xsh_ping.c File Reference

#include <xinu.h>
#include <stdio.h>
#include <string.h>

Include dependency graph for xsh_ping.c:

Go to the source code of this file.

Functions
shellcmd	xsh_ping (int nargs, char *args[])

Function Documentation

xsh_ping()

shellcmd xsh_ping	(	int	nargs,
		char *	args[]
	)

Definition at line 11 of file xsh_ping.c.

References dnslookup(), dot2ip(), FALSE, fprintf(), ICMP_ECHOREQST, icmp_recv(), icmp_register(), icmp_release(), icmp_send(), printf(), stderr, strlen(), strncmp(), SYSERR, TIMEOUT, and TRUE.

{
    uint32  ipaddr;         /* IP address in binary     */
    int32   retval;         /* return value         */
    int32   slot;           /* Slot in ICMP to use      */
    static  int32   seq = 0;    /* sequence number      */
    char    buf[56];        /* buffer of chars      */
    int32   i;          /* index into buffer        */
    int32   nextval;        /* next value to use        */
    bool8   dname;

    /* For argument '--help', emit help about the 'ping' command    */

    if (nargs == 2 && strncmp(args[1], "--help", 7) == 0) {
        printf("Use: %s  address\n\n", args[0]);
        printf("Description:\n");
        printf("\tUse ICMP Echo to ping a remote host\n");
        printf("Options:\n");
        printf("\t--help\t display this help and exit\n");
        printf("\taddress\t an IP address in dotted decimal\n");
        return 0;
    }

    /* Check for valid number of arguments */

    if (nargs != 2) {
        fprintf(stderr, "%s: invalid arguments\n", args[0]);
        fprintf(stderr, "Try '%s --help' for more information\n",
                args[0]);
        return 1;
    }

    dname = FALSE;
    for(i = 0; i < strlen(args[1]); i++) {
        if( ( (args[1][i] >= 65) && (args[1][i] <= 90) ) ||
            ( (args[1][i] >= 97) && (args[1][i] <= 122)) ) {
                dname = TRUE;
            break;
        }
    }

    if(dname == TRUE) {
        ipaddr = dnslookup(args[1]);
        if((int32)ipaddr == SYSERR) {
            fprintf(stderr, "DNS cannot resolve %s\n", args[1]);
            return 1;
        }
        printf("Pinging %d.%d.%d.%d\n", (ipaddr>>24)&0xff,
                        (ipaddr>>16)&0xff,
                        (ipaddr>>8)&0xff,
                        (ipaddr)&0xff);
    }
    else {
        /* convert argument to binary */

        retval = dot2ip(args[1], &ipaddr);
        if ((int32)retval == SYSERR) {
            fprintf(stderr, "%s: invalid IP address\n", args[0]);
            return 1;
        }
    }

    /* Register to receive an ICMP Echo Reply */

    slot = icmp_register(ipaddr);
    if (slot == SYSERR) {
        fprintf(stderr,"%s: ICMP registration failed\n", args[0]);
        return 1;
    }

    /* Fill the buffer with values - start with low-order byte of   */
    /*  the sequence number and increment           */

    nextval = seq;
    for (i = 0; i<sizeof(buf); i++) {
        buf[i] = 0xff & nextval++;
    }

    /* Send an ICMP Echo Request */
    retval = icmp_send(ipaddr, ICMP_ECHOREQST, slot,
                    seq++, buf, sizeof(buf));
    if (retval == SYSERR) {
        fprintf(stderr, "%s: no response from host %s\n", args[0], args[1]);
        icmp_release(slot);
        return 1;
    }

    /* Read a reply */

    retval = icmp_recv(slot, buf, sizeof(buf), 3000);
    icmp_release(slot);
    if (retval == TIMEOUT) {
        fprintf(stderr, "%s: no response from host %s\n", args[0],
                    args[1]);
        return 1;
    }

    if (retval != sizeof(buf)) {
        fprintf(stderr,"expected %d bytes but got back %d\n",
            sizeof(buf), retval);
        }
    fprintf(stderr, "host %s is alive\n", args[1]);
    return 0;
}

Here is the call graph for this function: