/* * BIRD -- Simple Network Management Protocol (SNMP) * * (c) 2022 Vojtech Vilimek * (c) 2022 CZ.NIC z.s.p.o * * Can be freely distributed and used under the terms of the GNU GPL. * */ #include "lib/unaligned.h" #include "subagent.h" #include "snmp_utils.h" #include "bgp_mib.h" /* ============================================================= * Problems * ------------------------------------------------------------ * * change of remote ip -> no notification, no update * same ip, different ports * distinct VRF (two interfaces with overlapping private addrs) * posible link-local addresses in LOCAL_IP * * context is allocated as copied, is it approach really needed? wouldn't it * sufficient just use the context in rx-buffer? * */ static void snmp_mib_fill2(struct snmp_proto *p, struct oid *oid, struct snmp_pdu *c); static uint parse_response(struct snmp_proto *p, byte *buf, uint size); static void do_response(struct snmp_proto *p, byte *buf, uint size); static uint parse_gets2_pdu(struct snmp_proto *p, byte *buf, uint size, uint *skip); static struct agentx_response *prepare_response(struct snmp_proto *p, struct snmp_pdu *c); static void response_err_ind(struct agentx_response *res, uint err, uint ind); static uint update_packet_size(struct snmp_proto *p, const byte *start, byte *end); static struct oid *search_mib(struct snmp_proto *p, const struct oid *o_start, const struct oid *o_end, struct oid *o_curr, struct snmp_pdu *c, enum snmp_search_res *result); u32 snmp_internet[] = { SNMP_ISO, SNMP_ORG, SNMP_DOD, SNMP_INTERNET }; static const char * const snmp_errs[] UNUSED = { #define SNMP_ERR_SHIFT 256 [AGENTX_RES_OPEN_FAILED - SNMP_ERR_SHIFT] = "Open failed", [AGENTX_RES_NOT_OPEN - SNMP_ERR_SHIFT] = "Not open", [AGENTX_RES_INDEX_WRONG_TYPE - SNMP_ERR_SHIFT] = "Index wrong type", [AGENTX_RES_INDEX_ALREADY_ALLOC - SNMP_ERR_SHIFT] = "Index already allocated", [AGENTX_RES_INDEX_NONE_AVAIL - SNMP_ERR_SHIFT] = "Index none availlable", [AGENTX_RES_NOT_ALLOCATED - SNMP_ERR_SHIFT] = "Not allocated", [AGENTX_RES_UNSUPPORTED_CONTEXT - SNMP_ERR_SHIFT] = "Unsupported contex", [AGENTX_RES_DUPLICATE_REGISTER - SNMP_ERR_SHIFT] = "Duplicate registration", [AGENTX_RES_UNKNOWN_REGISTER - SNMP_ERR_SHIFT] = "Unknown registration", [AGENTX_RES_UNKNOWN_AGENT_CAPS - SNMP_ERR_SHIFT] = "Unknown agent caps", [AGENTX_RES_PARSE_ERROR - SNMP_ERR_SHIFT] = "Parse error", [AGENTX_RES_REQUEST_DENIED - SNMP_ERR_SHIFT] = "Request denied", [AGENTX_RES_PROCESSING_ERR - SNMP_ERR_SHIFT] = "Processing error", }; static const char * const snmp_pkt_type[] UNUSED = { [AGENTX_OPEN_PDU] = "Open-PDU", [AGENTX_CLOSE_PDU] = "Close-PDU", [AGENTX_REGISTER_PDU] = "Register-PDU", [AGENTX_UNREGISTER_PDU] = "Unregister-PDU", [AGENTX_GET_PDU] = "Get-PDU", [AGENTX_GET_NEXT_PDU] = "GetNext-PDU", [AGENTX_GET_BULK_PDU] = "GetBulk-PDU", [AGENTX_TEST_SET_PDU] = "TestSet-PDU", [AGENTX_COMMIT_SET_PDU] = "CommitSet-PDU", [AGENTX_UNDO_SET_PDU] = "UndoSet-PDU", [AGENTX_CLEANUP_SET_PDU] = "CleanupSet-PDU", [AGENTX_NOTIFY_PDU] = "Notify-PDU", [AGENTX_PING_PDU] = "Ping-PDU", [AGENTX_INDEX_ALLOCATE_PDU] = "IndexAllocate-PDU", [AGENTX_INDEX_DEALLOCATE_PDU] = "IndexDeallocate-PDU", [AGENTX_ADD_AGENT_CAPS_PDU] = "AddAgentCaps-PDU", [AGENTX_REMOVE_AGENT_CAPS_PDU] = "RemoveAgentCaps-PDU", [AGENTX_RESPONSE_PDU] = "Response-PDU", }; static void open_pdu(struct snmp_proto *p, struct oid *oid) { const struct snmp_config *cf = SKIP_BACK(struct snmp_config, cf, p->p.cf); sock *sk = p->sock; struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); byte *buf = c.buffer; #define TIMEOUT_SIZE 4 /* 1B timeout, 3B zero padding */ if (c.size < AGENTX_HEADER_SIZE + TIMEOUT_SIZE + snmp_oid_size(oid) + + snmp_str_size(cf->description)) { snmp_manage_tbuf(p, &c); buf = c.buffer; } struct agentx_header *h = (struct agentx_header *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); SNMP_BLANK_HEADER(h, AGENTX_OPEN_PDU); c.byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; STORE_U32(h->session_id, 1); STORE_U32(h->transaction_id, 1); STORE_U32(h->packet_id, 1); c.size -= (4 + snmp_oid_size(oid) + snmp_str_size(cf->description)); c.buffer = snmp_put_fbyte(c.buffer, p->timeout); c.buffer = snmp_put_oid(c.buffer, oid); c.buffer = snmp_put_str(c.buffer, cf->description); uint s = update_packet_size(p, buf, c.buffer); sk_send(sk, s); #undef TIMEOUT_SIZE } void snmp_notify_pdu(struct snmp_proto *p, struct oid *oid, void *data, uint size, int include_uptime) { sock *sk = p->sock; struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); #define UPTIME_SIZE \ (6 * sizeof(u32)) /* sizeof( { u32 vb_type, u32 oid_hdr, u32 ids[4] } )*/ #define TRAP0_HEADER_SIZE \ (7 * sizeof(u32)) /* sizeof( { u32 vb_type, u32 oid_hdr, u32 ids[6] } ) */ uint sz = AGENTX_HEADER_SIZE + TRAP0_HEADER_SIZE + snmp_oid_size(oid) \ + size; if (include_uptime) sz += UPTIME_SIZE; if (c.size < sz) snmp_manage_tbuf(p, &c); struct agentx_header *h = (struct agentx_header *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); SNMP_BLANK_HEADER(h, AGENTX_NOTIFY_PDU); p->packet_id++; SNMP_SESSION(h, p); c.byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; if (include_uptime) { /* sysUpTime.0 oid */ struct oid uptime = { .n_subid = 4, .prefix = SNMP_MGMT, .include = 0, .pad = 0, }; u32 uptime_ids[] = { 1, 1, 3, 0 }; struct agentx_varbind *vb = snmp_create_varbind(c.buffer, &uptime); for (uint i = 0; i < uptime.n_subid; i++) STORE_U32(vb->name.ids[i], uptime_ids[i]); snmp_varbind_ticks(vb, c.size, (current_time() TO_S) / 100); ADVANCE(c.buffer, c.size, snmp_varbind_size(vb, c.byte_ord)); } /* snmpTrapOID.0 oid */ struct oid trap0 = { .n_subid = 6, .prefix = 6, .include = 0, .pad = 0, }; u32 trap0_ids[] = { 3, 1, 1, 4, 1, 0 }; struct agentx_varbind *trap_vb = snmp_create_varbind(c.buffer, &trap0); for (uint i = 0; i < trap0.n_subid; i++) STORE_U32(trap_vb->name.ids[i], trap0_ids[i]); trap_vb->type = AGENTX_OBJECT_ID; snmp_put_oid(SNMP_VB_DATA(trap_vb), oid); ADVANCE(c.buffer, c.size, snmp_varbind_size(trap_vb, c.byte_ord)); memcpy(c.buffer, data, size); ADVANCE(c.buffer, c.size, size); uint s = update_packet_size(p, sk->tbuf, c.buffer); sk_send(sk, s); #undef TRAP0_HEADER_SIZE #undef UPTIME_SIZE } /* index allocate / deallocate pdu * / static void de_allocate_pdu(struct snmp_proto *p, struct oid *oid, u8 type) { sock *sk = p->sock; byte *buf, *pkt; buf = pkt = sk->tbuf; uint size = sk->tbsize; if (size > AGENTX_HEADER_SIZE + ) { //snmp_log("de_allocate_pdu()"); struct agentx_header *h; SNMP_CREATE(pkt, struct agentx_header, h); SNMP_BLANK_HEADER(h, type); SNMP_SESSION(h,p); struct agentx_varbind *vb = (struct agentx_varbind *) pkt; STORE_16(vb->type, AGENTX_OBJECT_ID); STORE(vb->oid, } else {}//snmp_log("de_allocate_pdu(): insufficient size"); } */ /* Register-PDU / Unregister-PDU */ static void un_register_pdu(struct snmp_proto *p, struct oid *oid, uint len, uint index, u8 type, u8 is_instance, uint contid) { const struct snmp_config *cf = SKIP_BACK(struct snmp_config, cf, p->p.cf); sock *sk = p->sock; struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); byte *buf = c.buffer; /* conditional +4 for upper-bound (optinal field) */ uint sz = AGENTX_HEADER_SIZE + snmp_oid_size(oid) + ((len > 1) ? 4 : 0); const struct snmp_context *sc = NULL; if (contid) { sc = snmp_cont_get(p, contid); sz += snmp_str_size(sc->context); } if (c.size < sz) { //snmp_log("un_register_pdu() insufficient size"); snmp_manage_tbuf(p, &c); buf = c.buffer; } //snmp_log("un_register_pdu()"); struct agentx_header *h = (struct agentx_header *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); SNMP_HEADER(h, type, is_instance ? AGENTX_FLAG_INSTANCE_REGISTRATION : 0); p->packet_id++; SNMP_SESSION(h, p); c.byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; /* log("un_register_pdu contid %u s_cont (at 0x%p) %s", contid, sc, (sc && sc->context) ? sc->context : ""); */ SNMP_NON_DEFAULT_CONTEXT(h, c, contid); struct agentx_un_register_hdr *ur = (struct agentx_un_register_hdr *) c.buffer; /* do not override timeout */ STORE_U8(ur->timeout, p->timeout); /* default priority */ STORE_U8(ur->priority, cf->priority); STORE_U8(ur->range_subid, (len > 1) ? index : 0); STORE_U8(ur->pad, 0); ADVANCE(c.buffer, c.size, sizeof(struct agentx_un_register_hdr)); snmp_put_oid(c.buffer, oid); ADVANCE(c.buffer, c.size, snmp_oid_size(oid)); /* place upper-bound if needed */ if (len > 1) { STORE_PTR(c.buffer, len); ADVANCE(c.buffer, c.size, 4); } uint s = update_packet_size(p, buf, c.buffer); //snmp_log("sending (un)register %s", snmp_pkt_type[type]); sk_send(sk, s); } /* Register-PDU */ void snmp_register(struct snmp_proto *p, struct oid *oid, uint len, uint index, u8 is_instance, uint contid) { un_register_pdu(p, oid, len, index, AGENTX_REGISTER_PDU, is_instance, contid); } /* Unregister-PDU */ void UNUSED snmp_unregister(struct snmp_proto *p, struct oid *oid, uint len, uint index, uint contid) { un_register_pdu(p, oid, len, index, AGENTX_UNREGISTER_PDU, 0, contid); } static void close_pdu(struct snmp_proto *p, u8 reason) { sock *sk = p->sock; struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); byte *buf = c.buffer; /*snmp_log("close_pdu() size: %u %c %u", c.size, (c.size > AGENTX_HEADER_SIZE + 4) ? '>':'<', AGENTX_HEADER_SIZE); */ /* +4B for reason */ if (c.size < AGENTX_HEADER_SIZE + 4) { snmp_manage_tbuf(p, &c); buf = c.buffer; } struct agentx_header *h = (struct agentx_header *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); SNMP_BLANK_HEADER(h, AGENTX_CLOSE_PDU); p->packet_id++; SNMP_SESSION(h, p); c.byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; snmp_put_fbyte(c.buffer, reason); ADVANCE(c.buffer, c.size, 4); uint s = update_packet_size(p, buf, c.buffer); //snmp_log("preparing to sk_send() (close)"); sk_send(sk, s); } #if 0 static void UNUSED addagentcaps_pdu(struct snmp_proto *p, struct oid *cap, char *descr, uint descr_len, struct agentx_context *c) { ASSUME(descr != NULL && descr_len > 0); sock *sk = p->sock; //byte *buf = sk->tbuf; //uint size = sk->tbsize; // TO-DO rename to pkt and add pkt_start byte *buf = sk->tpos; uint size = sk->tbuf + sk->tbsize - sk->tpos; if (size < AGENTX_HEADER_SIZE + snmp_context_size(c) + snmp_oid_size(cap) + snmp_str_size_from_len(descr_len)) { /* TO-DO need more mem */ return; } struct agentx_header *h; SNMP_CREATE(buf, struct agentx_header, h); SNMP_BLANK_HEADER(h, AGENTX_ADD_AGENT_CAPS_PDU); SNMP_SESSION(h, p); ADVANCE(buf, size, AGENTX_HEADER_SIZE); uint in_pkt; if (c && c->length) { SNMP_HAS_CONTEXT(h); in_pkt = snmp_put_nstr(buf, c->context, c->length) - buf; ADVANCE(buf, size, in_pkt); } // memcpy(buf, cap, snmp_oid_size(cap)); ADVANCE(buf, size, snmp_oid_size(cap)); in_pkt = snmp_put_nstr(buf, descr, descr_len) - buf; ADVANCE(buf, size, in_pkt); // make a note in the snmp_proto structure //int ret = sk_send(sk, buf - sk->tbuf); sk_send(sk, buf - sk->tpos); } static void UNUSED removeagentcaps_pdu(struct snmp_proto *p, struct oid *cap, struct agentx_context *c) { sock *sk = p->sock; //byte *buf = sk->tbuf; //uint size = sk->tbsize; // TO-DO rename to pkt and add pkt_start byte *buf = sk->tpos; uint size = sk->tbuf + sk->tbsize - sk->tpos; if (size < AGENTX_HEADER_SIZE + snmp_context_size(c) + snmp_oid_size(cap)) { /* TO-DO need more mem */ return; } struct agentx_header *h; SNMP_CREATE(buf, struct agentx_header, h); SNMP_SESSION(h, p); ADVANCE(buf, size, AGENTX_HEADER_SIZE); uint in_pkt; if (c && c->length) { SNMP_HAS_CONTEXT(h); in_pkt = snmp_put_nstr(buf, c->context, c->length) - buf; ADVANCE(buf, size, in_pkt); } memcpy(buf, cap, snmp_oid_size(cap)); ADVANCE(buf, size, snmp_oid_size(cap)); // update state in snmp_proto structure sk_send(sk, buf - sk->tpos); } #endif static inline void refresh_ids(struct snmp_proto *p, struct agentx_header *h) { int byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; p->transaction_id = LOAD_U32(h->transaction_id, byte_ord); p->packet_id = LOAD_U32(h->packet_id, byte_ord); } /** * parse_pkt - parse recieved response packet * @p: * @pkt: packet buffer * @size: number of packet bytes in buffer * retval number of byte parsed * * Returns number of bytes parsed from RX-buffer. */ static uint parse_pkt(struct snmp_proto *p, byte *pkt, uint size, uint *skip) { //snmp_log("parse_pkt() pkt start: %p", pkt); if (size < AGENTX_HEADER_SIZE) return 0; uint parsed_len = 0; struct agentx_header *h = (void *) pkt; //snmp_log("parse_pkt got type %s (%d)", snmp_pkt_type[h->type], h->type); //snmp_log("parse_pkt rx size %u", size); //snmp_dump_packet((void *)h, MIN(h->payload, 256)); switch (h->type) { case AGENTX_RESPONSE_PDU: //snmp_log("parse_pkt returning parse_response"); parsed_len = parse_response(p, pkt, size); break; case AGENTX_GET_PDU: case AGENTX_GET_NEXT_PDU: case AGENTX_GET_BULK_PDU: refresh_ids(p, h); parsed_len = parse_gets2_pdu(p, pkt, size, skip); break; /* during