smux.c

开发snmp的开发包有两个开放的SNMP开发库

        } else if (result < 0) {
            /*
             * this can only happen if we go before the head 
             */
            add->sr_next = *head;
            *head = add;
            return 0;
        } else if ((snmp_oid_compare(add->sr_name, add->sr_name_len,
                                     rptr->sr_next->sr_name,
                                     rptr->sr_next->sr_name_len)) < 0) {
            /*
             * insert here 
             */
            add->sr_next = rptr->sr_next;
            rptr->sr_next = add;
            return 0;
        }
        prev = rptr;
    }
    /*
     * compare the last one 
     */
    result = snmp_oid_compare(add->sr_name, add->sr_name_len, rptr->sr_name, rptr->sr_name_len);
    if ((result == 0) && add->sr_priority == rptr->sr_priority)
        return -1;
    else  if (result < 0 ) {
        add->sr_next = rptr;
        if ( prev ) {
            prev->sr_next = add;
        } else {
            *head = add;
        }
    } else {
        rptr->sr_next = add;
        add->sr_next = NULL;
    }
    return 0;
}

/*
 * Find a replacement for this registration.  In order
 * of preference:
 *
 *      - Least difference in subtree length
 *      - Best (lowest) priority
 *
 * For example, if we need to replace .1.3.6.1.69, 
 * we would pick .1.3.6.1.69.1 instead of .1.3.6.69.1.1
 *
 */
static smux_reg *
smux_find_replacement(oid * name, size_t name_len)
{
    smux_reg       *rptr, *bestptr;
    int             bestlen, difflen;

    bestlen = SMUX_MAX_PRIORITY;
    bestptr = NULL;

    for (rptr = PassiveRegs; rptr; rptr = rptr->sr_next) {
        if (!snmp_oidtree_compare(rptr->sr_name, rptr->sr_name_len,
                                  name, name_len)) {
            if ((difflen = rptr->sr_name_len - name_len)
                < bestlen) {
                bestlen = difflen;
                bestptr = rptr;
            } else if ((difflen == bestlen) &&
                       (rptr->sr_priority < bestptr->sr_priority))
                bestptr = rptr;
        }
    }
    return bestptr;
}

u_char         *
smux_snmp_process(int exact,
                  oid * objid,
                  size_t * len,
                  size_t * return_len, u_char * return_type, int sd)
{
    u_char          packet[SMUXMAXPKTSIZE], *ptr, result[SMUXMAXPKTSIZE];
    int             length = SMUXMAXPKTSIZE;
    int             tmp_length;
    u_char          type;
    size_t          packet_len;

    /*
     * Send the query to the peer
     */
    smux_reqid++;

    if (exact)
        type = SMUX_GET;
    else
        type = SMUX_GETNEXT;

    if (smux_build(type, smux_reqid, objid, len, 0, NULL,
                   *len, packet, &length) < 0) {
        snmp_log(LOG_ERR, "[smux_snmp_process]: smux_build failed\n");
        return NULL;
    }
    DEBUGMSGTL(("smux", "[smux_snmp_process] oid from build: "));
    DEBUGMSGOID(("smux", objid, *len));
    DEBUGMSG(("smux", "\n"));

    if (send(sd, (char *) packet, length, 0) < 0) {
        snmp_log_perror("[smux_snmp_process] send failed");
    }

    DEBUGMSGTL(("smux",
                "[smux_snmp_process] Sent %d request to peer; %d bytes\n",
                (int) type, length));

    while (1) {
        /*
         * peek at what's received 
         */
        length = recv(sd, (char *) result, SMUXMAXPKTSIZE, MSG_PEEK);
        if (length <= 0) {
            if ((length == -1) && ((errno == EINTR) || (errno == EAGAIN)))
            {
               continue;
            }
            else
            {
               snmp_log_perror("[smux_snmp_process] peek failed");
               smux_peer_cleanup(sd);
               smux_snmp_select_list_del(sd);
               return NULL;
            }
        }

        DEBUGMSGTL(("smux", "[smux_snmp_process] Peeked at %d bytes\n",
                    length));
        DEBUGDUMPSETUP("smux_snmp_process", result, length);

