TCP服务器

其他 2018-11-18 02:02:11 阅读次数: 0

创建步骤：

1、使用socket()函数创建socket；     

int socket(int domain, int type, int protocol);
RETURN VALUE
       On  success,  a  file  descriptor  for  the new socket is returned. 
       On error, -1 is returned,

2、使用bind()函数绑定IP地址和端口信息到socket；

int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
RETURN VALUE
       On  success,  zero is returned.  On error, -1 is returned

3、设置允许的最大连接数，使用函数listen();

int listen(int sockfd, int backlog);
RETURN VALUE
       On  success,  zero is returned.  On error, -1 is returned

4、使用函数accept()等待来自客户端的连接请求；

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
RETURN VALUE
 On  success, return a nonnegative integer that is a descriptor for the accepted socket.
 On  error,  -1  is  returned

5、收发数据，用函数recv()、send()/sendto()或者read()、write()；

6、通信完毕，关闭网络连接close()。

TCP/IP协议中我们用到的IP是以“.”隔开的十进制数表示如127.1.1.12,
而在套接字的数据结构中使用的是32位的网络字节序的二进制数值。实现两者间转化的函数如下：

  #include <arpa/inet.h>
  int inet_aton(const char *cp,struct in_addr *inp)
  char *inet_ntoa(struct in_addr in)
  inet_addr(const char *cp)   
    // 函数里面a代表ascii ，n 代表network。
   // inet_aton是将a.b.c.d形式的IP转换为32位的网络字节序IP,存储在inp指针里面。
   // inet_ntoa是将32位网络字节序IP转换为a.b.c.d的格式。
   // inet_addr将a.b.c.d形式的IP转化为网络字节序的32位IP

网络传输的数据的方式：大端模式（大端字节序）

主机存储数据的方式不统一，可能是大端模式也可能是小端模式

    htons()    把unsigned short类型从主机序转换到网络序
    htonl()     把unsigned long类型从主机序转换到网络序
    ntohs()    把unsigned short类型从网络序转换到主机序
    ntohl()     把unsigned long类型从网络序转换到主机序

32bit的整数(0x01234567)从地址0x100开始

简单TCP server/client:

//TCPserver.c
#include<stdio.h>
#include<sys/socket.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<unistd.h>
#include<arpa/inet.h>
#define PORT 5678
int main(int argc,char *argv[])
{
	int sd,ad;
	int err;
	int client_addrlen;
	char buf[20];
	struct sockaddr_in server_addr, client_addr;
	sd = socket(AF_INET,SOCK_STREAM,0);
	if(sd == -1)
	{
		printf("creat socket error,errno = %d\n",errno);
		return -1;
	}
	memset(&server_addr,0,sizeof(struct sockaddr_in));
	server_addr.sin_family  = AF_INET;
	server_addr.sin_port = htons(PORT);
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//32bit IPv4 Address
	err = bind(sd ,(struct sockaddr *)&server_addr,sizeof(struct sockaddr));
	if(err == -1)
	{
		printf("bind error,errno is %d\n",errno);
		close(sd);
		return -1;
	}
	printf("bind success!\n");
	if(listen(sd ,10) == -1)
	{
		printf("listen error,errno is %d\n",errno);
		close(sd);
		return -1;
	}
	printf("listening...\n");
	while(1)
	{
		client_addrlen = sizeof(struct sockaddr);
		ad  = accept(sd ,(struct sockaddr *)&client_addr,&client_addrlen);
		if(ad == -1)
		{
			printf("accept error,errno is %d\n",errno);
			close(sd);
			return -1;
		}
		printf("Catch connect!client IP:%s;PORT:%d\n"
				,inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
		read(ad,&buf,20);
		printf("recv from client :%s\n",buf);
		close(ad);
	}
	close(sd);
	return 0;

