/* * 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 (be careful in recofing) * 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? * */ /** * * * * * Handling of malformed packet: * * When we find an error in PDU data, we create and send a response with error * defined by the RFC. We await until the packet is send and then we close the * communication socket. This implicitly closes the established session. We * chose this approach because we cannot easily mark the boundary between packets. * When we are reseting the connection, we change the snmp_state to SNMP_RESET. * In SNMP_RESET state we skip all received bytes and wait for snmp_tx_skip() * to be called. The socket's tx_hook is called when the TX-buffer is empty, * meaning our response (agentx-Response-PDU) was send. * * * Partial parsing: * * It may happen that we received only staring part of some PDU from the * communication socket. In most cases, if we recognize this situation we * immediately return, waiting for rest of the PDU to arrive. But for packets * like agentx-Get-PDU, agentx-GetNext-PDU and agentx-GetBulk-PDU it could be * costly as they could hold many VarBinds. We don't want to process these * packet twice because it is a lot work. We parse all VarBinds until we hit the * first incomplete one. The logic behind this is to release as much as * possible space from receive buffer. When we hit the first incomplete VarBind, * we store information about the parsing state and move the header inside the * receive buffer. * * Transmit packet context * */ 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); static void do_response(struct snmp_proto *p, byte *buf); static uint parse_gets_pdu(struct snmp_proto *p, byte *pkt); static struct agentx_response *prepare_response(struct snmp_proto *p, struct snmp_pdu *c); static void response_err_ind(struct snmp_proto *p, struct agentx_response *res, enum agentx_response_errs err, u16 ind); static uint update_packet_size(struct agentx_header *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 inline int snmp_is_active(struct snmp_proto *p) { /* Note: states in which we have opened socket */ return p->state == SNMP_OPEN || p->state == SNMP_REGISTER || p->state == SNMP_CONN; } /* * snmp_header - store packet information into buffer * @h: pointer to created packet header in TX-buffer * @type: created PDU type * @flags: set flags * * Payload length is set to zero legth. Padding is also zeroed. Real stored * flags are dependent on compile-time message byte-order configuration. */ static inline void snmp_header(struct agentx_header *h, enum agentx_pdu_types type, u8 flags) { STORE_U8(h->version, AGENTX_VERSION); STORE_U8(h->type, type); STORE_U8(h->flags, flags | SNMP_ORDER); STORE_U8(h->reserved, 0); STORE_U32(h->payload, 0); } /* * snmp_blank_header - create header with no flags except default * @h: pointer to created header in TX-buffer * @type: create PDU type * * Only flag possibly set may be packet byte order configuration. */ static inline void snmp_blank_header(struct agentx_header *h, enum agentx_pdu_types type) { snmp_header(h, type, (u8) 0); } /* * snmp_register_ok - registration of OID was successful * @p: SNMP protocol instance * @res: header of agentx-Response-PDU * @oid: OID that was successfully registered * @class: MIB subtree of @oid * * Send a notification to MIB (selected by @class) about successful registration * of @oid. */ static void snmp_register_ok(struct snmp_proto *p, struct agentx_response *res, struct oid *oid, u8 UNUSED class) { // todo switch based on oid type snmp_bgp_reg_ok(p, res, oid); } /* * snmp_regsiter_failed - registration of OID failed * @p: SNMP protocol instance * @res: header of agentx-Response-PDU * @oid: OID whose registration failed * @class: MIB subtree of @oid * * Send a notification to MIB (selected by @class) about @oid registration * failure. */ static void snmp_register_failed(struct snmp_proto *p, struct agentx_response *res, struct oid *oid, u8 UNUSED class) { // todo switch based on oid type snmp_bgp_reg_failed(p, res, oid); } /* * snmp_register_ack - handle registration response * @p: SNMP protocol instance * @res: header of agentx-Response-PDU * @class: MIB subtree associated with agentx-Register-PDU */ void snmp_register_ack(struct snmp_proto *p, struct agentx_response *res, u8 class) { struct snmp_registration *reg; WALK_LIST(reg, p->registration_queue) { // todo add support for more mib trees (other than BGP4-MIB) if (snmp_registration_match(reg, &res->h, class)) { struct snmp_registered_oid *ro = \ mb_alloc(p->p.pool, sizeof(struct snmp_registered_oid)); ro->n.prev = ro->n.next = NULL; ro->oid = reg->oid; rem_node(®->n); mb_free(reg); p->registrations_to_ack--; add_tail(&p->bgp_registered, &ro->n); if (res->error == AGENTX_RES_NO_ERROR) snmp_register_ok(p, res, ro->oid, class); else snmp_register_failed(p, res, ro->oid, class); return; } } } /* * snmp_error - handle a malformed packet * @p: SNMP protocol instance * * We wait until all packets are send. Then we close the socket which also * closes the established session on given socket. Finally we try to start a new * session. */ static inline void snmp_error(struct snmp_proto *p) { snmp_reset(p); //snmp_set_state(p, SNMP_RESET); } /* * snmp_simple_response - send an agentx-Response-PDU with no data payload * @p: SNMP protocol instance * @error: response PDU error fields value * @index: response PDU error index field value * * This function assumes that the buffer has enough space to fill in the AgentX * Response PDU. So it is the responsibility of the caller to provide that. */ static void snmp_simple_response(struct snmp_proto *p, enum agentx_response_errs error, u16 index) { sock *sk = p->sock; struct snmp_pdu c; snmp_pdu_context(&c, sk); ASSUME(c.size >= sizeof(struct agentx_response)); struct agentx_response *res = prepare_response(p, &c); response_err_ind(p, res, error, index); sk_send(sk, sizeof(struct agentx_response)); } /* * open_pdu - send an agentx-Open-PDU * @p: SNMP protocol instance * @oid: PDU OID description field value * * Other fields are filled based on @p configuration (timeout, subagent string * description) */ 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(&c, sk); #define TIMEOUT_SIZE sizeof(u32) /* 1B timeout, 3B zero padding */ /* Make sure that we have enough space in TX-buffer */ if (c.size < AGENTX_HEADER_SIZE + TIMEOUT_SIZE + snmp_oid_size(oid) + + snmp_str_size(cf->description)) snmp_manage_tbuf(p, &c); struct agentx_header *h = (void *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); snmp_blank_header(h, AGENTX_OPEN_PDU); 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)); if (p->timeout >= 1 S && p->timeout <= 255 S) /* use p->timeout ceiled up to whole second */ c.buffer = snmp_put_fbyte(c.buffer, (p->timeout % (1 S) == 0) ? p->timeout TO_S : p->timeout TO_S + 1); /* out of range fallbacks */ else if (p->timeout < 1 TO_US) c.buffer = snmp_put_fbyte(c.buffer, (u8) 1); else /* p->timeout > 255 TO_US */ c.buffer = snmp_put_fbyte(c.buffer, (u8) 255); c.buffer = snmp_put_oid(c.buffer, oid); c.buffer = snmp_put_str(c.buffer, cf->description); uint s = update_packet_size(h, c.buffer); sk_send(sk, s); #undef TIMEOUT_SIZE } /* * send_notify_pdu - send an agentx-Notify-PDU * @p: SNMP protocol instance * @oid: PDU notification Varbind name (OID) * @data: PDU Varbind payload * @size - PDU Varbind payload size * @include_uptime: flag enabling inclusion of sysUpTime.0 OID */ 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(&c, 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; /* Make sure that we have enough space in TX-buffer */ if (c.size < sz) snmp_manage_tbuf(p, &c); struct agentx_header *h = (void *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); snmp_blank_header(h, AGENTX_NOTIFY_PDU); p->packet_id++; /* New packet id */ snmp_session(p, h); if (include_uptime) { /* sysUpTime.0 oid */ struct oid uptime_oid = { .n_subid = 4, .prefix = SNMP_MGMT, .include = 0, .reserved = 0, }; /* {mgmt}.mib-2.system.sysUpTime.sysUpTimeInstance (0) */ u32 uptime_ids[] = { 1, 1, 3, 0 }; struct agentx_varbind *vb = snmp_create_varbind(c.buffer, &uptime_oid); for (uint i = 0; i < uptime_oid.n_subid; i++) STORE_U32(vb->name.ids[i], uptime_ids[i]); /* TODO use time from last reconfiguration instead? [config->load_time] */ btime uptime = current_time() - boot_time; snmp_varbind_ticks(vb, c.size, (uptime TO_S) / 100); ASSUME(snmp_test_varbind(vb)); ADVANCE(c.buffer, c.size, snmp_varbind_size_unsafe(vb)); } /* snmpTrapOID.0 oid */ struct oid trap0 = { .n_subid = 6, .prefix = 6, /* snmpV2 */ .include = 0, .reserved = 0, }; /* {snmpV2}.snmpModules.snmpAlarmNextIndex.snmpMIBObjects.snmpTrap.snmpTrapIOD.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_varbind_data(trap_vb), oid); ADVANCE(c.buffer, c.size, snmp_varbind_size_unsafe(trap_vb)); memcpy(c.buffer, data, size); ADVANCE(c.buffer, c.size, size); uint s = update_packet_size(h, c.buffer); sk_send(sk, s); #undef TRAP0_HEADER_SIZE #undef UPTIME_SIZE } /* * un_register_pdu - common functionality for registration PDUs * @p: SNMP protocol instance * @oid: OID to register/unregister * @bound: OIDs registration upper bound * @index: OIDs registration n_subid index * @type: register/unregister PDU type * @is_instance: flag enabling instance registration (used only for register) * @contid: context ID to register in (currently unsupported) * * Both register and unregister PDUs are capable of specifing a number of OIDs * by using pair of index and upper bound. The index (r.range_subid) points into * the OID's n_subid array to ID being threated as variable. The upper bound * (r.upper_bound) determins maximal value for n_subid selected by index. * The index and upper bound are passed as @index, and @bound respectively. * * Zero value for @is_instance means we want to register/unregister OID as a MIB * subtree, for nonzero value we are registering MIB tree an instance (leaf). * * This function in internal and shoulnd't be used outside the SNMP module, * see snmp_register() and snmp_unregister() functions. */ static void un_register_pdu(struct snmp_proto *p, struct oid *oid, u32 bound, uint index, enum agentx_pdu_types type, u8 is_instance, uint UNUSED contid) { /* used for agentx-Register-PDU and agentx-Unregister-PDU */ 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(&c, sk); #define BOUND_SIZE sizeof(u32) /* conditional +4 for upper-bound (optinal field) */ uint sz = AGENTX_HEADER_SIZE + snmp_oid_size(oid) + ((bound > 1) ? BOUND_SIZE : 0); if (c.size < sz) snmp_manage_tbuf(p, &c); struct agentx_header *h = (void *) 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(p, h); struct agentx_un_register_hdr *ur = (struct agentx_un_register_hdr *) c.buffer; /* 0 = do not override session message timeout */ STORE_U8(ur->timeout, 0); /* use selected priority */ STORE_U8(ur->priority, cf->priority); STORE_U8(ur->range_subid, (bound > 1) ? index : 0); STORE_U8(ur->reserved, 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 (bound > 1) { STORE_PTR(c.buffer, bound); ADVANCE(c.buffer, c.size, BOUND_SIZE); } uint s = update_packet_size(h, c.buffer); sk_send(sk, s); #undef BOUND_SIZE } /* * snmp_register - send an agentx-Register-PDU * @p: SNMP protocol instance * @oid: OID to register * @bound: OIDs registration upper bound * @index: OIDs registration n_subid index * @is_instance: flag enabling instance registration * @contid: context ID to register in (currently unsupported) * * For more detailed description see un_register_pdu() function. */ void snmp_register(struct snmp_proto *p, struct oid *oid, u32 bound, uint index, u8 is_instance, uint contid) { un_register_pdu(p, oid, bound, index, AGENTX_REGISTER_PDU, is_instance, contid); } /* * snmp_unregister - send an agentx-Unregister-PDU * @p: SNMP protocol instance * @oid: OID to uregister * @bound: OIDs unregistration upper bound * @index: OIDs unregistration n_subid index * @contid: context ID to unregister from (currently unsupported) * * For more detailed description see un_register_pdu() function. */ void UNUSED snmp_unregister(struct snmp_proto *p, struct oid *oid, u32 bound, uint index, uint contid) { un_register_pdu(p, oid, bound, index, AGENTX_UNREGISTER_PDU, 0, contid); } /* * close_pdu - send an agentx-Close-PDU * @p: SNMP protocol instance * @reason: reason for closure */ static void UNUSED close_pdu(struct snmp_proto *p, enum agentx_close_reasons reason) { sock *sk = p->sock; struct snmp_pdu c; snmp_pdu_context(&c, sk); #define REASON_SIZE sizeof(u32) if (c.size < AGENTX_HEADER_SIZE + REASON_SIZE) snmp_manage_tbuf(p, &c); struct agentx_header *h = (void *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); snmp_blank_header(h, AGENTX_CLOSE_PDU); p->packet_id++; snmp_session(p, h); snmp_put_fbyte(c.buffer, (u8) reason); ADVANCE(c.buffer, c.size, 4); uint s = update_packet_size(h, c.buffer); sk_send(sk, s); #undef REASON_SIZE } /* * parse_close_pdu - parse an agentx-Close-PDU * @p: SNMP protocol instance * @pkt_start: pointer to first byte of PDU * * Return number of bytes parsed from RX-buffer. */ static uint parse_close_pdu(struct snmp_proto *p, byte * const pkt_start) { TRACE(D_PACKETS, "SNMP received agentx-Close-PDU"); byte *pkt = pkt_start; struct agentx_close_pdu *pdu = (void *) pkt; pkt += sizeof(struct agentx_close_pdu); uint pkt_size = pdu->h.payload; if (pkt_size != sizeof(struct agentx_close_pdu)) { TRACE(D_PACKETS, "SNMP malformed agentx-Close-PDU, closing anyway"); snmp_simple_response(p, AGENTX_RES_GEN_ERROR, 0); snmp_set_state(p, SNMP_RESET); return MIN(pkt_size + AGENTX_HEADER_SIZE, sizeof(struct agentx_close_pdu)); } if (!snmp_test_close_reason(pdu->reason)) { TRACE(D_PACKETS, "SNMP invalid close reason %u", pdu->reason); snmp_simple_response(p, AGENTX_RES_GEN_ERROR, 0); snmp_set_state(p, SNMP_RESET); return pkt_size + AGENTX_HEADER_SIZE; } enum agentx_close_reasons reason = (enum agentx_close_reasons) pdu->reason; TRACE(D_PACKETS, "SNMP close reason %u", reason); snmp_simple_response(p, AGENTX_RES_NO_ERROR, 0); snmp_set_state(p, SNMP_RESET); return pkt_size + AGENTX_HEADER_SIZE; } /* * snmp_testset - check possibility of VarBind name and data setting * @p: SNMP protocol instance * @vb: checked VarBind * @oid: pool-allocated prefixed copy of VarBind name * @pkt_size: number of not parsed bytes in processed PDU * * Check done by specialized function for specific MIB subtree whether * the VarBind is valid for set action (changing to current value to value * in VarBind). * * Return 1 if the VarBind setting is possible, 0 otherwise. */ /* MUCH better signature would be static int snmp_testset(struct snmp_proto *p, const