/* * BIRD -- The Babel protocol * * Copyright (c) 2015--2016 Toke Hoiland-Jorgensen * (c) 2016--2017 Ondrej Zajicek <santiago@crfreenet.org> * (c) 2016--2017 CZ.NIC z.s.p.o. * * Can be freely distributed and used under the terms of the GNU GPL. * * This file contains the packet and TLV handling code for the protocol. */ #include "babel.h" struct babel_pkt_header { u8 magic; u8 version; u16 length; } PACKED; struct babel_tlv { u8 type; u8 length; u8 value[0]; } PACKED; struct babel_tlv_ack_req { u8 type; u8 length; u16 reserved; u16 nonce; u16 interval; } PACKED; struct babel_tlv_ack { u8 type; u8 length; u16 nonce; } PACKED; struct babel_tlv_hello { u8 type; u8 length; u16 flags; u16 seqno; u16 interval; } PACKED; struct babel_tlv_ihu { u8 type; u8 length; u8 ae; u8 reserved; u16 rxcost; u16 interval; u8 addr[0]; } PACKED; struct babel_tlv_router_id { u8 type; u8 length; u16 reserved; u64 router_id; } PACKED; struct babel_tlv_next_hop { u8 type; u8 length; u8 ae; u8 reserved; u8 addr[0]; } PACKED; struct babel_tlv_update { u8 type; u8 length; u8 ae; u8 flags; u8 plen; u8 omitted; u16 interval; u16 seqno; u16 metric; u8 addr[0]; } PACKED; struct babel_tlv_route_request { u8 type; u8 length; u8 ae; u8 plen; u8 addr[0]; } PACKED; struct babel_tlv_seqno_request { u8 type; u8 length; u8 ae; u8 plen; u16 seqno; u8 hop_count; u8 reserved; u64 router_id; u8 addr[0]; } PACKED; /* Hello flags */ #define BABEL_HF_UNICAST 0x8000 /* Update flags */ #define BABEL_UF_DEF_PREFIX 0x80 #define BABEL_UF_ROUTER_ID 0x40 struct babel_parse_state { struct babel_proto *proto; struct babel_iface *ifa; ip_addr saddr; ip_addr next_hop_ip4; ip_addr next_hop_ip6; u64 router_id; /* Router ID used in subsequent updates */ u8 def_ip6_prefix[16]; /* Implicit IPv6 prefix in network order */ u8 def_ip4_prefix[4]; /* Implicit IPv4 prefix in network order */ u8 router_id_seen; /* router_id field is valid */ u8 def_ip6_prefix_seen; /* def_ip6_prefix is valid */ u8 def_ip4_prefix_seen; /* def_ip4_prefix is valid */ u8 current_tlv_endpos; /* End of self-terminating TLVs (offset from start) */ }; enum parse_result { PARSE_SUCCESS, PARSE_ERROR, PARSE_IGNORE, }; struct babel_write_state { u64 router_id; u8 router_id_seen; ip_addr next_hop_ip4; ip_addr next_hop_ip6; u8 def_ip6_prefix[16]; /* Implicit IPv6 prefix in network order */ u8 def_ip6_pxlen; }; #define DROP(DSC,VAL) do { err_dsc = DSC; err_val = VAL; goto drop; } while(0) #define DROP1(DSC) do { err_dsc = DSC; goto drop; } while(0) #define LOG_PKT(msg, args...) \ log_rl(&p->log_pkt_tbf, L_REMOTE "%s: " msg, p->p.name, args) #define FIRST_TLV(p) ((struct babel_tlv *) (((struct babel_pkt_header *) p) + 1)) #define NEXT_TLV(t) ((struct babel_tlv *) (((byte *) t) + TLV_LENGTH(t))) #define TLV_LENGTH(t) (t->type == BABEL_TLV_PAD1 ? 1 : t->length + sizeof(struct babel_tlv)) #define TLV_OPT_LENGTH(t) (t->length + sizeof(struct babel_tlv) - sizeof(*t)) #define TLV_HDR(tlv,t,l) ({ tlv->type = t; tlv->length = l - sizeof(struct babel_tlv); }) #define TLV_HDR0(tlv,t) TLV_HDR(tlv, t, tlv_data[t].min_length) #define NET_SIZE(n) BYTES(net_pxlen(n)) static inline uint bytes_equal(u8 *b1, u8 *b2, uint maxlen) { uint i; for (i = 0; (i < maxlen) && (*b1 == *b2); i++, b1++, b2++) ; return i; } static inline uint get_time16(const void *p) { uint v = get_u16(p) * BABEL_TIME_UNITS; return MAX(BABEL_MIN_INTERVAL, v); } static inline void put_time16(void *p, uint v) { put_u16(p, v / BABEL_TIME_UNITS); } static inline void read_ip4_px(net_addr *n, const void *p, uint plen) { ip4_addr addr = {0}; memcpy(&addr, p, BYTES(plen)); net_fill_ip4(n, ip4_ntoh(addr), plen); } static inline void put_ip4_px(void *p, net_addr *n) { ip4_addr addr = ip4_hton(net4_prefix(n)); memcpy(p, &addr, NET_SIZE(n)); } static inline void read_ip6_px(net_addr *n, const void *p, uint plen) { ip6_addr addr = IPA_NONE; memcpy(&addr, p, BYTES(plen)); net_fill_ip6(n, ip6_ntoh(addr), plen); } static inline void put_ip6_px(void *p, net_addr *n) { ip6_addr addr = ip6_hton(net6_prefix(n)); memcpy(p, &addr, NET_SIZE(n)); } static inline ip6_addr get_ip6_ll(const void *p) { return ip6_build(0xfe800000, 0, get_u32(p+0), get_u32(p+4)); } static inline void put_ip6_ll(void *p, ip6_addr addr) { put_u32(p+0, _I2(addr)); put_u32(p+4, _I3(addr)); } /* * TLV read/write functions */ static int babel_read_ack_req(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_hello(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_ihu(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_router_id(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_next_hop(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_update(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_route_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static int babel_read_seqno_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state); static uint babel_write_ack(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); static uint babel_write_hello(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); static uint babel_write_ihu(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); static uint babel_write_update(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); static uint babel_write_route_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); static uint babel_write_seqno_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len); struct babel_tlv_data { u8 min_length; int (*read_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state); uint (*write_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state, uint max_len); void (*handle_tlv)(union babel_msg *m, struct babel_iface *ifa); }; static const struct babel_tlv_data tlv_data[BABEL_TLV_MAX] = { [BABEL_TLV_ACK_REQ] = { sizeof(struct babel_tlv_ack_req), babel_read_ack_req, NULL, babel_handle_ack_req }, [BABEL_TLV_ACK] = { sizeof(struct babel_tlv_ack), NULL, babel_write_ack, NULL }, [BABEL_TLV_HELLO] = { sizeof(struct babel_tlv_hello), babel_read_hello, babel_write_hello, babel_handle_hello }, [BABEL_TLV_IHU] = { sizeof(struct babel_tlv_ihu), babel_read_ihu, babel_write_ihu, babel_handle_ihu }, [BABEL_TLV_ROUTER_ID] = { sizeof(struct babel_tlv_router_id), babel_read_router_id, NULL, NULL }, [BABEL_TLV_NEXT_HOP] = { sizeof(struct babel_tlv_next_hop), babel_read_next_hop, NULL, NULL }, [BABEL_TLV_UPDATE] = { sizeof(struct babel_tlv_update), babel_read_update, babel_write_update, babel_handle_update }, [BABEL_TLV_ROUTE_REQUEST] = { sizeof(struct babel_tlv_route_request), babel_read_route_request, babel_write_route_request, babel_handle_route_request }, [BABEL_TLV_SEQNO_REQUEST] = { sizeof(struct babel_tlv_seqno_request), babel_read_seqno_request, babel_write_seqno_request, babel_handle_seqno_request }, }; static int babel_read_ack_req(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { struct babel_tlv_ack_req *tlv = (void *) hdr; struct babel_msg_ack_req *msg = &m->ack_req; msg->type = BABEL_TLV_ACK_REQ; msg->nonce = get_u16(&tlv->nonce); msg->interval = get_time16(&tlv->interval); msg->sender = state->saddr; if (!msg->interval) return PARSE_ERROR; return PARSE_SUCCESS; } static uint babel_write_ack(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state UNUSED, uint max_len UNUSED) { struct babel_tlv_ack *tlv = (void *) hdr; struct babel_msg_ack *msg = &m->ack; TLV_HDR0(tlv, BABEL_TLV_ACK); put_u16(&tlv->nonce, msg->nonce); return sizeof(struct babel_tlv_ack); } static int babel_read_hello(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { struct babel_tlv_hello *tlv = (void *) hdr; struct babel_msg_hello *msg = &m->hello; /* We currently don't support unicast Hello */ u16 flags = get_u16(&tlv->flags); if (flags & BABEL_HF_UNICAST) return PARSE_IGNORE; msg->type = BABEL_TLV_HELLO; msg->seqno = get_u16(&tlv->seqno); msg->interval = get_time16(&tlv->interval); msg->sender = state->saddr; return PARSE_SUCCESS; } static uint babel_write_hello(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state UNUSED, uint max_len UNUSED) { struct babel_tlv_hello *tlv = (void *) hdr; struct babel_msg_hello *msg = &m->hello; TLV_HDR0(tlv, BABEL_TLV_HELLO); put_u16(&tlv->seqno, msg->seqno); put_time16(&tlv->interval, msg->interval); return sizeof(struct babel_tlv_hello); } static int babel_read_ihu(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { struct babel_tlv_ihu *tlv = (void *) hdr; struct babel_msg_ihu *msg = &m->ihu; msg->type = BABEL_TLV_IHU; msg->ae = tlv->ae; msg->rxcost = get_u16(&tlv->rxcost); msg->interval = get_time16(&tlv->interval); msg->addr = IPA_NONE; msg->sender = state->saddr; if (msg->ae >= BABEL_AE_MAX) return PARSE_IGNORE; /* * We only actually read link-local IPs. In every other case, the addr field * will be 0 but validation will succeed. The handler takes care of these * cases. We handle them here anyway because we need the length for parsing * subtlvs. */ switch (msg->ae) { case BABEL_AE_IP4: if (TLV_OPT_LENGTH(tlv) < 4) return PARSE_ERROR; state->current_tlv_endpos += 4; break; case BABEL_AE_IP6: if (TLV_OPT_LENGTH(tlv) < 16) return PARSE_ERROR; state->current_tlv_endpos += 16; break; case BABEL_AE_IP6_LL: if (TLV_OPT_LENGTH(tlv) < 8) return PARSE_ERROR; msg->addr = ipa_from_ip6(get_ip6_ll(&tlv->addr)); state->current_tlv_endpos += 8; break; } return PARSE_SUCCESS; } static uint babel_write_ihu(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state UNUSED, uint max_len) { struct babel_tlv_ihu *tlv = (void *) hdr; struct babel_msg_ihu *msg = &m->ihu; if (ipa_is_link_local(msg->addr) && max_len < sizeof(struct babel_tlv_ihu) + 8) return 0; TLV_HDR0(tlv, BABEL_TLV_IHU); put_u16(&tlv->rxcost, msg->rxcost); put_time16(&tlv->interval, msg->interval); if (!ipa_is_link_local(msg->addr)) { tlv->ae = BABEL_AE_WILDCARD; return sizeof(struct babel_tlv_ihu); } put_ip6_ll(&tlv->addr, msg->addr); tlv->ae = BABEL_AE_IP6_LL; hdr->length += 8; return sizeof(struct babel_tlv_ihu) + 8; } static int babel_read_router_id(struct babel_tlv *hdr, union babel_msg *m UNUSED, struct babel_parse_state *state) { struct babel_tlv_router_id *tlv = (void *) hdr; state->router_id = get_u64(&tlv->router_id); state->router_id_seen = 1; return PARSE_IGNORE; } /* This is called directly from babel_write_update() */ static uint babel_write_router_id(struct babel_tlv *hdr, u64 router_id, struct babel_write_state *state, uint max_len UNUSED) { struct babel_tlv_router_id *tlv = (void *) hdr; /* We still assume that first min_length bytes are available and zeroed */ TLV_HDR0(tlv, BABEL_TLV_ROUTER_ID); put_u64(&tlv->router_id, router_id); state->router_id = router_id; state->router_id_seen = 1; return sizeof(struct babel_tlv_router_id); } static int babel_read_next_hop(struct babel_tlv *hdr, union babel_msg *m UNUSED, struct babel_parse_state *state) { struct babel_tlv_next_hop *tlv = (void *) hdr; switch (tlv->ae) { case BABEL_AE_WILDCARD: return PARSE_ERROR; case BABEL_AE_IP4: if (TLV_OPT_LENGTH(tlv) < sizeof(ip4_addr)) return PARSE_ERROR; state->next_hop_ip4 = ipa_from_ip4(get_ip4(&tlv->addr)); state->current_tlv_endpos += sizeof(ip4_addr); return PARSE_IGNORE; case BABEL_AE_IP6: if (TLV_OPT_LENGTH(tlv) < sizeof(ip6_addr)) return PARSE_ERROR; state->next_hop_ip6 = ipa_from_ip6(get_ip6(&tlv->addr)); state->current_tlv_endpos += sizeof(ip6_addr); return PARSE_IGNORE; case BABEL_AE_IP6_LL: if (TLV_OPT_LENGTH(tlv) < 8) return PARSE_ERROR; state->next_hop_ip6 = ipa_from_ip6(get_ip6_ll(&tlv->addr)); state->current_tlv_endpos += 8; return PARSE_IGNORE; default: return PARSE_IGNORE; } return PARSE_IGNORE; } /* This is called directly from babel_write_update() and