}

//TCP client
#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<unistd.h>
#include<arpa/inet.h>
//#define PORT 5678
//#define IP "127.0.0.1"
int main(int argc,char *argv[])
{
	int sockfd;
	int err;
	int client_addrlen;
	char *host;
	char buf[20];
	int port;
//	char buf[20] = "I am client";
	if(argc !=3)
	{

		printf("format error!format: %s  address  port\n",argv[0]);
		return -1;
	}
	if((host = argv[1])==NULL)
	{
		printf("please enter true address!\n");
		return -1;
	}
	if((port = atoi(argv[2]))<0)
	{
		printf("please enter true port!\n");
		return -1;
	}

	struct sockaddr_in server_addr, client_addr;
	sockfd = socket(AF_INET,SOCK_STREAM,0);
	if(sockfd == -1)
	{
		printf("creat socket error,errno = %d\n",errno);
		return -1;
	}
	printf("client sockfd is %d\n",sockfd);
	server_addr.sin_family = AF_INET;
	server_addr.sin_port  = htons(port);
	server_addr.sin_addr.s_addr  = inet_addr(host);
//	inet_aton(&IP,&server_addr.sin_addr);
	err = connect(sockfd,(struct sockaddr *)&server_addr,sizeof(server_addr));
 if(err==-1)
 {
	 printf("connect error,errno = %d\n",errno);
	 return -1;

 }
	printf("connected!Target server IP:%s PORT:%d \n",host,ntohs(server_addr.sin_port));
	printf("please enter message:");
	fgets(buf,20,stdin);
	write(sockfd,&buf,20);
	close(sockfd);
	return 0;

}

//升级版服务器端
#include<stdio.h>
#include<sys/socket.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<pthread.h>
#define PORT 5678
char ad[20],buf[20];
int i;
struct sockaddr_in server_addr, client_addr;

void *pthread_read(void *arg)
{
	while(1)
	{
		read(ad[(int)arg],buf,20);
		printf("client IP:%s, msg:%s\n",inet_ntoa(client_addr.sin_addr),buf);
	}

	return NULL;
}

int main(int argc,char *argv[])
{
	int sd;
	int err,err1;
	int client_addrlen;
	pthread_t ntid[20];
	sd = socket(AF_INET,SOCK_STREAM,0);
	if(sd == -1)
	{
		printf("creat socket error,errno = %d\n",errno);
		return -1;
	}
	memset(&server_addr,0,sizeof(struct sockaddr_in));
	server_addr.sin_family  = AF_INET;
	server_addr.sin_port = htons(PORT);
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//32bit IPv4 Address
	err = bind(sd ,(struct sockaddr *)&server_addr,sizeof(struct sockaddr));
	if(err == -1)
	{
		printf("bind error,errno is %d\n",errno);
		close(sd);
		return -1;
	}
	printf("bind success!\n");
	if(listen(sd ,10) == -1)
	{
		printf("listen error,errno is %d\n",errno);
		close(sd);
		return -1;
	}
	printf("listening...\n");
	client_addrlen = sizeof(struct sockaddr);
	while(1)
	{

		ad[i]= accept(sd,(struct sockaddr *)(&client_addr),&client_addrlen);
		if(ad[i] == -1)
		{
			printf("accept error,errno is %d\n",errno);
			close(sd);
			return -1;
		}
		printf("Catch connect!IP:%s;PORT:%d\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
		err1 = pthread_create(&ntid[i],NULL,pthread_read,(void *)i);
		if(err1!=0)
		{
			printf("creat thread error!\n");
			close(ad[i]);
		}
		i++;
	}
	close(sd);
	return 0;

}

//升级版客户端
int main(int argc,char *argv[])
{
	int sockfd;
	int err;
	int client_addrlen;
	char *host;
	char buf[20];
	int port;
	if(argc !=3)
	{

		printf("format error!format: %s  address  port\n",argv[0]);
		return -1;
	}
	if((host = argv[1])==NULL)
	{
		printf("please enter true address!\n");
		return -1;
	}
	if((port = atoi(argv[2]))<0)
	{
		printf("please enter true port!\n");
		return -1;
	}

	struct sockaddr_in server_addr, client_addr;
	sockfd = socket(AF_INET,SOCK_STREAM,0);
	if(sockfd == -1)
	{
		printf("creat socket error,errno = %d\n",errno);
		return -1;
	}
	printf("client sockfd is %d\n",sockfd);
	server_addr.sin_family = AF_INET;
	server_addr.sin_port  = htons(port);
	server_addr.sin_addr.s_addr  = inet_addr(host);
	err = connect(sockfd,(struct sockaddr *)&server_addr,sizeof(server_addr));
 if(err==-1)
 {
	 printf("connect error,errno = %d\n",errno);
	 return -1;

 }
	printf("connected!Target server IP:%s PORT:%d \n",host,ntohs(server_addr.sin_port));
	while(1)
	{
		printf("please enter message:");
		fgets(buf,20,stdin);
		write(sockfd,&buf,20);
	}
	close(sockfd);
	return 0;

}

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