struct agentx_varbind *vb, uint pkt_size); */ static int UNUSED snmp_testset(struct snmp_proto *p, const struct agentx_varbind *vb, struct oid *oid, uint pkt_size) { /* Hard-coded no support for writing */ (void)p;(void)vb;(void)oid;(void)pkt_size; snmp_simple_response(p, AGENTX_RES_NOT_WRITABLE, 1); return pkt_size + AGENTX_HEADER_SIZE; #if 0 if (!oid) return 0; switch (oid->ids[1]) { case SNMP_BGP4_MIB: return snmp_bgp_testset(p, vb, oid, pkt_size); default: return 0; } #endif } /* * refresh_ids - Copy current ids from packet to protocol * @p: SNMP protocol instance * @h: PDU header with new transaction_id and packet_id ids. */ static inline void refresh_ids(struct snmp_proto *p, struct agentx_header *h) { p->transaction_id = LOAD_U32(h->transaction_id); p->packet_id = LOAD_U32(h->packet_id); } /* * parse_test_set_pdu - parse an agentx-TestSet-PDU in buffer * @p: SNMP protocol instance * @pkt_start: first byte of test set PDU * @size: number of bytes received from a socket * * Return number of bytes parsed from RX-buffer. */ static inline uint parse_test_set_pdu(struct snmp_proto *p, byte * const pkt_start) { TRACE(D_PACKETS, "SNMP received agentx-TestSet-PDU"); byte *pkt = pkt_start; /* pointer to agentx-TestSet-PDU in RX-buffer */ uint s; /* final packat size */ struct agentx_response *res; /* pointer to reponse in TX-buffer */ struct agentx_header *h = (void *) pkt; pkt += AGENTX_HEADER_SIZE; //uint pkt_size = LOAD_U32(h->payload); sock *sk = p->sock; struct snmp_pdu c; snmp_pdu_context(&c, sk); if (c.size < AGENTX_HEADER_SIZE) snmp_manage_tbuf(p, &c); res = prepare_response(p, &c); /* 0 if there is piece, that we cannot set */ int all_possible = 0; /* the all_possible is currently hard-coded with no support for writing to mib * variables, when implementing the mentioned support, change the initializer * to 1 */ #if 0 // TODO think about future value setting data structure //struct agentx_transaction *tr = mb_alloc(...); void *tr = mb_alloc(p->pool, 16); struct agentx_varbind *vb; uint sz; while (size > 0 && all_possible) { vb = (void *) pkt; sz = snmp_varbind_size(vb, size); if (sz > pkt_size) { c.error = AGENTX_RES_PARSE_ERROR; all_possible = 0; break; } /* Unknown VarBind type check */ if (!snmp_test_varbind(vb)) { c.error = AGENTX_RES_PARSE_ERROR; all_possible = 0; break; } ADVANCE(pkt, size, snmp_varbind_size(vb, size)); // TODO remove the mb_alloc() in prefixize() struct oid *work = snmp_prefixize(p, &vb->name); (void)work; all_possible = snmp_testset(p, vb, tr, work, pkt_size); mb_free(work); } mb_free(tr); #endif s = update_packet_size(h, c.buffer); if (c.error != AGENTX_RES_NO_ERROR) { response_err_ind(p, res, c.error, c.index + 1); snmp_error(p); } else if (all_possible) { response_err_ind(p, res, AGENTX_RES_NO_ERROR, 0); } else { TRACE(D_PACKETS, "SNMP SET action failed (not writable)"); /* This is a recoverable error, we do not need to reset the connection */ //response_err_ind(p, res, AGENTX_RES_RESOURCE_UNAVAILABLE, c.index + 1); response_err_ind(p, res, AGENTX_RES_NOT_WRITABLE, c.index + 1); } sk_send(sk, s); return pkt - pkt_start; } /* * parse_sets_pdu - common functionality for commit set and undo set PDUs * @p: SNMP protocol instance * @pkt_start: pointer to first byte of on of set related PDU * @error: error status to use * * Return number of bytes parsed from RX-buffer. */ static uint parse_sets_pdu(struct snmp_proto *p, byte * const pkt_start, enum agentx_response_errs err) { byte *pkt = pkt_start; struct agentx_header *h = (void *) pkt; pkt += AGENTX_HEADER_SIZE; uint pkt_size = LOAD_U32(h->payload); if (pkt_size != 0) { TRACE(D_PACKETS, "SNMP received malformed set PDU (size)"); snmp_simple_response(p, AGENTX_RES_PARSE_ERROR, 0); // TODO best solution for possibly malicious pkt_size return AGENTX_HEADER_SIZE; // use varbind_list_size()?? } struct snmp_pdu c; snmp_pdu_context(&c, p->sock); if (c.size < sizeof(struct agentx_response)) snmp_manage_tbuf(p, &c); struct agentx_response *r = prepare_response(p, &c); // TODO free resource allocated by parse_test_set_pdu() // TODO do something meaningful //mb_free(tr); c.error = err; TRACE(D_PACKETS, "SNMP received set PDU with error %u", c.error); response_err_ind(p, r, c.error, 0); sk_send(p->sock, AGENTX_HEADER_SIZE); /* Reset the connection on unrecoverable error */ if (c.error != AGENTX_RES_NO_ERROR && c.error != err) snmp_error(p); return pkt - pkt_start; } /* * parse_commit_set_pdu - parse an agentx-CommitSet-PDU * @p: SNMP protocol instance * @pkt: pointer to first byte of PDU inside RX-buffer * * Return number of bytes parsed from RX-buffer. */ static inline uint parse_commit_set_pdu(struct snmp_proto *p, byte *pkt) { // don't forget to free resoures allocated by parse_test_set_pdu() //mb_free(tr); TRACE(D_PACKETS, "SNMP received agentx-CommitSet-PDU"); return parse_sets_pdu(p, pkt, AGENTX_RES_COMMIT_FAILED); } /* * parse_undo_set_pdu - parse an agentx-UndoSet-PDU * @p: SNMP protocol instance * @pkt: pointer to first byte of PDU inside RX-buffer * * Return number of bytes parsed from buffer. */ static inline uint parse_undo_set_pdu(struct snmp_proto *p, byte *pkt) { // don't forget to free resources allocated by parse_test_set_pdu() //mb_free(tr); TRACE(D_PACKETS, "SNMP received agentx-UndoSet-PDU"); return parse_sets_pdu(p, pkt, AGENTX_RES_UNDO_FAILED); } /* * parse_cleanup_set_pdu - parse an agentx-CleanupSet-PDU * @p: SNMP protocol instance * @pkt_start: pointer to first byte of PDU inside RX-buffer * * Return number of bytes parsed from RX-buffer. */ static uint parse_cleanup_set_pdu(struct snmp_proto *p, byte * const pkt_start) { TRACE(D_PACKETS, "SNMP received agentx-CleanupSet-PDU"); (void)p; // TODO don't forget to free resources allocated by parse_test_set_pdu() //mb_free(p->tr); byte *pkt = pkt_start; struct agentx_header *h = (void *) pkt; uint pkt_size = LOAD_U32(h->payload); /* errors are dropped silently, we must not send any agentx-Response-PDU */ if (pkt_size != 0) { // TODO should we free even for malformed packets ?? return AGENTX_HEADER_SIZE; } /* No agentx-Response-PDU is sent in response to agentx-CleanupSet-PDU */ return pkt_size; } /* * space_for_response - check if TX-buffer has space for agentx-Response-PDU * @sk: communication socket owned by SNMP protocol instance * * In some cases we send only the AgentX header but if we want to signal an * error, we need at least space for agentx-Response-PDU. This simplifies the * PDU space requirements testing. */ static inline int space_for_response(const sock *sk) { return ( (uint) (sk->tbuf + sk->tbsize - sk->tpos) >= sizeof(struct agentx_response) ); } /** * parse_pkt - parse received AgentX packet * @p: SNMP protocol instance * @pkt: first byte of PDU inside RX-buffer * @size: number of bytes received from a socket * * Return number of bytes parsed from RX-buffer. */ static uint parse_pkt(struct snmp_proto *p, byte *pkt, uint size) { /* TX-buffer free space */ ASSERT(snmp_is_active(p)); if (!space_for_response(p->sock)) return 0; ASSERT(snmp_is_active(p)); if (size < AGENTX_HEADER_SIZE) return 0; struct agentx_header *h = (void *) pkt; uint pkt_size = LOAD_U32(h->payload); /* RX side checks - too big packet */ if (pkt_size > SNMP_PKT_SIZE_MAX) { snmp_simple_response(p, AGENTX_RES_GEN_ERROR, 0); snmp_reset(p); return 0; // TODO return size?? } /* This guarantees that we have the full packet already received */ if (size < pkt_size + AGENTX_HEADER_SIZE) return 0; /* no bytes parsed */ /* We need to see the responses for PDU such as * agentx-Open-PDU, agentx-Register-PDU, ... * even when we are outside the SNMP_CONNECTED state */ if (h->type == AGENTX_RESPONSE_PDU) return parse_response(p, pkt); ASSERT(snmp_is_active(p)); if (p->state != SNMP_CONN || p->session_id != LOAD_U32(h->session_id)) { struct agentx_header copy = { .session_id = p->session_id, .transaction_id = p->transaction_id, .packet_id = p->packet_id, }; TRACE(D_PACKETS, "SNMP received PDU with unknown session id"); snmp_simple_response(p, AGENTX_RES_NOT_OPEN, 0); p->session_id = copy.session_id; p->transaction_id = copy.transaction_id; p->packet_id = copy.packet_id; log(L_INFO "restoring packet_id %u from temporal state", p->packet_id); /* * After unexpected state, we simply reset the session * only sending the agentx-Response-PDU. */ snmp_reset(p); return 0; // return size?? } ASSERT(snmp_is_active(p)); if (h->flags & AGENTX_NON_DEFAULT_CONTEXT) { // TODO add non-default context support TRACE(D_PACKETS, "SNMP received PDU with unexpected byte order"); snmp_simple_response(p, AGENTX_RES_UNSUPPORTED_CONTEXT, 0); /* We always accept the packet length as correct, up to set limit */ // TODO limit return pkt_size + AGENTX_HEADER_SIZE; } refresh_ids(p, h); switch (h->type) { case AGENTX_GET_PDU: case AGENTX_GET_NEXT_PDU: case AGENTX_GET_BULK_PDU: return parse_gets_pdu(p, pkt); case AGENTX_CLOSE_PDU: return parse_close_pdu(p, pkt); case AGENTX_TEST_SET_PDU: return parse_test_set_pdu(p, pkt); case AGENTX_COMMIT_SET_PDU: return parse_commit_set_pdu(p, pkt); case AGENTX_UNDO_SET_PDU: return parse_undo_set_pdu(p, pkt); case AGENTX_CLEANUP_SET_PDU: return parse_cleanup_set_pdu(p, pkt); default: /* We reset the connection for malformed packet (Unknown packet type) */ TRACE(D_PACKETS, "SNMP received unknown packet with type %u", h->type); snmp_set_state(p, SNMP_RESET); return 0; } } /* * parse_response - parse an agentx-Response-PDU * @p: SNMP protocol instance * @res: pointer of agentx-Response-PDU header in RX-buffer * * Return number of bytes parsed from RX-buffer. */ static uint parse_response(struct snmp_proto *p, byte *res) { struct agentx_response *r = (void *) res; struct agentx_header *h = (void *) r; // todo reject not compiled byte order uint pkt_size = LOAD_U32(h->payload); switch (r->error) { case