testing the connection should stay opened (we die if we screw up * and get CLOSE_PDU in response) case AGENTX_CLOSE_PDU: refresh_ids(p, h); parsed_len = parse_close_pdu(p, pkt, size); break; */ default: /* drop the packet with unknown type silently */ //snmp_log("unknown packet type %u", h->type); return 0; } //snmp_log("parse_pkt returning parsed length"); return parsed_len; } static uint parse_response(struct snmp_proto *p, byte *res, uint size) { //snmp_log("parse_response() g%u h%u", size, sizeof(struct agentx_header)); if (size < sizeof(struct agentx_response)) return 0; struct agentx_response *r = (void *) res; struct agentx_header *h = &r->h; int byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; uint pkt_size = LOAD_U32(h->payload, byte_ord); //snmp_log("p_res pkt_size %u", pkt_size); if (size < pkt_size + AGENTX_HEADER_SIZE) { //snmp_log("parse_response early return"); return 0; } /*snmp_log(" endianity: %s, session %u, transaction: %u", (h->flags & AGENTX_NETWORK_BYTE_ORDER) ? "big end": "little end", h->session_id, h->transaction_id); */ /*snmp_log(" sid: %3u\ttid: %3u\tpid: %3u", p->session_id, p->transaction_id, p->packet_id); */ //snmp_log(" pkt size %u", h->payload); //snmp_log(" pkt size %u", h->payload); if (r->error == AGENTX_RES_NO_ERROR) do_response(p, res, size); else /* erronous packet should be dropped quietly */ {}//snmp_log("an error occured '%s'", snmp_errs[get_u16(&r->error) - SNMP_ERR_SHIFT]); return pkt_size + AGENTX_HEADER_SIZE; } static void snmp_register_mibs(struct snmp_proto *p) { //snmp_log("snmp_register_mibs()"); snmp_bgp_register(p); /* snmp_ospf_regsiter(p); ... */ //snmp_log("registering all done"); } static void do_response(struct snmp_proto *p, byte *buf, uint size) { //snmp_log("do_response()"); struct agentx_response *r = (void *) buf; struct agentx_header *h = &r->h; int byte_ord = h->flags & AGENTX_NETWORK_BYTE_ORDER; /* TODO make it asynchronous for better speed */ switch (p->state) { case SNMP_INIT: case SNMP_LOCKED: /* silent drop of recieved packet */ break; case SNMP_OPEN: /* copy session info from recieved packet */ p->session_id = LOAD_U32(h->session_id, byte_ord); refresh_ids(p, h); /* the state needs to be changed before sending registering PDUs to * use correct do_response action on them */ snmp_log("changing state to REGISTER"); p->state = SNMP_REGISTER; snmp_register_mibs(p); //snmp_log("do_response state SNMP_INIT register list %u", list_length(&p->register_queue)); break; case SNMP_REGISTER:; //snmp_log("do_response state SNMP_REGISTER register list %u", list_length(&p->register_queue)); byte *pkt = buf; ADVANCE(pkt, size, AGENTX_HEADER_SIZE); uint clen; const char *context; SNMP_LOAD_CONTEXT((struct agentx_header *) buf, pkt, context, clen); if (size < snmp_str_size_from_len(clen)) return; ADVANCE(pkt, size, snmp_str_size_from_len(clen)); const struct oid *oid = (void *) pkt; snmp_register_ack(p, h, snmp_get_mib_class(oid)); if (p->register_to_ack == 0) { snmp_log("changing state to CONNECTED"); p->state = SNMP_CONN; proto_notify_state(&p->p, PS_UP); } break; case SNMP_CONN: break; case SNMP_STOP: break; default: die("unkonwn SNMP state"); } } u8 snmp_get_mib_class(const struct oid *oid) { // TODO check code paths for oid->n_subid < 3 if (oid->prefix != SNMP_MGMT && oid->ids[0] != SNMP_MIB_2) return SNMP_CLASS_INVALID; switch (oid->ids[1]) { case SNMP_BGP4_MIB: return SNMP_CLASS_BGP; default: return SNMP_CLASS_END; } } /* return 0 if the created varbind type is END_OF_MIB_VIEW, 1 otherwise */ static int snmp_get_next2(struct snmp_proto *p, struct oid *o_start, struct oid *o_end, struct snmp_pdu *c) { //snmp_log("get_next2()"); enum snmp_search_res r; //snmp_log("next2() o_end %p", o_end); struct oid *o_copy = search_mib(p, o_start, o_end, NULL, c, &r); //snmp_log("next2()2 o_end %p", o_end); struct agentx_varbind *vb = NULL; switch (r) { case SNMP_SEARCH_NO_OBJECT: case SNMP_SEARCH_NO_INSTANCE: case SNMP_SEARCH_END_OF_VIEW:; uint sz = snmp_varbind_hdr_size_from_oid(o_start); if (c->size < sz) { /* TODO create NULL varbind */ c->error = AGENTX_RES_GEN_ERROR; return 0; } vb = snmp_create_varbind(c->buffer, o_start); vb->type = AGENTX_END_OF_MIB_VIEW; ADVANCE(c->buffer, c->size, snmp_varbind_header_size(vb)); return 0; case