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

函數(shù)說明: 創(chuàng)建本地域socket

函數(shù)參數(shù):    

    domain: AF_UNIX or AF_LOCAL

    type: SOCK_STREAM或者SOCK_DGRAM

    protocol: 0 表示使用默認(rèn)協(xié)議

函數(shù)返回值:

    成功: 返回文件描述符.

    失敗: 返回-1, 并設(shè)置errno值.

創(chuàng)建socket成功以后, 會(huì)在內(nèi)核創(chuàng)建緩沖區(qū), 下圖是客戶端和服務(wù)端內(nèi)核緩沖區(qū)示意圖.

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

函數(shù)說明: 綁定套接字

函數(shù)參數(shù):

    socket: 由socket函數(shù)返回的文件描述符

    addr: 本地地址

    addlen: 本地地址長(zhǎng)度

函數(shù)返回值:

    成功: 返回文件描述符.

    失敗: 返回-1, 并設(shè)置errno值.

需要注意的是: bind函數(shù)會(huì)自動(dòng)創(chuàng)建socket文件, 若在調(diào)用bind函數(shù)之前socket文件已經(jīng)存在, 則調(diào)用bind會(huì)報(bào)錯(cuò), 可以使用unlink函數(shù)在bind之前先刪除文件.

struct sockaddr_un {

    sa_family_t sun_family;  /* AF_UNIX or AF_LOCAL*/

    char sun_path[108];  /* pathname */

};

tcp的本地套接字服務(wù)器流程：

    創(chuàng)建套接字  socket(AF_UNIX,SOCK_STREAM,0)

    綁定 struct sockaddr_un &強(qiáng)轉(zhuǎn)

    偵聽 listen 

    獲得新連接 accept 

    循環(huán)通信 read-write 

    關(guān)閉文件描述符 close

tcp本地套接字客戶端流程：

    調(diào)用socket創(chuàng)建套接字

    調(diào)用bind函數(shù)將socket文件描述和socket文件進(jìn)行綁定.

        不是必須的, 若無顯示綁定會(huì)進(jìn)行隱式綁定，但服務(wù)器不知道誰連接了.

    調(diào)用connect函數(shù)連接服務(wù)端

    循環(huán)通信read-write

    關(guān)閉文件描述符 close

//本地socket通訊服務(wù)端

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <sys/un.h>

int main(){

    //創(chuàng)建socket

    int lfd = socket(AF_UNIX,SOCK_STREAM,0);

    if(lfd<0){

        perror("socket error");

        return -1;

    }

    //刪除socket文件，避免bind失敗

    unlink("./server.sock");

    //綁定

    struct sockaddr_un serv;

    bzero(&serv,sizeof(serv));

    serv.sun_family = AF_UNIX;

    strcpy(serv.sun_path,"./server.sock");

    int ret = bind(lfd,(struct sockaddr *)&serv,sizeof(serv));

    if(ret<0){

        perror("bind error");

        return -1;

    }

    //監(jiān)聽

    listen(lfd,10);

    //接收新的鏈接-accept

    struct sockaddr_un client;

    bzero(&client,sizeof(client));

    socklen_t len = sizeof(client);

    int cfd = accept(lfd,(struct sockaddr*)&client,&len);

    if(cfd<0){

        perror("accept error");

        return -1;

    }

    printf("cient->[%s]\n",client.sun_path);

    int n;

    char buf[1024];

    while(1){

        //讀取數(shù)據(jù)

        memset(buf,0x00,sizeof(buf));

        n = read(cfd,buf,sizeof(buf));

        if(n<=0){

            printf("read error or client close ,n=[%d]\n",n);

            break;

        }

        printf("n=[%d],buf=[%s]\n",n,buf);

        //發(fā)送數(shù)據(jù)

        write(cfd,buf,n);

    }

    //關(guān)閉套接字

    close(lfd);

    return 0;

}

//本地socket通信客戶端

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <sys/un.h>

int main(){

    //創(chuàng)建socket

    int cfd = socket(AF_UNIX,SOCK_STREAM,0);

    if(cfd<0){

        perror("socket error");

        return -1;

    }

    //刪除socket文件，避免bind失敗

    unlink("./client.sock");

    //綁定

    struct sockaddr_un client;

    bzero(&client,sizeof(client));

    client.sun_family= AF_UNIX;

    strcpy(client.sun_path,"./client.sock");

    int ret = bind(cfd,(struct sockaddr*)&client,sizeof(client));

    if(ret<0){

        perror("bind error");

        return -1;

    }

    struct sockaddr_un serv;

    bzero(&serv,sizeof(serv));

    serv.sun_family = AF_UNIX;

    strcpy(serv.sun_path,"./server.sock");

    ret = connect(cfd,(struct sockaddr*)&serv,sizeof(serv));

    if(ret<0){

        perror("connect error");

        return -1;

    }

    int n;

    char buf[1024];

    while(1){

        memset(buf,0x00,sizeof(buf));

        n = read(STDIN_FILENO,buf,sizeof(buf));

        //發(fā)送數(shù)據(jù)

        write(cfd,buf,n);

        //讀取數(shù)據(jù)

        memset(buf,0x00,sizeof(buf));

        n = read(cfd,buf,sizeof(buf));

        if(n<=0){

            printf("read error or client close ,n=[%d]",n);

            break;

        }

        printf("n=[%d],buf=[%s]",n,buf);

    }

    close(cfd);

    return 0;

}