Client1u.c

/*
 *  File Client1u.C
 *      ECHO UDP CLIENT with the following feqatures:
 *      - Gets server IP address and port from keyboard
 *      - LINE/ORIENTED:
 *        > continuously reads lines from keyboard
 *        > sends each line to the server
 *        > waits for response (at most for a fixed amount of time) and diaplays it
 *      - Terminates when the "close" or "stop" line is entered
 */


#include     <stdlib.h>
#include     <string.h>
#include     <inttypes.h>
#include     "errlib.h"
#include     "sockwrap.h"

#define BUFLEN 128  /* BUFFER LENGTH */
#define TIMEOUT 15  /* TIMEOUT (seconds) */

/* FUNCTION PROTOTYPES */
int mygetline(char *line, size_t maxline, char *prompt);
void showAddr(char *str, struct sockaddr_in *a);
int iscloseorstop(char *buf);

/* GLOBAL VARIABLES */
char *prog_name;


int main(int argc, char *argv[])
{
    char            buf[BUFLEN];       /* transmission buffer */
    char        rbuf[BUFLEN];      /* reception buffer */

    uint32_t        taddr_n;  /* server IP addr. (net/host ord) */
    uint16_t        tport_n, tport_h;  /* server port number */

    int     s;
    struct sockaddr_in  saddr;
    fd_set      cset;
    struct timeval  tval;

    prog_name = argv[0];


    /* input IP address and port of server */
    mygetline(buf, BUFLEN, "Enter host IPv4 address (dotted notation):");
    taddr_n = inet_addr(buf);
    if (taddr_n == INADDR_NONE)
    err_sys("Invalid address");

    mygetline(buf, BUFLEN, "Enter port : ");
    if (sscanf(buf, "%" SCNu16, &tport_h)!=1)
    err_sys("Invalid port number");
    tport_n = htons(tport_h);

    /* create the socket */
    printf("Creating socket\n");
    s = Socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    printf("done. Socket number: %d\n",s);

    /* prepare server address structure */
    bzero(&saddr, sizeof(saddr));
    saddr.sin_family      = AF_INET;
    saddr.sin_port        = tport_n;
    saddr.sin_addr.s_addr = taddr_n;

    /* main client loop */
    printf("Use message 'close' or 'stop' to terminate program.\n");

    for (buf[0]='\0' ; !iscloseorstop(buf); ) //main loop where we get a line of text from the keyboard
    {
        size_t      len, n;
        struct sockaddr_in  from;
        socklen_t       fromlen;

        mygetline(buf, BUFLEN, "Enter line (max 127 char): ");
        len = strlen(buf);
        n=sendto(s, buf, len, 0, (struct sockaddr *) &saddr, sizeof(saddr));
        if (n != len)
        {
        printf("Write error\n");
        continue;
        }

        printf("waiting for response...\n");
        FD_ZERO(&cset);
        FD_SET(s, &cset);
        tval.tv_sec = TIMEOUT;
        tval.tv_usec = 0;
        n = Select(FD_SETSIZE, &cset, NULL, NULL, &tval);
        if (n>0)
            {
        /* receive datagram */
        fromlen = sizeof(struct sockaddr_in);
            n=recvfrom(s,rbuf,BUFLEN-1,0,(struct sockaddr *)&from,&fromlen);
                if (n != -1)
            {
            rbuf[n] = '\0';
            showAddr("Received response from", &from);
            printf(": [%s]\n", rbuf);

            }
        else printf("Error in receiving response\n");
        }
        else printf("No response received after %d seconds\n",TIMEOUT);
        printf("=======================================================\n");
    }
    close(s);
    exit(0);
}

/* Gets a line of text from standard input after having printed a prompt string
   Substitutes end of line with '\0'
   Empties standard input buffer but stores at most maxline-1 characters in the
   passed buffer
*/
int mygetline(char *line, size_t maxline, char *prompt)
{
    char    ch;
    size_t  i;

    printf("%s", prompt);
    for (i=0; i< maxline-1 && (ch = getchar()) != '\n' && ch != EOF; i++)
        *line++ = ch;
    *line = '\0';
    while (ch != '\n' && ch != EOF)
        ch = getchar();
    if (ch == EOF)
        return(EOF);
    else    return(1);
}

/* Utility function to display a string str
   followed by an internet address a, written
   in decimal notation
*/
void showAddr(char *str, struct sockaddr_in *a)
{
    char *p;

    p = inet_ntoa(a->sin_addr);
    printf("%s %s",str,p);
    printf("!%u\n", ntohs(a->sin_port));
}

/* Funzione per controllare se un buffer contiene la stringa "close" o "stop" */
int iscloseorstop(char *buf)
{
    return (!strcmp(buf, "close") || !strcmp(buf, "stop"));
}