SNMP_SEARCH_OK: default: break; } if (o_copy) { /* basicaly snmp_create_varbind(c->buffer, o_copy), but without any copying */ vb = (void *) c->buffer; snmp_mib_fill2(p, o_copy, c); /* override the error for GetNext-PDU object not find */ switch (vb->type) { case AGENTX_NO_SUCH_OBJECT: case AGENTX_NO_SUCH_INSTANCE: case AGENTX_END_OF_MIB_VIEW: vb->type = AGENTX_END_OF_MIB_VIEW; return 0; default: return 1; } } if (c->size < snmp_varbind_hdr_size_from_oid(o_start)) { // TODO FIXME this is a bit tricky as we need to renew all TX buffer pointers snmp_manage_tbuf(p, c); } vb = snmp_create_varbind(c->buffer, o_start); vb->type = AGENTX_END_OF_MIB_VIEW; ADVANCE(c->buffer, c->size, snmp_varbind_header_size(vb)); return 0; } /* returns 0 if the created varbind has type EndOfMibView, 1 otherwise */ static int snmp_get_bulk2(struct snmp_proto *p, struct oid *o_start, struct oid *o_end, struct agentx_bulk_state *state, struct snmp_pdu *c) { struct oid *o_curr = NULL; struct oid *o_predecessor = NULL; enum snmp_search_res r; uint i = 0; do { o_predecessor = o_curr; o_curr = search_mib(p, o_start, o_end, o_curr, c, &r); i++; } while (o_curr && i < state->repetition); // TODO check if the approach below works // it need to generate varbinds that will be only of type EndOfMibView /* Object Identifier fall-backs */ if (!o_curr) o_curr = o_predecessor; if (!o_curr) o_curr = o_start; uint sz = snmp_varbind_hdr_size_from_oid(o_curr); if (c->size < sz) { c->error = AGENTX_RES_GEN_ERROR; return 0; } /* we need the varbind handle to be able to override it's type */ struct agentx_varbind *vb = (void *) c->buffer; vb->type = AGENTX_END_OF_MIB_VIEW; if (r == SNMP_SEARCH_OK) /* the varbind will be recreated inside the snmp_mib_fill2() */ snmp_mib_fill2(p, o_curr, c); else ADVANCE(c->buffer, c->size, snmp_varbind_header_size(vb)); /* override the error for GetBulk-PDU object not found */ switch (vb->type) { case AGENTX_NO_SUCH_OBJECT: case AGENTX_NO_SUCH_INSTANCE: case AGENTX_END_OF_MIB_VIEW: vb->type = AGENTX_END_OF_MIB_VIEW; return 0; default: return 1; } } static inline uint update_packet_size(struct snmp_proto *p, const byte *start, byte *end) { struct agentx_header *h = (void *) p->sock->tpos; size_t s = snmp_pkt_len(start, end); STORE_U32(h->payload, s); return AGENTX_HEADER_SIZE + s; } static inline void response_err_ind(struct agentx_response *res, uint err, uint ind) { STORE_U32(res->error, err); if (err != AGENTX_RES_NO_ERROR && err != AGENTX_RES_PARSE_ERROR) STORE_U32(res->index, ind); else STORE_U32(res->index, 0); } static uint parse_gets2_pdu(struct snmp_proto *p, byte * const pkt_start, uint size, uint *skip) { // TODO checks for c.size underflow //snmp_log("parse_gets2_pdu()"); struct oid *o_start = NULL, *o_end = NULL; byte *pkt = pkt_start; struct agentx_header *h = (void *) pkt; ADVANCE(pkt, size, AGENTX_HEADER_SIZE); uint pkt_size = LOAD_U32(h->payload, h->flags & AGENTX_NETWORK_BYTE_ORDER); sock *sk = p->sock; struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); // TODO better handling of endianness c.byte_ord = 0; /* use little-endian */ uint clen; /* count of characters in context (without last '\0') */ const char *context; /* pointer to RX-buffer context */ /* alters pkt; assign context, clen */ SNMP_LOAD_CONTEXT(h, pkt, context, clen); /* * We need more data; for valid response we need to know full * header picture, including the context octet string */ if (size < clen) { //snmp_log("size %u < %u clen, returning 0", size, clen); goto wait; } /* * It is a malformed packet if the context octet string should be longer than * whole packet. */ if (pkt_size < clen) { /* for malformed packets consume full pkt_size [or size] */ c.error = AGENTX_RES_PARSE_ERROR; goto send; } /* The RFC does not consider the context octet string as a part of a header */ ADVANCE(pkt, pkt_size, clen); size -= clen; /* FIXME add support for c.context hashing c.context = ... */ /* * Get-Bulk processing stops if all the varbind have type END_OF_MIB_VIEW * has_any is true if some varbind has type other than END_OF_MIB_VIEW */ int has_any = 0; struct agentx_bulk_state bulk_state = { }; if (h->type == AGENTX_GET_BULK_PDU) { if (size < sizeof(struct agentx_getbulk)) goto wait; if (pkt_size < sizeof(struct agentx_getbulk)) { c.error = AGENTX_RES_PARSE_ERROR; goto send; } struct agentx_getbulk *bulk_info = (void *) pkt; ADVANCE(pkt, pkt_size, sizeof(struct agentx_getbulk)); bulk_state = (struct agentx_bulk_state) { .getbulk = { .non_repeaters = LOAD_U32(bulk_info->non_repeaters, c.byte_ord), .max_repetitions = LOAD_U32(bulk_info->max_repetitions, c.byte_ord), }, /* In contrast to the RFC, we use 0-based indices. */ .index = 0, .repetition = 0, }; } if (c.size < sizeof(struct agentx_response)) { snmp_manage_tbuf(p, &c); // TODO renew pkt, pkt_start pointers context clen } struct agentx_response *response_header = prepare_response(p, &c); uint ind = 0; while (c.error == AGENTX_RES_NO_ERROR && size > 0 && pkt_size > 0) { //snmp_log("iter %u size %u remaining %u/%u", ind + 1, c.buffer - sk->tpos, size, pkt_size); if (size < snmp_oid_sizeof(0)) goto partial; /* We load search range start OID */ const struct oid *o_start_b = (void *) pkt; uint sz; if ((sz = snmp_oid_size(o_start_b)) > pkt_size) { /* for malformed packets consume full pkt_size [or size] */ c.error = AGENTX_RES_PARSE_ERROR; /* Packet error, inconsistent values */ goto send; } /* * If we already have written same relevant data to the TX buffer, then * we send processed part, otherwise we don't have anything to send and * need to wait for more data to be recieved. */ if (sz > size && ind > 0) { //snmp_log("sz %u > %u size && ind %u > 1", sz, size, ind + 1); goto partial; /* send already processed part */ } else if (sz > size) { //snmp_log("sz %u > %u size; returning 0", sz, size); goto wait; } /* Update buffer pointer and remaining size counters. */ ADVANCE(pkt, pkt_size, sz); size -= sz; /* * We load search range end OID * The exactly same process of sanity checking is preformed while loading * the SearchRange's end OID */ const struct oid *o_end_b = (void *) pkt; if ((sz = snmp_oid_size(o_end_b)) > pkt_size) { c.error = AGENTX_RES_PARSE_ERROR; /* Packet error, inconsistent values */ goto send; } if (sz > size && ind > 0) { //snmp_log("sz2 %u > %u size && ind %u > 1", sz, size, ind + 1); size += snmp_oid_size(o_start_b); goto partial; } else if (sz > size) { //snmp_log("sz2 %u > %u size; returning 0", sz, size); goto wait; } ADVANCE(pkt, pkt_size, sz); size -= sz; // TODO check for oversized OIDs before any allocation (in prefixize()) /* We create copy of OIDs outside of rx-buffer and also prefixize them */ o_start = snmp_prefixize(p, o_start_b, c.byte_ord); o_end = snmp_prefixize(p, o_end_b, c.byte_ord); if (!snmp_is_oid_empty(o_end) && snmp_oid_compare(o_start, o_end) > 0) { //snmp_log("snmp_gets2() o_start does not preceed o_end, returning GEN_ERROR"); c.error = AGENTX_RES_GEN_ERROR; goto send; } /* TODO find mib_class, check if type is GET of GET_NEXT, act acordingly */ switch (h->type) { case AGENTX_GET_PDU: snmp_mib_fill2(p, o_start, &c); break; case AGENTX_GET_NEXT_PDU: snmp_get_next2(p, o_start, o_end, &c); break; case AGENTX_GET_BULK_PDU: if (ind >= bulk_state.getbulk.non_repeaters) bulk_state.repeaters++; // store the o_start, o_end /* The behavior of GetBulk pdu in the first iteration is * identical to GetNext pdu. */ has_any = has_any || snmp_get_next2(p, o_start, o_end, &c); break; default: die("incorrect usage"); } mb_free(o_start); o_start = NULL; mb_free(o_end); o_end = NULL; ind++; } /* while (c.error == AGENTX_RES_NO_ERROR && size > 0) */ if (h->type == AGENTX_GET_BULK_PDU) { for (bulk_state.repetition++; has_any && bulk_state.repetition < bulk_state.getbulk.max_repetitions; bulk_state.repetition++) { // TODO find propper start and end struct oid *start = NULL; struct oid *end = NULL; has_any = 0; for (bulk_state.index = 0; bulk_state.index < bulk_state.repeaters; bulk_state.repeaters++) has_any = has_any || snmp_get_bulk2(p, start, end, &bulk_state, &c); } } send:; //snmp_log("gets2: sending response ..."); struct agentx_response *res = (void *) sk->tbuf; /* We update the error, index pair on the beginning of the packet. */ response_err_ind(res, c.error, ind + 1); uint s = update_packet_size(p, (byte *) response_header, c.buffer); //snmp_log("sending response to Get-PDU, GetNext-PDU or GetBulk-PDU request (size %u)...", s); /* We send the message in TX-buffer. */ sk_send(sk, s); // TODO think through the error state mb_free(o_start); mb_free(o_end); /* number of