Skip suppressed routes (see bgp_rte_recalculate()) */ n = new->u.bgp.suppressed; o = old->u.bgp.suppressed; if (n > o) return 0; if (n < o) return 1; /* RFC 4271 9.1.2.1. Route resolvability test */ n = rte_resolvable(new); o = rte_resolvable(old); if (n > o) return 1; if (n < o) return 0; /* Start with local preferences */ x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); n = x ? x->u.data : new_bgp->cf->default_local_pref; o = y ? y->u.data : old_bgp->cf->default_local_pref; if (n > o) return 1; if (n < o) return 0; /* RFC 4271 9.1.2.2. a) Use AS path lengths */ if (new_bgp->cf->compare_path_lengths || old_bgp->cf->compare_path_lengths) { x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); n = x ? as_path_getlen(x->u.ptr) : AS_PATH_MAXLEN; o = y ? as_path_getlen(y->u.ptr) : AS_PATH_MAXLEN; if (n < o) return 1; if (n > o) return 0; } /* RFC 4271 9.1.2.2. b) Use origins */ x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN)); n = x ? x->u.data : ORIGIN_INCOMPLETE; o = y ? y->u.data : ORIGIN_INCOMPLETE; if (n < o) return 1; if (n > o) return 0; /* RFC 4271 9.1.2.2. c) Compare MED's */ /* Proper RFC 4271 path selection cannot be interpreted as finding * the best path in some ordering. It is implemented partially in * bgp_rte_recalculate() when deterministic_med option is * active. Without that option, the behavior is just an * approximation, which in specific situations may lead to * persistent routing loops, because it is nondeterministic - it * depends on the order in which routes appeared. But it is also the * same behavior as used by default in Cisco routers, so it is * probably not a big issue. */ if (new_bgp->cf->med_metric || old_bgp->cf->med_metric || (bgp_get_neighbor(new) == bgp_get_neighbor(old))) { x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); n = x ? x->u.data : new_bgp->cf->default_med; o = y ? y->u.data : old_bgp->cf->default_med; if (n < o) return 1; if (n > o) return 0; } /* RFC 4271 9.1.2.2. d) Prefer external peers */ if (new_bgp->is_internal > old_bgp->is_internal) return 0; if (new_bgp->is_internal < old_bgp->is_internal) return 1; /* RFC 4271 9.1.2.2. e) Compare IGP metrics */ n = new_bgp->cf->igp_metric ? new->attrs->igp_metric : 0; o = old_bgp->cf->igp_metric ? old->attrs->igp_metric : 0; if (n < o) return 1; if (n > o) return 0; /* RFC 4271 9.1.2.2. f) Compare BGP identifiers */ /* RFC 4456 9. a) Use ORIGINATOR_ID instead of local neighor ID */ x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGINATOR_ID)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGINATOR_ID)); n = x ? x->u.data : new_bgp->remote_id; o = y ? y->u.data : old_bgp->remote_id; /* RFC 5004 - prefer older routes */ /* (if both are external and from different peer) */ if ((new_bgp->cf->prefer_older || old_bgp->cf->prefer_older) && !new_bgp->is_internal && n != o) return 0; /* rest of RFC 4271 9.1.2.2. f) */ if (n < o) return 1; if (n > o) return 0; /* RFC 4456 9. b) Compare cluster list lengths */ x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_CLUSTER_LIST)); y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_CLUSTER_LIST)); n = x ? int_set_get_size(x->u.ptr) : 0; o = y ? int_set_get_size(y->u.ptr) : 0; if (n < o) return 1; if (n > o) return 0; /* RFC 4271 9.1.2.2. g) Compare peer IP adresses */ return (ipa_compare(new_bgp->cf->remote_ip, old_bgp->cf->remote_ip) < 0); } int bgp_rte_mergable(rte *pri, rte *sec) { struct bgp_proto *pri_bgp = (struct bgp_proto *) pri->attrs->src->proto; struct bgp_proto *sec_bgp = (struct bgp_proto *) sec->attrs->src->proto; eattr *x, *y; u32 p, s; /* Skip suppressed routes (see bgp_rte_recalculate()) */ if (pri->u.bgp.suppressed != sec->u.bgp.suppressed) return 0; /* RFC 4271 9.1.2.1. Route resolvability test */ if (!rte_resolvable(sec)) return 0; /* Start with local preferences */ x = ea_find(pri->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); y = ea_find(sec->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); p = x ? x->u.data : pri_bgp->cf->default_local_pref; s = y ? y->u.data : sec_bgp->cf->default_local_pref; if (p != s) return 0; /* RFC 4271 9.1.2.2. a) Use AS path lengths */ if (pri_bgp->cf->compare_path_lengths || sec_bgp->cf->compare_path_lengths) { x = ea_find(pri->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); y = ea_find(sec->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); p = x ? as_path_getlen(x->u.ptr) : AS_PATH_MAXLEN; s = y ? as_path_getlen(y->u.ptr) : AS_PATH_MAXLEN; if (p != s) return 0; // if (DELTA(p, s) > pri_bgp->cf->relax_multipath) // return 0; } /* RFC 4271 9.1.2.2. b) Use origins */ x = ea_find(pri->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN)); y = ea_find(sec->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN)); p = x ? x->u.data : ORIGIN_INCOMPLETE; s = y ? y->u.data : ORIGIN_INCOMPLETE; if (p != s) return 0; /* RFC 4271 9.1.2.2. c) Compare MED's */ if (pri_bgp->cf->med_metric || sec_bgp->cf->med_metric || (bgp_get_neighbor(pri) == bgp_get_neighbor(sec))) { x = ea_find(pri->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); y = ea_find(sec->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); p = x ? x->u.data : pri_bgp->cf->default_med; s = y ? y->u.data : sec_bgp->cf->default_med; if (p != s) return 0; } /* RFC 4271 9.1.2.2. d) Prefer external peers */ if (pri_bgp->is_internal != sec_bgp->is_internal) return 0; /* RFC 4271 9.1.2.2. e) Compare IGP metrics */ p = pri_bgp->cf->igp_metric ? pri->attrs->igp_metric : 0; s = sec_bgp->cf->igp_metric ? sec->attrs->igp_metric : 0; if (p != s) return 0; /* Remaining criteria are ignored */ return 1; } static inline int same_group(rte *r, u32 lpref, u32 lasn) { return (r->pref == lpref) && (bgp_get_neighbor(r) == lasn); } static inline int use_deterministic_med(rte *r) { struct proto *P = r->attrs->src->proto; return (P->proto == &proto_bgp) && ((struct bgp_proto *) P)->cf->deterministic_med; } int bgp_rte_recalculate(rtable *table, net *net, rte *new, rte *old, rte *old_best) { rte *r, *s; rte *key = new ? new : old; u32 lpref = key->pref; u32 lasn = bgp_get_neighbor(key); int old_is_group_best = 0; /* * Proper RFC 4271 path selection is a bit complicated, it cannot be * implemented just by rte_better(), because it is not a linear * ordering. But it can be splitted to two levels, where the lower * level chooses the best routes in each group of routes from the * same neighboring AS and higher level chooses the best route (with * a slightly different ordering) between the best-in-group routes. * * When deterministic_med is disabled, we just ignore this issue and * choose the best route by bgp_rte_better() alone. If enabled, the * lower level of the route selection is done here (for the group * to which the changed route belongs), all routes in group are * marked as suppressed, just chosen best-in-group is not. * * Global best route selection then implements higher level by * choosing between non-suppressed routes (as they are always * preferred over suppressed routes). Routes from BGP protocols * that do not set deterministic_med are just never suppressed. As * they do not participate in the lower level selection, it is OK * that this fn is not called for them. * * The idea is simple, the implementation is more problematic, * mostly because of optimizations in rte_recalculate() that * avoids full recalculation in most cases. * * We can assume that at least one of new, old is non-NULL and both * are from the same protocol with enabled deterministic_med. We * group routes by both neighbor AS (lasn) and preference (lpref), * because bgp_rte_better() does not handle preference itself. */ /* If new and old are from different groups, we just process that as two independent events */ if (new && old && !same_group(old, lpref, lasn)) { int i1, i2; i1 = bgp_rte_recalculate(table, net, NULL, old, old_best); i2 = bgp_rte_recalculate(table, net, new, NULL, old_best); return i1 || i2; } /* * We could find the best-in-group and then make some shortcuts like * in rte_recalculate, but as we would have to walk through all * net->routes just to find it, it is probably not worth. So we * just have two simpler fast cases that use just the old route. * We also set suppressed flag to avoid using it in bgp_rte_better(). */ if (new) new->u.bgp.suppressed = 1; if (old) { old_is_group_best = !old->u.bgp.suppressed; old->u.bgp.suppressed = 1; int new_is_better = new && bgp_rte_better(new, old); /* The first case - replace not best with worse (or remove not best) */ if (!old_is_group_best && !new_is_better) return 0; /* The second case - replace the best with better */ if (old_is_group_best && new_is_better) { /* new is best-in-group, the see discussion below - this is a special variant of NBG && OBG. From OBG we can deduce that same_group(old_best) iff (old == old_best) */ new->u.bgp.suppressed = 0; return (old == old_best); } } /* The default case - find a new best-in-group route */ r = new; /* new may not be in the list */ for (s=net->routes; rte_is_valid(s); s=s->next) if (use_deterministic_med(s) && same_group(s, lpref, lasn)) { s->u.bgp.suppressed = 1; if (!r || bgp_rte_better(s, r)) r = s; } /* Simple case - the last route in group disappears */ if (!r) return 0; /* Found best-in-group */ r->u.bgp.suppressed = 0; /* * There are generally two reasons why we have to force * recalculation (return 1): First, the new route may be wrongfully * chosen to be the best in the first case check in * rte_recalculate(), this may happen only if old_best is from the * same group. Second, another (different than new route) * best-in-group is chosen and that may be the proper best (although * rte_recalculate() without ignore that possibility). * * There are three possible cases according to whether the old route * was the best in group (OBG, stored in old_is_group_best) and * whether the new route is the best in group (NBG, tested by r == new). * These cases work even if old or new is NULL. * * NBG -> new is a possible candidate for the best route, so we just * check for the first reason using same_group(). * * !NBG && OBG -> Second reason applies, return 1 * * !NBG && !OBG -> Best in group does not change, old != old_best, * rte_better(new, old_best) is false and therefore * the first reason does not apply, return 0 */ if (r == new) return old_best && same_group(old_best, lpref, lasn); else return old_is_group_best; } static struct adata * bgp_aggregator_convert_to_new(struct adata *old, struct linpool *pool) { struct adata *newa = lp_alloc(pool, sizeof(struct adata) + 8); newa->length = 8; aggregator_convert_to_new(old, newa->data); return newa; } /* Take last req_as ASNs from path old2 (in 2B format), convert to 4B format * and append path old4 (in 4B format). */ static struct adata * bgp_merge_as_paths(struct adata *old2, struct adata *old4, int req_as, struct linpool *pool) { byte buf[old2->length * 2]; int ol = as_path_convert_to_new(old2, buf, req_as); int nl = ol + (old4 ? old4->length : 0); struct adata *newa = lp_alloc(pool, sizeof(struct adata) + nl); newa->length = nl; memcpy(newa->data, buf, ol); if (old4) memcpy(newa->data + ol, old4->data, old4->length); return newa; } static int as4_aggregator_valid(struct adata *aggr) { return aggr->length == 8; } /* Reconstruct 4B AS_PATH and AGGREGATOR according to RFC 4893 4.2.3 */ static void bgp_reconstruct_4b_atts(struct bgp_proto *p, rta *a, struct linpool *pool) { eattr *p2 =ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); eattr *p4 =ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS4_PATH)); eattr *a2 =ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AGGREGATOR)); eattr *a4 =ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS4_AGGREGATOR)); int a4_removed = 0; if (a4 && !as4_aggregator_valid(a4->u.ptr)) { log(L_WARN "%s: AS4_AGGREGATOR attribute