/* adapted from Sample 25_1 from "Computer Networks and Internets, 2nd ed by Comer */
/* sockclient.c - code for example client program that uses TCP */

#ifndef unix
#define WIN32
#include <windows.h>
#include <winsock.h>
#else
#define closesocket close
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#endif

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

#define PROTOPORT       5193            /* default protocol port number */

extern  int             errno;
char    localhost[] =   "localhost";    /* default host name            */
/*------------------------------------------------------------------------
 * Program:   client
 *
 * Purpose:   allocate a socket, connect to a server, and print all output
 *
 * Syntax:    client [ host [port] ]
 *
 *               host  - name of a computer on which server is executing
 *               port  - protocol port number server is using
 *
 * Note:      Both arguments are optional.  If no host name is specified,
 *            the client uses "localhost"; if no protocol port is
 *            specified, the client uses the default given by PROTOPORT.
 *
 *------------------------------------------------------------------------
 */
main(argc, argv)
    int     argc;
    char    *argv[];
{
    struct  hostent  *ptrh;  /* pointer to a host table entry       */
    struct  protoent *ptrp;  /* pointer to a protocol table entry   */
    struct  sockaddr_in sad; /* structure to hold an IP address     */
    int     sd;              /* socket descriptor                   */
    int     port;            /* protocol port number                */
    char    *host;           /* pointer to host name                */
    int     n;               /* number of characters read           */
    char    buf[1000];       /* buffer for data from the server     */
#ifdef WIN32
    WSADATA wsaData;
    WSAStartup(0x0101, &wsaData);
#endif
    struct passwd *ppwd;
    memset((char *)&sad,0,sizeof(sad)); /* clear sockaddr structure */
    sad.sin_family = AF_INET;         /* set family to Internet     */
    
    /* Check command-line argument for protocol port and extract    */
    /* port number if one is specified.  Otherwise, use the default */
    /* port value given by constant PROTOPORT                       */
    
    if (argc > 2) {                 /* if protocol port specified   */
	port = atoi(argv[2]);   /* convert to binary            */
    } else {
	port = PROTOPORT;       /* use default port number      */
    }
    if (port > 0)                   /* test for legal value         */
	sad.sin_port = htons((u_short)port);
    else {                          /* print error message and exit */
	fprintf(stderr,"bad port number %s\n",argv[2]);
	exit(1);
    }
    
    /* Check host argument and assign host name. */
    
    if (argc > 1) {
	host = argv[1];         /* if host argument specified   */
    } else {
	host = localhost;
    }
    
    /* Convert host name to equivalent IP address and copy to sad. */
    
    ptrh = gethostbyname(host);
    if ( ((char *)ptrh) == NULL ) {
	fprintf(stderr,"invalid host: %s\n", host);
	exit(1);
    }
    memcpy(&sad.sin_addr, ptrh->h_addr, ptrh->h_length);
    
    /* Map TCP transport protocol name to protocol number. */
    
    if ( ((int)(ptrp = getprotobyname("tcp"))) == 0) {
	fprintf(stderr, "cannot map \"tcp\" to protocol number");
	exit(1);
    }
    
    /* Create a socket. */
    
    sd = socket(PF_INET, SOCK_STREAM, ptrp->p_proto);
    if (sd < 0) {
	fprintf(stderr, "socket creation failed\n");
	exit(1);
    }
    
    /* Connect the socket to the specified server. */
    
    if (connect(sd, (struct sockaddr *)&sad, sizeof(sad)) < 0) {
	fprintf(stderr,"connect failed\n");
	exit(1);
    }
    
    /* Repeatedly read data from socket and write to user's screen. */
    
    if ((ppwd = getpwuid(getuid())) == NULL) {
	fprintf(stderr,"could not get user name\n");
	exit(1);
    }
    /* send our user name */
    send(sd, ppwd->pw_name, strlen(ppwd->pw_name)+1, 0);
    n = recv(sd, buf, sizeof(buf), 0);
    while (n > 0) {
	write(1,buf,n);
	n = recv(sd, buf, sizeof(buf), 0);
    }
    
    /* Close the socket. */
    
    closesocket(sd);
    
    /* Terminate the client program gracefully. */
    
    exit(0);
}