snmp_agent.c

来自「eCos操作系统源码」· C语言 代码 · 共 887 行 · 第 1/2 页

	    allDone = TRUE;		/* Check for some content */
	    for ( var_ptr = asp->start;
		  var_ptr != asp->end->next_variable;
		  var_ptr = var_ptr->next_variable ) {
				/* XXX: we don't know the size of the next
					OID, so assume the maximum length */
		if ( var_ptr->type != SNMP_ENDOFMIBVIEW )
		{
		var_ptr2 = snmp_add_null_var(asp->pdu, var_ptr->name, MAX_OID_LEN);
		for ( i=var_ptr->name_length ; i<MAX_OID_LEN ; i++)
		    var_ptr2->name[i] = 0;
		var_ptr2->name_length = var_ptr->name_length;

		    allDone = FALSE;
		}
	    }
	    if ( allDone )
		break;

	    asp->start = asp->end->next_variable;
	    while ( asp->end->next_variable != NULL )
		asp->end = asp->end->next_variable;
	    
	    status = handle_next_pass( asp );
	    if ( status != SNMP_ERR_NOERROR )
		break;
	    if ( asp->outstanding_requests != NULL )
		return 1;
	}
	break;

    case SNMP_MSG_SET:
    	    /*
	     * SETS require 3-4 passes through the var_op_list.  The first two
	     * passes verify that all types, lengths, and values are valid
	     * and may reserve resources and the third does the set and a
	     * fourth executes any actions.  Then the identical GET RESPONSE
	     * packet is returned.
	     * If either of the first two passes returns an error, another
	     * pass is made so that any reserved resources can be freed.
	     * If the third pass returns an error, another pass is made so that
	     * any changes can be reversed.
	     * If the fourth pass (or any of the error handling passes)
	     * return an error, we'd rather not know about it!
	     */
	if ( asp->mode == RESERVE1 ) {
            snmp_increment_statistic(STAT_SNMPINSETREQUESTS);
	    asp->rw      = WRITE;

	    status = handle_next_pass( asp );

	    if ( status != SNMP_ERR_NOERROR )
	        asp->mode = FREE;
	    else
	        asp->mode = RESERVE2;

	    if ( asp->outstanding_requests != NULL )
		return 1;
	}

	if ( asp->mode == RESERVE2 ) {
	    status = handle_next_pass( asp );

	    if ( status != SNMP_ERR_NOERROR )
	        asp->mode = FREE;
	    else
	        asp->mode = ACTION;

	    if ( asp->outstanding_requests != NULL )
		return 1;
	}

	if ( asp->mode == ACTION ) {
	    status = handle_next_pass( asp );

	    if ( status != SNMP_ERR_NOERROR )
	        asp->mode = UNDO;
	    else
	        asp->mode = COMMIT;

	    if ( asp->outstanding_requests != NULL )
		return 1;
	}

	if ( asp->mode == COMMIT ) {
	    status = handle_next_pass( asp );

	    if ( status != SNMP_ERR_NOERROR ) {
		status    = SNMP_ERR_COMMITFAILED;
	        asp->mode = FINISHED_FAILURE;
	    }
	    else
	        asp->mode = FINISHED_SUCCESS;

	    if ( asp->outstanding_requests != NULL )
		return 1;
	}

	if ( asp->mode == UNDO ) {
	    if (handle_next_pass( asp ) != SNMP_ERR_NOERROR )
		status = SNMP_ERR_UNDOFAILED;

	    asp->mode = FINISHED_FAILURE;
	    break;
	}

	if ( asp->mode == FREE ) {
	    (void) handle_next_pass( asp );
	    break;
	}

	break;

    case SNMP_MSG_RESPONSE:
        snmp_increment_statistic(STAT_SNMPINGETRESPONSES);
	free( asp );
	return 0;
    case SNMP_MSG_TRAP:
    case SNMP_MSG_TRAP2:
        snmp_increment_statistic(STAT_SNMPINTRAPS);
	free( asp );
	return 0;
    default:
        snmp_increment_statistic(STAT_SNMPINASNPARSEERRS);
	free( asp );
	return 0;
    }

