TCP通讯程序设计

1.编程模型

2.函数学习

struct sockaddr {
sa_family_t sa_family;
char sa_data[14];
}

struct sockaddr_in {
short int sin_family;
short int sin_family;
unsigned short int sin_port;
struct in_addr sin_addr;
unsigned char sin_zero[8];
}

struct in_addr {
unsigned long s_addr;
}

• in_addr_t inet_addr(const char *cp)
功能：将字符串形式的IP地址转化为整数型的IP地址(网络字节序)
范例： in_addr.saddr = inet_addr(“192.168.1.1” );
• char *inet_ntoa (struct in_addr)
功能：将整数形式的IP地址转化为字符串形式的IP地址

uint32_t htonl(uint32_t hostlong);
将32位的数据从主机字节序转换为网络字节序
in_addr.saddr = htonl(INADDR_ANY)

uint16_t htons(uint16_t hostshort);
将16位的数据从主机字节序转换为网络字节序

uint32_t ntohl(uint32_t netlong);
将32位的数据从网络字节序转换为主机字节序

uint16_t ntohs(uint16_t netshort);
将16位的数据从网络字节序转换为主机字节序

3.综合实例

/* tcp_server.c */

#include <stdio.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>

#define portnum 3333

int main()
{
int sockfd,newfd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
char buffer[128];
int nbyte;
int sin_size;

//创建socket
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
printf("create socket error\n");
exit(1);
}

//设置要绑定的地址
bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(portnum);
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

//绑定地址
bind(sockfd,(struct sockaddr*)&server_addr,sizeof(struct sockaddr));

//监听端口
listen(sockfd,5);

while(1)
{
//等待连接
sin_size = sizeof(struct sockaddr);
newfd = accept(sockfd,(struct sockaddr*)&client_addr,&sin_size);
printf("server get connection from %s\n",inet_ntoa(client_addr.sin_addr));

//接收数据
nbyte = recv(newfd,buffer,128,0);
buffer[nbyte] = '\0';
printf("server received :%s",buffer);

//结束连接
close(newfd);
}
close(sockfd);

return 0;
}

/* tcp_client.c */

#include <stdio.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>

int main()
{
int sockfd;
char buffer[128];
struct sockaddr_in server_addr;

//创建套接字
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
printf("create socket error\n");
exit(1);
}

//设置要绑定的地址
bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(3333);
server_addr.sin_addr.s_addr = inet_addr("192.168.1.2");

//连接服务器
connect(sockfd,(struct sockaddr*)(&server_addr),sizeof(struct sockaddr));

//发送数据到服务器
printf("please input char :\n");
fgets(buffer,128,stdin);
send(sockfd,buffer,strlen(buffer),0);

//关闭连接
close(sockfd);
return 0;
}