套接字socket---网络套接字

网络套接字

采用回路网络连接到一个网络套接字
回路网路只包含一台计算机，通常称为localhost，IP地址为127.0.0.1，可以在/etc/hosts文件中找到

例子：

客户端发一个A给服务器，服务器收到A，加1改成B，返回给客户端，客户端显示收到的字符

server1.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
	int server_sockfd, client_sockfd;
	int server_len, client_len;
	//sockaddr_in:网络套接字的地址
	struct sockaddr_in server_address;
	struct sockaddr_in client_address;
	//第一个参数域AF_INET
	server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
	//命名网络套接字
	server_address.sin_family = AF_INET;
	//inet_addr:把一个字符串形式的IP地址变成整数
	server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
	server_address.sin_port = 9734;
	server_len = sizeof(server_address);
	//套接字命名
	bind(server_sockfd, (struct sockaddr *)&server_address, server_len);
	//创建长度为5的监听队列
	listen(server_sockfd, 5);
	while(1)
	{
		char ch;
		printf("server waiting\n");
		client_len = sizeof(client_address);
		client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_address, &client_len);
		read(client_sockfd, &ch, 1);
		ch++;
		write(client_sockfd, &ch, 1);
		close(client_sockfd);
	}
}

client1.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
int main()
{
	int sockfd;
	int len;
	struct sockaddr_in address;//地址格式
	int result;
	char ch = 'A';
	sockfd = socket(AF_INET, SOCK_STREAM, 0);//生成套接字
	address.sin_family = AF_INET;
	//inet_addr的返回值已经是网络字节序
	address.sin_addr.s_addr = inet_addr("127.0.0.1");//格式转换
	address.sin_port = 9734;
	len = sizeof(address);
	result = connect(sockfd, (struct sockaddr *)&address, len);
	if (result == -1)
	{
		perror("oops:client2");
		exit(1);
	}
	write(sockfd, &ch, 1);
	read(sockfd, &ch, 1);
	printf("char from server = %c\n", ch);
	close(sockfd);
	exit(0);

}

字节序问题

不同计算机的字节序不一样，例如intel机器一般采用小端方式，而motorola一般采用大端方式，因此传输信息时会造成混乱。

扫描二维码关注公众号，回复： 3609970 查看本文章

网络字节序：客户和服务器在传输之前，将内部整数表示方式转换为网络字节序可解决字节序问题。

#include <netinet/in.h>
unsigned long int htonl(unsigned long int hostlong); //host to net本地字节序转换为网络字节序
unsigned short int htons(unsigned short int hostshort); //host to net本地字节序转换为网络字节序
unsigned long int ntohl(unsigned long int netlong); //net to host网络字节序转换为本地字节序
unsigned short int ntohs(unsigned short int netshort); //net to host网络字节序转换为本地字节序

server2.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
	int server_sockfd, client_sockfd;
	int server_len, client_len;
	//sockaddr_in:网络套接字的地址
	struct sockaddr_in server_address;
	struct sockaddr_in client_address;
	//第一个参数域AF_INET
	server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
	//命名网络套接字
	server_address.sin_family = AF_INET;
	//INADDR_ANY:任何机器都允许连接服务器上
	server_address.sin_addr.s_addr = htonl(INADDR_ANY);
	server_address.sin_port = htons(9734);
	server_len = sizeof(server_address);
	//套接字命名
	bind(server_sockfd, (struct sockaddr *)&server_address, server_len);
	//创建长度为5的监听队列
	listen(server_sockfd, 5);
	while(1)
	{
		char ch;
		printf("server waiting\n");
		client_len = sizeof(client_address);
		client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_address, &client_len);
		read(client_sockfd, &ch, 1);
		ch++;
		write(client_sockfd, &ch, 1);
		close(client_sockfd);
	}
}

client2.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
int main()
{
	int sockfd;
	int len;
	struct sockaddr_in address;//地址格式
	int result;
	char ch = 'A';
	sockfd = socket(AF_INET, SOCK_STREAM, 0);//生成套接字
	address.sin_family = AF_INET;
	//inet_addr的返回值已经是网络字节序
	address.sin_addr.s_addr = inet_addr("127.0.0.1");//格式转换
	address.sin_port = htons(9734);
	len = sizeof(address);
	result = connect(sockfd, (struct sockaddr *)&address, len);
	if (result == -1)
	{
		perror("oops:client2");
		exit(1);
	}
	write(sockfd, &ch, 1);
	read(sockfd, &ch, 1);
	printf("char from server = %c\n", ch);
	close(sockfd);
	exit(0);

}

套接字socket---网络套接字

猜你喜欢