sendmsg SCM_RIGHTS problem

[Andrey G. Kaplanov]

Respected colleagues! I have are problem of send SCM_RIGHTS message through AF_UNIX socket. Below - examples of server and client sources. Sendmsg gives an error : Invalid argument. That I do;make wrong? //////////////////////////// Server ///////////////////////////////// #   include <unistd.h> #   include <stdio.h> #   include <string.h> #   include <fcntl.h> #   include <sys/types.h> #   include <sys/stat.h> #   include <sys/stropts.h> #   include <sys/socket.h> #   include <sys/errno.h> #   include <sys/timex.h> #   include <linux/un.h> void main() {     sockaddr_un addr;     int sock = socket(AF_UNIX, SOCK_STREAM, 0);     addr.sun_family = AF_UNIX;     memset(addr.sun_path, 0, UNIX_PATH_MAX);     strncpy(addr.sun_path, "sock", UNIX_PATH_MAX-1);     unlink("sock");     bind(sock, (sockaddr *)&addr, sizeof(sockaddr_un));     listen(sock, 5);     if (accept(sock, (struct sockaddr*)0, (size_t *)0) == -1)     {         fprintf(stderr, "accept error %s\n", strerror(errno));         exit(1);     }     printf("accepted\n");     getchar(); } ////////////////////////// Client ////////////////////////////////// #   include <unistd.h> #   include <stdio.h> #   include <string.h> #   include <fcntl.h> #   include <sys/types.h> #   include <sys/stat.h> #   include <sys/stropts.h> #   include <sys/socket.h> #   include <sys/errno.h> #   include <sys/timex.h> #   include <linux/un.h> void main() {     sockaddr_un addr;     int dsc = socket(PF_UNIX, SOCK_STREAM, 0);     addr.sun_family = AF_UNIX;     strcpy(addr.sun_path, "sock");     if (::connect(dsc, (sockaddr *)&addr, sizeof(sockaddr_un)) != 0)     {         fprintf(stderr, "connect error %s\n", strerror(errno));         exit(1);     }     msghdr msg;     char cbuf[CMSG_SPACE(CMSG_LEN(sizeof(int)))];     msg.msg_name = 0;     msg.msg_namelen = 0;     msg.msg_iov = 0;     msg.msg_iovlen = 0;     msg.msg_control = cbuf;     msg.msg_controllen = CMSG_SPACE(CMSG_LEN(sizeof(int)));     msg.msg_flags = 0;     cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);     cmsg->cmsg_len = CMSG_LEN(sizeof(int));     cmsg->cmsg_level = SOL_SOCKET;     cmsg->cmsg_type = SCM_RIGHTS;     *((int *)CMSG_DATA(cmsg)) = dsc;     if (sendmsg(dsc, &msg, 0) == -1)     {         fprintf(stderr, "sendmsg error %s\n", strerror(errno));         exit(1);     } }