/* dgramclnt.c:

*

* Example datagram client:

*/

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <time.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

/*

* This function reports the error and

* exits back to the shell:

*/

static void

bail(const char *on_what) {

fputs(strerror(errno),stderr);

fputs(": ",stderr);

fputs(on_what,stderr);

fputc('

' ,stderr);

exit(1);

}

int

main(int argc,char **argv) {

int z;

int x;

char *srvr_addr = NULL;

struct sockaddr_in adr_srvr;/* AF_INET */

struct sockaddr_in adr;

/* AF_INET */

int len_inet;

/* length */

int s;

/* Socket */

char dgram

[512];

/* Recv buffer */

/*

* Use a server address from the command

* line, if one has been provided.

* Otherwise, this program will default

* to using the arbitrary address

* 127.0.0.23:

*/

if ( argc >= 2 ) {

/* Addr on cmdline: */

srvr_addr = argv[1];

} else {

/* Use default address: */

srvr_addr = "127.0.0.23";

}

/*

* Create a socket address, to use

* to contact the server with:

*/

memset(&adr_srvr,0,sizeof adr_srvr);

adr_srvr.sin_family = AF_INET;

adr_srvr.sin_port = htons(9090);

adr_srvr.sin_addr.s_addr =inet_addr(srvr_addr);

if ( adr_srvr.sin_addr.s_addr == INADDR_NONE )

bail("bad address.");

len_inet = sizeof adr_srvr;

/*

* Create a UDP socket to use:

*/

s = socket(AF_INET,SOCK_DGRAM,0);

if ( s == -1 )

bail("socket()");

for (;;) {

/*

* Prompt user for a date format string:

*/

fputs("

Enter format string: ",stdout);

if ( !fgets(dgram,sizeof dgram,stdin) )

break;

/* EOF */

z = strlen(dgram);

if ( z > 0 && dgram[-z] == '

' )

dgram[z] = 0;

/* Stomp out newline */

/*

* Send format string to server:

*/

z = sendto(s,

/* Socket to send result */

dgram, /* The datagram result to snd */

strlen(dgram), /* The datagram lngth */

0,

/* Flags: no options */

(struct sockaddr *)&adr_srvr,/* addr */

len_inet); /* Server address length */

if ( z < 0 )

bail("sendto(2)");

/*

* Test if we asked for a server shutdown:

*/

if (!strcasecmp(dgram,"QUIT") )

break;

/* Yes, we quit too */

/*

* Wait for a response:

*/

x = sizeof adr;

z = recvfrom(s,

/* Socket */

dgram,

/* Receiving buffer */

sizeof dgram,

/* Max recv buf size */

0,

/* Flags: no options */

(struct sockaddr *)&adr,

/* Addr */

&x);

/* Addr len, in & out */

if ( z < 0 )

bail("recvfrom(2)");

dgram[z] = 0;

/* null terminate *

/*

* Report Result:

*/

printf("Result from %s port %u :

\t'%s'

",

inet_ntoa(adr.sin_addr),

(unsigned)ntohs(adr.sin_port),

dgram);

}

/*

* Close the socket and exit:

*/

close(s);

putchar('

');

return 0;

}