bytes parsed from RX-buffer */ return pkt - pkt_start; partial: //snmp_log("partial packet"); /* The context octet is not added into response pdu. */ /* need to tweak RX buffer packet size */ //snmp_log("old rx-buffer size %u", h->payload); (c.byte_ord) ? put_u32(&h->payload, pkt_size) : (h->payload = pkt_size); //snmp_log("new rx-buffer size %u", h->payload); *skip = AGENTX_HEADER_SIZE; /* number of bytes parsed from RX-buffer */ return pkt - pkt_start; wait: mb_free(o_start); mb_free(o_end); p->packet_id--; /* we did not use the packetID */ return 0; } void snmp_start_subagent(struct snmp_proto *p) { //snmp_log("snmp_start_subagent() starting subagent"); //snmp_log("DEBUG p->bgp_local_as %u", p->bgp_local_as); /* blank oid means unsupported */ struct oid *blank = snmp_oid_blank(p); open_pdu(p, blank); p->state = SNMP_OPEN; mb_free(blank); } void snmp_stop_subagent(struct snmp_proto *p) { //snmp_log("snmp_stop_subagent() state %d", p->state); if (p->state == SNMP_STOP) close_pdu(p, AGENTX_CLOSE_SHUTDOWN); } static inline int oid_prefix(struct oid *o, u32 *prefix, uint len) { for (uint i = 0; i < len; i++) if (o->ids[i] != prefix[i]) return 0; return 1; } int snmp_rx(sock *sk, uint size) { //snmp_log("snmp_rx() size %u", size); //snmp_dump_packet(sk->tbuf, 64); struct snmp_proto *p = sk->data; byte *pkt_start = sk->rbuf; byte *end = pkt_start + size; //snmp_log("snmp_rx rbuf 0x%p rpos 0x%p", sk->rbuf, sk->rpos); /* * In some cases we want to save the header for future parsing, skip is number * of bytes that should not be overriden by memmove() */ uint skip = 0; //snmp_log("snmp_rx before loop"); while (end >= pkt_start + AGENTX_HEADER_SIZE && skip == 0) { uint parsed_len = parse_pkt(p, pkt_start, size, &skip); /*snmp_log("snmp_rx loop end %p parsed >>> %u <<< curr %p", end, parsed_len, pkt_start + parsed_len); */ //snmp_log("snmp_rx loop2 rpos 0x%p", sk->rpos); if (parsed_len == 0) break; pkt_start += parsed_len; size -= parsed_len; } //snmp_log("snmp_rx loop finished"); /* Incomplete packets */ if (skip != 0 || pkt_start != end) { //snmp_log("snmp_rx memmove"); //snmp_dump_packet(sk->rbuf, SNMP_RX_BUFFER_SIZE); memmove(sk->rbuf + skip, pkt_start, size); //snmp_log("after change; sk->rbuf 0x%p sk->rpos 0x%p", sk->rbuf, sk->rpos); //snmp_dump_packet(sk->rbuf, size + skip); //snmp_log("tweaking rpos 0x%p (size %u skip %u)", sk->rpos, size, skip); sk->rpos = sk->rbuf + size + skip; //snmp_log("snmp_rx returing 0"); return 0; } //snmp_log("snmp_rx returning 1"); return 1; } /* Ping-PDU */ void snmp_ping(struct snmp_proto *p) { sock *sk = p->sock; //snmp_dump_packet(sk->tpos, AGENTX_HEADER_SIZE + 4); //snmp_log("snmp_ping sk->tpos 0x%p", sk->tpos); struct snmp_pdu c = SNMP_PDU_CONTEXT(sk); if (c.size < AGENTX_HEADER_SIZE) snmp_manage_tbuf(p, &c); //snmp_log("ping_pdu()"); struct agentx_header *h = (struct agentx_header *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); SNMP_BLANK_HEADER(h, AGENTX_PING_PDU); p->packet_id++; SNMP_SESSION(h, p); c.byte_ord = AGENTX_NETWORK_BYTE_ORDER; //snmp_log("sending ping packet ... tpos 0x%p", sk->tpos); //snmp_dump_packet(sk->tpos, AGENTX_HEADER_SIZE + 4); /* sending only header -> pkt - buf */ uint s = update_packet_size(p, sk->tpos, c.buffer); sk_send(sk, s); } static inline int is_bgp4_mib_prefix(struct oid *o) { if (o->prefix == SNMP_MGMT && o->ids[0] == SNMP_MIB_2 && o->ids[1] == SNMP_BGP4_MIB) return 1; else return 0; } static inline int has_inet_prefix(struct oid *o) { return (o->n_subid > 4 && o->ids[0] == 1 && o->ids[1] == 3 && o->ids[2] == 6 && o->ids[3] == 1); } /** * snmp_search_check_end_oid - check if oid is before SearchRange end * * @found: best oid found in MIB tree * @bound: upper bound specified in SearchRange * * check if found oid meet the SearchRange upper bound condition in * lexicographical order, returns boolean value */ int snmp_search_check_end_oid(const struct oid *found, const struct oid *bound) { /*snmp_log("upper_bound_check(*f, *b) %p %p is_empty() %d", found, bound, snmp_is_oid_empty(bound)); */ if (snmp_is_oid_empty(bound)) return 1; return (snmp_oid_compare(found, bound) < 0); } /* tree is tree with "internet" prefix .1.3.6.1 working only with o_start, o_end allocated in heap (not from buffer)*/ static struct oid * search_mib(struct