    if ( asp->outstanding_requests != NULL ) {
	asp->status = status;
	asp->next = agent_session_list;
	agent_session_list = asp;
    }
    else {
		/*
		 * May need to "dumb down" a SET error status for a
		 *  v1 query.  See RFC2576 - section 4.3
		 */
	if (( asp->pdu->command == SNMP_MSG_SET ) &&
	    ( asp->pdu->version == SNMP_VERSION_1 )) {
	    switch ( status ) {
		case SNMP_ERR_WRONGVALUE:
		case SNMP_ERR_WRONGENCODING:
		case SNMP_ERR_WRONGTYPE:
		case SNMP_ERR_WRONGLENGTH:
		case SNMP_ERR_INCONSISTENTVALUE:
			status = SNMP_ERR_BADVALUE;
			break;
		case SNMP_ERR_NOACCESS:
		case SNMP_ERR_NOTWRITABLE:
		case SNMP_ERR_NOCREATION:
		case SNMP_ERR_INCONSISTENTNAME:
		case SNMP_ERR_AUTHORIZATIONERROR:
			status = SNMP_ERR_NOSUCHNAME;
			break;
		case SNMP_ERR_RESOURCEUNAVAILABLE:
		case SNMP_ERR_COMMITFAILED:
		case SNMP_ERR_UNDOFAILED:
			status = SNMP_ERR_GENERR;
			break;
	    }
	}
		/*
		 * Similarly we may need to "dumb down" v2 exception
		 *  types to throw an error for a v1 query.
		 *  See RFC2576 - section 4.1.2.3
		 */
	if (( asp->pdu->command != SNMP_MSG_SET ) &&
	    ( asp->pdu->version == SNMP_VERSION_1 )) {
		for ( var_ptr = asp->pdu->variables, i=0 ;
			var_ptr != NULL ;
			var_ptr = var_ptr->next_variable, i++ ) {
		    switch ( var_ptr->type ) {
			case SNMP_NOSUCHOBJECT:
			case SNMP_NOSUCHINSTANCE:
			case SNMP_ENDOFMIBVIEW:
			case ASN_COUNTER64:
				status = SNMP_ERR_NOSUCHNAME;
				asp->pdu->errindex=i;
				break;
		    }
		}
	}
	if ( status == SNMP_ERR_NOERROR ) {
	    snmp_increment_statistic_by(
		(asp->pdu->command == SNMP_MSG_SET ?
			STAT_SNMPINTOTALSETVARS : STAT_SNMPINTOTALREQVARS ),
	    	count_varbinds( asp->pdu ));
	}
	else {
		/*
		 * Use a copy of the original request
		 *   to report failures.
		 */
	    i = asp->pdu->errindex;
	    snmp_free_pdu( asp->pdu );
	    asp->pdu = snmp_clone_pdu( pdu );
	    asp->pdu->errindex = i;
	}
	asp->pdu->command = SNMP_MSG_RESPONSE;
	asp->pdu->errstat = status;
	snmp_send( asp->session, asp->pdu );
	snmp_increment_statistic(STAT_SNMPOUTPKTS);
	snmp_increment_statistic(STAT_SNMPOUTGETRESPONSES);
	free( asp );
    }

    return 1;
}


int
handle_next_pass(struct agent_snmp_session  *asp)
{
    int status;
    struct snmp_pdu *pdu = asp->pdu;
    struct request_list *req_p, *next_req;


        if ( asp->outstanding_requests != NULL )
	    return SNMP_ERR_NOERROR;
	status = handle_var_list( asp );
        if ( asp->outstanding_requests != NULL ) {
	    if ( status == SNMP_ERR_NOERROR ) {
		/* Send out any subagent requests */
		for ( req_p = asp->outstanding_requests ;
			req_p != NULL ; req_p = req_p->next_request ) {

