cegwsend.c File Reference

Control Area Network - Ethernet - Gateway - Send (Utility) More...

#include <linux/version.h>
#include <linux/if_ether.h>
#include <getopt.h>
#include <stdlib.h>
#include "can.h"
#include <string.h>
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <net/ethernet.h>
#include <netpacket/packet.h>
#include <assert.h>

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Functions
void	convert_to_mac (const char *string1)
	converts a string from the console to a MAC address More...
static void	die (const char *msg)
	It prints an error message in case of a failure and exits the program. More...
static unsigned char	gethex (const char *s, char **end)
unsigned char *	convert_to_hex (const char *s, int *length)
int	main (int argc, char *argv[])

Variables
char *	mac

Detailed Description

Control Area Network - Ethernet - Gateway - Send (Utility)

Author

Jakob Pfeiffer (jakob.nosp@m..pfe.nosp@m.iffer.nosp@m.@in..nosp@m.tum.d.nosp@m.e)

A Ethernet package is created here and sent to the Interface

Date

July, 2013

Copyright

GNU Public License v3 or higher

Definition in file cegwsend.c.

Function Documentation

unsigned char* convert_to_hex	(	const char *	s,
		int *	length
	)

Definition at line 91 of file cegwsend.c.

References gethex().

Referenced by main().

                                                         {
    unsigned char *hex = malloc((strlen(s) +1) / 3);
    unsigned char *p;
    for(p = hex; *s; p++)
        *p = gethex(s, (char **) &s);
    *length = p - hex;
    return hex;
}

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void convert_to_mac

(

const char *

string1

)

converts a string from the console to a MAC address

Parameters

string1

the string that should be converted to a MAC

Returns

MAC address with the length of 6 Bytes

Definition at line 53 of file cegwsend.c.

References mac.

Referenced by main().

{
    /* i is used in the for loop */
    int i;
    char* string2;

    /*
    * A MAC address has the length of 6 Bytes.
    * We need to allocate enough memory to store it.
    */
    mac = (char *) malloc(6);
    mac[0] = strtoul(string1, &string2, 16);
    for(i = 1; i <= 5; i++){
        mac[i] = strtoul(string2 + 1, &string2, 16);
    }
}

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static void die ( const char *  msg )

static

It prints an error message in case of a failure and exits the program.

Parameters

msg	The error message which should be written on the console

Returns

EXIT_FAILURE

Definition at line 78 of file cegwsend.c.

Referenced by main().

{
    perror(msg);
    exit(EXIT_FAILURE);
}

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static unsigned char gethex ( const char *  s, char **  end  )

static

Definition at line 84 of file cegwsend.c.

Referenced by convert_to_hex().

                                                      {
    assert(s);
    while(isspace(*s)) s++;
    assert(*s);
    return strtoul(s, end, 16);
}

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int main	(	int	argc,
		char *	argv[]
	)

Definition at line 109 of file cegwsend.c.

References can_frame::can_dlc, can_frame::can_id, canfd_frame::can_id, CANFD_MAX_DLEN, convert_to_hex(), convert_to_mac(), die(), canfd_frame::flags, canfd_frame::len, and mac.

{
    /* c is used for calling getopt_long() */
    int c;
    /*
    * src points at the beginning of the memory space in which the MAC address
    * of the message's receiver will be written
    */
    char *src;
    src = (char *) malloc(6);
    /*
    * dest points at the beginning of the memory space in which the MAC
    * address of the message's sender will be written
    */
    char *dest;
    dest = (char *) malloc(6);
    /* type is the identifier of the EtherType */
    ushort type;
    /*
    * raw_index points at the beginning of the raw data in argv[].
    * If raw_index == -1, then no data exists
    */
    int raw_index = -1;
    /*
    * name_index is the index of argv in which the name of the ethernet
    * device begins. If name_index == -1, then there is no name
    */
    int name_index = -1;

