example.c

snmp的源代码,已经在我的ubuntu下编译通过

    case EXAMPLETIMETICKS:
        /*
         * Here both assumptions are correct,
         *  so we just need to set up the answer.
         */
        long_ret = 363136200;   /* 42 days, 42 minutes and 42.0 seconds */
        return (u_char *) & long_ret;

    case EXAMPLEIPADDRESS:
        /*
         * ipaddresses get returned as a long.  ick 
         */
        /*
         * we're returning 127.0.0.1 
         */
        long_ret = ntohl(INADDR_LOOPBACK);
        return (u_char *) & long_ret;

    case EXAMPLECOUNTER:
        long_ret = 42;
        return (u_char *) & long_ret;

    case EXAMPLEGAUGE:
        long_ret = 42;          /* Do we detect a theme running through these answers? */
        return (u_char *) & long_ret;

    case EXAMPLETRIGGERTRAP:
        /*
         * This object is essentially "write-only".
         * It only exists to trigger the sending of a trap.
         * Reading it will always return 0.
         */
        long_ret = 0;
        *write_method = write_exampletrap;
        return (u_char *) & long_ret;

    case EXAMPLETRIGGERTRAP2:
        /*
         * This object is essentially "write-only".
         * It only exists to trigger the sending of a v2 trap.
         * Reading it will always return 0.
         */
        long_ret = 0;
        *write_method = write_exampletrap2;
        return (u_char *) & long_ret;

    default:
        /*
         *  This will only be triggered if there's a problem with
         *   the coding of the module.  SNMP requests that reference
         *   a non-existant OID will be directed elsewhere.
         *  If this branch is reached, log an error, so that
         *   the problem can be investigated.
         */
        DEBUGMSGTL(("snmpd", "unknown sub-id %d in examples/var_example\n",
                    vp->magic));
    }
    /*
     * If we fall through to here, fail by returning NULL.
     * This is essentially a continuation of the 'default' case above.
     */
    return NULL;
}

        /*********************
	 *
	 *  Writeable object SET handling routines
	 *
	 *********************/
int
write_exampleint(int action,
                 u_char * var_val,
                 u_char var_val_type,
                 size_t var_val_len,
                 u_char * statP, oid * name, size_t name_len)
{
    /*
     * Define an arbitrary maximum permissible value 
     */
#define MAX_EXAMPLE_INT	100
    static long     intval;
    static long     old_intval;

    switch (action) {
    case RESERVE1:
        /*
         *  Check that the value being set is acceptable
         */
        if (var_val_type != ASN_INTEGER) {
            DEBUGMSGTL(("example", "%x not integer type", var_val_type));
            return SNMP_ERR_WRONGTYPE;
        }
        if (var_val_len > sizeof(long)) {
            DEBUGMSGTL(("example", "wrong length %x", var_val_len));
            return SNMP_ERR_WRONGLENGTH;
        }

        intval = *((long *) var_val);
        if (intval > MAX_EXAMPLE_INT) {
            DEBUGMSGTL(("example", "wrong value %x", intval));
            return SNMP_ERR_WRONGVALUE;
        }
        break;

    case RESERVE2:
        /*
         *  This is conventially where any necesary
         *   resources are allocated (e.g. calls to malloc)
         *  Here, we are using static variables
         *   so don't need to worry about this.
         */
        break;

    case FREE:
        /*
         *  This is where any of the above resources
         *   are freed again (because one of the other
         *   values being SET failed for some reason).
         *  Again, since we are using static variables
         *   we don't need to worry about this either.
         */
        break;

    case ACTION:
        /*
         *  Set the variable as requested.
         *   Note that this may need to be reversed,
         *   so save any information needed to do this.
         */
        old_intval = example_int;
        example_int = intval;
        break;

    case UNDO:
        /*
         *  Something failed, so re-set the
         *   variable to its previous value
         *  (and free any allocated resources).
         */
        example_int = old_intval;
        break;

    case COMMIT:
        /*
         *  Everything worked, so we can discard any
         *   saved information, and make the change
         *   permanent (e.g. write to the config file).
         *  We also free any allocated resources.
         *
         *  In this case, there's nothing to do.
         */
        break;

    }
    return SNMP_ERR_NOERROR;
}

int
write_exampletrap(int action,
                  u_char * var_val,
                  u_char var_val_type,
                  size_t var_val_len,
                  u_char * statP, oid * name, size_t name_len)
{
    long            intval;

    DEBUGMSGTL(("example", "write_exampletrap entered: action=%d\n",
                action));
    switch (action) {
    case RESERVE1:
        /*
         *  The only acceptable value is the integer 1
         */
        if (var_val_type != ASN_INTEGER) {
            DEBUGMSGTL(("example", "%x not integer type", var_val_type));
            return SNMP_ERR_WRONGTYPE;
        }
        if (var_val_len > sizeof(long)) {
            DEBUGMSGTL(("example", "wrong length %x", var_val_len));
            return SNMP_ERR_WRONGLENGTH;
        }

        intval = *((long *) var_val);
        if (intval != 1) {
            DEBUGMSGTL(("example", "wrong value %x", intval));
            return SNMP_ERR_WRONGVALUE;
        }
        break;

    case RESERVE2:
        /*
         * No resources are required.... 
         */
        break;

