linux_socket_tcp基礎代碼

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h> // for struct sockaddr_in 
#include <netinet/ip.h> /* superset of previous */
#include <arpa/inet.h>  //for  inet_pton
#include<stdio.h>
#include<ctype.h>
#include<string.h>
#include <unistd.h>

#define SPORT 6666
#define SIP "127.0.0.1"
int main(void)
{
    int sfd = socket(AF_INET,SOCK_STREAM,0);
    if(sfd<0)
    {
        printf("創建套接字失敗\n");
        return -1;
    }
    int nfd = 0;
    int ret = 0;
    struct sockaddr_in addr;
    struct sockaddr_in caddr;
    memset(&caddr,0,sizeof(caddr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(SPORT);
    int num = 0;
    ret = inet_pton(AF_INET,SIP,&addr.sin_addr);
    /* inet_pton 這個地方自己老是掉進去,就是這個傳入參數,目前我將struct socdaddr_in 中的sin-addr傳進去,綁定端口就會成功.*/
    socklen_t clen = sizeof(caddr);
    int n = 0;
    char buf[BUFSIZ];
    memset(buf,0,BUFSIZ); 
    //addr.sin_addr.s_addr=htonl(INADDR_ANY);
    char tmp[128];
    ret = bind(sfd,(struct sockaddr *)&addr,sizeof(addr));
    if(ret <0)
    {
        printf("綁定端口失敗\n");
        return -1;
    }
    listen(sfd,128);
    nfd = accept(sfd,(struct sockaddr*)&caddr,&clen);
    printf("客戶端端口:%d \n",ntohs(caddr.sin_port));
    inet_ntop(AF_INET,&caddr.sin_addr,tmp,128);
    printf("客戶端ip:%s \n",tmp);
    /*這個地方:accept之後,接收到一個客戶端連接,之後就會往下走,所以要想實現高併發,
    這個地方需要針對accept 採用多線程多進程 */
    while(1)
    {
        n = read(nfd,buf,sizeof(buf));
        for(int i = 0; i < n;i++)
        {
            buf[i] = toupper(buf[i]);
        }

        write(nfd,buf,n);
    }

    close(nfd);
    close(sfd);
    return 0;
}

客戶端代碼：

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h> // for struct sockaddr_in 
#include <netinet/ip.h> /* superset of previous */
#include <arpa/inet.h>  //for  inet_pton
#include<stdio.h>
#include<ctype.h>
#include<string.h>
#include <unistd.h>

#define SPORT 6666
#define SIP "127.0.0.1"
int main(void)
{
    int sfd = socket(AF_INET,SOCK_STREAM,0);
    if(sfd<0)
    {
        printf("創建套接字失敗\n");
        return -1;
    }
    char buf[BUFSIZ];
    bzero(buf,BUFSIZ);
    int ret = 0;
    int n = 0;
    struct sockaddr_in addr;
    bzero(&addr,sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(SPORT);
    ret = inet_pton(AF_INET,SIP,&addr.sin_addr);

    connect(sfd,(struct sockaddr*)&addr,sizeof(addr));
    while(1)
    {
        fgets(buf,sizeof(buf),stdin);
        write(sfd,buf,strlen(buf));
        n = read(sfd,buf,strlen(buf));
        write(stdout,buf,n);
    }

    close(sfd);
    return 0;
}