smux.c

snmp的源代码,已经在我的ubuntu下编译通过

                smux_list_detach(&ActiveRegs, &rptr);
                free(rptr);
            }
            smux_send_rrsp(sd, rpriority);
            return ptr;
        }
        /*
         * search the passive list for this registration 
         */
        rptr =
            smux_find_match(PassiveRegs, sd, oid_name, oid_name_len,
                            priority);
        if (rptr) {
            rpriority = rptr->sr_priority;
            smux_list_detach(&PassiveRegs, &rptr);
            free(rptr);
            smux_send_rrsp(sd, rpriority);
            return ptr;
        }
        /*
         * This peer cannot unregister the tree, it does not
         * * belong to him.  Send him an error.
         */
        smux_send_rrsp(sd, -1);
        return ptr;

    } else if ((operation == SMUX_REGOP_REGISTER_RO) ||
               (operation == SMUX_REGOP_REGISTER_RW)) {
        if (priority < -1) {
            DEBUGMSGTL(("smux",
                        "[smux_rreq_process] peer fd %d invalid priority",
                        sd, priority));
            smux_send_rrsp(sd, -1);
            return NULL;
        }
        if ((nrptr = malloc(sizeof(smux_reg))) == NULL) {
            snmp_log_perror("[smux_rreq_process] malloc");
            smux_send_rrsp(sd, -1);
            return NULL;
        }
        nrptr->sr_priority = priority;
        nrptr->sr_name_len = oid_name_len;
        nrptr->sr_fd = sd;
        for (i = 0; i < (int) oid_name_len; i++)
            nrptr->sr_name[i] = oid_name[i];

        /*
         * See if this tree matches or scopes any of the
         * * active trees.
         */
        for (rptr = ActiveRegs; rptr; rptr = rptr->sr_next) {
            result =
                snmp_oid_compare(oid_name, oid_name_len, rptr->sr_name,
                                 rptr->sr_name_len);
            if (result == 0) {
                if ((oid_name_len == rptr->sr_name_len)) {
                    if ((nrptr->sr_priority == -1)) {
                        nrptr->sr_priority = rptr->sr_priority;
                        do {
                            nrptr->sr_priority++;
                        } while (smux_list_add(&PassiveRegs, nrptr));
                        goto done;
                    } else if (nrptr->sr_priority < rptr->sr_priority) {
                        /*
                         * Better priority.  There are no better
                         * * priorities for this tree in the passive list,
                         * * so replace the current active tree.
                         */
                        smux_replace_active(rptr, nrptr);
                        goto done;
                    } else {
                        /*
                         * Equal or worse priority 
                         */
                        do {
                            nrptr->sr_priority++;
                        } while (smux_list_add(&PassiveRegs, nrptr) == -1);
                        goto done;
                    }
                } else if (oid_name_len < rptr->sr_name_len) {
                    /*
                     * This tree scopes a current active
                     * * tree.  Replace the current active tree.
                     */
                    smux_replace_active(rptr, nrptr);
                    goto done;
                } else {        /* oid_name_len > rptr->sr_name_len */
                    /*
                     * This tree is scoped by a current
                     * * active tree.  
                     */
                    do {
                        nrptr->sr_priority++;
                    } while (smux_list_add(&PassiveRegs, nrptr) == -1);
                    goto done;
                }
            }
        }
        /*
         * We didn't find it in the active list.  Add it at
         * * the requested priority.
         */
        if (nrptr->sr_priority == -1)
            nrptr->sr_priority = 0;
        smux_list_add(&ActiveRegs, nrptr);
        register_mib("smux", (struct variable *)
                     smux_variables, sizeof(struct variable2),
                     1, nrptr->sr_name, nrptr->sr_name_len);
      done:
        smux_send_rrsp(sd, nrptr->sr_priority);
        return ptr;
    } else {
        DEBUGMSGTL(("smux", "[smux_rreq_process] unknown operation\n"));
        smux_send_rrsp(sd, -1);
        return NULL;
    }
}

/*
 * Find the registration with a matching descriptor, OID and priority.  If
 * the priority is -1 then find a registration with a matching descriptor,
 * a matching OID, and the highest priority.
 */
static smux_reg *
smux_find_match(smux_reg * regs, int sd, oid * oid_name,
                size_t oid_name_len, long priority)
{
    smux_reg       *rptr, *bestrptr;

    bestrptr = NULL;
    for (rptr = regs; rptr; rptr = rptr->sr_next) {
        if (rptr->sr_fd != sd)
            continue;
        if (snmp_oid_compare
            (rptr->sr_name, rptr->sr_name_len, oid_name, oid_name_len))
            continue;
        if (rptr->sr_priority == priority)
            return rptr;
        if (priority != -1)
            continue;
        if (bestrptr) {
            if (bestrptr->sr_priority > rptr->sr_priority)
                bestrptr = rptr;
        } else {
            bestrptr = rptr;
        }
    }
    return bestrptr;
}

static void
smux_replace_active(smux_reg * actptr, smux_reg * pasptr)
{
    smux_list_detach(&ActiveRegs, &actptr);
    unregister_mib(actptr->sr_name, actptr->sr_name_len);

    smux_list_detach(&PassiveRegs, &pasptr);
    (void) smux_list_add(&ActiveRegs, pasptr);

    register_mib("smux", (struct variable *) smux_variables,
                 sizeof(struct variable2), 1, pasptr->sr_name,
                 pasptr->sr_name_len);
    free(actptr);
}

static void
smux_list_detach(smux_reg ** head, smux_reg ** m_remove)
{
    smux_reg       *rptr, *rptr2;

    if (*head == NULL) {
        DEBUGMSGTL(("smux", "[smux_list_detach] Ouch!"));
        return;
    }
    if (*head == *m_remove) {
        *m_remove = *head;
        *head = (*head)->sr_next;
        return;
    }
    for (rptr = *head, rptr2 = rptr->sr_next; rptr2;
         rptr2 = rptr2->sr_next, rptr = rptr->sr_next) {
        if (rptr2 == *m_remove) {
            *m_remove = rptr2;
            rptr->sr_next = rptr2->sr_next;
            return;
        }
    }
}

/*
 * Attempt to add a registration (in order) to a list.  If the
 * add fails (because of an existing registration with equal
 * priority) return -1.
 */
static int
smux_list_add(smux_reg ** head, smux_reg * add)
{
    smux_reg       *rptr;
    int             result;

    if (*head == NULL) {
        *head = add;
        (*head)->sr_next = NULL;
        return 0;
    }
    for (rptr = *head; rptr->sr_next; rptr = rptr->sr_next) {
        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)) {
            /*
             * same tree, same pri, nope 
             */
            return -1;
        } 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;
        }
    }
    /*
     * compare the last one 
     */
    if ((snmp_oid_compare(add->sr_name, add->sr_name_len, rptr->sr_name,
                          rptr->sr_name_len) == 0)
        && add->sr_priority == rptr->sr_priority)
        return -1;
    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];
    size_t          length = SMUXMAXPKTSIZE;
    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) {
            snmp_log_perror("[smux_snmp_process] peek failed");
            smux_peer_cleanup(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 
         */
        length = recv(sd, (char *) result, length, 0);
        if (length < 0) {
            snmp_log_perror("[smux_snmp_process] recv failed");
            smux_peer_cleanup(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