smux.c

开发snmp的开发包有两个开放的SNMP开发库

        if (send(rptr->sr_fd, buf, len, 0) < 0) {
            DEBUGMSGTL(("smux", "[var_smux_write] send failed\n"));
            return SNMP_ERR_GENERR;
        }

        while (1) {
            /*
             * peek at what's received 
             */
            if ((len = recv(rptr->sr_fd, buf,
                            SMUXMAXPKTSIZE, MSG_PEEK)) <= 0) {
                if ((len == -1) && ((errno == EINTR) || (errno == EAGAIN)))
                {
                   continue;
                }
                DEBUGMSGTL(("smux",
                            "[var_smux_write] peek failed or timed out\n"));
                /*
                 * do we need to do a peer cleanup in this case?? 
                 */
                smux_peer_cleanup(rptr->sr_fd);
                smux_snmp_select_list_del(rptr->sr_fd);
                return SNMP_ERR_GENERR;
            }

            DEBUGMSGTL(("smux", "[var_smux_write] Peeked at %d bytes\n",
                        len));
            DEBUGDUMPSETUP("var_smux_write", buf, len);

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

            /*
             * receive the first packet 
             */
            tmp_len = len;
            do
            {
               len = tmp_len;
               len = recv(rptr->sr_fd, buf, len, 0);
            }
            while((len == -1) && ((errno == EINTR) || (errno == EAGAIN)));

            if (len <= 0) {
                DEBUGMSGTL(("smux",
                            "[var_smux_write] recv failed or timed out\n"));
                smux_peer_cleanup(rptr->sr_fd);
                smux_snmp_select_list_del(rptr->sr_fd);
                return SNMP_ERR_GENERR;
            }

            DEBUGMSGTL(("smux", "[var_smux_write] Received %d bytes\n",
                        len));

            if (buf[0] == SMUX_TRAP) {
                DEBUGMSGTL(("smux", "[var_smux_write] Received trap\n"));
                snmp_log(LOG_INFO, "Got trap from peer on fd %d\n",
                         rptr->sr_fd);
                ptr = asn_parse_header(buf, &len, &type);
                smux_trap_process(ptr, &len);


                /*
                 * go and peek at received data again 
                 */
                /*
                 * we could receive the reply or another trap 
                 */
            } else {
                ptr = buf;
                ptr = asn_parse_header(ptr, &len, &type);
                if ((ptr == NULL) || type != SNMP_MSG_RESPONSE)
                    return SNMP_ERR_GENERR;

                ptr =
                    asn_parse_int(ptr, &len, &type, &reqid, sizeof(reqid));
                if ((ptr == NULL) || type != ASN_INTEGER)
                    return SNMP_ERR_GENERR;

                ptr =
                    asn_parse_int(ptr, &len, &type, &errsts,
                                  sizeof(errsts));
                if ((ptr == NULL) || type != ASN_INTEGER)
                    return SNMP_ERR_GENERR;

                if (errsts) {
                    DEBUGMSGTL(("smux",
                                "[var_smux_write] errsts returned\n"));
                    return (errsts);
                }

                ptr =
                    asn_parse_int(ptr, &len, &type, &erridx,
                                  sizeof(erridx));
                if ((ptr == NULL) || type != ASN_INTEGER)
                    return SNMP_ERR_GENERR;

                reterr = SNMP_ERR_NOERROR;
                break;
            }
        }                       /* while (1) */
        break;                  /* case Action == RESERVE1 */

    case RESERVE2:
        DEBUGMSGTL(("smux", "[var_smux_write] entering RESERVE2\n"));
        reterr = SNMP_ERR_NOERROR;
        break;                  /* case Action == RESERVE2 */

    case FREE:
    case COMMIT:
        ptr = sout;
        *(ptr++) = (u_char) SMUX_SOUT;
        *(ptr++) = (u_char) 1;
        if (action == FREE) {
            *ptr = (u_char) 1;  /* rollback */
            DEBUGMSGTL(("smux",
                        "[var_smux_write] entering FREE - sending RollBack \n"));
        } else {
            *ptr = (u_char) 0;  /* commit */
            DEBUGMSGTL(("smux",
                        "[var_smux_write] entering FREE - sending Commit \n"));
        }

