网络通信方式可选择一台主机里的两个虚拟机，也可以两台主机里的两个虚拟机，本文采用方式二。
主机一IP地址为192.168.1.109
主机二IP地址为192.168.1.24
必须使两台主机在一个网段内，并且可以ping通才可进行以下操作。
客户端（主机一）代码
TCP_client.c
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char *argv[])
{
unsigned short port = 8000;
char *server_ip = "192.168.1.24"; //设置第二个主机ip地址为服务器地址，进行TCP通信
char send_buf[512] = "hello every!"; //设置发送的内容
char recv_buf[512] = "";
int sockfd = 0;
int err_log = 0;
struct sockaddr_in server_addr;
if( argc > 1 )
server_ip = argv[1];
if( argc > 2 )
port = atoi(argv[2]);
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port);
inet_pton(AF_INET, server_ip, &server_addr.sin_addr);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
{
perror("socket");
exit(-1);
}
err_log = connect(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if(err_log != 0)
{
perror("connect");
close(sockfd);
exit(-1);
}
send(sockfd, send_buf, strlen(send_buf), 0);
recv(sockfd, recv_buf, sizeof(recv_buf), 0);
printf("%s\n", recv_buf);
close(sockfd);
return 0;
}服务器端（主机二）代码
TCP_server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
char recv_buf[2048] = "";
int sockfd = 0;
int connfd = 0;
int err_log = 0;
struct sockaddr_in my_addr;
unsigned short port = 8000;
if(argc > 1)
port = atoi(argv[1]);
printf("TCP Server Started at port %d!\n", port);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
{
perror("socket");
exit(-1);
}
bzero(&my_addr, sizeof(my_addr));
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(port);
my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
printf("Binding server to port %d\n", port);
err_log = bind(sockfd, (struct sockaddr*)&my_addr, sizeof(my_addr));
if( err_log != 0)
{
perror("binding");
close(sockfd);
exit(-1);
}
err_log = listen(sockfd, 10);
if(err_log != 0)
{
perror("listen");
close(sockfd);
exit(-1);
}
printf("Waiting client...\n");
while(1)
{
size_t recv_len = 0;
struct sockaddr_in client_addr;
char cli_ip[INET_ADDRSTRLEN] = "";
socklen_t cliaddr_len = sizeof(client_addr);
connfd = accept(sockfd, (struct sockaddr*)&client_addr, &cliaddr_len);
if(connfd < 0)
{
perror("accept");
continue;
}
inet_ntop(AF_INET, &client_addr.sin_addr, cli_ip, INET_ADDRSTRLEN);
printf("client ip = %s\n", cli_ip);
while((recv_len = recv(connfd, recv_buf, sizeof(recv_buf), 0)) > 0)
send(connfd, recv_buf, recv_len, 0);
printf("%s\n",recv_buf);
close(connfd);
printf("client closed!\n");
}
close(sockfd);
return 0;
}客户端输入代码
gcc TCP_client.c -o TCP_client
./TCP_clent
服务器端输入代码
gcc TCP_server.c -o TCP_server
./TCP_server
客户端（主机一）代码
UDP_client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main (int argc, char *argv[])
{
int sockfd = 0;
struct sockaddr_in server_addr;
unsigned short port = 8000;
char *ser_ip = "192.168.1.24";
if(argc >1)
ser_ip = argv[1];
if(argc >2)
port = atoi(argv[2]);
sockfd = socket (AF_INET, SOCK_DGRAM, 0);
if(sockfd < 0)
{
perror("socket error!");
exit(-1);
}
bzero (&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port);
inet_pton(AF_INET, ser_ip,&server_addr.sin_addr);
printf("ready send data to UDP server %s:%d!\n",ser_ip,port);
while (1)
{
char send_buf[2048] = "";
int len = 0;
fgets(send_buf, sizeof(send_buf),stdin);
send_buf[strlen(send_buf)-1] ='\0';
sendto(sockfd, send_buf, strlen(send_buf),0,(struct sockaddr*)&server_addr,sizeof(server_addr));
