C Program on implementing ICMPv6 Router Solicitation Message using Raw sockets
How to use the binary:
Neelkanth $sudo ./a.out
Invalid input : 1
Help section
=====================================
Enter 2 arguments:
1. Outgoing Interface Name
2. Source IPV6 Address
Input Arguments: (null)
Neelkanth $sudo ./a.out wlp4s0 fe80::ad6:3956:56b0:97d7
MAC address for interface wlp4s0 is 7c:b0:c2:19:8e:f8Index for interface wlp4s0 is 3
The are bytes from the packets for calculating the checksum:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
fe80 0 0 0 ad6 3956 56b0 97d7 ff02 0 0 0 0 0 0 2 0 10 0 3a 8500 0 0 0 101 7cb0 c219 8ef8
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
sum: 4884
1's complement of sum is answer(Final Checksum): b77b
#####################################################
C Program Start here...
#####################################################
/*
*##############################################################################################*
* ICMPv6 Router solicitation Multicast Message C program
*
*##############################################################################################
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h> /* close() */
#include <string.h> /* strcpy, memset(), and memcpy() */
#include <netdb.h> /* struct addrinfo */
#include <sys/types.h> /* needed for socket(), uint8_t, uint16_t */
#include <sys/socket.h> /* needed for socket() */
#include <netinet/in.h> /* IPPROTO_ICMPV6, INET6_ADDRSTRLEN */
#include <netinet/ip.h> /* IP_MAXPACKET (which is 65535) */
#include <netinet/ip6.h> /* struct ip6_hdr */
#include <netinet/icmp6.h> /* struct icmp6_hdr and ICMP6_ECHO_REQUEST */
#include <arpa/inet.h> /* inet_pton() and inet_ntop() */
#include <sys/ioctl.h> /* macro ioctl is defined */
#include <bits/ioctls.h> /* defines values for argument "request" of ioctl. */
#include <net/if.h> /* struct ifreq */
#include <linux/if_ether.h> /* ETH_P_IP = 0x0800, ETH_P_IPV6 = 0x86DD */
#include <linux/if_packet.h> /* struct sockaddr_ll (see man 7 packet) */
#include <net/ethernet.h>
#include <errno.h> /* errno, perror() */
/* Various Header Lengths */
#define ETH_HDRLEN 14 /* Ethernet header length */
#define IPV6_HDRLEN 40 /* IPv6 header length */
#define ICMPV6_RS_HDRLEN 8 /* ICMPv6 header length for router solicitation */
#define ICMPV6_OPTION_HDLEN 8 /* ICMPv6 option header length for router solicitation */
/*
* Function prototypes
*/
uint16_t checksum(uint16_t *, int);
uint16_t icmp6_checksum(struct ip6_hdr,
struct nd_router_solicit,
uint8_t *,
int);
char *allocate_strmem(int);
uint8_t *allocate_ustrmem(int);
/*
*#####################################################################################
* MAIN FUNCTION STARTS HERE
*#####################################################################################
*/
int main (int argc, char **argv)
{
int i, status, datalen, frame_length, sd, bytes;
uint8_t *src_mac = NULL,
*dst_mac = NULL,
*ether_frame = NULL;
struct addrinfo hints;
char *interface = NULL,
*src_ip = NULL,
*multicast_icmpv6_dest_ipaddr = NULL;
struct sockaddr_in6 dest_ipv6_header_multicast;
struct sockaddr_in6 *dest_ipv6_header_multicast_ptr;
struct sockaddr_ll device;
void *tmp;
struct ifreq ifr;
char dest_mac_in_str[24] = {0};
/*
* Structures for ipv6 , icmpv6 router Solicitation and
* icmpv6 options header.
*/
struct ip6_hdr ipv6_hdr;
struct icmp6_hdr icmphdr;
struct nd_router_solicit rs;
unsigned char icmpv6_option1[ICMPV6_OPTION_HDLEN]={0};
/*
* argv[1]: Outgoing Interface
* argv[2]: source ipv6 address
* argv[3]: destination ipv6 address
*/
if (argc != 3) {
printf("Invalid input : %d\n", argc);
printf("Help section\n"
"=====================================\n"
"Enter 2 arguments:\n"
"1. Outgoing Interface Name\n"
"2. Source IPV6 Address\n"
);
printf("Input Arguments: %s %s\n", argv[1], argv[2]);
return -1;
}
/*
* Allocate memory for various arrays.