		    snmp_async_send( req_p->session,  req_p->pdu,
				      req_p->callback, req_p->cb_data );
		}
		asp->pdu = snmp_clone_pdu( pdu );
		asp->pdu->variables = pdu->variables;
		pdu->variables = NULL;
	    }
	    else {
	    	/* discard outstanding requests */
		for ( req_p = asp->outstanding_requests ;
			req_p != NULL ; req_p = next_req ) {
			
			next_req = req_p->next_request;
			free( req_p );
		}
		asp->outstanding_requests = NULL;
	    }
	}
	return status;
}


int
handle_var_list(struct agent_snmp_session  *asp)
{
    struct variable_list *varbind_ptr;
    u_char  statType;
    u_char *statP;
    size_t  statLen;
    u_short acl;
    WriteMethod *write_method;
    AddVarMethod *add_method;
    int	    noSuchObject = TRUE;
    int     count, view;
    
    count = 0;
    varbind_ptr = asp->start;
    if ( !varbind_ptr ) {
	return SNMP_ERR_NOERROR;
    }

    while (1) {
    
	count++;
statp_loop:
	statP = getStatPtr(  varbind_ptr->name,
			   &varbind_ptr->name_length,
			   &statType, &statLen, &acl,
			   asp->exact, &write_method, asp->pdu, &noSuchObject);
			   
	if (statP == NULL && (asp->rw != WRITE || write_method == NULL)) {
	        /*  Careful -- if the varbind was lengthy, it will have
		    allocated some memory.  */
	        snmp_set_var_value(varbind_ptr, NULL, 0);
	    	varbind_ptr->val.integer   = NULL;
	    	varbind_ptr->val_len = 0;
		if ( asp->exact ) {
	            if ( noSuchObject == TRUE ){
		        statType = SNMP_NOSUCHOBJECT;
		    } else {
		        statType = SNMP_NOSUCHINSTANCE;
		    }
		} else {
	            statType = SNMP_ENDOFMIBVIEW;
		}
		if (asp->pdu->version == SNMP_VERSION_1) {
		    asp->pdu->errstat = SNMP_ERR_NOSUCHNAME;
		    asp->pdu->errindex = count;
		    return SNMP_ERR_NOSUCHNAME;
		}
		else if (asp->rw == WRITE) {
		    asp->pdu->errstat =
			( noSuchObject	? SNMP_ERR_NOTWRITABLE
					: SNMP_ERR_NOCREATION );
		    asp->pdu->errindex = count;
		    return asp->pdu->errstat;
		}
		else
		    varbind_ptr->type = statType;
	}
                /* Delegated variables should be added to the
                   relevant outgoing request */
        else if ( IS_DELEGATED(statType)) {
                add_method = (AddVarMethod*)statP;
                statType = (*add_method)( asp, varbind_ptr );
        }
		/* GETNEXT/GETBULK should just skip inaccessible entries */
	else if ((view = in_a_view(varbind_ptr->name, &varbind_ptr->name_length,
				   asp->pdu, varbind_ptr->type))
			 && !asp->exact) {
		if (view != 5) send_easy_trap(SNMP_TRAP_AUTHFAIL, 0);
		goto statp_loop;
	}
		/* Other access problems are permanent */
	else if (( asp->rw == WRITE && !(acl & 2)) || view) {
	    if (asp->pdu->version == SNMP_VERSION_1 || asp->rw != WRITE) {
		if (ds_get_boolean(DS_APPLICATION_ID, DS_AGENT_VERBOSE))
                  DEBUGMSGTL(("snmp_agent", "    >> noSuchName (read-only)\n"));
		ERROR_MSG("read-only");
		statType = SNMP_ERR_NOSUCHNAME;
	    }
	    else {
		if (ds_get_boolean(DS_APPLICATION_ID, DS_AGENT_VERBOSE))
                  DEBUGMSGTL(("snmp_agent", "    >> notWritable\n"));
		ERROR_MSG("Not Writable");
		statType = SNMP_ERR_NOTWRITABLE;
	    }
	    asp->pdu->errstat = statType;
	    asp->pdu->errindex = count;
	    send_easy_trap(SNMP_TRAP_AUTHFAIL, 0);
	    return statType;
        }
	else {
            /* dump verbose info */
	    if (ds_get_boolean(DS_APPLICATION_ID, DS_AGENT_VERBOSE) && statP)
	        dump_var(varbind_ptr->name, varbind_ptr->name_length,
				statType, statP, statLen);