len = recvfrom(sockfd, send_buf, sizeof(send_buf),0,NULL,NULL);
printf("%s\n",send_buf);
}
close(sockfd);
return 0;
}服务器端（主机二）代码
UDP_server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
int sockfd = 0;
int error_log = 0;
struct sockaddr_in bind_addr;
unsigned short port = 8000;
if (argc > 1)
port = atoi(argv[1]);
printf("UDP server Started!\n");
sockfd = socket(AF_INET, SOCK_DGRAM,0);
if (sockfd < 0)
{
perror("socket error");
exit(-1);
}
bzero(&bind_addr, sizeof(bind_addr));
bind_addr.sin_family = AF_INET;
bind_addr.sin_port = htons(port);
bind_addr.sin_addr.s_addr = htonl(INADDR_ANY);
printf("Binding server to port %d\n", port);
error_log = bind(sockfd, (struct sockaddr *)&bind_addr, sizeof(bind_addr));
if (error_log != 0)
{
perror("bind error");
close(sockfd);
exit(-1);
}
printf("waiting data from other client...\n");
while(1)
{
char recv_buf[1024] = "";
char cli_ip[INET_ADDRSTRLEN] = "";
int recv_len =0;
struct sockaddr_in client_addr;
socklen_t client_addr_len = sizeof(client_addr);
recv_len = recvfrom(sockfd, recv_buf,sizeof(recv_buf), 0 ,(struct sockaddr*)&client_addr,&client_addr_len);
inet_ntop(AF_INET, &client_addr.sin_addr,cli_ip,INET_ADDRSTRLEN);
printf("clinet ip = %s\n", cli_ip);
printf("recver message :%s\n",recv_buf);
sendto(sockfd, recv_buf,recv_len,0,(struct sockaddr*)&client_addr,&client_addr_len);
}
close(sockfd);
return 0;
}客户端输入代码
gcc UDP_client.c -o UDP_client
./UDP_client
hello
服务器端输入代码
gcc UDP_server.c -o UDP_server
./UDP_server
四、UDP广播发送端（主机一）代码
send.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <arpa/inet.h>
int main(){
char msg[128] = "I am broadCast message from server!";
struct sockaddr_in saddr, caddr;
socklen_t slen, clen;
int lfd, ret;
lfd = socket(AF_INET, SOCK_DGRAM, 0);
if(lfd < 0){
perror("socket create error");
exit(1);
}
int flag = 1;
setsockopt(lfd, SOL_SOCKET, SO_BROADCAST | SO_REUSEADDR, &flag, sizeof(flag) );
caddr.sin_family = AF_INET;
caddr.sin_port = htons(4001);
caddr.sin_addr.s_addr = inet_addr("192.168.1.255");
clen = sizeof(caddr);
int n = sendto(lfd, msg, strlen(msg), 0, (struct sockaddr *)&caddr, clen);
if(n < 0){
perror("sendto Error:");
exit(1);
}
close(lfd);
return 0;
}
接收端（主机二）代码
recv.c
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<netdb.h>
#include<sys/socket.h>
#include<sys/wait.h>
#include<arpa/inet.h>
int main(){
int sockListen;
if((sockListen = socket(AF_INET, SOCK_DGRAM, 0)) == -1){
printf("socket fail\n");
return -1;
}
int set = 1;
setsockopt(sockListen, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(int));
struct sockaddr_in recvAddr;
memset(&recvAddr, 0, sizeof(struct sockaddr_in));
recvAddr.sin_family = AF_INET;
recvAddr.sin_port = htons(4001);
recvAddr.sin_addr.s_addr = INADDR_ANY;
if(bind(sockListen, (struct sockaddr *)&recvAddr, sizeof(struct sockaddr)) == -1){
printf("bind fail\n");
return -1;
}
int recvbytes;
char recvbuf[128];
int addrLen = sizeof(struct sockaddr_in);
if((recvbytes = recvfrom(sockListen, recvbuf, 128, 0,
(struct sockaddr *)&recvAddr, &addrLen)) != -1){
recvbuf[recvbytes] = '\0';
printf("receive a broadCast messgse:%s\n", recvbuf);
}else{
printf("recvfrom fail\n");
}
close(sockListen);
return 0;
}
发送端输入代码
gcc send.c -o send
./send
接收端输入代码
gcc recv.c -o recv
./recv