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");

}