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83 lines
1.9 KiB
83 lines
1.9 KiB
/* CC0 license (public domain) - see LICENSE file for details */
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#include <ccan/fdpass/fdpass.h>
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#include <sys/socket.h>
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#include <errno.h>
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#include <string.h>
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bool fdpass_send(int sockout, int fd)
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{
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/* From the cmsg(3) manpage: */
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struct msghdr msg = { 0 };
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struct cmsghdr *cmsg;
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struct iovec iov;
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char c = 0;
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union { /* Ancillary data buffer, wrapped in a union
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in order to ensure it is suitably aligned */
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char buf[CMSG_SPACE(sizeof(fd))];
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struct cmsghdr align;
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} u;
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msg.msg_control = u.buf;
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msg.msg_controllen = sizeof(u.buf);
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memset(&u, 0, sizeof(u));
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cmsg = CMSG_FIRSTHDR(&msg);
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
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memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
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msg.msg_name = NULL;
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msg.msg_namelen = 0;
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_flags = 0;
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/* Keith Packard reports that 0-length sends don't work, so we
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* always send 1 byte. */
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iov.iov_base = &c;
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iov.iov_len = 1;
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return sendmsg(sockout, &msg, 0) == 1;
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}
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int fdpass_recv(int sockin)
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{
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/* From the cmsg(3) manpage: */
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struct msghdr msg = { 0 };
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struct cmsghdr *cmsg;
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struct iovec iov;
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int fd;
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char c;
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union { /* Ancillary data buffer, wrapped in a union
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in order to ensure it is suitably aligned */
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char buf[CMSG_SPACE(sizeof(fd))];
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struct cmsghdr align;
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} u;
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msg.msg_control = u.buf;
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msg.msg_controllen = sizeof(u.buf);
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msg.msg_name = NULL;
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msg.msg_namelen = 0;
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_flags = 0;
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iov.iov_base = &c;
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iov.iov_len = 1;
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if (recvmsg(sockin, &msg, 0) < 0)
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return -1;
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cmsg = CMSG_FIRSTHDR(&msg);
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if (!cmsg
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|| cmsg->cmsg_len != CMSG_LEN(sizeof(fd))
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|| cmsg->cmsg_level != SOL_SOCKET
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|| cmsg->cmsg_type != SCM_RIGHTS) {
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errno = -EINVAL;
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return -1;
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}
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memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
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return fd;
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}
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