SNMP Manager Programmer's Guide

Encoding and Decoding Packets

SNMP Manager Programmer’s Guide–134249

6-14

SNMP_memory_alloc()

buffer

is a pointer to the descriptor structure of the buffer for which you want to know the

number of used bytes.

The sample manager SNMPGT calls EBufferUsed() to determine how many bytes to

write to the buffer used to transmit a request. The variable sndbuff is the encoded-

packet buffer used for requests. Because the UDP transport protocol requires that the

first information in the buffer transmitted be the socket structure, the response packet in

the buffer described by ebuff is written into sndbuff following this structure:

#define TBSIZE 2048;

unsigned char sndbuff[TBSIZE];

struct sockaddr_in dest;

EBUFFER_T ebuff;

memcpy (sndbuff, (void*) &dest, sizeof(dest));

memcpy (sndbuff + sizeof(struct sockaddr_in), ebuff.start_bp,

EBufferUsed(&ebuff));

SNMP_memory_alloc()

This function allocates buffer memory dynamically. It is a define for the C function

malloc.

need

is the number of bytes to dynamically allocate.

The sample manager SNMPGET dynamically allocates a 2000-byte buffer for the

encoded-packet buffer, then calls EBufferSetup() to prepare the buffer for receiving the

encoded packet:

EBUFFER_T ebuff;

int need;

char *buffp;

need = 2000;

if ((buffp = (char *)SNMP_memory_alloc(need)) ==0

return (-1);

EBufferSetup(BFL_IS_DYNAMIC, &ebuff, buffp, need);

SNMP_memory_alloc(need);

#define SNMP_memory_alloc(need) malloc(need)