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<td width="68%" background="DDl_back2.jpg" height="44"><big><big><font face="黑体"><p align="center">               ● UNIX网络编程                       (BM: clown)                </font></big></big></td></tr>
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<tr><td width="100%" colspan="2" height="100" align="center" valign="top"><br><p align="center">[<a href="index.htm">回到开始</a>][<a href="10.htm">上一层</a>][<a href="183.htm">下一篇</a>]
<hr><p align="left"><small>发信人: clown (梧桐叶), 信区: UNP <br>

标  题: 接收发送者的凭证程序 <br>

发信站: UNIX编程 (2001年09月24日21:07:48 星期一), 站内信件 <br>

  <br>

//server <br>

#include <sys/un.h> <br>

#include <netinet/in.h> <br>

#include <sys/types.h> <br>

#include <sys/socket.h> <br>

#include <sys/param.h> <br>

//#include <sys/ucred.h> <br>

#include <string.h> <br>

#include <signal.h> <br>

#include <sys/wait.h> <br>

#include <errno.h> <br>

  <br>

#define PATH "/tmp/tcpdomain" <br>

  <br>

void sig_chld(int signo); <br>

void str_echo(int sockfd); <br>

int read_cred(int fd, void *ptr, int nbytes, struct ucred *fcredptr); <br>

  <br>

int main() <br>

int main() <br>

{ <br>

    int listenfd, connfd; <br>

    pid_t childpid; <br>

    socklen_t clilen; <br>

    struct sockaddr_un cliaddr, servaddr; <br>

    int optval, optlen; <br>

    errno = 0; <br>

    if((listenfd = socket(AF_LOCAL, SOCK_STREAM, 0)) < 0) { <br>

        printf("create socket error\n"); <br>

        exit(1); <br>

    } <br>

    memset(&servaddr, 0, sizeof(servaddr)); <br>

    servaddr.sun_family = AF_LOCAL; <br>

    strncpy(servaddr.sun_path, PATH, sizeof(servaddr.sun_path)-1); <br>

  <br>

    optval = 1; <br>

    optlen = sizeof(int); <br>

    if(setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&optval,  o <br>

ptlen) == -1) { <br>

        printf("setsockopt error\n"); <br>

        exit(1); <br>

    } <br>

    } <br>

  <br>

    unlink(PATH); <br>

    if(bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) { <br>

        printf("bind error\n"); <br>

        exit(1); <br>

    } <br>

    if(listen(listenfd, 5) < 0) { <br>

        printf("listen error\n"); <br>

        exit(1); <br>

    } <br>

    signal(SIGCHLD, sig_chld); <br>

    for( ; ; ) { <br>

        clilen = sizeof(cliaddr); <br>

        memset(&cliaddr, 0, clilen); <br>

        if((connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen)) < 0 <br>

) <br>

{ <br>

            printf("accept error\n"); <br>

            exit(1); <br>

        } <br>

        printf("client: %s, len: %d\n", cliaddr.sun_path, clilen); <br>

        if((childpid = fork()) == 0) {  //child process <br>



            close(listenfd); <br>

            str_echo(connfd); <br>

            exit(0); <br>

        } <br>

        close(connfd);  //parent process <br>

    } <br>

    close(listenfd); <br>

    return 0; <br>

} <br>

  <br>

void str_echo(int sockfd) <br>

{ <br>

    ssize_t n; <br>

    const int on = 1; <br>

    char line[32]; <br>

    struct ucred cred; <br>

    if(setsockopt(sockfd, SOL_SOCKET, SCM_CREDENTIALS, &on, sizeof(on)) < 0) { <br>

        printf("setsockopt LOCAL_CREDS error\n"); <br>

        exit(1); <br>

    } <br>

    if((n = read_cred(sockfd, NULL, 0, &cred)) < 0) { <br>

        printf("read_cred returned a error\n"); <br>



        exit(1); <br>

    } else if(cred.pid== 0) <br>

        printf("no credentials returned\n"); <br>

    else { <br>

        printf("real uid: %d, gid: %d, pid: %d\n", cred.uid, cred.gid, cred.pid) <br>

; <br>

    } <br>

    for( ; ; ) { <br>

        if((n = recv(sockfd, line, 31, 0)) == 0) <br>

            return; //connection closed <br>

        else if( n < 0) { <br>

            printf("receive error\n"); <br>

            return; <br>

        } <br>

        line[n] = '\0'; <br>

        printf("%s", line); <br>

        if(send(sockfd, line, strlen(line), 0) < 0) { <br>

            printf("send error\n"); <br>

            return; <br>

        } <br>

    } <br>

} <br>

} <br>

  <br>

void sig_chld(int signo) <br>

{ <br>

    pid_t pid; <br>

    int stat; <br>

    while((pid = waitpid(-1, &stat, WNOHANG)) > 0) <br>

        printf("child %d terminated\n", pid); <br>

    return; <br>

} <br>

  <br>

int read_cred(int fd, void *ptr, int nbytes, struct ucred *fcredptr) <br>

{ <br>

    struct msghdr msg; <br>

    struct iovec iov[1]; <br>

    int n; <br>

    union { <br>

        struct cmsghdr cm; <br>

        char control[CMSG_SPACE(sizeof(struct ucred))]; <br>

    } control_un; <br>

    struct cmsghdr *cmptr; <br>

    msg.msg_control = control_un.control; <br>

    msg.msg_controllen = sizeof(control_un.control); <br>



    msg.msg_name = NULL; <br>

    msg.msg_namelen = 0; <br>

    iov[0].iov_base = ptr; <br>

    iov[0].iov_len = nbytes; <br>

    msg.msg_iov = iov; <br>

    msg.msg_iovlen = 1; <br>

    if((n = recvmsg(fd, &msg, 0)) < 0) { <br>

        perror("recvmsg"); <br>

        return n; <br>

    } <br>

    if(fcredptr) { <br>

        if(msg.msg_controllen > sizeof(struct cmsghdr)) { <br>

            cmptr = CMSG_FIRSTHDR(&msg); <br>

            if(cmptr->cmsg_len != CMSG_LEN(sizeof(struct ucred))) { <br>

                printf("control length: %d, length of struct ucred: %d\n", cmptr <br>

->cmsg_l <br>

en, sizeof(struct ucred)); <br>

                exit(1); <br>

            } else if(cmptr->cmsg_level != SOL_SOCKET) { <br>

                printf("control level != SOL_SOCKET\n"); <br>

                exit(1); <br>

            } else if(cmptr->cmsg_type != SCM_CREDENTIALS) { <br>



                printf("control type != SCM_CREDENTIALS\n"); <br>

                exit(1); <br>

            } <br>

            memcpy(fcredptr, CMSG_DATA(cmptr), sizeof(struct ucred)); <br>

        } else <br>

            bzero(fcredptr, sizeof(struct ucred)); <br>

    } <br>

    return n; <br>

} <br>

  <br>

客户程序可以使用上面的回射程序中的客户程序，执行结构如下： <br>

client: , len: 2 <br>

recvmsg: Resource temporarily unavailable <br>

read_cred returned a error <br>

  <br>

  <br>

-- <br>

易朽的是生命，似那转瞬即谢的花朵；然而永存的，是对未来的渴望， <br>

是那生生世世传递下来的，不朽的，生的激情。每一朵勇敢开放的花， <br>

都是一个死亡唇边的微笑。 <br>

※ 来源:·UNIX编程 www.tiaozhan.com/unixbbs/·[FROM: 211.69.205.23] <br>

</small><hr>
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