The mkDPIresponse() Function

Syntax

#include <snmp_dpi.h>

unsigned char    *mkDPIresponse( /* Make a DPI response packet*/
  snmp_dpi_hdr     *hdr_p,       /* ptr to packet to respnd to*/
  long int          error_code,  /* error code: SNMP_ERROR_xxx*/
  long int          error_index, /* index to varBind in error */
  snmp_dpi_set_packet *packet_p);/* ptr to varBinds, a chain  */
                                 /* of dpi_set_packets        */

Parameters

hdr_p

A pointer to the parse tree of the DPI request to which this DPI packet will be the response. The function uses this parse tree to copy the packet_id and the DPI version and release, so that the DPI packet is correctly formatted as a response.
error_code
The error code.

See DPI RESPONSE Error Codes for a list of valid codes.

error_index
Specifies the first varBind in error. Counting starts at 1 for the first varBind. This field should be zero if there is no error.
packet_p
A pointer to a chain of snmp_dpi_set_packet structures. This partial parse tree will be freed by the mkDPIresponse() function. So upon return you cannot reference it anymore. Pass a NULL pointer if there are no varBinds to be returned.

Return Values

If successful, a pointer to a static DPI packet buffer is returned. The first two bytes of the buffer in network byte order contain the length of the remaining packet. The macro DPI_PACKET_LEN can be used to calculate the total length of the DPI packet.

If failure, a NULL pointer is returned.

Note: The static buffer for the DPI packet is shared by other mkDPIxxxx() functions that create a serialized DPI packet.

Description

The mkDPIresponse() function is used at the subagent side to prepare a DPI RESPONSE packet to a GET, GETNEXT, GETBULK, SET, COMMIT or UNDO request. The resulting packet can be sent to the DPI peer, which is normally a DPI capable SNMP agent.

Examples

  #include <snmp_dpi.h>  unsigned char       *pack_p;
  snmp_dpi_hdr        *hdr_p;
  snmp_dpi_set_packet *set_p;
  long int             num;

  hdr_p = pDPIpacket(pack_p);     /* parse incoming packet */
                                  /* assume it's in pack_p */
  if (hdr_p) {
     /* analyze packet, assume GET, no error */
     set_p = mkDPIset(snmp_dpi_set_packet_NULL_p,
                      "1.3.6.1.2.3.4.5.", "1.0",
                      SNMP_TYPE_Integer32,
                      sizeof(num), &num);
     if (set_p) {
        pack_p = mkDPIresponse(hdr_p,
                      SNMP_ERROR_noError, 0L, set_p);
        if (pack_p) {
           /* send packet to subagent */
        } /* endif */
     } /* endif */
  } /* endif */

The mkDPIresponse() function is used at the agent side to prepare a DPI RESPONSE packet to an OPEN, REGISTER or UNREGISTER request. In the case of a RESPONSE to a REGISTER request and if there is no error, the actually assigned priority must be passed in the error_index parameter. The resulting packet can be sent to the DPI peer, which is normally a subagent.

Examples

  #include <snmp_dpi.h>
  unsigned char       *pack_p;
  snmp_dpi_hdr        *hdr_p;
  long int             priority;

  hdr_p = pDPIpacket(pack_p);     /* parse incoming packet */
                                  /* assume it's in pack_p */
  if (hdr_p) {
     /* analyze packet, assume REGISTER and OK */
     pack_p = mkDPIresponse(hdr_p,
                   SNMP_ERROR_DPI_noError,
                   priority,
                   snmp_dpi_set_packet_NULL_p);
     if (pack_p) {
        /* send packet to subagent */
     } /* endif */
  } /* endif */

Related Information

The pDPIpacket() Function
The snmp_dpi_hdr Structure
The snmp_dpi_next_packet Structure

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