/* * Copyright (c) 2004-2005 * Hartmut Brandt. * All rights reserved. * Copyright (c) 2001-2003 * Fraunhofer Institute for Open Communication Systems (FhG Fokus). * All rights reserved. * * Author: Harti Brandt * Kendy Kutzner * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $Begemot: bsnmp/lib/snmpclient.c,v 1.31 2005/05/23 11:10:13 brandt_h Exp $ * * Support functions for SNMP clients. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef HAVE_ERR_H #include #endif #include "asn1.h" #include "snmp.h" #include "snmpclient.h" #include "snmppriv.h" /* ---------------------------------------------------------------------------- */ #define LIST_EMPTY(head) ((head)->lh_first == NULL) #define LIST_FIRST(head) ((head)->lh_first) #define LIST_NEXT(elm, field) ((elm)->field.le_next) #define LIST_FOREACH(var, head, field) \ for ((var) = LIST_FIRST((head)); \ (var); \ (var) = LIST_NEXT((var), field)) /* ---------------------------------------------------------------------------- */ /* global context */ struct snmp_client snmp_client; /* List of all outstanding requests */ struct sent_pdu { int reqid; struct snmp_pdu *pdu; struct timeval time; u_int retrycount; snmp_send_cb_f callback; void *arg; void *timeout_id; LIST_ENTRY(sent_pdu) entries; }; LIST_HEAD(sent_pdu_list, sent_pdu); static struct sent_pdu_list sent_pdus; /* * Set the error string */ static void seterr(struct snmp_client *sc, const char *fmt, ...) { va_list ap; va_start(ap, fmt); vsnprintf(sc->error, sizeof(sc->error), fmt, ap); va_end(ap); } /* * Initialize a client structure */ void snmp_client_init(struct snmp_client *c) { memset(c, 0, sizeof(*c)); c->version = SNMP_V2c; c->trans = SNMP_TRANS_UDP; c->chost = NULL; c->cport = NULL; strcpy(c->read_community, "public"); strcpy(c->write_community, "private"); c->timeout.tv_sec = 3; c->timeout.tv_usec = 0; c->retries = 3; c->dump_pdus = 0; c->txbuflen = c->rxbuflen = 10000; c->fd = -1; c->max_reqid = INT32_MAX; c->min_reqid = 0; c->next_reqid = 0; } /* * Open UDP client socket */ static int open_client_udp(const char *host, const char *port) { int error; char *ptr; struct addrinfo hints, *res0, *res; /* copy host- and portname */ if (snmp_client.chost == NULL) { if ((snmp_client.chost = malloc(1 + sizeof(DEFAULT_HOST))) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } strcpy(snmp_client.chost, DEFAULT_HOST); } if (host != NULL) { if ((ptr = malloc(1 + strlen(host))) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } free(snmp_client.chost); snmp_client.chost = ptr; strcpy(snmp_client.chost, host); } if (snmp_client.cport == NULL) { if ((snmp_client.cport = malloc(1 + sizeof(DEFAULT_PORT))) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } strcpy(snmp_client.cport, DEFAULT_PORT); } if (port != NULL) { if ((ptr = malloc(1 + strlen(port))) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } free(snmp_client.cport); snmp_client.cport = ptr; strcpy(snmp_client.cport, port); } /* open connection */ memset(&hints, 0, sizeof(hints)); hints.ai_flags = AI_CANONNAME; hints.ai_family = AF_INET; hints.ai_socktype = SOCK_DGRAM; hints.ai_protocol = 0; error = getaddrinfo(snmp_client.chost, snmp_client.cport, &hints, &res0); if (error != 0) { seterr(&snmp_client, "%s: %s", snmp_client.chost, gai_strerror(error)); return (-1); } res = res0; for (;;) { if ((snmp_client.fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1) { if ((res = res->ai_next) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); freeaddrinfo(res0); return (-1); } } else if (connect(snmp_client.fd, res->ai_addr, res->ai_addrlen) == -1) { if ((res = res->ai_next) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); freeaddrinfo(res0); return (-1); } } else break; } freeaddrinfo(res0); return (0); } /* * SNMP_OPEN */ int snmp_open(const char *host, const char *port, const char *readcomm, const char *writecomm) { struct timeval tout; /* still open ? */ if (snmp_client.fd != -1) { errno = EBUSY; seterr(&snmp_client, "%s", strerror(errno)); return (-1); } /* copy community strings */ if (readcomm != NULL) { strncpy(snmp_client.read_community, readcomm, sizeof(snmp_client.read_community)); snmp_client.read_community[sizeof(snmp_client.read_community) - 1] = 0; } if (writecomm != NULL) { strncpy(snmp_client.write_community, writecomm, sizeof(snmp_client.write_community)); snmp_client.write_community[sizeof(snmp_client.write_community) - 1] = 0; } switch (snmp_client.trans) { case SNMP_TRANS_UDP: if (open_client_udp(host, port)) return (-1); break; default: seterr(&snmp_client, "bad transport mapping"); return (-1); } tout.tv_sec = 0; tout.tv_usec = 0; if (setsockopt(snmp_client.fd, SOL_SOCKET, SO_SNDTIMEO, &tout, sizeof(struct timeval)) == -1) { seterr(&snmp_client, "%s", strerror(errno)); (void)close(snmp_client.fd); snmp_client.fd = -1; if (snmp_client.local_path[0] != '\0') (void)remove(snmp_client.local_path); return (-1); } /* initialize list */ LIST_INIT(&sent_pdus); return (0); } /* * SNMP_CLOSE * * closes connection to snmp server * - function cannot fail * - clears connection * - clears list of sent pdus * * input: * void * return: * void */ void snmp_close(void) { struct sent_pdu *p1; if (snmp_client.fd != -1) { (void)close(snmp_client.fd); snmp_client.fd = -1; if (snmp_client.local_path[0] != '\0') (void)remove(snmp_client.local_path); } while(!LIST_EMPTY(&sent_pdus)){ p1 = LIST_FIRST(&sent_pdus); if (p1->timeout_id != NULL) snmp_client.timeout_stop(p1->timeout_id); LIST_REMOVE(p1, entries); free(p1); } free(snmp_client.chost); free(snmp_client.cport); } /* * initialize a snmp_pdu structure */ void snmp_pdu_create(struct snmp_pdu *pdu, u_int op) { memset(pdu,0,sizeof(struct snmp_pdu)); if (op == SNMP_PDU_SET) strncpy(pdu->community, snmp_client.write_community, sizeof(pdu->community)); else strncpy(pdu->community, snmp_client.read_community, sizeof(pdu->community)); pdu->community[sizeof(pdu->community) - 1] = 0; pdu->type = op; pdu->version = snmp_client.version; pdu->error_status = 0; pdu->error_index = 0; pdu->nbindings = 0; } /* add pairs of (struct asn_oid, enum snmp_syntax) to an existing pdu */ /* added 10/04/02 by kek: check for MAX_BINDINGS */ int snmp_add_binding(struct snmp_v1_pdu *pdu, ...) { va_list ap; const struct asn_oid *oid; u_int ret; va_start(ap, pdu); ret = pdu->nbindings; while ((oid = va_arg(ap, const struct asn_oid *)) != NULL) { if (pdu->nbindings >= SNMP_MAX_BINDINGS){ va_end(ap); return (-1); } pdu->bindings[pdu->nbindings].var = *oid; pdu->bindings[pdu->nbindings].syntax = va_arg(ap, enum snmp_syntax); pdu->nbindings++; } va_end(ap); return (ret); } static int32_t snmp_next_reqid(struct snmp_client * c) { int32_t i; i = c->next_reqid; if (c->next_reqid >= c->max_reqid) c->next_reqid = c->min_reqid; else c->next_reqid++; return (i); } /* * Send request and return request id. */ static int32_t snmp_send_packet(struct snmp_pdu * pdu) { u_char *buf; struct asn_buf b; ssize_t ret; if ((buf = malloc(snmp_client.txbuflen)) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } pdu->request_id = snmp_next_reqid(&snmp_client); b.asn_ptr = buf; b.asn_len = snmp_client.txbuflen; if (snmp_pdu_encode(pdu, &b)) { seterr(&snmp_client, "%s", strerror(errno)); free(buf); return (-1); } if (snmp_client.dump_pdus) snmp_pdu_dump(pdu); if ((ret = send(snmp_client.fd, buf, b.asn_ptr - buf, 0)) == -1) { seterr(&snmp_client, "%s", strerror(errno)); free(buf); return (-1); } free(buf); return pdu->request_id; } /* * to be called when a snmp request timed out */ static void snmp_timeout(void * listentry_ptr) { struct sent_pdu *listentry = listentry_ptr; #if 0 warnx("snmp request %i timed out, attempt (%i/%i)", listentry->reqid, listentry->retrycount, snmp_client.retries); #endif listentry->retrycount++; if (listentry->retrycount > snmp_client.retries) { /* there is no answer at all */ LIST_REMOVE(listentry, entries); listentry->callback(listentry->pdu, NULL, listentry->arg); free(listentry); } else { /* try again */ /* new request with new request ID */ listentry->reqid = snmp_send_packet(listentry->pdu); listentry->timeout_id = snmp_client.timeout_start(&snmp_client.timeout, snmp_timeout, listentry); } } int32_t snmp_pdu_send(struct snmp_pdu *pdu, snmp_send_cb_f func, void *arg) { struct sent_pdu *listentry; int32_t id; if ((listentry = malloc(sizeof(struct sent_pdu))) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } /* here we really send */ if ((id = snmp_send_packet(pdu)) == -1) { free(listentry); return (-1); } /* add entry to list of sent PDUs */ listentry->pdu = pdu; if (gettimeofday(&listentry->time, NULL) == -1) warn("gettimeofday() failed"); listentry->reqid = pdu->request_id; listentry->callback = func; listentry->arg = arg; listentry->retrycount=1; listentry->timeout_id = snmp_client.timeout_start(&snmp_client.timeout, snmp_timeout, listentry); LIST_INSERT_HEAD(&sent_pdus, listentry, entries); return (id); } /* * Receive an SNMP packet. * * tv controls how we wait for a packet: if tv is a NULL pointer, * the receive blocks forever, if tv points to a structure with all * members 0 the socket is polled, in all other cases tv specifies the * maximum time to wait for a packet. * * Return: * -1 on errors * 0 on timeout * +1 if packet received */ static int snmp_receive_packet(struct snmp_pdu *pdu, struct timeval *tv) { int dopoll, setpoll; int flags; int saved_errno; u_char *buf; int ret; struct asn_buf abuf; int32_t ip; #ifdef bsdi int optlen; #else socklen_t optlen; #endif if ((buf = malloc(snmp_client.rxbuflen)) == NULL) { seterr(&snmp_client, "%s", strerror(errno)); return (-1); } dopoll = setpoll = 0; flags = 0; if (tv != NULL) { /* poll or timeout */ if (tv->tv_sec != 0 || tv->tv_usec != 0) { /* wait with timeout */ if (setsockopt(snmp_client.fd, SOL_SOCKET, SO_RCVTIMEO, tv, sizeof(*tv)) == -1) { seterr(&snmp_client, "setsockopt: %s", strerror(errno)); free(buf); return (-1); } optlen = sizeof(*tv); if (getsockopt(snmp_client.fd, SOL_SOCKET, SO_RCVTIMEO, tv, &optlen) == -1) { seterr(&snmp_client, "getsockopt: %s", strerror(errno)); free(buf); return (-1); } /* at this point tv_sec and tv_usec may appear * as 0. This happens for timeouts lesser than * the clock granularity. The kernel rounds these to * 0 and this would result in a blocking receive. * Instead of an else we check tv_sec and tv_usec * again below and if this rounding happens, * switch to a polling receive. */ } if (tv->tv_sec == 0 && tv->tv_usec == 0) { /* poll */ dopoll = 1; if ((flags = fcntl(snmp_client.fd, F_GETFL, 0)) == -1) { seterr(&snmp_client, "fcntl: %s", strerror(errno)); free(buf); return (-1); } if (!(flags & O_NONBLOCK)) { setpoll = 1; flags |= O_NONBLOCK; if (fcntl(snmp_client.fd, F_SETFL, flags) == -1) { seterr(&snmp_client, "fcntl: %s", strerror(errno)); free(buf); return (-1); } } } } ret = recv(snmp_client.fd, buf, snmp_client.rxbuflen, 0); saved_errno = errno; if (tv != NULL) { if (dopoll) { if (setpoll) { flags &= ~O_NONBLOCK; (void)fcntl(snmp_client.fd, F_SETFL, flags); } } else { tv->tv_sec = 0; tv->tv_usec = 0; (void)setsockopt(snmp_client.fd, SOL_SOCKET, SO_RCVTIMEO, tv, sizeof(*tv)); } } if (ret == -1) { free(buf); if (errno == EAGAIN || errno == EWOULDBLOCK) return (0); seterr(&snmp_client, "recv: %s", strerror(saved_errno)); return (-1); } if (ret == 0) { /* this happens when we have a streaming socket and the * remote side has closed it */ free(buf); seterr(&snmp_client, "recv: socket closed by peer"); errno = EPIPE; return (-1); } abuf.asn_ptr = buf; abuf.asn_len = ret; if (SNMP_CODE_OK != (ret = snmp_pdu_decode(&abuf, pdu, &ip))) { seterr(&snmp_client, "snmp_decode_pdu: failed %d", ret); free(buf); return (-1); } free(buf); if (snmp_client.dump_pdus) snmp_pdu_dump(pdu); return (+1); } static int snmp_deliver_packet(struct snmp_pdu * resp) { struct sent_pdu *listentry; if (resp->type != SNMP_PDU_RESPONSE) { warn("ignoring snmp pdu %u", resp->type); return (-1); } LIST_FOREACH(listentry, &sent_pdus, entries) if (listentry->reqid == resp->request_id) break; if (listentry == NULL) return (-1); LIST_REMOVE(listentry, entries); listentry->callback(listentry->pdu, resp, listentry->arg); snmp_client.timeout_stop(listentry->timeout_id); free(listentry); return (0); } int snmp_receive(int blocking) { int ret; struct timeval tv; struct snmp_pdu * resp; memset(&tv, 0, sizeof(tv)); resp = malloc(sizeof(struct snmp_pdu)); if (resp == NULL) { seterr(&snmp_client, "no memory for returning PDU"); return (-1) ; } if ((ret = snmp_receive_packet(resp, blocking ? NULL : &tv)) <= 0) { free(resp); return (ret); } ret = snmp_deliver_packet(resp); snmp_pdu_free(resp); free(resp); return (ret); } /* * Check a GETNEXT response. Here we have three possible outcomes: -1 an * unexpected error happened. +1 response is ok and is within the table 0 * response is ok, but is behind the table or error is NOSUCHNAME. The req * should point to a template PDU which contains the base OIDs and the * syntaxes. This is really only useful to sweep non-sparse tables. */ static int ok_getnext(const struct snmp_pdu * req, const struct snmp_pdu * resp) { u_int i; if (resp->version != req->version) { warnx("SNMP GETNEXT: response has wrong version"); return (-1); } if (resp->error_status == SNMP_ERR_NOSUCHNAME) return (0); if (resp->error_status != SNMP_ERR_NOERROR) { warnx("SNMP GETNEXT: error %d", resp->error_status); return (-1); } if (resp->nbindings != req->nbindings) { warnx("SNMP GETNEXT: bad number of bindings in response"); return (-1); } for (i = 0; i < req->nbindings; i++) { if (!asn_is_suboid(&req->bindings[i].var, &resp->bindings[i].var)) { if (i != 0) warnx("SNMP GETNEXT: inconsistent table " "response"); return (0); } if (resp->version != SNMP_V1 && resp->bindings[i].syntax == SNMP_SYNTAX_ENDOFMIBVIEW) return (0); if (resp->bindings[i].syntax != req->bindings[i].syntax) { warnx("SNMP GETNEXT: bad syntax in response"); return (0); } } return (1); } /* * Check a GET response. Here we have three possible outcomes: -1 an * unexpected error happened. +1 response is ok. 0 NOSUCHNAME The req should * point to a template PDU which contains the OIDs and the syntaxes. This * is only useful for SNMPv1 or single object GETS. */ static int ok_get(const struct snmp_pdu * req, const struct snmp_pdu * resp) { u_int i; if (resp->version != req->version) { warnx("SNMP GET: response has wrong version"); return (-1); } if (resp->error_status == SNMP_ERR_NOSUCHNAME) return (0); if (resp->error_status != SNMP_ERR_NOERROR) { warnx("SNMP GET: error %d", resp->error_status); return (-1); } if (resp->nbindings != req->nbindings) { warnx("SNMP GET: bad number of bindings in response"); return (-1); } for (i = 0; i < req->nbindings; i++) { if (asn_compare_oid(&req->bindings[i].var, &resp->bindings[i].var) != 0) { warnx("SNMP GET: bad OID in response"); return (-1); } if (snmp_client.version != SNMP_V1 && (resp->bindings[i].syntax == SNMP_SYNTAX_NOSUCHOBJECT || resp->bindings[i].syntax == SNMP_SYNTAX_NOSUCHINSTANCE)) return (0); if (resp->bindings[i].syntax != req->bindings[i].syntax) { warnx("SNMP GET: bad syntax in response"); return (-1); } } return (1); } /* * Check the reponse to a SET PDU. We check: - the error status must be 0 - * the number of bindings must be equal in response and request - the * syntaxes must be the same in response and request - the OIDs must be the * same in response and request */ static int ok_set(const struct snmp_pdu * req, const struct snmp_pdu * resp) { u_int i; if (resp->version != req->version) { warnx("SNMP SET: response has wrong version"); return (-1); } if (resp->error_status == SNMP_ERR_NOSUCHNAME) { warnx("SNMP SET: error %d", resp->error_status); return (0); } if (resp->error_status != SNMP_ERR_NOERROR) { warnx("SNMP SET: error %d", resp->error_status); return (-1); } if (resp->nbindings != req->nbindings) { warnx("SNMP SET: bad number of bindings in response"); return (-1); } for (i = 0; i < req->nbindings; i++) { if (asn_compare_oid(&req->bindings[i].var, &resp->bindings[i].var) != 0) { warnx("SNMP SET: wrong OID in response to SET"); return (-1); } if (resp->bindings[i].syntax != req->bindings[i].syntax) { warnx("SNMP SET: bad syntax in response"); return (-1); } } return (1); } /* * Simple checks for response PDUs against request PDUs. Return values: 1=ok, * 0=nosuchname or