snmp_api.c

snmp up 2

 * dequeues any pending requests, and closes any sockets allocated for
 * the session.  Returns 0 on error, 1 otherwise.
 */
int
snmp_sess_close(void *sessp)
{
    struct session_list *slp = (struct session_list *) sessp;
    netsnmp_transport *transport;
    struct snmp_internal_session *isp;
    netsnmp_session *sesp = NULL;
    struct snmp_secmod_def *sptr;

    if (slp == NULL) {
        return 0;
    }

    if ((sptr = find_sec_mod(slp->session->securityModel)) != NULL &&
        sptr->session_close != NULL) {
        (*sptr->session_close) (slp->session);
    }

    isp = slp->internal;
    slp->internal = 0;

    if (isp) {
        netsnmp_request_list *rp, *orp;

        SNMP_FREE(isp->packet);

        /*
         * Free each element in the input request list.  
         */
        rp = isp->requests;
        while (rp) {
            orp = rp;
            rp = rp->next_request;
            snmp_free_pdu(orp->pdu);
            free((char *) orp);
        }

        free((char *) isp);
    }

    transport = slp->transport;
    slp->transport = 0;

    if (transport) {
        transport->f_close(transport);
        netsnmp_transport_free(transport);
    }

    sesp = slp->session;
    slp->session = 0;

    /*
     * The following is necessary to avoid memory leakage when closing AgentX 
     * sessions that may have multiple subsessions.  These hang off the main
     * session at ->subsession, and chain through ->next.  
     */

    if (sesp != NULL && sesp->subsession != NULL) {
        netsnmp_session *subsession = sesp->subsession, *tmpsub;

        while (subsession != NULL) {
            DEBUGMSGTL(("snmp_sess_close",
                        "closing session %p, subsession %p\n", sesp,
                        subsession));
            tmpsub = subsession->next;
            snmp_free_session(subsession);
            subsession = tmpsub;
        }
    }

    snmp_free_session(sesp);
    free((char *) slp);
    return 1;
}

int
snmp_close(netsnmp_session * session)
{
    struct session_list *slp = NULL, *oslp = NULL;

    {                           /*MTCRITICAL_RESOURCE */
        snmp_res_lock(MT_LIBRARY_ID, MT_LIB_SESSION);
        if (Sessions && Sessions->session == session) { /* If first entry */
            slp = Sessions;
            Sessions = slp->next;
        } else {
            for (slp = Sessions; slp; slp = slp->next) {
                if (slp->session == session) {
                    if (oslp)   /* if we found entry that points here */
                        oslp->next = slp->next; /* link around this entry */
                    break;
                }
                oslp = slp;
            }
        }
        snmp_res_unlock(MT_LIBRARY_ID, MT_LIB_SESSION);
    }                           /*END MTCRITICAL_RESOURCE */
    if (slp == NULL) {
        return 0;
    }
    return snmp_sess_close((void *) slp);
}

int
snmp_close_sessions(void)
{
    struct session_list *slp;

    snmp_res_lock(MT_LIBRARY_ID, MT_LIB_SESSION);
    while (Sessions) {
        slp = Sessions;
        Sessions = Sessions->next;
        snmp_sess_close((void *) slp);
    }
    snmp_res_unlock(MT_LIBRARY_ID, MT_LIB_SESSION);
    return 1;
}

static int
snmpv3_build_probe_pdu(netsnmp_pdu **pdu)
{
    struct usmUser *user;

    /*
     * create the pdu 
     */
    if (!pdu)
        return -1;
    *pdu = snmp_pdu_create(SNMP_MSG_GET);
    if (!(*pdu))
        return -1;
    (*pdu)->version = SNMP_VERSION_3;
    (*pdu)->securityName = strdup("");
    (*pdu)->securityNameLen = strlen((*pdu)->securityName);
    (*pdu)->securityLevel = SNMP_SEC_LEVEL_NOAUTH;
    (*pdu)->securityModel = SNMP_SEC_MODEL_USM;