    /*
    * getopt_long is used here for reading the arguments from the command line
    */
    while (1){
        static struct option long_options[] = {
            /* source MAC address */
            {"src", required_argument, 0, 's'},
            /* destination MAC address */
            {"dst", required_argument, 0, 'd'},
            /* packet type ID field */
            {"type", required_argument, 0, 't'},
            /* raw data */
            {"raw", required_argument, 0, 'r'},
            /* name of the network interface */
            {"interface", required_argument, 0, 'i'},
            {0, 0, 0, 0}
        };
        /* getopt_long stores the option index here. */
        int option_index = 0;

        c = getopt_long(argc, argv, "s:d:t:r:i:", long_options, &option_index);

        /* Detect the end of the options. */
        if(c == -1)
            break;

        switch (c){
            case 0:
                /* If this option set a flag, do nothing else now. */
                if(long_options[option_index].flag != 0)
                    break;
                printf("option %s", long_options[option_index].name);
                if(optarg)
                    printf(" with arg %s", optarg);
                printf("\n");
                break;

            case 's':
                printf("option -s with value `%s'\n", optarg);
                /*
                * convert the argument to a valid MAC address
                */
                convert_to_mac(optarg);
                /*
                * convert_to_mac writes the address down in mac.
                * It must be stored in src now.
                */
                memcpy(src, mac, 6);
                break;

            case 'd':
                printf("option -d with value `%s'\n", optarg);
                /*
                * convert the argument to al valid MAC address
                */
                convert_to_mac(optarg);
                /*
                * convert_to_mac writes the address down in mac.
                * It must be stored in dest now.
                */
                memcpy(dest, mac, 6);
                break;

            case 't':
                printf("option -t with value `%s'\n", optarg);
                /*
                * The EtherType is defined by a number with the length of
                * 2 Bytes (e. g. 0x8000 for the Internet Protocol). The
                * argument from the console must be converted to a number.
                * This happens here.
                */
                if(strcmp(optarg, "ipv4") == 0){
                    /*
                    * The EtherType of Internet Protocol, Version 4 is
                    * 0x0800
                    */
                    type = 0x0800;
                } else if(strcmp(optarg, "ipv6") == 0){
                    /*
                    * The EtherType of Internet Protocol, Version 6 is
                    * 0x86DD
                    */
                    type = 0x86DD;
                } else if(strcmp(optarg, "can") == 0){
                    /*
                    * The EtherType of Controller Area Network is 0x000C
                    */
                    type = 0x000C;
                } else if(strcmp(optarg, "canfd") == 0){
                    /*
                    * The EtherType of CAN flexible data rate is 0x000D
                    */
                    type = 0x000D;
                    /*
                    * 0x88B5 and 0x88B6 have been
                    * reserved for experimental use
                    */
                } else if(strcmp(optarg, "none") == 0){
                    type = 0x88B5;
                /*
                * If the identifier was typed in like "0x1234" we cut off
                * the 0x and convert the number. If instead it was written
                * down like "1234" we simply convert the argument from the
                * console to a number.
                */
                } else if(strncmp(optarg, "0x", 2) == 0){
                    type = strtoul(optarg + 2, &optarg, 16);
                } else {
                    type = strtoul(optarg, &optarg, 16);
                }
                break;

            case 'r':
                printf("option -r with value `%s'\n", optarg);
                raw_index = optind - 1;
                break;

            case 'i':
                printf("option -i with value `%s'\n", optarg);
                name_index = optind - 1;
                break;

            case '?':
                /* getopt_long already printed error message- */
                break;

            default:
                abort();
        }
    }
    /* mac is not needed anymore */
    free(mac);

    printf("source: %hhX", *src);
    printf(":%hhX", *(src + 1));
    printf(":%hhX", *(src + 2));
    printf(":%hhX", *(src + 3));
    printf(":%hhX", *(src + 4));
    printf(":%hhX\n", *(src + 5));
    printf("destination: %hhX", *dest);
    printf(":%hhX", *(dest + 1));
    printf(":%hhX", *(dest + 2));
    printf(":%hhX", *(dest + 3));
    printf(":%hhX", *(dest + 4));
    printf(":%hhX\n", *(dest + 5));
    printf("type: %hX \n", type);

    /*
    * Create the AF_PACKET socket
    */
    int fd = socket(AF_PACKET, SOCK_DGRAM, htons(type));
    /*
    * In case of a failure the allocated memory must be freed and die is called
    */
    if (fd == -1){
        free(dest);
        free(src);
        die(strerror(errno));
    }

