Linux14三次握手，四次挥手（未完）

1.三次握手

1.1主要函数

htons主机转网络字节序列
struct sockaddr 通用套接字地址
struct sockaddr_in ipv4专用的套接字地址

1.2过程

tcp是面向连接的，可靠的，流式服务
udp是无连接的，不可靠的数据报服务

2.四次挥手

2.1过程

3.代码实现

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<assert.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
int main()
{
    int sockfd=socket(AF_INET,SOCK_STREAM,0);
    assert(sockfd!=-1);

    struct sockaddr_in saddr,caddr;
    memset(&saddr,0,sizeof(saddr));
    saddr.sin_family=AF_INET;
    saddr.sin_port=htons(6000);
    saddr.sin_addr.s_addr=inet_addr("127.0.0.1");

    int res=bind(sockfd,(struct sockaddr*)&saddr,sizeof(saddr));
    assert(res!=-1);

    listen(sockfd,5);//creat listen list;
    //finished sharked,unfinished~,list
    
    while(1)
    {
        int len =sizeof(caddr);
        int c = accept(sockfd,(struct sockaddr*)&caddr,&len);//link taojiezi
        if(c<0)
        {
            continue;
        }

        printf("accept c=%d,ip=%s,port=%d\n",c,inet_ntoa(caddr.sin_addr),ntohs(caddr.sin_port));
        while(1)
        {
            char buff[128]={0};
            //int n=recv(c,buff,127,0);//n==0,close;
            int n=recv(c,buff,1,0);//n==0,close;
            if(n<=0)
            {
                break;
            }
            printf("buff==%s\n",buff);
            send(c,"ok",2,0);
        }
        printf("one client over!!\n");
        close(c);
        
   }


}

cli.c

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<assert.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
int main()
{
    int sockfd=socket(AF_INET,SOCK_STREAM,0);
    assert(sockfd!=-1);

    struct sockaddr_in saddr;
    memset(&saddr,0,sizeof(saddr));
    saddr.sin_family=AF_INET;
    saddr.sin_port=htons(6000);
    saddr.sin_addr.s_addr=inet_addr("127.0.0.1");

    int res=connect(sockfd,(struct sockaddr*)&saddr,sizeof(saddr));
    assert(res!=-1);
    while(1)
    {
        char buff[128]={0};
        printf("input:\n");
        fgets(buff,128,stdin);

        if(strncmp(buff,"end",3)==0)
        {
            break;
        }

        send(sockfd,buff,strlen(buff),0);
        memset(buff,0,128);
        recv(sockfd,buff,127,0);
        printf("buff==%s\n",buff);
    }
    close(sockfd);
}

实验结果图

4.udp服务

4.1udp_ser.c

udp_ser.c

#include<stdio.h>
#include<unistd.h>
#include<assert.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdlib.h>
int main()
{
    int sockfd=socket(AF_INET,SOCK_DGRAM,0);
    assert(sockfd!=-1);

    struct sockaddr_in saddr,caddr;
    memset(&saddr,0,sizeof(saddr));
    saddr.sin_family=AF_INET;
    saddr.sin_port=htons(6000);
    saddr.sin_addr.s_addr=inet_addr("127.0.1");

    int res=bind(sockfd,(struct sockaddr*)&saddr,sizeof(saddr));
    assert(res!=-1);

    while(1)
    {
        int len=sizeof(caddr);
        char buff[128]={0};
        int n=recvfrom(sockfd,buff,127,0,(struct sockaddr*)&caddr,&len);
        if(n==-1)
        {
            continue;
        }
        printf("port:%d,buff==%s\n",ntohs(caddr.sin_port),buff);

        sendto(sockfd,"0k",2,0,(struct sockaddr*)&caddr,sizeof(caddr));

    }


}

4.2udp_cli

#include<stdio.h>
#include<unistd.h>
#include<assert.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdlib.h>
int main()
{
    int sockfd=socket(AF_INET,SOCK_DGRAM,0);
    assert(sockfd!=-1);

    struct sockaddr_in saddr,caddr;
    memset(&saddr,0,sizeof(saddr));
    saddr.sin_family=AF_INET;
    saddr.sin_port=htons(6000);
    saddr.sin_addr.s_addr=inet_addr("127.0.1");

    while(1)
    {
        char buff[128]={0};
        printf("input:\n");

        fgets(buff,128,stdin);
        if(strncmp(buff,"end",3)==0)
        {
            break;
        }
        sendto(sockfd,buff,strlen(buff),0,(struct sockaddr*)&saddr,sizeof(saddr));

        int len =sizeof(saddr);
        memset(buff,0,128);

        recvfrom(sockfd,buff,127,0,(struct sockaddr*)&saddr,&len);
        printf("buff==%s\n",buff);

    }
    //close(s);


}