        /*
         * determine if we received more than one packet 
         */
        packet_len = length;
        ptr = asn_parse_header(result, &packet_len, &type);
        packet_len += (ptr - result);
        if (length > packet_len) {
            /*
             * set length to receive only the first packet 
             */
            length = packet_len;
        }

        /*
         * receive the first packet 
         */
        tmp_length = length;
        do
        {
           length = tmp_length;
           length = recv(sd, (char *) result, length, 0);
        }
        while((length == -1) && ((errno == EINTR) || (errno == EAGAIN)));

        if (length <= 0) {
           snmp_log_perror("[smux_snmp_process] recv failed");
           smux_peer_cleanup(sd);
           smux_snmp_select_list_del(sd);
           return NULL;
        }

        DEBUGMSGTL(("smux", "[smux_snmp_process] Received %d bytes\n",
                    length));

        if (result[0] == SMUX_TRAP) {
            DEBUGMSGTL(("smux", "[smux_snmp_process] Received trap\n"));
            snmp_log(LOG_INFO, "Got trap from peer on fd %d\n", sd);
            ptr = asn_parse_header(result, &length, &type);
            smux_trap_process(ptr, &length);

            /*
             * go and peek at received data again 
             */
            /*
             * we could receive the reply or another trap 
             */
        } else {
            /*
             * Interpret reply 
             */
            ptr = smux_parse(result, objid, len, return_len, return_type);
            /*
             * ptr will point to query result or NULL if error 
             */
            break;
        }
    }                           /* while (1) */

    return ptr;
}

static u_char  *
smux_parse(u_char * rsp,
           oid * objid,
           size_t * oidlen, size_t * return_len, u_char * return_type)
{
    size_t          length = SMUXMAXPKTSIZE;
    u_char         *ptr, type;
    long            reqid, errstat, errindex;

    ptr = rsp;

    /*
     * Return pointer to the snmp/smux return value.
     * return_len should contain the number of bytes in the value
     * returned above.
     * objid is the next object, with len for GETNEXT.
     * objid and len are not changed for GET
     */
    ptr = asn_parse_header(ptr, &length, &type);
    if (ptr == NULL || type != SNMP_MSG_RESPONSE)
        return NULL;

    if ((ptr = asn_parse_int(ptr, &length, &type, &reqid,
                             sizeof(reqid))) == NULL) {
        DEBUGMSGTL(("smux", "[smux_parse] parse of reqid failed\n"));
        return NULL;
    }
    if ((ptr = asn_parse_int(ptr, &length, &type, &errstat,
                             sizeof(errstat))) == NULL) {
        DEBUGMSGTL(("smux",
                    "[smux_parse] parse of error status failed\n"));
        return NULL;
    }
    if ((ptr = asn_parse_int(ptr, &length, &type, &errindex,
                             sizeof(errindex))) == NULL) {
        DEBUGMSGTL(("smux", "[smux_parse] parse of error index failed\n"));
        return NULL;
    }

    /*
     * XXX How to send something intelligent back in case of an error 
     */
    DEBUGMSGTL(("smux",
                "[smux_parse] Message type %d, reqid %d, errstat %d, \n\terrindex %d\n",
                (int) type, reqid, errstat, errindex));
    if (ptr == NULL || errstat != SNMP_ERR_NOERROR)
        return NULL;

    /*
     * stuff to return 
     */
    return (smux_parse_var
            (ptr, &length, objid, oidlen, return_len, return_type));
}


static u_char  *
smux_parse_var(u_char * varbind,
               size_t * varbindlength,
               oid * objid,
               size_t * oidlen, size_t * varlength, u_char * vartype)
{
    oid             var_name[MAX_OID_LEN];
    size_t          var_name_len;
    size_t          var_val_len;
    u_char         *var_val;
    size_t          str_len, objid_len;
    size_t          len;
    u_char         *ptr;
    u_char          type;

    ptr = varbind;
    len = *varbindlength;

    DEBUGMSGTL(("smux", "[smux_parse_var] before any processing: "));
    DEBUGMSGOID(("smux", objid, *oidlen));
    DEBUGMSG(("smux", "\n"));

    ptr = asn_parse_header(ptr, &len, &type);
    if (ptr == NULL || type != (ASN_SEQUENCE | ASN_CONSTRUCTOR)) {
        snmp_log(LOG_NOTICE, "[smux_parse_var] Panic: type %d\n",
                 (int) type);
        return NULL;
    }