is invalid, skipping attribute", p->p.name); a4 = NULL; a4_removed = 1; } if (a2) { u32 a2_as = get_u16(a2->u.ptr->data); if (a4) { if (a2_as != AS_TRANS) { /* Routes were aggregated by old router and therefore AS4_PATH * and AS4_AGGREGATOR is invalid * * Convert AS_PATH and AGGREGATOR to 4B format and finish. */ a2->u.ptr = bgp_aggregator_convert_to_new(a2->u.ptr, pool); p2->u.ptr = bgp_merge_as_paths(p2->u.ptr, NULL, AS_PATH_MAXLEN, pool); return; } else { /* Common case, use AS4_AGGREGATOR attribute */ a2->u.ptr = a4->u.ptr; } } else { /* Common case, use old AGGREGATOR attribute */ a2->u.ptr = bgp_aggregator_convert_to_new(a2->u.ptr, pool); if ((a2_as == AS_TRANS) && !a4_removed) log(L_WARN "%s: AGGREGATOR attribute contain AS_TRANS, but AS4_AGGREGATOR is missing", p->p.name); } } else if (a4) log(L_WARN "%s: AS4_AGGREGATOR attribute received, but AGGREGATOR attribute is missing", p->p.name); int p2_len = as_path_getlen_int(p2->u.ptr, 2); int p4_len = p4 ? validate_as4_path(p, p4->u.ptr) : -1; if (p4 && (p4_len < 0)) log(L_WARN "%s: AS4_PATH attribute is malformed, skipping attribute", p->p.name); if ((p4_len <= 0) || (p2_len < p4_len)) p2->u.ptr = bgp_merge_as_paths(p2->u.ptr, NULL, AS_PATH_MAXLEN, pool); else p2->u.ptr = bgp_merge_as_paths(p2->u.ptr, p4->u.ptr, p2_len - p4_len, pool); } static void bgp_remove_as4_attrs(struct bgp_proto *p, rta *a) { unsigned id1 = EA_CODE(EAP_BGP, BA_AS4_PATH); unsigned id2 = EA_CODE(EAP_BGP, BA_AS4_AGGREGATOR); ea_list **el = &(a->eattrs); /* We know that ea_lists constructed in bgp_decode attrs have one attribute per ea_list struct */ while (*el != NULL) { unsigned fid = (*el)->attrs[0].id; if ((fid == id1) || (fid == id2)) { *el = (*el)->next; if (p->as4_session) log(L_WARN "%s: Unexpected AS4_* attributes received", p->p.name); } else el = &((*el)->next); } } /** * bgp_decode_attrs - check and decode BGP attributes * @conn: connection * @attr: start of attribute block * @len: length of attribute block * @pool: linear pool to make all the allocations in * @mandatory: 1 iff presence of mandatory attributes has to be checked * * This function takes a BGP attribute block (a part of an Update message), checks * its consistency and converts it to a list of BIRD route attributes represented * by a &rta. */ struct rta * bgp_decode_attrs(struct bgp_conn *conn, byte *attr, uint len, struct linpool *pool, int mandatory) { struct bgp_proto *bgp = conn->bgp; rta *a = lp_alloc(pool, sizeof(struct rta)); uint flags, code, l, i, type; int errcode; byte *z, *attr_start; byte seen[256/8]; ea_list *ea; struct adata *ad; int withdraw = 0; bzero(a, sizeof(rta)); a->source = RTS_BGP; a->scope = SCOPE_UNIVERSE; a->cast = RTC_UNICAST; /* a->dest = RTD_ROUTER; -- set in bgp_set_next_hop() */ a->from = bgp->cf->remote_ip; /* Parse the attributes */ bzero(seen, sizeof(seen)); DBG("BGP: Parsing attributes\n"); while (len) { if (len < 2) goto malformed; attr_start = attr; flags = *attr++; code = *attr++; len -= 2; if (flags & BAF_EXT_LEN) { if (len < 2) goto malformed; l = get_u16(attr); attr += 2; len -= 2; } else { if (len < 1) goto malformed; l = *attr++; len--; } if (l > len) goto malformed; len -= l; z = attr; attr += l; DBG("Attr %02x %02x %d\n", code, flags, l); if (seen[code/8] & (1 << (code%8))) goto malformed; if (ATTR_KNOWN(code)) { struct attr_desc *desc = &bgp_attr_table[code]; if (desc->expected_length >= 0 && desc->expected_length != (int) l) { errcode = 5; goto err; } if ((desc->expected_flags ^ flags) & (BAF_OPTIONAL | BAF_TRANSITIVE)) { errcode = 4; goto err; } if (!desc->allow_in_ebgp && !bgp->is_internal) continue; if (desc->validate) { errcode = desc->validate(bgp, z, l); if (errcode > 0) goto err; if (errcode == IGNORE) continue; if (errcode <= WITHDRAW) { log(L_WARN "%s: Attribute %s is malformed, withdrawing update", bgp->p.name, desc->name); withdraw = 1; } } else if (code == BA_AS_PATH) { /* Special case as it might also trim the attribute */ if (validate_as_path(bgp, z, &l) < 0) { errcode = 11; goto err; } } type = desc->type; } else /* Unknown attribute */ { if (!