    /*
     * create the empty user 
     */
    user = usm_get_user(NULL, 0, (*pdu)->securityName);
    if (user == NULL) {
        user = (struct usmUser *) calloc(1, sizeof(struct usmUser));
        if (user == NULL) {
            snmp_free_pdu(*pdu);
            *pdu = (netsnmp_pdu *) NULL;
            return -1;
        }
        user->name = strdup((*pdu)->securityName);
        user->secName = strdup((*pdu)->securityName);
        user->authProtocolLen = sizeof(usmNoAuthProtocol) / sizeof(oid);
        user->authProtocol =
            snmp_duplicate_objid(usmNoAuthProtocol, user->authProtocolLen);
        user->privProtocolLen = sizeof(usmNoPrivProtocol) / sizeof(oid);
        user->privProtocol =
            snmp_duplicate_objid(usmNoPrivProtocol, user->privProtocolLen);
        usm_add_user(user);
    }
    return 0;
}

static void
snmpv3_calc_msg_flags(int sec_level, int msg_command, u_char * flags)
{
    *flags = 0;
    if (sec_level == SNMP_SEC_LEVEL_AUTHNOPRIV)
        *flags = SNMP_MSG_FLAG_AUTH_BIT;
    else if (sec_level == SNMP_SEC_LEVEL_AUTHPRIV)
        *flags = SNMP_MSG_FLAG_AUTH_BIT | SNMP_MSG_FLAG_PRIV_BIT;

    if (SNMP_CMD_CONFIRMED(msg_command))
        *flags |= SNMP_MSG_FLAG_RPRT_BIT;

    return;
}

static int
snmpv3_verify_msg(netsnmp_request_list *rp, netsnmp_pdu *pdu)
{
    netsnmp_pdu    *rpdu;

    if (!rp || !rp->pdu || !pdu)
        return 0;
    /*
     * Reports don't have to match anything according to the spec 
     */
    if (pdu->command == SNMP_MSG_REPORT)
        return 1;
    rpdu = rp->pdu;
    if (rp->request_id != pdu->reqid || rpdu->reqid != pdu->reqid)
        return 0;
    if (rpdu->version != pdu->version)
        return 0;
    if (rpdu->securityModel != pdu->securityModel)
        return 0;
    if (rpdu->securityLevel != pdu->securityLevel)
        return 0;

    if (rpdu->contextEngineIDLen != pdu->contextEngineIDLen ||
        memcmp(rpdu->contextEngineID, pdu->contextEngineID,
               pdu->contextEngineIDLen))
        return 0;
    if (rpdu->contextNameLen != pdu->contextNameLen ||
        memcmp(rpdu->contextName, pdu->contextName, pdu->contextNameLen))
        return 0;
    if (rpdu->securityEngineIDLen != pdu->securityEngineIDLen ||
        memcmp(rpdu->securityEngineID, pdu->securityEngineID,
               pdu->securityEngineIDLen))
        return 0;
    if (rpdu->securityNameLen != pdu->securityNameLen ||
        memcmp(rpdu->securityName, pdu->securityName,
               pdu->securityNameLen))
        return 0;
    return 1;
}


/*
 * SNMPv3
 * * Takes a session and a pdu and serializes the ASN PDU into the area
 * * pointed to by packet.  out_length is the size of the data area available.
 * * Returns the length of the completed packet in out_length.  If any errors
 * * occur, -1 is returned.  If all goes well, 0 is returned.
 */
static int
snmpv3_build(u_char ** pkt, size_t * pkt_len, size_t * offset,
             netsnmp_session * session, netsnmp_pdu *pdu)
{
    int             ret;

    session->s_snmp_errno = 0;
    session->s_errno = 0;

    /*
     * do validation for PDU types 
     */
    switch (pdu->command) {
    case SNMP_MSG_RESPONSE:
    case SNMP_MSG_TRAP2:
    case SNMP_MSG_REPORT:
        pdu->flags &= (~UCD_MSG_FLAG_EXPECT_RESPONSE);
        /*
         * Fallthrough 
         */
    case SNMP_MSG_GET:
    case SNMP_MSG_GETNEXT:
    case SNMP_MSG_SET:
    case SNMP_MSG_INFORM:
        if (pdu->errstat == SNMP_DEFAULT_ERRSTAT)
            pdu->errstat = 0;
        if (pdu->errindex == SNMP_DEFAULT_ERRINDEX)
            pdu->errindex = 0;
        break;

    case SNMP_MSG_GETBULK:
        if (pdu->max_repetitions < 0) {
            session->s_snmp_errno = SNMPERR_BAD_REPETITIONS;
            return -1;
        }
        if (pdu->non_repeaters < 0) {
            session->s_snmp_errno = SNMPERR_BAD_REPEATERS;
            return -1;
        }
        break;

    case SNMP_MSG_TRAP:
        session->s_snmp_errno = SNMPERR_V1_IN_V2;
        return -1;

    default:
        session->s_snmp_errno = SNMPERR_UNKNOWN_PDU;
        return -1;
    }

    if (pdu->securityEngineIDLen == 0) {
        if (session->securityEngineIDLen) {
            snmpv3_clone_engineID(&pdu->securityEngineID,
                                  &pdu->securityEngineIDLen,
                                  session->securityEngineID,
                                  session->securityEngineIDLen);
        }
    }