returns -1 if a next hop should be written but there is not enough space. */ static int babel_write_next_hop(struct babel_tlv *hdr, ip_addr addr, struct babel_write_state *state, uint max_len) { struct babel_tlv_next_hop *tlv = (void *) hdr; if (ipa_zero(addr)) { /* Should not happen */ return 0; } else if (ipa_is_ip4(addr) && !ipa_equal(addr, state->next_hop_ip4)) { uint len = sizeof(struct babel_tlv_next_hop) + sizeof(ip4_addr); if (len > max_len) return -1; TLV_HDR(tlv, BABEL_TLV_NEXT_HOP, len); tlv->ae = BABEL_AE_IP4; put_ip4(&tlv->addr, ipa_to_ip4(addr)); state->next_hop_ip4 = addr; return len; } else if (ipa_is_ip6(addr) && !ipa_equal(addr, state->next_hop_ip6)) { uint len = sizeof(struct babel_tlv_next_hop) + sizeof(ip6_addr); if (len > max_len) return -1; TLV_HDR(tlv, BABEL_TLV_NEXT_HOP, len); tlv->ae = BABEL_AE_IP6; put_ip6(&tlv->addr, ipa_to_ip6(addr)); state->next_hop_ip6 = addr; return len; } return 0; } static int babel_read_update(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { struct babel_tlv_update *tlv = (void *) hdr; struct babel_msg_update *msg = &m->update; msg->type = BABEL_TLV_UPDATE; msg->interval = get_time16(&tlv->interval); msg->seqno = get_u16(&tlv->seqno); msg->metric = get_u16(&tlv->metric); /* Length of received prefix data without omitted part */ int len = BYTES(tlv->plen) - (int) tlv->omitted; u8 buf[16] = {}; if ((len < 0) || ((uint) len > TLV_OPT_LENGTH(tlv))) return PARSE_ERROR; switch (tlv->ae) { case BABEL_AE_WILDCARD: if (tlv->plen > 0) return PARSE_ERROR; if (msg->metric != 65535) return PARSE_ERROR; msg->wildcard = 1; break; case BABEL_AE_IP4: if (tlv->plen > IP4_MAX_PREFIX_LENGTH) return PARSE_ERROR; /* Cannot omit data if there is no saved prefix */ if (tlv->omitted && !state->def_ip4_prefix_seen) return PARSE_ERROR; /* Update must have next hop, unless it is retraction */ if (ipa_zero(state->next_hop_ip4) && (msg->metric != BABEL_INFINITY)) return PARSE_ERROR; /* Merge saved prefix and received prefix parts */ memcpy(buf, state->def_ip4_prefix, tlv->omitted); memcpy(buf + tlv->omitted, tlv->addr, len); ip4_addr prefix4 = get_ip4(buf); net_fill_ip4(&msg->net, prefix4, tlv->plen); if (tlv->flags & BABEL_UF_DEF_PREFIX) { put_ip4(state->def_ip4_prefix, prefix4); state->def_ip4_prefix_seen = 1; } msg->next_hop = state->next_hop_ip4; break; case BABEL_AE_IP6: if (tlv->plen > IP6_MAX_PREFIX_LENGTH) return PARSE_ERROR; /* Cannot omit data if there is no saved prefix */ if (tlv->omitted && !state->def_ip6_prefix_seen) return PARSE_ERROR; /* Merge saved prefix and received prefix parts */ memcpy(buf, state->def_ip6_prefix, tlv->omitted); memcpy(buf + tlv->omitted, tlv->addr, len); ip6_addr prefix6 = get_ip6(buf); net_fill_ip6(&msg->net, prefix6, tlv->plen); if (tlv->flags & BABEL_UF_DEF_PREFIX) { put_ip6(state->def_ip6_prefix, prefix6); state->def_ip6_prefix_seen = 1; } if (tlv->flags & BABEL_UF_ROUTER_ID) { state->router_id = ((u64) _I2(prefix6)) << 32 | _I3(prefix6); state->router_id_seen = 1; } msg->next_hop = state->next_hop_ip6; break; case BABEL_AE_IP6_LL: /* ??? */ return PARSE_IGNORE; default: return PARSE_IGNORE; } /* Update must have Router ID, unless it is retraction */ if (!state->router_id_seen && (msg->metric != BABEL_INFINITY)) { DBG("Babel: No router ID seen before update\n"); return PARSE_ERROR; } msg->router_id = state->router_id; msg->sender = state->saddr; state->current_tlv_endpos += len; return PARSE_SUCCESS; } static uint babel_write_update(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state, uint max_len) { struct babel_msg_update *msg = &m->update; uint len0 = 0; /* * When needed, we write Router-ID TLV before Update TLV and return size of * both of them. There is enough space for the Router-ID TLV, because * sizeof(struct babel_tlv_router_id) == sizeof(struct babel_tlv_update). * * Router ID is not used for retractions, so do not use it in such case. */ if ((msg->metric < BABEL_INFINITY) && (!state->router_id_seen || (msg->router_id != state->router_id))) { len0 = babel_write_router_id(hdr, msg->router_id, state, max_len); hdr = NEXT_TLV(hdr); } /* * We also may add Next Hop TLV for regular updates. It may fail for not * enough space or it may be unnecessary as the next hop is the same as the * last one already announced. So we handle all three cases. */ if (msg->metric < BABEL_INFINITY) { int l = babel_write_next_hop(hdr, msg->next_hop, state, max_len - len0); if (l < 0) return 0; if (l) { len0 += l; hdr = NEXT_TLV(hdr); } } struct babel_tlv_update *tlv = (void *) hdr; uint len = sizeof(struct babel_tlv_update) + NET_SIZE(&msg->net); if (len0 + len > max_len) return 0; memset(tlv, 0, sizeof(struct babel_tlv_update)); TLV_HDR(tlv, BABEL_TLV_UPDATE, len); if (msg->wildcard) { tlv->ae = BABEL_AE_WILDCARD; tlv->plen = 0; } else if (msg->net.type == NET_IP4) { tlv->ae = BABEL_AE_IP4; tlv->plen = net4_pxlen(&msg->net); put_ip4_px(tlv->addr, &msg->net); } else { tlv->ae = BABEL_AE_IP6; tlv->plen = net6_pxlen(&msg->net); /* Address compression - omit initial matching bytes */ u8 buf[16], omit; put_ip6(buf, net6_prefix(&msg->net)); omit = bytes_equal(buf, state->def_ip6_prefix, MIN(tlv->plen, state->def_ip6_pxlen) / 8); if (omit > 0) { memcpy(tlv->addr, buf + omit, NET_SIZE(&msg->net) - omit); tlv->omitted = omit; tlv->length -= omit; len -= omit; } else { put_ip6_px(tlv->addr, &msg->net); tlv->flags |= BABEL_UF_DEF_PREFIX; put_ip6(state->def_ip6_prefix, net6_prefix(&msg->net)); state->def_ip6_pxlen = tlv->plen; } } put_time16(&tlv->interval, msg->interval); put_u16(&tlv->seqno, msg->seqno); put_u16(&tlv->metric, msg->metric); return len0 + len; } static int babel_read_route_request(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state UNUSED) { struct babel_tlv_route_request *tlv = (void *) hdr; struct babel_msg_route_request *msg = &m->route_request; msg->type = BABEL_TLV_ROUTE_REQUEST; switch (tlv->ae) { case BABEL_AE_WILDCARD: /* Wildcard requests must have plen 0 */ if (tlv->plen > 0) return PARSE_ERROR; msg->full = 1; return PARSE_SUCCESS; case BABEL_AE_IP4: if (tlv->plen > IP4_MAX_PREFIX_LENGTH) return PARSE_ERROR; if (TLV_OPT_LENGTH(tlv) < BYTES(tlv->plen)) return PARSE_ERROR; read_ip4_px(&msg->net, tlv->addr, tlv->plen); state->current_tlv_endpos += BYTES(tlv->plen); return PARSE_SUCCESS; case BABEL_AE_IP6: if (tlv->plen > IP6_MAX_PREFIX_LENGTH) return PARSE_ERROR; if (TLV_OPT_LENGTH(tlv) < BYTES(tlv->plen)) return PARSE_ERROR; read_ip6_px(&msg->net, tlv->addr, tlv->plen); state->current_tlv_endpos += BYTES(tlv->plen); return PARSE_SUCCESS; case BABEL_AE_IP6_LL: return PARSE_ERROR; default: return PARSE_IGNORE; } return PARSE_IGNORE; } static uint babel_write_route_request(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state UNUSED, uint max_len) { struct babel_tlv_route_request *tlv = (void *) hdr; struct babel_msg_route_request *msg = &m->route_request; uint len = sizeof(struct babel_tlv_route_request) + NET_SIZE(&msg->net); if (len > max_len) return 0; TLV_HDR(tlv, BABEL_TLV_ROUTE_REQUEST, len); if (msg->full) { tlv->ae = BABEL_AE_WILDCARD; tlv->plen = 0; } else if (msg->net.type == NET_IP4) { tlv->ae = BABEL_AE_IP4; tlv->plen = net4_pxlen(&msg->net); put_ip4_px(tlv->addr, &msg->net); } else { tlv->ae = BABEL_AE_IP6; tlv->plen = net6_pxlen(&msg->net); put_ip6_px(tlv->addr, &msg->net); } return len; } static int babel_read_seqno_request(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { struct babel_tlv_seqno_request *tlv = (void *) hdr; struct babel_msg_seqno_request *msg = &m->seqno_request; msg->type = BABEL_TLV_SEQNO_REQUEST; msg->seqno = get_u16(&tlv->seqno); msg->hop_count = tlv->hop_count; msg->router_id = get_u64(&tlv->router_id); msg->sender = state->saddr; if (tlv->hop_count == 0) return PARSE_ERROR; switch (tlv->ae) { case BABEL_AE_WILDCARD: return PARSE_ERROR; case BABEL_AE_IP4: if (tlv->plen > IP4_MAX_PREFIX_LENGTH) return PARSE_ERROR; if (TLV_OPT_LENGTH(tlv) < BYTES(tlv->plen)) return PARSE_ERROR; read_ip4_px(&msg->net, tlv->addr, tlv->plen); state->current_tlv_endpos += BYTES(tlv->plen); return PARSE_SUCCESS; case BABEL_AE_IP6: if (tlv->plen > IP6_MAX_PREFIX_LENGTH) return PARSE_ERROR; if (TLV_OPT_LENGTH(tlv) < BYTES(tlv->plen)) return PARSE_ERROR; read_ip6_px(&msg->net, tlv->addr, tlv->plen); state->current_tlv_endpos += BYTES(tlv->plen); return PARSE_SUCCESS; case BABEL_AE_IP6_LL: return PARSE_ERROR; default: return PARSE_IGNORE; } return PARSE_IGNORE; } static uint babel_write_seqno_request(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state UNUSED, uint max_len) { struct babel_tlv_seqno_request *tlv = (void *) hdr; struct babel_msg_seqno_request *msg = &m->seqno_request; uint len = sizeof(struct babel_tlv_seqno_request) + NET_SIZE(&msg->net); if (len > max_len) return 0; TLV_HDR(tlv, BABEL_TLV_SEQNO_REQUEST, len); if (msg->net.type == NET_IP4) { tlv->ae = BABEL_AE_IP4; tlv->plen = net4_pxlen(&msg->net); put_ip4_px(tlv->addr, &msg->net); } else { tlv->ae = BABEL_AE_IP6; tlv->plen = net6_pxlen(&msg->net); put_ip6_px(tlv->addr, &msg->net); } put_u16(&tlv->seqno, msg->seqno); tlv->hop_count = msg->hop_count; put_u64(&tlv->router_id, msg->router_id); return len; } static inline int babel_read_subtlvs(struct babel_tlv *hdr, union babel_msg *msg UNUSED, struct babel_parse_state *state) { struct babel_tlv *tlv; for (tlv = (void *) hdr + state->current_tlv_endpos; (void *) tlv < (void *) hdr + TLV_LENGTH(hdr); tlv = NEXT_TLV(tlv)) { /* * The subtlv type space is non-contiguous (due to the mandatory bit), so * use a switch for dispatch instead of the mapping array we use for TLVs */ switch (tlv->type) { case BABEL_SUBTLV_PAD1: case BABEL_SUBTLV_PADN: /* FIXME: Framing errors in PADN are silently ignored, see babel_process_packet() */ break; default: /* Unknown mandatory subtlv; PARSE_IGNORE ignores the whole TLV */ if (tlv->type > 128) { DBG("Babel: Mandatory subtlv %d found; skipping TLV\n", tlv->type); return PARSE_IGNORE; } break; } } return PARSE_SUCCESS; } static inline int babel_read_tlv(struct babel_tlv *hdr, union babel_msg *msg, struct babel_parse_state *state) { if ((hdr->type <= BABEL_TLV_PADN) || (hdr->type >= BABEL_TLV_MAX) || !tlv_data[hdr->type].read_tlv) return PARSE_IGNORE; if (TLV_LENGTH(hdr) < tlv_data[hdr->type].min_length) return PARSE_ERROR; state->current_tlv_endpos = tlv_data[hdr->type].min_length; memset(msg, 0, sizeof(*msg)); int res = tlv_data[hdr->type].read_tlv(hdr, msg, state); if (res != PARSE_SUCCESS) return res; return babel_read_subtlvs(hdr, msg, state); } static uint babel_write_tlv(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len) { if ((msg->type <= BABEL_TLV_PADN) || (msg->type >= BABEL_TLV_MAX) || !tlv_data[msg->type].write_tlv) return 0; if (tlv_data[msg->type].min_length > max_len) return 0; memset(hdr, 0, tlv_data[msg->type].min_length); return tlv_data[msg->type].write_tlv(hdr, msg, state, max_len); } /* * Packet RX/TX functions */ static int babel_send_to(struct babel_iface *ifa, ip_addr dest) { sock *sk = ifa->sk; struct babel_pkt_header *hdr = (void *) sk->tbuf; int len = get_u16(&hdr->length) + sizeof(struct babel_pkt_header); DBG("Babel: Sending %d bytes to %I\n", len, dest); return sk_send_to(sk, len, dest, 0); } /** * babel_write_queue - Write a TLV queue to a transmission buffer * @ifa: Interface holding the transmission buffer * @queue: TLV queue to write (containing internal-format TLVs) * * This function writes a packet to the interface transmission buffer with as * many TLVs from the &queue as will fit in the buffer. It returns the number of * bytes written (NOT