*/
src_mac = allocate_ustrmem(6);
dst_mac = allocate_ustrmem(6);
ether_frame = allocate_ustrmem(IP_MAXPACKET);
interface = allocate_strmem(40);
src_ip = allocate_strmem(INET6_ADDRSTRLEN);
multicast_icmpv6_dest_ipaddr = allocate_strmem(INET6_ADDRSTRLEN);
/*
*****************************************************************************
* INTERFACE, SOURCE IPV6 ADDRESS, DESTINATION IPV6 ADDRESS,
* DESTINATION MAC ADDRESS AND SOURCE MAC ADDRESS
*****************************************************************************
* */
/* Interface to send packet through. */
strcpy(interface, argv[1]);
/* Source IPv6 address: you need to fill this out */
strcpy(src_ip, argv[2]);
/* All Router Address */
strcpy(multicast_icmpv6_dest_ipaddr, "ff02::2");
/* Set destination MAC address: you need to fill these out */
strcpy(dest_mac_in_str, "33:33:00:00:00:02");
sscanf(dest_mac_in_str, "%x:%x:%x:%x:%x:%x",
(unsigned int *) &dst_mac[0],
(unsigned int *) &dst_mac[1],
(unsigned int *) &dst_mac[2],
(unsigned int *) &dst_mac[3],
(unsigned int *) &dst_mac[4],
(unsigned int *) &dst_mac[5]);
/* Submit request for a socket descriptor to look up interface. */
if ((sd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) < 0) {
perror("socket() failed to get socket descriptor for using ioctl() ");
exit (EXIT_FAILURE);
}
/* Use ioctl() to look up interface name and get its MAC address. */
memset(&ifr, 0, sizeof (ifr));
snprintf(ifr.ifr_name, sizeof (ifr.ifr_name), "%s", interface);
if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0) {
perror("ioctl() failed to get source MAC address ");
return (EXIT_FAILURE);
}
close(sd);
/* Copy source MAC address. */
memcpy(src_mac, ifr.ifr_hwaddr.sa_data, 6 * sizeof (uint8_t));
/*
* Print Source MAC address of source interface from which the
* packet will go out.
*/
printf("MAC address for interface %s is ", interface);
for(i=0; i<5; i++) {
printf ("%02x:", src_mac[i]);
}
printf("%02x\n", src_mac[5]);
/******************************************************************************/
/*
* Find interface index from interface name and store index in
* struct sockaddr_ll device,
* which will be used as an argument of sendto().
*/
memset(&device, 0, sizeof (device));
if ((device.sll_ifindex = if_nametoindex(interface)) == 0) {
perror("if_nametoindex() failed to obtain interface index ");
exit(EXIT_FAILURE);
}
printf("Index for interface %s is %i\n", interface, device.sll_ifindex);
/*
*#################################################################################
* THE ACTUAL ICMPV6 PACKET HEADER FORMATION BEGINS FROM THIS PLACE
*#################################################################################
*/
/* Fill out sockaddr_ll. */
device.sll_family = AF_PACKET;
memcpy (device.sll_addr, src_mac, 6 * sizeof (uint8_t));
device.sll_halen = 6;
/*
*
*Frame 4282: 86 bytes on wire (688 bits), 86 bytes captured (688 bits) on interface 0
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ L2 Ethernet header
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Ethernet II, Src: IntelCor_19:8e:f8 (7c:b0:c2:19:8e:f8), Dst: IPv6mcast_ff:11:aa:6e (33:33:ff:11:aa:6e)
Destination: IPv6mcast_ff:11:aa:6e (33:33:ff:11:aa:6e)
Address: IPv6mcast_ff:11:aa:6e (33:33:ff:11:aa:6e)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: IntelCor_19:8e:f8 (7c:b0:c2:19:8e:f8)
Address: IntelCor_19:8e:f8 (7c:b0:c2:19:8e:f8)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv6 (0x86dd)
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ L3 IPV6 header
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Internet Protocol Version 6, Src: fe80::ad6:3956:56b0:97d7, Dst: ff02::1:ff00:1
0110 .... = Version: 6
.... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
.... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
.... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
.... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
Payload Length: 32
Next Header: ICMPv6 (58)
Hop Limit: 255
Source: fe80::ad6:3956:56b0:97d7
Destination: ff02::1:ff00:1
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ ICMPV6 header (24 bytes)
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Internet Control Message Protocol v6
Type: router Solicitation (135)
Code: 0
Checksum: 0x7c24 [correct]
[Checksum Status: Good]
Reserved: 00000000
Target Address: fe80::1
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ ICMPV6 option header (8 bytes)
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
ICMPv6 Option (Source link-layer address : 7c:b0:c2:19:8e:f8)
Type: Source link-layer address (1)
Length: 1 (8 bytes)
Link-layer address: IntelCor_19:8e:f8 (7c:b0:c2:19:8e:f8)
*/
/*
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
* IPV6 HEADER
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*/
/*
* 0 and 1) IPv6 version (4 bits), Traffic class (8 bits), Flow label (20 bits) = [32 bits or 4 bytes]
* 2) Payload length = ICMP header(24 bytes) + ICMP option header(8 bytes) = [32 bytes]
* 3) Next header (8 bits): 58 for ICMP = [1 byte]
* 4) Hop limit (8 bits): default to maximum value = [1 byte]
* 5) Source IPv6 address (128 bits) = [16 bytes]
* 6) Destination IPv6 address (128 bits) = [16 bytes]
*/
ipv6_hdr.ip6_flow = htonl ((6 << 28) | (0 << 20) | 0);
ipv6_hdr.ip6_plen = htons(ICMPV6_RS_HDRLEN + ICMPV6_OPTION_HDLEN);
ipv6_hdr.ip6_nxt = IPPROTO_ICMPV6;
ipv6_hdr.ip6_hops = 255;
if ((status = inet_pton(AF_INET6, src_ip, &(ipv6_hdr.ip6_src))) != 1) {
fprintf (stderr, "inet_pton() failed.\nError message: %s", strerror (status));
exit (EXIT_FAILURE);
}
if ((status = inet_pton(AF_INET6, multicast_icmpv6_dest_ipaddr, &(ipv6_hdr.ip6_dst))) != 1) {
fprintf (stderr, "inet_pton() failed.\nError message: %s", strerror (status));
exit (EXIT_FAILURE);
}
/*
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
* ICMPV6 HEADER
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*/
/* Populate icmp6_hdr portion of router solicit struct. */
memset(&rs, 0, sizeof(rs));
rs.nd_rs_hdr.icmp6_type = ND_ROUTER_SOLICIT; /* 133 (RFC 4861) */
rs.nd_rs_hdr.icmp6_code = 0; /* zero for router solicitation (RFC 4861) */
rs.nd_rs_hdr.icmp6_cksum = htons(0); /* zero when calculating checksum */
rs.nd_rs_reserved = htonl(0); /* Reserved - must be set to zero (RFC 4861) */
/*
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
* ICMPV6 OPTIONS HEADER
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*/
icmpv6_option1[0] = 1; /* Option Type - "source link layer address" (Section 4.6 of RFC 4861) */
icmpv6_option1[1] = ICMPV6_OPTION_HDLEN/8; /* Option Length - units of 8 octets (RFC 4861) */
for (i = 0; i < 6; i++) {
icmpv6_option1[i+2] = (uint8_t) src_mac[i];
}
/*
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
* Ethernet frame header.
*@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*/
#define ETH_DEST_MAC_OFFSET 0
#define ETH_DEST_MAC_LEN 6
#define ETH_SRC_MAC_OFFSET (ETH_DEST_MAC_OFFSET + ETH_DEST_MAC_LEN)
#define ETH_SRC_MAC_LEN 6
#define ETH_ETHERTYPE_LB_OFFSET (ETH_SRC_MAC_OFFSET + ETH_SRC_MAC_LEN)
#define ETH_ETHERTYPE_UB_OFFSET (ETH_ETHERTYPE_LB_OFFSET + 1)
#define ETHER_TYPE_LEN 2
/*
* Ethernet frame length =
* ethernet header (MAC + MAC + ether type) + IP6 header + ICMPV6 header + ICMPV6 OPTIONS header
*/
frame_length = ETH_DEST_MAC_LEN + ETH_SRC_MAC_LEN +
ETHER_TYPE_LEN + IPV6_HDRLEN + ICMPV6_RS_HDRLEN + ICMPV6_OPTION_HDLEN;
/* Destination and Source MAC addresses */
memcpy (ether_frame, dst_mac, ETH_DEST_MAC_LEN * sizeof (uint8_t));
memcpy (ether_frame + ETH_SRC_MAC_OFFSET, src_mac, ETH_SRC_MAC_LEN * sizeof (uint8_t));
/*
* Next is ethernet type code (ETH_P_IPV6 for IPv6).