    if (pdu->contextEngineIDLen == 0) {
        if (session->contextEngineIDLen) {
            snmpv3_clone_engineID(&pdu->contextEngineID,
                                  &pdu->contextEngineIDLen,
                                  session->contextEngineID,
                                  session->contextEngineIDLen);
        } else if (pdu->securityEngineIDLen) {
            snmpv3_clone_engineID(&pdu->contextEngineID,
                                  &pdu->contextEngineIDLen,
                                  pdu->securityEngineID,
                                  pdu->securityEngineIDLen);
        }
    }

    if (pdu->contextName == NULL) {
        if (!session->contextName) {
            session->s_snmp_errno = SNMPERR_BAD_CONTEXT;
            return -1;
        }
        pdu->contextName = strdup(session->contextName);
        if (pdu->contextName == NULL) {
            session->s_snmp_errno = SNMPERR_GENERR;
            return -1;
        }
        pdu->contextNameLen = session->contextNameLen;
    }
    if (pdu->securityModel == SNMP_DEFAULT_SECMODEL) {
        pdu->securityModel = session->securityModel;
        if (pdu->securityModel == SNMP_DEFAULT_SECMODEL) {
            pdu->securityModel = SNMP_SEC_MODEL_USM;
        }
    }
    if (pdu->securityNameLen == 0 && pdu->securityName == 0) {
        if (session->securityNameLen == 0) {
            session->s_snmp_errno = SNMPERR_BAD_SEC_NAME;
            return -1;
        }
        pdu->securityName = strdup(session->securityName);
        if (pdu->securityName == NULL) {
            session->s_snmp_errno = SNMPERR_GENERR;
            return -1;
        }
        pdu->securityNameLen = session->securityNameLen;
    }
    if (pdu->securityLevel == 0) {
        if (session->securityLevel == 0) {
            session->s_snmp_errno = SNMPERR_BAD_SEC_LEVEL;
            return -1;
        }
        pdu->securityLevel = session->securityLevel;
    }
    DEBUGMSGTL(("snmp_build",
                "Building SNMPv3 message (secName:\"%s\", secLevel:%s)...\n",
                ((session->securityName) ? (char *) session->securityName :
                 ((pdu->securityName) ? (char *) pdu->securityName :
                  "ERROR: undefined")), secLevelName[pdu->securityLevel]));

    DEBUGDUMPSECTION("send", "SNMPv3 Message");
#ifdef USE_REVERSE_ASNENCODING
    if (netsnmp_ds_get_boolean(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_REVERSE_ENCODE)) {
        ret = snmpv3_packet_realloc_rbuild(pkt, pkt_len, offset,
                                           session, pdu, NULL, 0);
    } else {
#endif
        ret = snmpv3_packet_build(session, pdu, *pkt, pkt_len, NULL, 0);
#ifdef USE_REVERSE_ASNENCODING
    }
#endif
    DEBUGINDENTLESS();
    if (-1 != ret) {
        session->s_snmp_errno = ret;
    }

    return ret;

}                               /* end snmpv3_build() */




static u_char  *
snmpv3_header_build(netsnmp_session * session, netsnmp_pdu *pdu,
                    u_char * packet, size_t * out_length,
                    size_t length, u_char ** msg_hdr_e)
{
    u_char         *global_hdr, *global_hdr_e;
    u_char         *cp;
    u_char          msg_flags;
    long            max_size;
    long            sec_model;
    u_char         *pb, *pb0e;

    /*
     * Save current location and build SEQUENCE tag and length placeholder
     * * for SNMP message sequence (actual length inserted later)
     */
    cp = asn_build_sequence(packet, out_length,
                            (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
                            length);
    if (cp == NULL)
        return NULL;
    if (msg_hdr_e != NULL)
        *msg_hdr_e = cp;
    pb0e = cp;


    /*
     * store the version field - msgVersion
     */
    DEBUGDUMPHEADER("send", "SNMP Version Number");
    cp = asn_build_int(cp, out_length,
                       (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                 ASN_INTEGER), (long *) &pdu->version,
                       sizeof(pdu->version));
    DEBUGINDENTLESS();
    if (cp == NULL)
        return NULL;

    global_hdr = cp;
    /*
     * msgGlobalData HeaderData 
     */
    DEBUGDUMPSECTION("send", "msgGlobalData");
    cp = asn_build_sequence(cp, out_length,
                            (u_char) (ASN_SEQUENCE | ASN_CONSTR