counting the packet header). The function is called by * babel_send_queue() and babel_send_unicast() to construct packets for * transmission, and uses per-TLV helper functions to convert the * internal-format TLVs to their wire representations. * * The TLVs in the queue are freed after they are written to the buffer. */ static uint babel_write_queue(struct babel_iface *ifa, list *queue) { struct babel_proto *p = ifa->proto; struct babel_write_state state = { .next_hop_ip6 = ifa->addr }; if (EMPTY_LIST(*queue)) return 0; byte *pos = ifa->sk->tbuf; byte *end = pos + ifa->tx_length; struct babel_pkt_header *pkt = (void *) pos; pkt->magic = BABEL_MAGIC; pkt->version = BABEL_VERSION; pkt->length = 0; pos += sizeof(struct babel_pkt_header); struct babel_msg_node *msg; WALK_LIST_FIRST(msg, *queue) { if (pos >= end) break; int len = babel_write_tlv((struct babel_tlv *) pos, &msg->msg, &state, end - pos); if (!len) break; pos += len; rem_node(NODE msg); sl_free(p->msg_slab, msg); } uint plen = pos - (byte *) pkt; put_u16(&pkt->length, plen - sizeof(struct babel_pkt_header)); return plen; } void babel_send_queue(void *arg) { struct babel_iface *ifa = arg; while ((babel_write_queue(ifa, &ifa->msg_queue) > 0) && (babel_send_to(ifa, IP6_BABEL_ROUTERS) > 0)); } static inline void babel_kick_queue(struct babel_iface *ifa) { /* * Only schedule send event if there is not already data in the socket buffer. * Otherwise we may overwrite the data already in the buffer. */ if ((ifa->sk->tpos == ifa->sk->tbuf) && !ev_active(ifa->send_event)) ev_schedule(ifa->send_event); } /** * babel_send_unicast - send a single TLV via unicast to a destination * @msg: TLV to send * @ifa: Interface to send via * @dest: Destination of the TLV * * This function is used to send a single TLV via unicast to a designated * receiver. This is used for replying to certain incoming requests, and for * sending unicast requests to refresh routes before they expire. */ void babel_send_unicast(union babel_msg *msg, struct babel_iface *ifa, ip_addr dest) { struct babel_proto *p = ifa->proto; struct babel_msg_node *msgn = sl_alloc(p->msg_slab); list queue; msgn->msg = *msg; init_list(&queue); add_tail(&queue, NODE msgn); babel_write_queue(ifa, &queue); babel_send_to(ifa, dest); /* We could overwrite waiting packet here, we may have to kick TX queue */ if (!EMPTY_LIST(ifa->msg_queue)) babel_kick_queue(ifa); } /** * babel_enqueue - enqueue a TLV for transmission on an interface * @msg: TLV to enqueue (in internal TLV format) * @ifa: Interface to enqueue to * * This function is called to enqueue a TLV for subsequent transmission on an * interface. The transmission event is triggered whenever a TLV is enqueued; * this ensures that TLVs will be transmitted in a timely manner, but that TLVs * which are enqueued in rapid succession can be transmitted together in one * packet. */ void babel_enqueue(union babel_msg *msg, struct babel_iface *ifa) { struct babel_proto *p = ifa->proto; struct babel_msg_node *msgn = sl_alloc(p->msg_slab); msgn->msg = *msg; add_tail(&ifa->msg_queue, NODE msgn); babel_kick_queue(ifa); } /** * babel_process_packet - process incoming data packet * @pkt: Pointer to the packet data * @len: Length of received packet * @saddr: Address of packet sender * @ifa: Interface packet was received on. * * This function is the main processing hook of incoming Babel packets. It * checks that the packet header is well-formed, then processes the TLVs * contained in the packet. This is done in two passes: First all TLVs are * parsed into the internal TLV format. If a TLV parser fails, processing of the * rest of the packet is aborted. * * After the parsing step, the TLV handlers are called for each parsed TLV in * order. */ static void babel_process_packet(struct babel_pkt_header *pkt, int len, ip_addr saddr, struct babel_iface *ifa) { struct babel_proto *p = ifa->proto; struct babel_tlv *tlv; struct babel_msg_node *msg; list msgs; int res; int plen = sizeof(struct babel_pkt_header) + get_u16(&pkt->length); byte *pos; byte *end = (byte *)pkt + plen; struct babel_parse_state state = { .proto = p, .ifa = ifa, .saddr = saddr, .next_hop_ip6 = saddr, }; if ((pkt->magic != BABEL_MAGIC) || (pkt->version != BABEL_VERSION)) { TRACE(D_PACKETS, "Strange packet from %I via %s - magic %d version %d", saddr, ifa->iface->name, pkt->magic, pkt->version); return; } if (plen > len) { LOG_PKT("Bad packet from %I via %s - %s (%u)", saddr, ifa->iface->name, "length mismatch", plen); return; } TRACE(D_PACKETS, "Packet received from %I via %s", saddr, ifa->iface->name); init_list(&msgs); /* First pass through the packet TLV by TLV, parsing each into internal data structures. */ for (tlv = FIRST_TLV(pkt); (byte *)tlv < end; tlv = NEXT_TLV(tlv)) { /* Ugly special case */ if (tlv->type == BABEL_TLV_PAD1) continue; /* The end of the common TLV header */ pos = (byte *)tlv + sizeof(struct babel_tlv); if ((pos > end) || (pos + tlv->length > end)) { LOG_PKT("Bad TLV from %I via %s type %d pos %d - framing error", saddr, ifa->iface->name, tlv->type, (byte *)tlv - (byte *)pkt); break; } msg = sl_alloc(p->msg_slab); res = babel_read_tlv(tlv, &msg->msg, &state); if (res == PARSE_SUCCESS) { add_tail(&msgs, NODE msg); } else if (res == PARSE_IGNORE) { DBG("Babel: Ignoring TLV of type %d\n", tlv->type); sl_free(p->msg_slab, msg); } else /* PARSE_ERROR */ { LOG_PKT("Bad TLV from %I via %s type %d pos %d - parse error", saddr, ifa->iface->name, tlv->type, (byte *)tlv - (byte *)pkt); sl_free(p->msg_slab, msg); break; } } /* Parsing done, handle all parsed TLVs */ WALK_LIST_FIRST(msg, msgs) { if (tlv_data[msg->msg.type].handle_tlv) tlv_data[msg->msg.type].handle_tlv(&msg->msg, ifa); rem_node(NODE msg); sl_free(p->msg_slab, msg); } } static void babel_err_hook(sock *sk, int err) { struct babel_iface *ifa = sk->data; struct babel_proto *p = ifa->proto; log(L_ERR "%s: Socket error on %s: %M", p->p.name, ifa->iface->name, err); /* FIXME: Drop queued TLVs here? */ } static void babel_tx_hook(sock *sk) { struct babel_iface *ifa = sk->data; DBG("Babel: TX hook called (iface %s, src %I, dst %I)\n", sk->iface->name, sk->saddr, sk->daddr); babel_send_queue(ifa); } static int babel_rx_hook(sock *sk, uint len) { struct babel_iface *ifa = sk->data; struct babel_proto *p = ifa->proto; const char *err_dsc = NULL; uint err_val = 0; if (sk->lifindex != ifa->iface->index) return 1; DBG("Babel: RX hook called (iface %s, src %I, dst %I)\n", sk->iface->name, sk->faddr, sk->laddr); /* Silently ignore my own packets */ if (ipa_equal(sk->faddr, sk->saddr)) return 1; if (!ipa_is_link_local(sk->faddr)) DROP1("wrong src address"); if (sk->fport != ifa->cf->port) DROP("wrong src port", sk->fport); if (len < sizeof(struct babel_pkt_header)) DROP("too short", len); if (sk->flags & SKF_TRUNCATED) DROP("truncated", len); babel_process_packet((struct babel_pkt_header *) sk->rbuf, len, sk->faddr, ifa); return 1; drop: LOG_PKT("Bad packet from %I via %s - %s (%u)", sk->faddr, sk->iface->name, err_dsc, err_val); return 1; } int babel_open_socket(struct babel_iface *ifa) { struct babel_proto *p = ifa->proto; sock *sk; sk = sk_new(ifa->pool); sk->type = SK_UDP; sk->sport = ifa->cf->port; sk->dport = ifa->cf->port; sk->iface = ifa->iface; sk->saddr = ifa->addr; sk->vrf = p->p.vrf; sk->rx_hook = babel_rx_hook; sk->tx_hook = babel_tx_hook; sk->err_hook = babel_err_hook; sk->data = ifa; sk->tos = ifa->cf->tx_tos; sk->priority = ifa->cf->tx_priority; sk->ttl = 1; sk->flags = SKF_LADDR_RX; if (sk_open(sk) < 0) goto err; if (sk_setup_multicast(sk) < 0) goto err; if (sk_join_group(sk, IP6_BABEL_ROUTERS) < 0) goto err; ifa->sk = sk; return 1; err: sk_log_error(sk, p->p.name); rfree(sk); return 0; }