    /*
    * Name/index number of the interface
    * If there is no name, we have a problem and the program must end
    */
    if(name_index == -1){
        free(dest);
        free(src);
        die("name/index number of the network interface required");
    }
    struct ifreq ifr;
    size_t if_name_len = strlen(argv[name_index]);
    if(if_name_len < sizeof(ifr.ifr_name)){
        memcpy(ifr.ifr_name, argv[name_index], if_name_len);
        ifr.ifr_name[if_name_len] = 0;
    } else {
        printf("sizeof(ifr.ifr_name): %d", sizeof(ifr.ifr_name));
        printf(" sollte groesser sein als if_name_len: %d", if_name_len);
        free(src);
        free(dest);
        die("interface name is too long");
    }
    if(ioctl(fd, SIOCGIFINDEX, &ifr) == -1){
        free(src);
        free(dest);
        die(strerror(errno));
    }
    int ifindex = ifr.ifr_ifindex;

    /*
    * Construct the destination address
    */
    struct sockaddr_ll addr = {0};
    addr.sll_family = AF_PACKET;
    addr.sll_ifindex = ifindex;
    addr.sll_halen = ETHER_ADDR_LEN;
    addr.sll_protocol = htons(type);
    memcpy(addr.sll_addr, dest, ETHER_ADDR_LEN);
    /* dest is not needed anymore */
    free(dest);

    /*
    * Prepare the data to be sent. If it exists, of course
    */
    if(raw_index == -1){
        free(src);
        die("No data to be sent");
    }
    /*
    * Here, the raw data is converted from a string to a number
    */
    unsigned char *data = NULL;
    int length = strlen(argv[raw_index]);
    data = convert_to_hex(argv[raw_index], &length);
    int data_length = ((strlen(argv[raw_index]) + 1) / 3);
    /*
    * If the package is a can package, a can frame must be
    * written into the payload
    */
    if(type == 0x000C){
        /*
        * The maximum data which fits in a can frame
        * is 8 Bytes. If the data is too long, the
        * program terminates.
        */
        if(data_length > 8){
            free(src);
            free(data);
            die("The raw data is too long for a can frame");
        }
        struct can_frame frame;
        memset(frame.data, 0, 8);
        frame.can_id = 0;
        frame.can_dlc = data_length;
        memcpy(frame.data, data, data_length);
        /*
        * A Ethernet frame which contains the can frame in
        * its payload is sent
        */
        if(sendto(fd, &frame, sizeof(struct can_frame), 0, (struct sockaddr*)&addr, sizeof(addr)) == -1){
            free(data);
            free(src);
            die(strerror(errno));
        }
    } else if(type == 0x000D){
        printf("Ja, wir haben einen canfd\n");
        /*
        * The maximum data which fits in a canfd frame
        * is 64 Bytes. If the data is too long, the
        * program terminates.
        */
        if(data_length > CANFD_MAX_DLEN){
            free(data);
            free(src);
            die("The raw data is too long for a canfd frame");
        }
        static struct canfd_frame frame;
        memset(frame.data, 0, CANFD_MAX_DLEN);
        frame.can_id = 0;
        frame.flags = 0;
        frame.len = data_length;
        memcpy(frame.data, data, data_length);
        printf("Alles kopiert und so. Wird gleich gesendet.\n");
        /*
        * A Ethernet frame which contains the canfd frame
        * in its payload is sent
        */
        if(sendto(fd, &frame, sizeof(struct canfd_frame), 0, (struct sockaddr*)&addr, sizeof(addr)) == -1){
            free(data);
            free(src);
            die(strerror(errno));
        }
        printf("Jap, gesendet.\n");
    } else {
        /* Finally, let's send the package */
        if(sendto(fd, data, data_length, 0, (struct sockaddr*)&addr, sizeof(addr)) == -1){
            free(data);
            free(src);
            die(strerror(errno));
        }
    }
        /*
        * Nerver forget to free the allocated memory
        */
        free(data);
        free(src);
        return EXIT_SUCCESS;
}

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Variable Documentation

char* mac

Definition at line 45 of file cegwsend.c.

Referenced by convert_to_mac(), and main().