网络编程1：简易的TCP socket编程

返回：Linux网络编程学习笔记

1.参考链接

（1）【Linux网络编程】TCP网络编程中connect()、listen()和accept()三者之间的关系：

https://blog.csdn.net/dengjin20104042056/article/details/52357452

（2）Linux网络编程基础-03_TCP/IP网络编程

https://blog.csdn.net/Set_Mode/article/details/90229239

2.关键函数

（1）socket

NAME
       socket - create an endpoint for communication

SYNOPSIS
       #include           /* See NOTES */
       #include 

       int socket(int domain, int type, int protocol);

（2）bind

NAME
       bind - bind a name to a socket

SYNOPSIS
       #include           /* See NOTES */
       #include 

       int bind(int sockfd, const struct sockaddr *addr,
                socklen_t addrlen);

（3）listen

NAME
       listen - listen for connections on a socket

SYNOPSIS
       #include           /* See NOTES */
       #include 

       int listen(int sockfd, int backlog);

（4）accept

NAME
       accept, accept4 - accept a connection on a socket

SYNOPSIS
       #include           /* See NOTES */
       #include 

       int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

       #define _GNU_SOURCE             /* See feature_test_macros(7) */
       #include 

       int accept4(int sockfd, struct sockaddr *addr,
                   socklen_t *addrlen, int flags);

（5）read

NAME
       read - read from a file descriptor

SYNOPSIS
       #include 

       ssize_t read(int fd, void *buf, size_t count);

（6）write

NAME
       write - write to a file descriptor

SYNOPSIS
       #include 

       ssize_t write(int fd, const void *buf, size_t count);

3.代码

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc,char *argv[])
{
int tcp_fd,ret,accept_fd,i;
char buf[1024];
char IPdotdec[20]="127.0.0.1";
struct in_addr addr_pton;
socklen_t client_addr_len;
struct sockaddr_in service_addr,client_addr;
service_addr.sin_family=AF_INET;
service_addr.sin_port=htons(9527);
service_addr.sin_addr.s_addr=htonl(INADDR_ANY);

//memset(service_addr,sizeof(service_addr),0);


//1.socket
        tcp_fd=socket(AF_INET,SOCK_STREAM,0);
        if(tcp_fd<0)
        {
                perror("error socket!\n");
                exit(1);
        }
//2.bind
        ret=bind(tcp_fd,(struct sockaddr*)&service_addr,sizeof(service_addr));
        if(ret!=0)
        {
                perror("error bind!\n");
                exit(1);
        }
//3.listen
        listen(tcp_fd,128);
//4.accept
        client_addr_len=sizeof(client_addr);
        accept_fd=accept(tcp_fd,(struct sockaddr*)&client_addr,&client_addr_len);
        if(accept_fd<0)
        {
                perror("error accept!\n");
                exit(1);
        }
//5.read & write
        int count=5;
        while(1)
        {
                ret=read(accept_fd,buf,1024);
                if(ret>0)
                {
                        printf("client_data_in:%s\n",buf);
                        //write(STDOUT_FILENO,buf,ret);
                        for(i=0;i

4.代码调试

使用nc命令测试服务器端socket服务端代码逻辑功能：

（1）代码编写和运行服务

root@wang-virtual-machine:/home/wang/03-linux-net-work/0404-socket# vim service.c
root@wang-virtual-machine:/home/wang/03-linux-net-work/0404-socket# gcc -o service service.c
root@wang-virtual-machine:/home/wang/03-linux-net-work/0404-socket# ./service
（2）在另一个端口测试nc命令

root@wang-virtual-machine:/home/wang# nc 127.0.0.1 9527

（3）调试记录

5.遇到的问题

（1）将sin_addr写成sa_addr；

（2）bind函数参数写错，把sockaddr写成了socketaddr：

 int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);

（3）理解htonl与inet_pton函数的使用场景