/*
 * fping: fast-ping, file-ping, favorite-ping, funky-ping
 *
 *   Ping a list of target hosts in a round robin fashion.
 *   A better ping overall.
 *
 * fping website:  http://www.fping.org
 *
 * Current maintainer of fping: David Schweikert
 * Please send suggestions and patches to: david@schweikert.ch
 *
 *
 * Original author:  Roland Schemers  <schemers@stanford.edu>
 * IPv6 Support:     Jeroen Massar    <jeroen@unfix.org / jeroen@ipng.nl>
 * Improved main loop: David Schweikert <david@schweikert.ch>
 * Debian Merge, TOS settings: Tobi Oetiker <tobi@oetiker.ch>
 * Bugfixes, byte order & senseful seq.-numbers: Stephan Fuhrmann (stephan.fuhrmann AT 1und1.de)
 *
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Stanford University.  The name of the University may not be used
 * to endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#define _DEFAULT_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/in_systm.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <ctype.h>

#include "ping.h"

char* ping_buffer_ipv4 = 0;
size_t ping_pkt_size_ipv4;

int open_ping_socket_ipv4(int *socktype)
{
    struct protoent* proto;
    int s;

    /* confirm that ICMP is available on this machine */
    if ((proto = getprotobyname("icmp")) == NULL)
        printf("icmp: unknown protocol");

    /* create raw socket for ICMP calls (ping) */
    *socktype = SOCK_RAW;
    s = socket(AF_INET, *socktype, proto->p_proto);
    if (s < 0) {
        /* try non-privileged icmp (works on Mac OSX without privileges, for example) */
        *socktype = SOCK_DGRAM;
        s = socket(AF_INET, *socktype, proto->p_proto);
        if (s < 0) {
            return -1;
        }
    }

    /* Make sure that we use non-blocking IO */
    {
        int flags;

        if ((flags = fcntl(s, F_GETFL, 0)) < 0)
            perror("fcntl");

        if (fcntl(s, F_SETFL, flags | O_NONBLOCK) < 0)
            perror("fcntl");
    }

    return s;
}

void init_ping_buffer_ipv4(size_t ping_data_size)
{
    /* allocate ping buffer */
    ping_pkt_size_ipv4 = ping_data_size + ICMP_MINLEN;
    ping_buffer_ipv4 = (char*)calloc(1, ping_pkt_size_ipv4);
    if (!ping_buffer_ipv4)
        printf("can't malloc ping packet");
}

void uninit_ping_buffer_ipv4(void)
{
    free(ping_buffer_ipv4);
    ping_buffer_ipv4 = NULL;
}

void socket_set_src_addr_ipv4(int s, struct in_addr* src_addr, int *ident)
{
    struct sockaddr_in sa;
    socklen_t len = sizeof(sa);

    memset(&sa, 0, len);
    sa.sin_family = AF_INET;
    sa.sin_addr = *src_addr;
    if (bind(s, (struct sockaddr*)&sa, len) < 0)
        printf("cannot bind source address");

    if (ident) {
        memset(&sa, 0, len);
        if (getsockname(s, (struct sockaddr *)&sa, &len) < 0)
            printf("can't get ICMP socket identity");

        if (sa.sin_port)
            *ident = sa.sin_port;
    }
}

unsigned short calcsum(unsigned short* buffer, int length)
{
    unsigned long sum;

    /* initialize sum to zero and loop until length (in words) is 0 */
    for (sum = 0; length > 1; length -= 2) /* sizeof() returns number of bytes, we're interested in number of words */
        sum += *buffer++; /* add 1 word of buffer to sum and proceed to the next */

    /* we may have an extra byte */
    if (length == 1)
        sum += (char)*buffer;

    sum = (sum >> 16) + (sum & 0xFFFF); /* add high 16 to low 16 */
    sum += (sum >> 16); /* add carry */
    return ~sum;
}

int socket_sendto_ping_ipv4(int s, struct sockaddr* saddr, socklen_t saddr_len, uint16_t icmp_seq_nr, uint16_t icmp_id_nr)
{
    struct icmp* icp;
    int n;

    icp = (struct icmp*)ping_buffer_ipv4;

    icp->icmp_type = ICMP_ECHO;
    icp->icmp_code = 0;
    icp->icmp_cksum = 0;
    icp->icmp_seq = htons(icmp_seq_nr);
    icp->icmp_id = icmp_id_nr;

    if (random_data_flag) {
        for (n = ((char*)&icp->icmp_data - (char*)icp); n < ping_pkt_size_ipv4; ++n) {
            ping_buffer_ipv4[n] = random() & 0xFF;
        }
    }

    icp->icmp_cksum = calcsum((unsigned short*)icp, ping_pkt_size_ipv4);

    n = sendto(s, icp, ping_pkt_size_ipv4, 0, saddr, saddr_len);

    return n;
}
