tcp與udp的比較分析

tcp ：不記錄訊息邊界
udp：記錄訊息邊界

        用到的結構體
    struct sockaddr_un
    {
      __SOCKADDR_COMMON (sun_);
                        =====》#define __SOCKADDR_COMMON(sa_prefix) sa_family_t sa_prefix##family
                               =====》int sun_family;
                               =====》協議族 AF_UNIX

      char sun_path[108];    //進行本地通訊的路徑名   
    };     

    例子：
    struct sockaddr_un serveraddr;

    serveraddr.sun_family = AF_UNIX;
    //serveraddr.sun_path = "server_socket";
    strcpy(serveraddr.sun_path,  “server_socket”);
 

3、UDP本地通訊
流程：
伺服器：
建立套接字 socket
填充本地資訊結構體 sockaddr_un
繫結套接字 bind
通訊 recvfrom/sendto
客戶端：
建立套接字 socket
填充本地資訊結構體 sockaddr_un
通訊 sendto/recvfrom （如果需要接受伺服器的資訊，需要繫結）

4、TCP本地通訊

伺服器（server）

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/un.h>

//實現tcp本地通訊伺服器

#define N 128

#define errlog(errmsg) do{perror(errmsg); exit(1);}while(0)

int main(int argc, const char
 
 *argv[])
{
    int sockfd;
    struct sockaddr_un serveraddr, clientaddr;
    int acceptfd;
    char buf[N] = {};
    socklen_t addrlen = sizeof(struct sockaddr_un);

    //建立套接字 socket
    if((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
    {
        errlog("fail to socket");
    }

    //填充本地資訊結構體 sockaddr_un
    serveraddr.sun_family = AF_UNIX;
    strcpy(serveraddr.sun_path, "server_socket");

    //繫結套接字 bind
    if(bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
    {
        errlog("fail to bind");
    }

    //將套接字設定為監聽狀態 listen
    if(listen(sockfd, 10) < 0)
    {
        errlog("fail to listen");
    }

    //阻塞等待客戶端的連線請求 accept
    if((acceptfd = accept(sockfd, (struct sockaddr *)&clientaddr, &addrlen)) < 0)
    {
        errlog("fail to accept");
    }

    //通訊 recv/send
    while(1)
    {
        if(recv(acceptfd, buf, N, 0) < 0)
        {
            errlog("fail to recv");
        }

        printf("from client >>> %s\n", buf);

        strcat(buf, " from client ...");

        if(send(acceptfd, buf, N, 0) < 0)
        {
            errlog("fail to send");
        }
    }

    close(acceptfd);
    close(sockfd);

    return 0;
}

客戶端（client）

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/un.h>

//實現tcp本地通訊客戶端

#define N 128

#define errlog(errmsg) do{perror(errmsg); exit(1);}while(0)

int main(int argc, const char *argv[])
{
    int sockfd;
    struct sockaddr_un serveraddr;
    int acceptfd;
    char buf[N] = {};
    socklen_t addrlen = sizeof(struct sockaddr_un);

    //建立套接字 socket
    if((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
    {
        errlog("fail to socket");
    }

    //填充本地資訊結構體 sockaddr_un
    serveraddr.sun_family = AF_UNIX;
    strcpy(serveraddr.sun_path, "server_socket");


    //傳送客戶端的連線請求 connect
    if(connect(sockfd, (struct sockaddr *)&serveraddr, addrlen) < 0)
    {
        errlog("fail to connect");
    }

    //通訊 recv/send
    while(1)
    {
        fgets(buf, N, stdin);
        buf[strlen(buf) - 1] = '\0';

        if(send(sockfd, buf, N, 0) < 0)
        {
            errlog("fail to send");
        }

        if(recv(sockfd, buf, N, 0) < 0)
        {
            errlog("fail to recv");
        }

        printf("%s\n", buf);
    }

    close(sockfd);

    return 0;
}

4、UDP本地通訊

伺服器（server）

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <sys/un.h>

#define N 128

#define errlog(errmsg) do{perror(errmsg); exit(1);}while(0)

int main(int argc, const char *argv[])
{
    int sockfd;
    struct sockaddr_un serveraddr, clientaddr;
    socklen_t addrlen = sizeof(struct sockaddr_un);
    char buf[N] = {};

    //memset bzero 清空結構體（初始化）

    //建立套接字
    if((sockfd = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0)
    {
        errlog("fail to socket");
    }

    //填充本地資訊結構體
    serveraddr.sun_family = AF_UNIX;
    strcpy(serveraddr.sun_path, "server_socket");

    //將套接字與IP地址和埠號繫結
    if(bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
    {
        errlog("fail to bind");
    }

    while(1)
    {
        if(recvfrom(sockfd, buf, N, 0, (struct sockaddr *)&clientaddr, &addrlen) < 0)
        {
            errlog("fail to recvfrom");
        }

        if(strncmp(buf, "quit", 4) == 0)
        {
            break;
        }
        else
        {
            printf("from client %s\n", buf);

            strcat(buf, " from server...");

            if(sendto(sockfd, buf, N, 0, (struct sockaddr *)&clientaddr, sizeof(clientaddr)) < 0)
            {
                errlog("fail to sendto");
            }
        }


    }
    close(sockfd);

    return 0;
}

客戶端（client）

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/un.h>

#define N 128

#define errlog(errmsg) do{perror(errmsg); exit(1);}while(0)

int main(int argc, const char *argv[])
{
    int sockfd;
    struct sockaddr_un serveraddr, clientaddr;
    char buf[N] = {};

    socklen_t addrlen = sizeof(struct sockaddr_un);

    //建立套接字
    if((sockfd = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0)
    {
        errlog("fail to socket");
    }

    //填充網路資訊結構體
    serveraddr.sun_family = AF_UNIX;
    strcpy(serveraddr.sun_path, "server_socket");

    //填充客戶端網路資訊結構體
    clientaddr.sun_family = AF_UNIX;
    strcpy(clientaddr.sun_path, "client_socket");

    //繫結客戶端的資訊
    if(bind(sockfd, (struct sockaddr *)&clientaddr, addrlen) < 0)
    {
        errlog("fail to bind");
    }

    while(1)
    {
        fgets(buf, N, stdin);
        buf[strlen(buf) - 1] = '\0';

        if(sendto(sockfd, buf, N, 0, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
        {
            errlog("fail to sendto");
        }
        if(strncmp(buf, "quit", 4) == 0)
        {
            break;
        }
        else
        {
            if(recvfrom(sockfd, buf, N, 0, (struct sockaddr *)&serveraddr, &addrlen) < 0)
            {
                errlog("fail to recvfrom");
            }
            printf("%s\n", buf);
        }

    }

    close(sockfd);
    return 0;
}