/* client.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>
#pragma comment(lib, "Ws2_32.lib")
#define PROTOPORT 5193 /* default protocol port number */
extern int errno;
char localhost[]="localhost"; /* default host name */
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 len; /* number of characters read */
char buf[128]; /* buffer for data from the server */
char sendbuffer[128];
#ifdef WIN32
WSADATA wsaData;
WSAStartup(0x0101, &wsaData);
#endif
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 UDP transport protocol name to protocol number. */
if ( ((int)(ptrp = getprotobyname("udp"))) == 0) {
fprintf(stderr, "cannot map \"udp\" to protocol number");
exit(1);
}
/* Create a socket. */
sd = socket(PF_INET, SOCK_DGRAM, ptrp->p_proto);
if (sd < 0) {
fprintf(stderr, "socket creation failed\n");
exit(1);
}
//主循环——收发信息
len = sizeof(sad);
while(1)
{
gets(sendbuffer);
sendto(sd,sendbuffer,strlen(sendbuffer)+1,0,(struct sockaddr *)&sad,len);
recvfrom(sd,buf,128,0,(struct sockaddr *)&sad,&len);
printf("服务器 said:%s\n",buf);
}
/* Close the socket. */
closesocket(sd);
WSACleanup();
getchar();
exit(0);
}