AGENTX_RES_NO_ERROR: TRACE(D_PACKETS, "SNMP received agetnx-Response-PDU"); do_response(p, res); break; /* Registration errors */ case AGENTX_RES_DUPLICATE_REGISTER: case AGENTX_RES_REQUEST_DENIED: case AGENTX_RES_UNKNOWN_REGISTER: // TODO more direct path to mib-specific code TRACE(D_PACKETS, "SNMP received agentx-Response-PDU with error %u", r->error); byte *pkt = res + sizeof(struct agentx_response); struct oid *failed = (void *) pkt; snmp_register_ack(p, r, snmp_get_mib_class(failed)); break; /* * We found ourselves in an unexpected situation. To enter a well defined * state as well as give the AgentX master agent room to fix the errors on * his side, we perform a hard reset of the connections. */ case AGENTX_RES_NOT_OPEN: case AGENTX_RES_OPEN_FAILED: case AGENTX_RES_UNKNOWN_AGENT_CAPS: case AGENTX_RES_UNSUPPORTED_CONTEXT: /* currently we don't use contexts */ case AGENTX_RES_PARSE_ERROR: case AGENTX_RES_PROCESSING_ERR: default: DBG("SNMP agentx-Response-PDU with unexpected error %u", r->error); snmp_set_state(p, SNMP_DOWN); break; } return pkt_size + AGENTX_HEADER_SIZE; } /* * snmp_register_mibs - register all MIB subtrees * @p: SNMP protocol instance */ void snmp_register_mibs(struct snmp_proto *p) { snmp_bgp_register(p); /* snmp_ospf_regsiter(p); ... */ } /* * do_response - act on agentx-Response-PDU and protocol state * @p: SNMP protocol instance * @pkt: RX-buffer with PDU bytes * * Return number of bytes parsed from RX-buffer. */ static void do_response(struct snmp_proto *p, byte *pkt) { struct agentx_response *r = (void *) pkt; struct agentx_header *h = (void *) r; /* TODO make it asynchronous for better speed */ switch (p->state) { case SNMP_INIT: case SNMP_LOCKED: /* silent drop of received packet */ break; case SNMP_OPEN: /* copy session info from received packet */ p->session_id = LOAD_U32(h->session_id); refresh_ids(p, h); tm_start(p->ping_timer, 0); /* the state needs to be changed before sending registering PDUs to * use correct do_response action on them */ snmp_set_state(p, SNMP_REGISTER); break; case SNMP_REGISTER:; pkt += AGENTX_HEADER_SIZE; const struct oid *oid = (void *) pkt; snmp_register_ack(p, r, snmp_get_mib_class(oid)); if (p->registrations_to_ack == 0) snmp_set_state(p, SNMP_CONN); break; case SNMP_CONN: break; case SNMP_STOP: break; default: die("unkonwn SNMP state"); } } /* * snmp_get_mib_class - classify MIB tree belongings of OID * @oid: OID to be classified based on prefix */ 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; } } /* * snmp_get_next - process single agentx-GetNext-PDU search range * @p: SNMP protocol instance * @o_start: SearchRange start OID * @o_end: SearchRange end OID * @c: transmit PDU context to use * * Return 0 if the created VarBind type is endOfMibView, 1 otherwise. */ static int snmp_get_next2(struct snmp_proto *p, struct oid *o_start, struct oid *o_end, struct snmp_pdu *c) { enum snmp_search_res r; struct oid *o_copy = search_mib(p, o_start, o_end, NULL, c, &r); 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 && c->size >= sizeof(struct agentx_varbind)) { struct agentx_varbind *vb_null = snmp_create_varbind_null(c->buffer); ADVANCE(c->buffer, c->size, snmp_varbind_size_unsafe(vb_null)); c->error = AGENTX_RES_GEN_ERROR; return 0; } else if (c->size < sz) { 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)) 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; } /* * snmp_get_bulk - process one iteration of get bulk PDU * @p: SNMP protocol instance * @o_start: SearchRange start OID * @o_end: SearchRange end OID * @state: state of get bulk PDU processing * @c: transmit PDU context to use * * Return 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; } } /* * update_packet_size - set PDU size * @start - pointer to PDU data start (excluding header size) * @end - pointer after the last PDU byte * * Return number of bytes in TX-buffer (including header size). */ static inline uint update_packet_size(struct agentx_header *start, byte *end) { uint s = snmp_pkt_len((byte *) start, end); STORE_U32(start->payload, s); return AGENTX_HEADER_SIZE + s; } /* * response_err_ind - update response error and index * @p: SNMP protocol instance * @res: response PDU header * @err: error status * @ind: index of error, ignored for noAgentXError * * Update agentx-Response-PDU header fields res.error and it's res.index. If the * error is not noError, also set the corrent response PDU payload size. */ static inline void response_err_ind(struct snmp_proto *p, struct agentx_response *res, enum agentx_response_errs err, u16 ind) { STORE_U32(res->error, (u16) err); // TODO deal with auto-incrementing of snmp_pdu context c.ind if (err != AGENTX_RES_NO_ERROR && err != AGENTX_RES_GEN_ERROR) { TRACE(D_PACKETS, "Last PDU resulted in error %u", err); STORE_U32(res->index, ind); TRACE(D_PACKETS, "Storing packet size %u (was %u)", sizeof(struct agentx_response) - AGENTX_HEADER_SIZE, LOAD_U32(res->h.payload)); STORE_U32(res->h.payload, sizeof(struct agentx_response) - AGENTX_HEADER_SIZE); } else if (err == AGENTX_RES_GEN_ERROR) { TRACE(D_PACKETS, "Last PDU resulted in error %u", err); STORE_U32(res->index, 0); TRACE(D_PACKETS, "Storing packet size %u (was %u)", sizeof(struct agentx_response) - AGENTX_HEADER_SIZE, LOAD_U32(res->h.payload)); STORE_U32(res->h.payload, sizeof(struct agentx_response) - AGENTX_HEADER_SIZE); } else STORE_U32(res->index, 0); } static uint parse_gets_error(struct snmp_proto *p, struct snmp_pdu *c, uint len) { TRACE(D_PACKETS, "SNMP error %u while parsing gets PDU", c->error); if (c->index > UINT16_MAX) snmp_simple_response(p, AGENTX_RES_GEN_ERROR, UINT16_MAX); else snmp_simple_response(p, AGENTX_RES_GEN_ERROR, c->index); return len + AGENTX_HEADER_SIZE; } /* * parse_gets_pdu - parse received gets PDUs * @p: SNMP protocol instance * @pkt_start: pointer to first byte of received PDU * * Gets PDUs are agentx-Get-PDU, agentx-GetNext-PDU, agentx-GetBulk-PDU. * * Return number of bytes parsed from RX-buffer */ static uint parse_gets_pdu(struct snmp_proto *p, byte * const pkt_start) { // TODO checks for c.size underflow struct oid *o_start = NULL, *o_end = NULL; byte *pkt = pkt_start; struct agentx_header *h = (void *) pkt; pkt += AGENTX_HEADER_SIZE; uint pkt_size = LOAD_U32(h->payload); sock *sk = p->sock; struct snmp_pdu c; snmp_pdu_context(&c, sk); /* * 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 (pkt_size < sizeof(struct agentx_getbulk)) { c.error = AGENTX_RES_PARSE_ERROR; c.index = 0; return parse_gets_error(p, &c, pkt_size); } 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), .max_repetitions = LOAD_U32(bulk_info->max_repetitions), }, /* In contrast to the RFC, we use 0-based indices. */ .index = 0, .repetition = 0, }; } struct agentx_response *response_header = prepare_response(p, &c); while (c.error == AGENTX_RES_NO_ERROR && pkt_size > 0) { /* 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) { c.error = AGENTX_RES_PARSE_ERROR; return parse_gets_error(p, &c, pkt_size); } /* Update buffer pointer and remaining size counters. */ ADVANCE(pkt, pkt_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; return parse_gets_error(p, &c, pkt_size); } ADVANCE(pkt, pkt_size, sz); /* We don't too to check for oversided OID because the PDU has 8k size limit */ /* We create copy of OIDs outside of rx-buffer and also prefixize them */ o_start = snmp_prefixize(p, o_start_b); o_end = snmp_prefixize(p, o_end_b); ASSERT(o_start); ASSERT(o_end); if (!snmp_is_oid_empty(o_end) && snmp_oid_compare(o_start, o_end) > 0) { c.error = AGENTX_RES_GEN_ERROR; mb_free(o_start); mb_free(o_end); return parse_gets_error(p, &c, pkt_size); } /* TODO find mib_class, check if type is GET of GET_NEXT, act accordingly */ 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 (c.index >= 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 = snmp_get_next2(p, o_start, o_end, &c) | has_any; break; default: die("incorrect usage"); } mb_free(o_start); o_start = NULL; mb_free(o_end); o_end = NULL; c.index++; } /* 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 = snmp_get_bulk2(p, start, end, &bulk_state, &c) || has_any; } } /* We update the error, index pair on the beginning of the packet. */ response_err_ind(p, response_header, c.error, c.index + 1); uint s = update_packet_size(&response_header->h, c.buffer); /* We send the message in TX-buffer. */ sk_send(sk, s); // TODO think through the error state /* number of bytes parsed from RX-buffer */ mb_free(o_start); mb_free(o_end); return pkt - pkt_start; } /* * snmp_start_subagent - send session open request * @p: SNMP protocol instance * * Send agentx-Open-PDU with configured OID and string description. */ void snmp_start_subagent(struct snmp_proto *p) { ASSUME(p->state == SNMP_OPEN); /* blank oid means unsupported */ struct oid *blank = snmp_oid_blank(p); open_pdu(p, blank); mb_free(blank); } /* * snmp_stop_subagent - close established session * @p: SNMP protocol instance * * Send agentx-Close-PDU on established session. */ void snmp_stop_subagent(struct snmp_proto *p) { tm_stop(p->ping_timer); /* This cause problems with net-snmp daemon witch halts afterwards */ //close_pdu(p, AGENTX_CLOSE_SHUTDOWN); } /* * snmp_rx - handle received PDUs in RX-buffer in normal operation * @sk: communication socket * @size: number of bytes received */ int snmp_rx(sock *sk, uint size) { log(L_INFO "snmp_rx with size %u", size); struct snmp_proto *p = sk->data; byte *pkt_start = sk->rbuf; byte *end = pkt_start + size; while (snmp_is_active(p) && end >= pkt_start + AGENTX_HEADER_SIZE) { uint parsed_len = parse_pkt(p, pkt_start, size); if (parsed_len == 0) break; pkt_start += parsed_len; size -= parsed_len; } /* We flush the RX-buffer on errors */ if (!snmp_is_active(p) || pkt_start == end) return 1; /* The whole RX-buffer