Cellular Network Infrastructure » Core Network (CN) » OsmoGGSN (former OpenGGSN)

#include <stdio.h>

#include <stdint.h>

struct ipcp_hdr {

	uint8_t code;

	uint8_t id;

	uint16_t len;

	uint8_t options[0];

};

enum ipcp_options {

	IPCP_OPT_IPADDR = 3,

	IPCP_OPT_PRIMARY_DNS = 129,

	IPCP_OPT_SECONDARY_DNS = 131,

};

struct ipcp_option_hdr {

	uint8_t type;

	uint8_t len;

	uint8_t data[0];

};

/* determine if IPCP contains given option */

static struct ipcp_option_hdr *ipcp_contains_option(struct ipcp_hdr *ipcp, enum ipcp_options opt)

{

	uint8_t *cur = ipcp->options;

	printf("ipcp->code=%x\n", ipcp->code);

	printf("ipcp->id=%x\n", ipcp->id);

	printf("ipcp->len=%x\n", ipcp->len);

	/* iterate over Options and check if protocol contained */

	while (cur + 2 <= ((uint8_t *)ipcp) + ipcp->len) {

		struct ipcp_option_hdr *cur_opt = (struct ipcp_option_hdr *) cur;

		printf("\n");

		printf("cur_opt->type=%x\n", cur_opt->type);

		printf("cur_opt->len=%x\n", cur_opt->len);

		if (cur_opt->type == opt)

			return cur_opt;

		cur += cur_opt->len;

	}

	return NULL;

}

void main(void)

{

	struct ipcp_hdr *ipcp;

	uint8_t pco_ipcp[] = {0x01, 0x5e, 0x00, 0x0a, 0x81, 0x06, 0x00, 0x00, 0x00, 0x00 };

	ipcp = (struct ipcp_hdr*) (pco_ipcp);  /* 2=type + 1=len */

	printf("Hello, ipcp\n");

	ipcp_contains_option(ipcp, IPCP_OPT_PRIMARY_DNS);

	printf("I am done!\n");

}