		/*  FINALLY we can act on SET requests ....*/
	    if ( asp->rw == WRITE ) {
	        if ( write_method != NULL ) {
		    statType = (*write_method)(asp->mode,
                                               varbind_ptr->val.string,
                                               varbind_ptr->type,
                                               varbind_ptr->val_len, statP,
                                               varbind_ptr->name,
                                               varbind_ptr->name_length);
                    if (statType != SNMP_ERR_NOERROR) {
                      asp->pdu->errstat = statType;
                      asp->pdu->errindex = count;
                      return statType;
                    }
		}
		else {
                    if (!goodValue(varbind_ptr->type, varbind_ptr->val_len,
                                    statType, statLen)){
                        if (asp->pdu->version == SNMP_VERSION_1)
                            statType = SNMP_ERR_BADVALUE;
                        else
                            statType = SNMP_ERR_WRONGTYPE; /* poor approximation */
			asp->pdu->errstat = statType;
			asp->pdu->errindex = count;
			return statType;
                    }
                    /* actually do the set if necessary */
                    if (asp->mode == COMMIT)
                        setVariable(varbind_ptr->val.string, varbind_ptr->type,
                                    varbind_ptr->val_len, statP, statLen);
                }
	    }
		/* ... or save the results from assorted GETs */
	    else {
		     snmp_set_var_value(varbind_ptr, statP, statLen);
		     varbind_ptr->type = statType;
	    }
	}
	
	if ( varbind_ptr == asp->end )
	     return SNMP_ERR_NOERROR;
	varbind_ptr = varbind_ptr->next_variable;
	if ( asp->mode == RESERVE1 )
	    snmp_vars_inc++;
    }
}



static int
goodValue(u_char inType, 
	  size_t inLen,
	  u_char actualType,
	  size_t actualLen)
{
    if (inLen > actualLen)
	return FALSE;
    return (inType == actualType);
}

static void
setVariable(u_char *var_val,
	    u_char var_val_type,
	    size_t var_val_len,
	    u_char *statP,
	    size_t statLen)
{
    size_t buffersize = 1000;

    switch(var_val_type){
	case ASN_INTEGER:
	    asn_parse_int(var_val, &buffersize, &var_val_type, (long *)statP, statLen);
	    break;
	case ASN_COUNTER:
	case ASN_GAUGE:
	case ASN_TIMETICKS:
	    asn_parse_unsigned_int(var_val, &buffersize, &var_val_type, (u_long *)statP, statLen);
	    break;
	case ASN_COUNTER64:
	    asn_parse_unsigned_int64(var_val, &buffersize, &var_val_type,
				     (struct counter64 *)statP, statLen);
	    break;
	case ASN_OCTET_STR:
	case ASN_IPADDRESS:
	case ASN_OPAQUE:
	case ASN_NSAP:
	    asn_parse_string(var_val, &buffersize, &var_val_type, statP, &statLen);
	    break;
	case ASN_OBJECT_ID:
	    asn_parse_objid(var_val, &buffersize, &var_val_type, (oid *)statP, &statLen);
	    break;
	case ASN_BIT_STR:
	    asn_parse_bitstring(var_val, &buffersize, &var_val_type, statP, &statLen);
	    break;
    }
}