    /*
     * get hold of the objid and the asn1 coded value 
     */
    var_name_len = MAX_OID_LEN;
    ptr = snmp_parse_var_op(ptr, var_name, &var_name_len, vartype,
                            &var_val_len, &var_val, &len);

    *oidlen = var_name_len;
    memcpy(objid, var_name, var_name_len * sizeof(oid));

    DEBUGMSGTL(("smux", "[smux_parse_var] returning oid : "));
    DEBUGMSGOID(("smux", objid, *oidlen));
    DEBUGMSG(("smux", "\n"));
    /*
     * XXX 
     */
    len = SMUXMAXPKTSIZE;
    DEBUGMSGTL(("smux",
                "[smux_parse_var] Asn coded len of var %d, type %d\n",
                var_val_len, (int) *vartype));

    switch ((short) *vartype) {
    case ASN_INTEGER:
        *varlength = sizeof(long);
        asn_parse_int(var_val, &len, vartype,
                      (long *) &smux_long, *varlength);
        return (u_char *) & smux_long;
        break;
    case ASN_COUNTER:
    case ASN_GAUGE:
    case ASN_TIMETICKS:
    case ASN_UINTEGER:
        *varlength = sizeof(u_long);
        asn_parse_unsigned_int(var_val, &len, vartype,
                               (u_long *) & smux_ulong, *varlength);
        return (u_char *) & smux_ulong;
        break;
    case ASN_COUNTER64:
        *varlength = sizeof(smux_counter64);
        asn_parse_unsigned_int64(var_val, &len, vartype,
                                 (struct counter64 *) &smux_counter64,
                                 *varlength);
        return (u_char *) & smux_counter64;
        break;
    case ASN_IPADDRESS:
        *varlength = 4;
        /*
         * consume the tag and length, but just copy here
         * because we know it is an ip address
         */
        if ((var_val = asn_parse_header(var_val, &len, &type)) == NULL)
            return NULL;
        memcpy((u_char *) & (smux_sa.sin_addr.s_addr), var_val,
               *varlength);
        return (u_char *) & (smux_sa.sin_addr.s_addr);
        break;
    case ASN_OCTET_STR:
        /*
         * XXX 
         */
        if (len == 0)
            return NULL;
        str_len = SMUXMAXSTRLEN;
        asn_parse_string(var_val, &len, vartype, smux_str, &str_len);
        *varlength = str_len;
        return smux_str;
        break;
    case ASN_OPAQUE:
    case ASN_NSAP:
    case ASN_OBJECT_ID:
        objid_len = MAX_OID_LEN;
        asn_parse_objid(var_val, &len, vartype, smux_objid, &objid_len);
        *varlength = objid_len * sizeof(oid);
        return (u_char *) smux_objid;
        break;
    case SNMP_NOSUCHOBJECT:
    case SNMP_NOSUCHINSTANCE:
    case SNMP_ENDOFMIBVIEW:
    case ASN_NULL:
        return NULL;
        break;
    case ASN_BIT_STR:
        /*
         * XXX 
         */
        if (len == 0)
            return NULL;
        str_len = SMUXMAXSTRLEN;
        asn_parse_bitstring(var_val, &len, vartype, smux_str, &str_len);
        *varlength = str_len;
        return (u_char *) smux_str;
        break;
    default:
        snmp_log(LOG_ERR, "bad type returned (%x)\n", *vartype);
        return NULL;
        break;
    }
}

/*
 * XXX This is a bad hack - do not want to muck with ucd code 
 */
static int
smux_build(u_char type,
           long reqid,
           oid * objid,
           size_t * oidlen,
           u_char val_type,
           u_char * val, size_t val_len, u_char * packet, size_t * length)
{
    u_char         *ptr, *save1, *save2;
    size_t          len;
    long            errstat = 0;
    long            errindex = 0;

    /*
     * leave space for Seq and length 
     */
    save1 = packet;
    ptr = packet + 4;
    len = *length - 4;

    /*
     * build reqid 
     */
    ptr = asn_build_int(ptr, &len,
                                 (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                           ASN_INTEGER), &reqid,
                                 sizeof(reqid));
    if (ptr == NULL) {
        return -1;
    }

    /*