#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

externint    errno;

int    UDPecho(constchar *host, constchar *service);
int    errexit(constchar *format, ...);
int    connectUDP(constchar *host, constchar *service);

#define    LINELEN        128

/*------------------------------------------------------------------------ * main - UDP client for ECHO service *------------------------------------------------------------------------ */int
main(int argc, char *argv[])
{
    char    *host = "localhost";
    char    *service = "echo";

    switch (argc) {
    case 1:
        host = "localhost";
        break;
    case 3:
        service = argv[2];
        /* FALL THROUGH */case 2:
        host = argv[1];
        break;
    default:
        fprintf(stderr, "usage: UDPecho [host [port]]\n");
        exit(1);
    }
    UDPecho(host, service);
    exit(0);
}

/*------------------------------------------------------------------------ * UDPecho - send input to ECHO service on specified host and print reply *------------------------------------------------------------------------ */int
UDPecho(constchar *host, constchar *service)
{
    char    buf[LINELEN+1];        /* buffer for one line of text    */int    s, nchars;        /* socket descriptor, read count*/

    s = connectUDP(host, service);

    while (fgets(buf, sizeof(buf), stdin)) {
        buf[LINELEN] = '\0';    /* insure null-terminated */
        nchars = strlen(buf);
        (void) write(s, buf, nchars);

        if (read(s, buf, nchars) < 0)
            errexit("socket read failed: %s\n",
                    strerror(errno));
        fputs(buf, stdout);
    }
}