similar, -1=failure, -2=no response at all */ int snmp_pdu_check(const struct snmp_pdu *req, const struct snmp_pdu *resp) { if (resp == NULL) return (-2); switch (req->type) { case SNMP_PDU_GET: return (ok_get(req, resp)); case SNMP_PDU_SET: return (ok_set(req, resp)); case SNMP_PDU_GETNEXT: return (ok_getnext(req, resp)); } errx(1, "%s: bad pdu type %i", __func__, req->type); } int snmp_dialog(struct snmp_v1_pdu *req, struct snmp_v1_pdu *resp) { u_int i; int32_t reqid; int ret; struct timeval tv = snmp_client.timeout; struct timeval end; struct snmp_pdu pdu; /* * Make a copy of the request and replace the syntaxes by NULL * if this is a GET,GETNEXT or GETBULK. */ pdu = *req; if (pdu.type == SNMP_PDU_GET || pdu.type == SNMP_PDU_GETNEXT || pdu.type == SNMP_PDU_GETBULK) { for (i = 0; i < pdu.nbindings; i++) pdu.bindings[i].syntax = SNMP_SYNTAX_NULL; } for (i = 0; i <= snmp_client.retries; i++) { (void)gettimeofday(&end, NULL); timeradd(&end, &snmp_client.timeout, &end); if ((reqid = snmp_send_packet(&pdu)) == -1) return (-1); for (;;) { (void)gettimeofday(&tv, NULL); if (timercmp(&end, &tv, <=)) break; timersub(&end, &tv, &tv); if ((ret = snmp_receive_packet(resp, &tv)) == 0) /* timeout */ break; if (ret > 0) { if (reqid == resp->request_id) return (0); /* not for us */ (void)snmp_deliver_packet(resp); } if (ret < 0 && errno == EPIPE) /* stream closed */ return (-1); } } errno = ETIMEDOUT; seterr(&snmp_client, "retry count exceeded"); return (-1); } /* * parse a server specification * * [trans::][community@][server][:port] */ int snmp_parse_server(struct snmp_client *sc, const char *str) { const char *p, *s = str; /* look for a double colon */ for (p = s; *p != '\0'; p++) { if (*p == '\\' && p[1] != '\0') { p++; continue; } if (*p == ':' && p[1] == ':') break; } if (*p != '\0') { if (p > s) { if (p - s == 3 && strncmp(s, "udp", 3) == 0) sc->trans = SNMP_TRANS_UDP; else if (p - s == 6 && strncmp(s, "stream", 6) == 0) sc->trans = SNMP_TRANS_LOC_STREAM; else if (p - s == 5 && strncmp(s, "dgram", 5) == 0) sc->trans = SNMP_TRANS_LOC_DGRAM; else { seterr(sc, "unknown SNMP transport '%.*s'", (int)(p - s), s); return (-1); } } s = p + 2; } /* look for a @ */ for (p = s; *p != '\0'; p++) { if (*p == '\\' && p[1] != '\0') { p++; continue; } if (*p == '@') break; } if (*p != '\0') { if (p - s > SNMP_COMMUNITY_MAXLEN) { seterr(sc, "community string too long"); return (-1); } strncpy(sc->read_community, s, p - s); sc->read_community[p - s] = '\0'; strncpy(sc->write_community, s, p - s); sc->write_community[p - s] = '\0'; s = p + 1; } /* look for a colon */ for (p = s; *p != '\0'; p++) { if (*p == '\\' && p[1] != '\0') { p++; continue; } if (*p == ':') break; } if (*p == ':') { if (p > s) { /* host:port */ free(sc->chost); if ((sc->chost = malloc(p - s + 1)) == NULL) { seterr(sc, "%s", strerror(errno)); return (-1); } strncpy(sc->chost, s, p - s); sc->chost[p - s] = '\0'; } /* port */ free(sc->cport); if ((sc->cport = malloc(strlen(p + 1) + 1)) == NULL) { seterr(sc, "%s", strerror(errno)); return (-1); } strcpy(sc->cport, p + 1); } else if (p > s) { /* host */ free(sc->chost); if ((sc->chost = malloc(strlen(s) + 1)) == NULL) { seterr(sc, "%s", strerror(errno)); return (-1); } strcpy(sc->chost, s); } return (0); }