        if ((send(rptr->sr_fd, sout, 3, 0)) < 0) {
            DEBUGMSGTL(("smux",
                        "[var_smux_write] send rollback/commit failed\n"));
            return SNMP_ERR_GENERR;
        }

        reterr = SNMP_ERR_NOERROR;
        break;                  /* case Action == COMMIT */

    default:
        break;
    }
    return reterr;
}


int
smux_accept(int sd)
{
    u_char          data[SMUXMAXPKTSIZE], *ptr, type;
    struct sockaddr_in in_socket;
    struct timeval  tv;
    int             fail, fd, alen;
    int             length;
    ssize_t         len;

    alen = sizeof(struct sockaddr_in);
    /*
     * this may be too high 
     */
    tv.tv_sec = 5;
    tv.tv_usec = 0;

    /*
     * connection request 
     */
    DEBUGMSGTL(("smux", "[smux_accept] Calling accept()\n"));
    errno = 0;
    if ((fd = accept(sd, (struct sockaddr *) &in_socket, &alen)) < 0) {
        snmp_log_perror("[smux_accept] accept failed");
        return -1;
    } else {
        snmp_log(LOG_INFO, "[smux_accept] accepted fd %d from %s:%d\n",
                 fd, inet_ntoa(in_socket.sin_addr),
                 ntohs(in_socket.sin_port));
        if (npeers + 1 == SMUXMAXPEERS) {
            snmp_log(LOG_ERR,
                     "[smux_accept] denied peer on fd %d, limit %d reached",
                     fd, SMUXMAXPEERS);
            close(sd);
            return -1;
        }

        /*
         * now block for an OpenPDU 
         */
        do
        {
           length = recv(fd, (char *) data, SMUXMAXPKTSIZE, 0);
        }
        while((length == -1) && ((errno == EINTR) || (errno == EAGAIN)));

        if (length <= 0) {
            DEBUGMSGTL(("smux",
                        "[smux_accept] peer on fd %d died or timed out\n",
                        fd));
            close(fd);
            return -1;
        }
        /*
         * try to authorize him 
         */
        ptr = data;
        len = length;
        if ((ptr = asn_parse_header(ptr, &len, &type)) == NULL) {
            smux_send_close(fd, SMUXC_PACKETFORMAT);
            close(fd);
            DEBUGMSGTL(("smux", "[smux_accept] peer on %d sent bad open"));
            return -1;
        } else if (type != (u_char) SMUX_OPEN) {
            smux_send_close(fd, SMUXC_PROTOCOLERROR);
            close(fd);
            DEBUGMSGTL(("smux",
                        "[smux_accept] peer on %d did not send open: (%d)\n",
                        type));
            return -1;
        }
        ptr = smux_open_process(fd, ptr, &len, &fail);
        if (fail) {
            smux_send_close(fd, SMUXC_AUTHENTICATIONFAILURE);
            close(fd);
            DEBUGMSGTL(("smux",
                        "[smux_accept] peer on %d failed authentication\n",
                        fd));
            return -1;
        }

        /*
         * he's OK 
         */
#ifdef SO_RCVTIMEO
        if (setsockopt
            (fd, SOL_SOCKET, SO_RCVTIMEO, (void *) &tv, sizeof(tv)) < 0) {
            DEBUGMSGTL(("smux",
                        "[smux_accept] setsockopt(SO_RCVTIMEO) failed fd %d\n",
                        fd));
            snmp_log_perror("smux_accept: setsockopt SO_RCVTIMEO");
        }
#endif
        npeers++;
        DEBUGMSGTL(("smux", "[smux_accept] fd %d\n", fd));

        /*
         * Process other PDUs already read, e.g. a registerRequest. 
         */
        len = length - (ptr - data);
        if (smux_pdu_process(fd, ptr, len) < 0) {
            /*
             * Easy come, easy go.  Clean-up is already done. 
             */
            return -1;
        }
    }
    return fd;
}

int
smux_process(int fd)
{
    int             length, tmp_length;
    u_char          data[SMUXMAXPKTSIZE];
    u_char          type, *ptr;
    size_t          packet_len;

    do
    {
       length = recv(fd, (char *) data, SMUXMAXPKTSIZE, MSG_PEEK);
    }
    while((length == -1) && ((errno == EINTR) || (errno == EAGAIN)));

    if (length <= 0)
    {
       snmp_log_perror("[smux_process] peek failed");
       smux_peer_cleanup(fd);
       return -1;
    }