* http://www.iana.org/assignments/ethernet-numbers
*/
ether_frame[ETH_ETHERTYPE_LB_OFFSET] = ETH_P_IPV6 / 256;
ether_frame[ETH_ETHERTYPE_UB_OFFSET] = ETH_P_IPV6 % 256;
/* Next is ethernet frame data (IPv6 header + ICMPV6 header + ICMPV6 option header). */
/* IPv6 header */
memcpy (ether_frame + ETH_HDRLEN,
&ipv6_hdr, IPV6_HDRLEN * sizeof (uint8_t));
struct nd_router_solicit *ns_ptr = NULL;
/* ICMPV6 header */
memcpy (ether_frame + ETH_HDRLEN + IPV6_HDRLEN,
&rs, ICMPV6_RS_HDRLEN * sizeof (uint8_t));
/* ICMPV6 Option header */
memcpy(ether_frame + ETH_HDRLEN + IPV6_HDRLEN + ICMPV6_RS_HDRLEN,
icmpv6_option1, ICMPV6_OPTION_HDLEN * sizeof (uint8_t));
/*
* In order to update the checksum, retrieve the location of checksum
* from the packet
*/
ns_ptr = (struct nd_router_solicit *)(ether_frame + ETH_HDRLEN + IPV6_HDRLEN);
ns_ptr->nd_rs_hdr.icmp6_cksum = icmp6_checksum(ipv6_hdr, /* ipv6 header structure */
rs, /* icmpv6 RS header structure */
icmpv6_option1, /* icmpv6 options header */
ICMPV6_OPTION_HDLEN);
/*
* Create a raw socket to put the packet on the Wire.
*/
if ((sd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) < 0) {
perror("socket() failed ");
exit (EXIT_FAILURE);
}
/* Send ethernet frame to socket. */
if ((bytes = sendto(sd, ether_frame, frame_length, 0,
(struct sockaddr *) &device,
sizeof (device))) <= 0) {
perror("sendto() failed");
exit(EXIT_FAILURE);
}
/* Close socket descriptor. */
close (sd);
/* Free allocated memory. */
free (src_mac);
free (dst_mac);
free (ether_frame);
free (interface);
free (multicast_icmpv6_dest_ipaddr);
free (src_ip);
return (EXIT_SUCCESS);
}
/* Computing the internet checksum (RFC 1071). */
/* Note that the internet checksum does not preclude collisions. */
uint16_t checksum(uint16_t *addr, int len)
{
int count = len;
register uint32_t sum = 0;
uint16_t answer = 0;
/* Sum up 2-byte values until none or only one byte left. */
printf("The are bytes from the packets for calculating the checksum:\n");
printf("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n");
while (count > 1) {
printf("%x ", htons(*addr));
sum += *(addr++);
count -= 2;
}
printf("\n@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n");
printf("\n");
/* Add left-over byte, if any. */
if (count > 0) {
sum += *(uint8_t *)addr;
}
/*
* Fold 32-bit sum into 16 bits; we lose information by doing this,
* increasing the chances of a collision.
* sum = (lower 16 bits) + (upper 16 bits shifted right 16 bits)
*/
while (sum >> 16) {
sum = (sum & 0xffff) + (sum >> 16);
}
printf("sum: %x\n", sum);
/* Checksum is one's compliment of sum. */
answer = ~sum;
printf("1's complement of sum is answer(Final Checksum): %x\n", answer);
return (answer);
}
/* Build IPv6 ICMP pseudo-header and call checksum function (Section 8.1 of RFC 2460). */
uint16_t icmp6_checksum (struct ip6_hdr ipv6_hdr,
struct nd_router_solicit nd,
uint8_t *payload, int payloadlen)
{
char buf[IP_MAXPACKET] = {0};
char *ptr = NULL;
int chksumlen = 0;
int i = 0;
/* ptr points to beginning of buffer buf */
ptr = &buf[0];
/* Copy source IP address into buf (128 bits) */
memcpy (ptr, &ipv6_hdr.ip6_src.s6_addr, sizeof (ipv6_hdr.ip6_src.s6_addr));
ptr += sizeof (ipv6_hdr.ip6_src);
chksumlen += sizeof (ipv6_hdr.ip6_src);
/* Copy destination IP address into buf (128 bits) */
memcpy (ptr, &ipv6_hdr.ip6_dst.s6_addr, sizeof (ipv6_hdr.ip6_dst.s6_addr));
ptr += sizeof (ipv6_hdr.ip6_dst.s6_addr);
chksumlen += sizeof (ipv6_hdr.ip6_dst.s6_addr);
/*
* Copy Upper Layer Packet length into buf (32 bits).
