linux下Socket编程（一）简介

int socket(int domain, int type, int protocol);  //返回sockfd(描述符)

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

include <netinet/in.h>
 
struct sockaddr {
    unsigned short    sa_family;    // 2 bytes address family, AF_xxx
    char              sa_data[14];     // 14 bytes of protocol address
};
 
// IPv4 AF_INET sockets:
 
struct sockaddr_in {
    short            sin_family;       // 2 bytes e.g. AF_INET, AF_INET6
    unsigned short   sin_port;    // 2 bytes e.g. htons(3490)
    struct in_addr   sin_addr;     // 4 bytes see struct in_addr, below
    char             sin_zero[8];     // 8 bytes zero this if you want to
};
 
struct in_addr {
    unsigned long s_addr;          // 4 bytes load with inet_pton()
};

int listen(int sockfd, int backlog);

struct inet_connection_sock {
   /* inet_sock has to be the first member! */
   struct inet_sock      icsk_inet;
   struct request_sock_queue icsk_accept_queue;
   struct inet_bind_bucket   *icsk_bind_hash;
   //....省略后面的代码
}

#include <sys/types.h>
#include <sys/socket.h>
int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

#include <unistd.h>
int close(int fd);

struct sockaddr_in sockaddrClient;
int clientl=sizeof(sockaddrClient);
// if((connfd = accept(sock,NULL,NULL))==-1) {
if((connfd = accept(sock,(struct sockaddr*)&sockaddrClient,(socklen_t *)&clientl))==-1) {
        printf("accpet socket error: %s errno :%d\n",strerror(errno),errno);
}
unsigned short port= ntohs(sockaddrClient.sin_port);
const char *ip=inet_ntop(AF_INET,(void *)&sockaddrClient.sin_addr,cilentIp,16);
printf("client %s:%d\n",cilentIp,port);

#include <arpa/inet.h>
const char *inet_ntop(int af, const void *src,char *dst, socklen_t size);

const char *ip=inet_ntop(AF_INET,(void *)&sockaddrClient.sin_addr,cilentIp,16);
if(ip!=NULL){
  printf("ip is :%s",ip);
}

#include <arpa/inet.h>
int inet_pton(int af, const char *src, void *dst);

char *servInetAddr = "127.0.0.1";
//端口号由外部传入
int port=atoi(argv[1]);
sockaddr.sin_port = htons(port);
inet_pton(AF_INET,servInetAddr,&sockaddr.sin_addr);

#include "stdio.h"
//socket相关函数需要
#include <sys/types.h>
#include <sys/socket.h>
//close函数需要
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <errno.h>
#include <arpa/inet.h>
#include <thread>
#include <iostream>
#include "SocketThread.h"
using namespace std;

#define MAXLINE 1024

int main(int argc,char ** argv){
        int connfd;
        char buff[MAXLINE];
        int n;
        //创建一个socket
        int sock=socket(AF_INET,SOCK_STREAM,0);
        if(sock==-1) {
                printf("create socket failed\n" );
        }
        //监听的端口
        unsigned short bindPort=8888;
        if(argc>=2) {
                //如果外部自定义了端口，则用外部自定义的端口
                bindPort=atoi(argv[1]);
        }
        printf("create socket success! %d\n", sock);
        struct sockaddr_in sockaddr;
        memset(&sockaddr,0,sizeof(sockaddr));
        sockaddr.sin_family=AF_INET;
        sockaddr.sin_addr.s_addr=htonl(INADDR_ANY);
        sockaddr.sin_port=htons(bindPort);
        //开始绑定
        //这里要注意要使用::  这样就调用的全局的bind函数，而不是std中的bind
        ::bind(sock,(struct sockaddr *)&sockaddr,sizeof(sockaddr));
        //监听，最多支持10个连接
        listen(sock,10);
        char cilentIp[20];
        while (true) {
                /* code */
                struct sockaddr_in sockaddrClient;
                int clientl=sizeof(sockaddrClient);
                printf("wait for client connect\n" );
                //不关心客户端的信息
                // if((connfd = accept(sock,NULL,NULL))==-1) {
                //接受客户端连接的同时，获取客户端的信息
                if((connfd = accept(sock,(struct sockaddr*)&sockaddrClient,(socklen_t *)&clientl))==-1) {
                        printf("accpet socket error: %s errno :%d\n",strerror(errno),errno);
                }
                //获取端口
                unsigned short port= ntohs(sockaddrClient.sin_port);
                //网络Ip=>主机Ip
                const char *ip=inet_ntop(AF_INET,(void *)&sockaddrClient.sin_addr,cilentIp,16);
                printf("client %s:%d\n",cilentIp,port);
                //使用线程
                SocketThread* st=new SocketThread(connfd);
                thread t(&SocketThread::run,st);
                t.detach();
        }
        int ret=close(sock);
        if(ret==-1) {
                printf("socket close failed\n");
        }else{
                printf("%d close success!\n",sock );
        }
        return 0;
}