(flags & BAF_OPTIONAL)) { errcode = 2; goto err; } type = EAF_TYPE_OPAQUE; } // Only OPTIONAL and TRANSITIVE attributes may have non-zero PARTIAL flag // if (!((flags & BAF_OPTIONAL) && (flags & BAF_TRANSITIVE)) && (flags & BAF_PARTIAL)) // { errcode = 4; goto err; } seen[code/8] |= (1 << (code%8)); ea = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr)); ea->next = a->eattrs; a->eattrs = ea; ea->flags = 0; ea->count = 1; ea->attrs[0].id = EA_CODE(EAP_BGP, code); ea->attrs[0].flags = flags; ea->attrs[0].type = type; if (type & EAF_EMBEDDED) ad = NULL; else { ad = lp_alloc(pool, sizeof(struct adata) + l); ea->attrs[0].u.ptr = ad; ad->length = l; memcpy(ad->data, z, l); } switch (type) { case EAF_TYPE_ROUTER_ID: case EAF_TYPE_INT: if (l == 1) ea->attrs[0].u.data = *z; else ea->attrs[0].u.data = get_u32(z); break; case EAF_TYPE_IP_ADDRESS: ipa_ntoh(*(ip_addr *)ad->data); break; case EAF_TYPE_INT_SET: case EAF_TYPE_LC_SET: case EAF_TYPE_EC_SET: { u32 *z = (u32 *) ad->data; for(i=0; ilength/4; i++) z[i] = ntohl(z[i]); break; } } } if (withdraw) goto withdraw; #ifdef IPV6 /* If we received MP_REACH_NLRI we should check mandatory attributes */ if (bgp->mp_reach_len != 0) mandatory = 1; #endif /* If there is no (reachability) NLRI, we should exit now */ if (! mandatory) return a; /* Check if all mandatory attributes are present */ for(i=0; i < ARRAY_SIZE(bgp_mandatory_attrs); i++) { code = bgp_mandatory_attrs[i]; if (!(seen[code/8] & (1 << (code%8)))) { bgp_error(conn, 3, 3, &bgp_mandatory_attrs[i], 1); return NULL; } } /* When receiving attributes from non-AS4-aware BGP speaker, * we have to reconstruct 4B AS_PATH and AGGREGATOR attributes */ if (! bgp->as4_session) bgp_reconstruct_4b_atts(bgp, a, pool); bgp_remove_as4_attrs(bgp, a); /* If the AS path attribute contains our AS, reject the routes */ if (bgp_as_path_loopy(bgp, a)) goto withdraw; /* Two checks for IBGP loops caused by route reflection, RFC 4456 */ if (bgp_originator_id_loopy(bgp, a) || bgp_cluster_list_loopy(bgp, a)) goto withdraw; /* If there's no local preference, define one */ if (!(seen[0] & (1 << BA_LOCAL_PREF))) bgp_attach_attr(&a->eattrs, pool, BA_LOCAL_PREF, bgp->cf->default_local_pref); return a; withdraw: return NULL; malformed: bgp_error(conn, 3, 1, NULL, 0); return NULL; err: bgp_error(conn, 3, errcode, attr_start, z+l-attr_start); return NULL; } int bgp_get_attr(eattr *a, byte *buf, int buflen) { uint i = EA_ID(a->id); struct attr_desc *d; int len; if (ATTR_KNOWN(i)) { d = &bgp_attr_table[i]; len = bsprintf(buf, "%s", d->name); buf += len; if (d->format) { *buf++ = ':'; *buf++ = ' '; d->format(a, buf, buflen - len - 2); return GA_FULL; } return GA_NAME; } bsprintf(buf, "%02x%s", i, (a->flags & BAF_TRANSITIVE) ? " [t]" : ""); return GA_NAME; } void bgp_init_bucket_table(struct bgp_proto *p) { p->hash_size = 256; p->hash_limit = p->hash_size * 4; p->bucket_hash = mb_allocz(p->p.pool, p->hash_size * sizeof(struct bgp_bucket *)); init_list(&p->bucket_queue); p->withdraw_bucket = NULL; // fib_init(&p->prefix_fib, p->p.pool, sizeof(struct bgp_prefix), 0, bgp_init_prefix); } void bgp_get_route_info(rte *e, byte *buf, ea_list *attrs) { eattr *p = ea_find(attrs, EA_CODE(EAP_BGP, BA_AS_PATH)); eattr *o = ea_find(attrs, EA_CODE(EAP_BGP, BA_ORIGIN)); u32 origas; buf += bsprintf(buf, " (%d", e->pref); if (e->u.bgp.suppressed) buf += bsprintf(buf, "-"); if (e->attrs->hostentry) { if (!rte_resolvable(e)) buf += bsprintf(buf, "/-"); else if (e->attrs->igp_metric >= IGP_METRIC_UNKNOWN) buf += bsprintf(buf, "/?"); else buf += bsprintf(buf, "/%d", e->attrs->igp_metric); } buf += bsprintf(buf, ") ["); if (p && as_path_get_last(p->u.ptr, &origas)) buf += bsprintf(buf, "AS%u", origas); if (o) buf += bsprintf(buf, "%c", "ie?"[o->u.data]); strcpy(buf, "]"); }