/* Copyright (C) 2011-2015 P.D. Buchan (pdbuchan@yahoo.com)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
// Send an IPv4 ARP packet via raw socket at the link layer (ethernet frame).
// Values set for ARP request.
#include
#include
#include // close()
#include // strcpy, memset(), and memcpy()
#include // struct addrinfo
#include // needed for socket(), uint8_t, uint16_t
#include // needed for socket()
#include // IPPROTO_RAW, INET_ADDRSTRLEN
#include // IP_MAXPACKET (which is 65535)
#include // inet_pton() and inet_ntop()
#include // macro ioctl is defined
#include // defines values for argument "request" of ioctl.
#include // struct ifreq
#include // ETH_P_ARP = 0x0806
#include // struct sockaddr_ll (see man 7 packet)
#include
#include // errno, perror()
// Define a struct for ARP header
typedef struct _arp_hdr arp_hdr;
struct _arp_hdr {
uint16_t htype;
uint16_t ptype;
uint8_t hlen;
uint8_t plen;
uint16_t opcode;
uint8_t sender_mac[6];
uint8_t sender_ip[4];
uint8_t target_mac[6];
uint8_t target_ip[4];
};
// Define some constants.
#define ETH_HDRLEN 14 // Ethernet header length
#define IP4_HDRLEN 20 // IPv4 header length
#define ARP_HDRLEN 28 // ARP header length
#define ARPOP_REQUEST 1 // Taken from
// Function prototypes
char *allocate_strmem (int);
uint8_t *allocate_ustrmem (int);
int
main (int argc, char **argv) {
int i, status, frame_length, sd, bytes;
char *interface, *target, *src_ip;
arp_hdr arphdr;
uint8_t *src_mac, *dst_mac, *ether_frame;
struct addrinfo hints, *res;
struct sockaddr_in *ipv4;
struct sockaddr_ll device;
struct ifreq ifr;
// 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);
target = allocate_strmem (40);
src_ip = allocate_strmem (INET_ADDRSTRLEN);
// Interface to send packet through.
strcpy (interface, "eno1");
// Submit request for a socket descriptor to look up interface.
if ((sd = socket (AF_INET, SOCK_RAW, IPPROTO_RAW)) < 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)); // Report source MAC address to stdout. 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); // Set destination MAC address: broadcast address memset (dst_mac, 0xff, 6 * sizeof (uint8_t)); // Source IPv4 address: you need to fill this out strcpy (src_ip, "192.168.0.240"); // Destination URL or IPv4 address (must be a link-local node): you need to fill this out strcpy (target, "192.168.0.239"); // Fill out hints for getaddrinfo(). memset (&hints, 0, sizeof (struct addrinfo)); hints.ai_family = AF_INET; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = hints.ai_flags | AI_CANONNAME; // Source IP address if ((status = inet_pton (AF_INET, src_ip, &arphdr.sender_ip)) != 1) { fprintf (stderr, "inet_pton() failed for source IP address.\nError message: %s", strerror (status)); exit (EXIT_FAILURE); } // Resolve target using getaddrinfo(). if ((status = getaddrinfo (target, NULL, &hints, &res)) != 0) { fprintf (stderr, "getaddrinfo() failed for target: %s\n", gai_strerror (status)); exit (EXIT_FAILURE); } ipv4 = (struct sockaddr_in *) res->ai_addr;
memcpy (&arphdr.target_ip, &ipv4->sin_addr, 4 * sizeof (uint8_t));
freeaddrinfo (res);
// Fill out sockaddr_ll.
device.sll_family = AF_PACKET;
memcpy (device.sll_addr, src_mac, 6 * sizeof (uint8_t));
device.sll_halen = 6;
// ARP header
// Hardware type (16 bits): 1 for ethernet
arphdr.htype = htons (1);
// Protocol type (16 bits): 2048 for IP
arphdr.ptype = htons (ETH_P_IP);
// Hardware address length (8 bits): 6 bytes for MAC address
arphdr.hlen = 6;
// Protocol address length (8 bits): 4 bytes for IPv4 address
arphdr.plen = 4;
// OpCode: 1 for ARP request
arphdr.opcode = htons (ARPOP_REQUEST);
// Sender hardware address (48 bits): MAC address
memcpy (&arphdr.sender_mac, src_mac, 6 * sizeof (uint8_t));
// Sender protocol address (32 bits)
// See getaddrinfo() resolution of src_ip.
// Target hardware address (48 bits): zero, since we don't know it yet.
memset (&arphdr.target_mac, 0, 6 * sizeof (uint8_t));
// Target protocol address (32 bits)
// See getaddrinfo() resolution of target.
// Fill out ethernet frame header.
// Ethernet frame length = ethernet header (MAC + MAC + ethernet type) + ethernet data (ARP header)
frame_length = 6 + 6 + 2 + ARP_HDRLEN;
// Destination and Source MAC addresses
memcpy (ether_frame, dst_mac, 6 * sizeof (uint8_t));
memcpy (ether_frame + 6, src_mac, 6 * sizeof (uint8_t));
// Next is ethernet type code (ETH_P_ARP for ARP).
// http://www.iana.org/assignments/ethernet-numbers
ether_frame[12] = ETH_P_ARP / 256;
ether_frame[13] = ETH_P_ARP % 256;
// Next is ethernet frame data (ARP header).
// ARP header
memcpy (ether_frame + ETH_HDRLEN, &arphdr, ARP_HDRLEN * sizeof (uint8_t));
// Submit request for a raw socket descriptor.
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 (target);
free (src_ip);
return (EXIT_SUCCESS);
}
// Allocate memory for an array of chars.
char *
allocate_strmem (int len) {
void *tmp;
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;
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);
}
}