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#define MAXLINE 1024
int main(int argc,char **argv)
{
        //连接的地址
        const char *servInetAddr = "127.0.0.1";
        int socketfd;
        struct sockaddr_in sockaddr;
        char recvline[MAXLINE], sendline[MAXLINE];
        int n;
        unsigned short port=8888;
        if(argc >= 2)
        {
                //端口号由外部传入
                port=atoi(argv[1]);
        }
        socketfd = socket(AF_INET,SOCK_STREAM,0);
        memset(&sockaddr,0,sizeof(sockaddr));
        sockaddr.sin_family = AF_INET;
        sockaddr.sin_port = htons(port);
        //主机Ip=>网络Ip
        inet_pton(AF_INET,servInetAddr,&sockaddr.sin_addr);
        //连接服务端
        if((connect(socketfd,(struct sockaddr*)&sockaddr,sizeof(sockaddr))) < 0 )
        {
                printf("connect error :[%s] errno: %d\n",strerror(errno),errno);
                exit(0);
        }
        printf("send message to server\n");
        int cmp=0;
        while(true) {
                printf("input your mssage\n");
                fgets(sendline,1024,stdin);
                //判断输入，如果是exit则退出并关闭连接
                int cmp=strcmp(sendline,"exit\n");
                if(cmp==0) {
                        break;
                }
                //发送数据。
                if((send(socketfd,sendline,strlen(sendline),0)) < 0)
                {
                        printf("send mes error: [%s] errno : %d",strerror(errno),errno);
                        exit(0);
                }
                memset(sendline,0,sizeof(sendline));
        }
        close(socketfd);
        printf("exit\n");
        exit(0);
}

#ifndef SOCKET_THREAD_H
#define SOCKET_THREAD_H
#include <iostream>
#include <unistd.h>
#include <sys/socket.h>

using namespace std;
class SocketThread{
private:
  int sock;
public:
    SocketThread(int sock){
        this->sock=sock;
    }
    ~SocketThread(){
      cout<<"release"<<endl;
    }
    void run(){
        int n=0;
        cout<<"new thread for socket "<<this->sock<<endl;
        char buff[1024];
        for(;; ) {
                n = recv(this->sock,buff,1024,0);
                if(n<=0) {
                        //如果客户端断开了，这里就跳出循环
                        break;
                }
                buff[n] = '\0';
                printf("%d=>%s",n,buff);
        }
        close(this->sock);
        cout<<this->sock<<" closed"<<endl;
    }
};
#endif

all: server client
objects = SocketThread.h server.cpp

server : $(objects)
    # g++ -o server $(objects)
    g++ -lpthread -o server $(objects)  -std=c++0x

client : client.cpp
    g++ -o client client.cpp

.PHONY : clean
clean :
    -rm  server client