    case FREE:
        /*
         * ... so no resources need be freed 
         */
        break;

    case ACTION:
        /*
         *  Having triggered the sending of a trap,
         *   it would be impossible to revoke this,
         *   so we can't actually invoke the action here.
         */
        break;

    case UNDO:
        /*
         * We haven't done anything yet,
         * so there's nothing to undo 
         */
        break;

    case COMMIT:
        /*
         *  Everything else worked, so it's now safe
         *   to trigger the trap.
         *  Note that this is *only* acceptable since
         *   the trap sending routines are "failsafe".
         *  (In fact, they can fail, but they return no
         *   indication of this, which is the next best thing!)
         */
        DEBUGMSGTL(("example", "write_exampletrap sending the trap\n",
                    action));
        send_easy_trap(SNMP_TRAP_ENTERPRISESPECIFIC, 99);
        DEBUGMSGTL(("example", "write_exampletrap trap sent\n", action));
        break;

    }
    return SNMP_ERR_NOERROR;
}

/*
 * this documents how to send a SNMPv2 (and higher) trap via the
 * send_v2trap() API.
 * 
 * Coding SNMP-v2 Trap:
 * 
 * The SNMPv2-Trap PDU contains at least a pair of object names and
 * values: - sysUpTime.0 whose value is the time in hundredths of a
 * second since the netwok management portion of system was last
 * reinitialized.  - snmpTrapOID.0 which is part of the trap group SNMPv2
 * MIB whose value is the object-id of the specific trap you have defined
 * in your own MIB.  Other variables can be added to caracterize the
 * trap.
 * 
 * The function send_v2trap adds automaticallys the two objects but the
 * value of snmpTrapOID.0 is 0.0 by default. If you want to add your trap
 * name, you have to reconstruct this object and to add your own
 * variable.
 * 
 */



int
write_exampletrap2(int action,
                   u_char * var_val,
                   u_char var_val_type,
                   size_t var_val_len,
                   u_char * statP, oid * name, size_t name_len)
{
    long            intval;

    /*
     * these variales will be used when we send the trap 
     */
    oid             objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };     /* snmpTrapOID.0 */
    oid             demo_trap[] = { 1, 3, 6, 1, 4, 1, 2021, 13, 990 };  /*demo-trap */
    oid             example_string_oid[] =
        { 1, 3, 6, 1, 4, 1, 2021, 254, 1, 0 };
    static netsnmp_variable_list var_trap;
    static netsnmp_variable_list var_obj;

    DEBUGMSGTL(("example", "write_exampletrap2 entered: action=%d\n",
                action));
    switch (action) {
    case RESERVE1:
        /*
         *  The only acceptable value is the integer 1
         */
        if (var_val_type != ASN_INTEGER) {
            DEBUGMSGTL(("example", "%x not integer type", var_val_type));
            return SNMP_ERR_WRONGTYPE;
        }
        if (var_val_len > sizeof(long)) {
            DEBUGMSGTL(("example", "wrong length %x", var_val_len));
            return SNMP_ERR_WRONGLENGTH;
        }

        intval = *((long *) var_val);
        if (intval != 1) {
            DEBUGMSGTL(("example", "wrong value %x", intval));
            return SNMP_ERR_WRONGVALUE;
        }
        break;

    case RESERVE2:
        /*
         * No resources are required.... 
         */
        break;

    case FREE:
        /*
         * ... so no resources need be freed 
         */
        break;

    case ACTION:
        /*
         *  Having triggered the sending of a trap,
         *   it would be impossible to revoke this,
         *   so we can't actually invoke the action here.
         */
        break;

    case UNDO:
        /*
         * We haven't done anything yet,
         * so there's nothing to undo 
         */
        break;

    case COMMIT:
        /*
         *  Everything else worked, so it's now safe
         *   to trigger the trap.
         *  Note that this is *only* acceptable since
         *   the trap sending routines are "failsafe".
         *  (In fact, they can fail, but they return no
         *   indication of this, which is the next best thing!)
         */

        /*
         * trap definition objects 
         */

        var_trap.next_variable = &var_obj;      /* next variable */
        var_trap.name = objid_snmptrap; /* snmpTrapOID.0 */
        var_trap.name_length = sizeof(objid_snmptrap) / sizeof(oid);    /* number of sub-ids */
        var_trap.type = ASN_OBJECT_ID;
        var_trap.val.objid = demo_trap; /* demo-trap objid */
        var_trap.val_len = sizeof(demo_trap);   /* length in bytes (not number of subids!) */


        /*
         * additional objects 
         */


        var_obj.next_variable = NULL;   /* No more variables after this one */
        var_obj.name = example_string_oid;
        var_obj.name_length = sizeof(example_string_oid) / sizeof(oid); /* number of sub-ids */
        var_obj.type = ASN_OCTET_STR;   /* type of variable */
        var_obj.val.string = example_str;       /* value */
        var_obj.val_len = strlen(example_str);
        DEBUGMSGTL(("example", "write_exampletrap2 sending the v2 trap\n",
                    action));
        send_v2trap(&var_trap);
        DEBUGMSGTL(("example", "write_exampletrap2 v2 trap sent\n",
                    action));

        break;

    }
    return SNMP_ERR_NOERROR;
}