The DPIawait_packet_from_agent() function

Format

#include <snmp_dpi.h>
 
int DPIawait_packet_from_agent(    /* await a DPI packet      */
  int                   handle,    /* on this connection      */
  int                   timeout,   /* timeout in seconds      */
  unsigned char       **message_p, /* receives ptr to data    */
  unsigned long        *length);   /* receives length of data */

Parameters

handle

A handle as obtained with a DPIconnect_to_agent_xxxx() call.

timeout

A timeout value in seconds. There are two special values:

-1: Causes the function to wait forever until a packet arrives.
0: Means that the function will check only if a packet is waiting. If not, an immediate return is made. If there is a packet, it will be returned.

message_p

The address of a pointer that will receive the address of a static DPI packet buffer or, if there is no packet, a NULL pointer.

length

The address of an unsigned long integer that will receive the length of the received DPI packet or, if there is no packet, a 0 value.

Return codes

If successful, a 0 (DPI_RC_OK) is returned. The buffer pointer and length of the caller will be set to point to the received DPI packet and to the length of that packet.
If not successful, a negative integer is returned, which indicates the kind of error that occurred. See Return codes from DPI transport-related functions for a list of possible error codes.

DPI_RC_NOK: This is a return code indicating the DPI code is out of sync or has a bug.
DPI_RC_EOF: End of file on the connection. The connection has been closed.
DPI_RC_IO_ERROR: An error occurred with an underlying select() or recvfrom() call, or a DPI packet was read that was less than 2 bytes. DPI uses the first 2 bytes to get the packet length.
DPI_RC_INVALID_HANDLE: A bad handle was passed as input. Either the handle is not valid, or it describes a connection that has been disconnected.
DPI_RC_TIMEOUT: No packet was received during the specified timeout period.
DPI_RC_PACKET_TOO_LARGE: The packet received was too large.

Usage

The DPIawait_packet_from_agent() function is used at the subagent side to await a DPI packet from the DPI-capable SNMP agent. The programmer can specify how long to wait.

Examples

  #include <snmp_dpi.h>
  int                  handle;
  unsigned char       *pack_p;
  unsigned long        length;
 
  handle = DPIconnect_to_agent_TCP("127.0.0.1", "public");
  if (handle < 0) {
     printf("Error %d from connect\n",handle);
     exit(1);
  } /* endif */
  /* do useful stuff */
  rc = DPIawait_packet_from_agent(handle, -1,
                            &pack_p, &length);
  if (rc) {
     printf("Error %d from await packet\n");
     exit(1);
  } /* endif */
  /* handle the packet */

Format

Parameters

Return codes

Usage

Examples

Context