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

    tmp_length = length;
    do
    {
       length = tmp_length;
       length = recv(fd, (char *) data, length, 0);
    }
    while((length == -1) && ((errno == EINTR) || (errno == EAGAIN)));

    if (length <= 0) {
        /*
         * the peer went away, close this descriptor 
         * * and delete it from the list
         */
        DEBUGMSGTL(("smux",
                    "[smux_process] peer on fd %d died or timed out\n",
                    fd));
        smux_peer_cleanup(fd);
        return -1;
    }

    return smux_pdu_process(fd, data, length);
}

static int
smux_pdu_process(int fd, u_char * data, size_t length)
{
    int             error;
    size_t          len;
    u_char         *ptr, type;

    DEBUGMSGTL(("smux", "[smux_pdu_process] Processing %d bytes\n",
                length));

    error = 0;
    ptr = data;
    while (error == 0 && ptr != NULL && ptr < data + length) {
        len = length - (ptr - data);
        ptr = asn_parse_header(ptr, &len, &type);
        DEBUGMSGTL(("smux", "[smux_pdu_process] type is %d\n",
                    (int) type));
        switch (type) {
        case SMUX_OPEN:
            smux_send_close(fd, SMUXC_PROTOCOLERROR);
            DEBUGMSGTL(("smux",
                        "[smux_pdu_process] peer on fd %d sent duplicate open?\n",
                        fd));
            smux_peer_cleanup(fd);
            error = -1;
            break;
        case SMUX_CLOSE:
            ptr = smux_close_process(fd, ptr, &len);
            smux_peer_cleanup(fd);
            error = -1;
            break;
        case SMUX_RREQ:
            ptr = smux_rreq_process(fd, ptr, &len);
            break;
        case SMUX_RRSP:
            error = -1;
            smux_send_close(fd, SMUXC_PROTOCOLERROR);
            smux_peer_cleanup(fd);
            DEBUGMSGTL(("smux",
                        "[smux_pdu_process] peer on fd %d sent RRSP!\n",
                        fd));
            break;
        case SMUX_SOUT:
            error = -1;
            smux_send_close(fd, SMUXC_PROTOCOLERROR);
            smux_peer_cleanup(fd);
            DEBUGMSGTL(("smux", "This shouldn't have happened!\n"));
            break;
        case SMUX_TRAP:
            snmp_log(LOG_INFO, "Got trap from peer on fd %d\n", fd);
            if (ptr != 0)
            {
               DEBUGMSGTL(("smux", "[smux_pdu_process] call smux_trap_process.\n"));
               ptr = smux_trap_process(ptr, &len);
            }
            else
            {
               DEBUGMSGTL(("smux", "[smux_pdu_process] smux_trap_process not called: ptr=NULL.\n"));
               DEBUGMSGTL(("smux", "[smux_pdu_process] Error: \n%s\n", snmp_api_errstring(0)));
            }
            /*
             * watch out for close on top of this...should return correct end 
             */
            break;
        default:
            smux_send_close(fd, SMUXC_PACKETFORMAT);
            smux_peer_cleanup(fd);
            DEBUGMSGTL(("smux", "[smux_pdu_process] Wrong type %d\n",
                        (int) type));
            error = -1;
            break;
        }
    }
    return error;
}

static u_char  *
smux_open_process(int fd, u_char * ptr, size_t * len, int *fail)
{
    u_char          type;
    long            version;
    oid             oid_name[MAX_OID_LEN];
    char            passwd[SMUXMAXSTRLEN];
    char            descr[SMUXMAXSTRLEN];
    char            oid_print[SMUXMAXSTRLEN];
    int             i;
    size_t          oid_name_len, string_len;

    if (!(ptr = asn_parse_int(ptr, len, &type, &version, sizeof(version)))) {
        DEBUGMSGTL(("smux", "[smux_open_process] version parse failed\n"));
        *fail = TRUE;
        return ((ptr += *len));
    }
    DEBUGMSGTL(("smux",
                "[smux_open_process] version %d, len %d, type %d\n",
                version, *len, (int) type));

    oid_name_len = MAX_OID_LEN;
    if ((ptr = asn_parse_objid(ptr, len, &type, oid_name,