* Should not be greater than 65535 (i.e., 2 bytes).
*/
*ptr = 0; ptr++;
*ptr = 0; ptr++;
*ptr = (ICMPV6_RS_HDRLEN + payloadlen) / 256;
ptr++;
*ptr = (ICMPV6_RS_HDRLEN + payloadlen) % 256;
ptr++;
chksumlen += 4;
/* Copy zero field to buf (24 bits) */
*ptr = 0; ptr++;
*ptr = 0; ptr++;
*ptr = 0; ptr++;
chksumlen += 3;
/* Copy next header field to buf (8 bits) */
memcpy (ptr, &ipv6_hdr.ip6_nxt, sizeof (ipv6_hdr.ip6_nxt));
ptr += sizeof (ipv6_hdr.ip6_nxt);
chksumlen += sizeof (ipv6_hdr.ip6_nxt);
/* Copy ICMPv6 type to buf (8 bits) */
memcpy (ptr, &nd.nd_rs_hdr.icmp6_type, sizeof (nd.nd_rs_hdr.icmp6_type));
ptr += sizeof (nd.nd_rs_hdr.icmp6_type);
chksumlen += sizeof (nd.nd_rs_hdr.icmp6_type);
/* Copy ICMPv6 code to buf (8 bits) */
memcpy (ptr, &nd.nd_rs_hdr.icmp6_code, sizeof (nd.nd_rs_hdr.icmp6_code));
ptr += sizeof (nd.nd_rs_hdr.icmp6_code);
chksumlen += sizeof (nd.nd_rs_hdr.icmp6_code);
/* Copy ICMPv6 ID to buf (16 bits) */
memcpy (ptr, &nd.nd_rs_hdr.icmp6_id, sizeof (nd.nd_rs_hdr.icmp6_id));
ptr += sizeof (nd.nd_rs_hdr.icmp6_id);
chksumlen += sizeof (nd.nd_rs_hdr.icmp6_id);
/* Copy ICMPv6 sequence number to buff (16 bits) */
memcpy (ptr, &nd.nd_rs_hdr.icmp6_seq, sizeof (nd.nd_rs_hdr.icmp6_seq));
ptr += sizeof (nd.nd_rs_hdr.icmp6_seq);
chksumlen += sizeof (nd.nd_rs_hdr.icmp6_seq);
/*
* Copy ICMPv6 checksum to buf (16 bits)
* Zero, since we don't know it yet.
*/
*ptr = 0; ptr++;
*ptr = 0; ptr++;
chksumlen += 2;
/* Copy ICMPv6 payload to buf */
memcpy (ptr, payload, payloadlen * sizeof (uint8_t));
ptr += payloadlen;
chksumlen += payloadlen;
/* Pad to the next 16-bit boundary */
for (i=0; i<payloadlen%2; i++, ptr++) {
*ptr = 0;
ptr += 1;
chksumlen += 1;
}
return checksum ((uint16_t *) buf, chksumlen);
}
/*
* Allocate memory for an array of chars.
*/
char *allocate_strmem(int len)
{
void *tmp = NULL;
if (len <= 0) {
fprintf (stderr, "ERROR: Cannot allocate memory because len = %i in allocate_strmem().\n", len);
exit (EXIT_FAILURE);
}
tmp = (char *) malloc (len * sizeof (char));
if (tmp != NULL) {
memset (tmp, 0, len * sizeof (char));
return (tmp);
} else {
fprintf (stderr, "ERROR: Cannot allocate memory for array allocate_strmem().\n");
exit (EXIT_FAILURE);
}
}
/* Allocate memory for an array of unsigned chars. */
uint8_t *allocate_ustrmem(int len)
{
void *tmp = NULL;
if (len <= 0) {
fprintf (stderr, "ERROR: Cannot allocate memory because len = %i in allocate_ustrmem().\n", len);
exit (EXIT_FAILURE);
}
tmp = (uint8_t *) malloc (len * sizeof (uint8_t));
if (tmp != NULL) {
memset (tmp, 0, len * sizeof (uint8_t));
return (tmp);
} else {
fprintf (stderr, "ERROR: Cannot allocate memory for array allocate_ustrmem().\n");
exit (EXIT_FAILURE);
}
}