snmp_proto *p, const struct oid *o_start, const struct oid *o_end, struct oid *o_curr, struct snmp_pdu *c, enum snmp_search_res *result) { //snmp_log("search_mib()"); ASSUME(o_start != NULL); if (o_curr && (o_curr->n_subid < 2 || o_curr->ids[0] != 1)) return NULL; if (!o_curr && (o_start->n_subid < 2 || o_start->ids[0] != 1)) return NULL; if (!o_curr) { o_curr = snmp_oid_duplicate(p->pool, o_start); // XXX is it right time to free o_start right now (here) ? // not for use in snmp_get_next2() the o_start comes and ends in _gets2_() } const struct oid *blank = NULL; if (!snmp_is_oid_empty(o_end) && snmp_get_mib_class(o_curr) < snmp_get_mib_class(o_end)) { o_end = blank = snmp_oid_blank(p); //snmp_log("search_mib() o_end points to blank oid now %p", o_end); } enum snmp_search_res r; switch (o_curr->ids[1]) { case SNMP_BGP4_MIB: r = snmp_bgp_search2(p, &o_curr, o_end, c->context); if (r == SNMP_SEARCH_OK) { *result = r; break; return o_curr; } // TODO add early break for o_end less then thinkable maximum in each tree /* fall through */ default: if (o_curr) mb_free(o_curr); o_curr = snmp_oid_duplicate(p->pool, o_start); *result = SNMP_SEARCH_END_OF_VIEW; break; } if (o_end == blank) mb_free((void *) blank); return o_curr; } /** * snmp_prefixize - return prefixed oid copy if possible * @proto: allocation pool holder * @oid: from packet loaded object identifier * @byte_ord: byte order of @oid * * Returns prefixed (meaning with nonzero prefix field) oid copy of @oid if * possible, NULL otherwise. Returned pointer is always allocated from @proto's * pool not a pointer to recieve buffer (from which is most likely @oid). */ struct oid * snmp_prefixize(struct snmp_proto *proto, const struct oid *oid, int byte_ord) { ASSERT(oid != NULL); //snmp_log("snmp_prefixize()"); if (snmp_is_oid_empty(oid)) { /* allocate new zeroed oid */ //snmp_log("blank"); return snmp_oid_blank(proto); } /* already in prefixed form */ else if (oid->prefix != 0) { struct oid *new = snmp_oid_duplicate(proto->pool, oid); //snmp_log("already prefixed"); return new; } if (oid->n_subid < 5) return NULL; //{ snmp_log("too small"); return NULL; } for (int i = 0; i < 4; i++) if (LOAD_U32(oid->ids[i], byte_ord) != snmp_internet[i]) return NULL; //{ snmp_log("different prefix"); return NULL; } /* validity check here */ if (oid->ids[4] >= 256) return NULL; //{ snmp_log("outside byte first id"); return NULL; } struct oid *new = mb_alloc(proto->pool, sizeof(struct oid) + MAX((oid->n_subid - 5) * sizeof(u32), 0)); memcpy(new, oid, sizeof(struct oid)); new->n_subid = oid->n_subid - 5; /* validity check before allocation => ids[4] < 256 and can be copied to one byte new->prefix */ new->prefix = oid->ids[4]; memcpy(&new->ids, &oid->ids[5], new->n_subid * sizeof(u32)); return new; } static void snmp_mib_fill2(struct snmp_proto *p, struct oid *oid, struct snmp_pdu *c) { ASSUME(oid != NULL); if (c->size < snmp_varbind_hdr_size_from_oid(oid)) snmp_manage_tbuf(p, c); struct agentx_varbind *vb = snmp_create_varbind(c->buffer, oid); if (oid->n_subid < 2 || (oid->prefix != SNMP_MGMT && oid->ids[0] != SNMP_MIB_2)) { vb->type = AGENTX_NO_SUCH_OBJECT; ADVANCE(c->buffer, c->size, snmp_varbind_header_size(vb)); return; } u8 mib_class = snmp_get_mib_class(oid); switch (mib_class) { case SNMP_CLASS_BGP: snmp_bgp_fill(p, vb, c); break; case SNMP_CLASS_INVALID: case SNMP_CLASS_END: default: break; vb->type = AGENTX_NO_SUCH_OBJECT; ADVANCE(c->buffer, c->size, snmp_varbind_header_size(vb)); } } /** * * Important note: After managing insufficient buffer size all in buffer pointers * are invalidated! */ void snmp_manage_tbuf(struct snmp_proto UNUSED *p, struct snmp_pdu *c) { //snmp_log("snmp_manage_tbuf()"); sock *sk = p->sock; sk_set_tbsize(sk, sk->tbsize + 2048); c->size += 2048; } static struct agentx_response * prepare_response(struct snmp_proto *p, struct snmp_pdu *c) { //snmp_log("prepare_response()"); struct agentx_response *r = (void *) c->buffer; struct agentx_header *h = &r->h; SNMP_BLANK_HEADER(h, AGENTX_RESPONSE_PDU); SNMP_SESSION(h, p); /* protocol doesn't care about subagent upTime */ STORE_U32(r->uptime, 0); STORE_U16(r->error, AGENTX_RES_NO_ERROR); STORE_U16(r->index, 0); ADVANCE(c->buffer, c->size, sizeof(struct agentx_response)); return r; } #undef SNMP_ERR_SHIFT