was consumed */ /* Incomplete packet parsing */ memmove(sk->rbuf, pkt_start, size); sk->rpos = sk->rbuf + size; return 0; } /* * snmp_tx - handle TX-buffer * @sk: communication socket owned by SNMP protocol instance * * The snmp_tx hook is used only to delay the processing in cases we don't have * enough space in TX-buffer. Therefore we simply call the snmp_rx hook. */ void snmp_tx(sock *sk) { log(L_INFO "snmp_tx()"); /* We still not have enough space */ if (!space_for_response(sk)) return; /* There is nothing to process, no bytes in RX-buffer */ if (sk_tx_buffer_empty(sk)) return; snmp_rx(sk, sk->tpos - sk->tbuf); } /* * snmp_ping - send an agentx-Ping-PDU * @p: SNMP protocol instance */ void snmp_ping(struct snmp_proto *p) { if (!snmp_is_active(p)) return; sock *sk = p->sock; struct snmp_pdu c; snmp_pdu_context(&c, sk); if (c.size < AGENTX_HEADER_SIZE) return; int unused = sk->tbuf + sk->tbsize - c.buffer; if (unused < AGENTX_HEADER_SIZE) return; //struct agentx_header *h = (void *) sk->tpos; struct agentx_header *h = (void *) c.buffer; ADVANCE(c.buffer, c.size, AGENTX_HEADER_SIZE); snmp_blank_header(h, AGENTX_PING_PDU); p->packet_id++; log(L_INFO "incrementing packet_id to %u (ping)", p->packet_id); snmp_session(p, h); /* sending only header */ uint s = update_packet_size(h, (byte *) h + AGENTX_HEADER_SIZE); sk_send(sk, s); } /** * 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) { if (snmp_is_oid_empty(bound)) return 1; return (snmp_oid_compare(found, bound) < 0); } /* * search_mib - search for successor of given OID * @p: SNMP protocol instance * @o_start: search starting OID * @o_end: search ending OID * @o_curr: current OID inside @o_start, @o_end interval * @c: transmit PDU context to use * @result: search result state * * Perform a search in MIB tree in SearchRange from @o_start to @o_end. * If the @o_start has set include the search is inclusive, the @o_end has * always the include flag cleared. For agentx-GetNext-PDU, the o_curr is always * NULL, for agentx-GetBulk-PDU it could have non-NULL value. In such case the * @o_curr effectively replaces the role of @o_start. It is mandatory to pass * @o_start and @o_end only allocated from @p protocol's memory pool. * * Return found OID or NULL. */ /* 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 UNUSED *c, enum snmp_search_res *result) { // TODO flip retval and result (maybe on more place to stay consistent) // TODO remove unnecessary o_start/o_curr duplication 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 _gets_() } 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); } enum snmp_search_res r; switch (o_curr->ids[1]) { case SNMP_BGP4_MIB: r = snmp_bgp_search(p, &o_curr, o_end, 0); 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) /* cast drops const qualifier */ mb_free((struct oid *)blank); return o_curr; } /** * snmp_prefixize - return prefixed OID copy if possible * @proto: allocation pool holder * @oid: from packet loaded object identifier * * Return 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 RX-buffer (from which is most likely @oid). */ struct oid * snmp_prefixize(struct snmp_proto *proto, const struct oid *oid) { ASSUME(oid != NULL); if (snmp_is_oid_empty(oid)) { /* allocate new zeroed oid */ return snmp_oid_blank(proto); } /* already in prefixed form */ else if (oid->prefix != 0) { struct oid *new = snmp_oid_duplicate(proto->pool, oid); return new; } if (oid->n_subid < 5) return NULL; for (int i = 0; i < 4; i++) if (LOAD_U32(oid->ids[i]) != snmp_internet[i]) return NULL; /* validity check here */ if (oid->ids[4] >= 256) 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; } /* * snmp_mib_fill - append a AgentX VarBind to PDU * @p: SNMP protocol instance * @oid: OID to use as VarBind v.name * @c: transmit PDU context to use * * Append new AgentX VarBind at the end of created PDU. The content (v.data) * is handled in function specialized for given MIB subtree. The binding is * created only if the v.name matches some variable name precisely. */ 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)); } } /* * snmp_manage_tbuf - handle situation with too short transmit buffer * @p: SNMP protocol instance * @c: transmit packet context to use * * 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) { sock *sk = p->sock; log(L_INFO "snmp_manage_tbuf()"); sk_set_tbsize(sk, sk->tbsize + 2048); c->size += 2048; } /* * prepare_response - fill buffer with AgentX PDU header * @p: SNMP protocol instance * @c: transmit PDU context to use * * Prepare known parts of AgentX packet header into the TX-buffer held by @c. */ static struct agentx_response * prepare_response(struct snmp_proto *p, struct snmp_pdu *c) { struct agentx_response *r = (void *) c->buffer; struct agentx_header *h = &r->h; snmp_blank_header(h, AGENTX_RESPONSE_PDU); snmp_session(p, h); /* 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; }