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-rw-r--r--src/util/unix_recv_fd.c178
1 files changed, 178 insertions, 0 deletions
diff --git a/src/util/unix_recv_fd.c b/src/util/unix_recv_fd.c
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+/*++
+/* NAME
+/* unix_recv_fd 3
+/* SUMMARY
+/* receive file descriptor
+/* SYNOPSIS
+/* #include <iostuff.h>
+/*
+/* int unix_recv_fd(fd)
+/* int fd;
+/* DESCRIPTION
+/* unix_recv_fd() receives a file descriptor via the specified
+/* UNIX-domain socket. The result value is the received descriptor.
+/*
+/* Arguments:
+/* .IP fd
+/* File descriptor that connects the sending and receiving processes.
+/* DIAGNOSTICS
+/* unix_recv_fd() returns -1 upon failure.
+/* LICENSE
+/* .ad
+/* .fi
+/* The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/* Wietse Venema
+/* IBM T.J. Watson Research
+/* P.O. Box 704
+/* Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h> /* includes <sys/types.h> */
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <iostuff.h>
+
+/* unix_recv_fd - receive file descriptor */
+
+int unix_recv_fd(int fd)
+{
+ const char *myname = "unix_recv_fd";
+
+ /*
+ * This code does not work with version <2.2 Linux kernels, and it does
+ * not compile with version <2 Linux libraries.
+ */
+#ifdef CANT_USE_SEND_RECV_MSG
+ msg_warn("%s: your system has no support for file descriptor passing",
+ myname);
+ return (-1);
+#else
+ struct msghdr msg;
+ int newfd;
+ struct iovec iov[1];
+ char buf[1];
+
+ /*
+ * Adapted from: W. Richard Stevens, UNIX Network Programming, Volume 1,
+ * Second edition. Except that we use CMSG_LEN instead of CMSG_SPACE, for
+ * portability to some LP64 environments. See also unix_send_fd.c.
+ */
+#if defined(CMSG_SPACE) && !defined(NO_MSGHDR_MSG_CONTROL)
+ union {
+ struct cmsghdr just_for_alignment;
+ char control[CMSG_SPACE(sizeof(newfd))];
+ } control_un;
+ struct cmsghdr *cmptr;
+
+ memset((void *) &msg, 0, sizeof(msg)); /* Fix 200512 */
+ msg.msg_control = control_un.control;
+ if (unix_pass_fd_fix & UNIX_PASS_FD_FIX_CMSG_LEN) {
+ msg.msg_controllen = CMSG_LEN(sizeof(newfd)); /* Fix 200506 */
+ } else {
+ msg.msg_controllen = sizeof(control_un.control); /* normal */
+ }
+#else
+ msg.msg_accrights = (char *) &newfd;
+ msg.msg_accrightslen = sizeof(newfd);
+#endif
+
+ msg.msg_name = 0;
+ msg.msg_namelen = 0;
+
+ /*
+ * XXX We don't want to pass any data, just a file descriptor. However,
+ * setting msg.msg_iov = 0 and msg.msg_iovlen = 0 causes trouble: we need
+ * to read_wait() before we can receive the descriptor, and the code
+ * fails after the first descriptor when we attempt to receive a sequence
+ * of descriptors.
+ */
+ iov->iov_base = buf;
+ iov->iov_len = sizeof(buf);
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 1;
+
+ if (recvmsg(fd, &msg, 0) < 0)
+ return (-1);
+
+#if defined(CMSG_SPACE) && !defined(NO_MSGHDR_MSG_CONTROL)
+ if ((cmptr = CMSG_FIRSTHDR(&msg)) != 0
+ && cmptr->cmsg_len == CMSG_LEN(sizeof(newfd))) {
+ if (cmptr->cmsg_level != SOL_SOCKET)
+ msg_fatal("%s: control level %d != SOL_SOCKET",
+ myname, cmptr->cmsg_level);
+ if (cmptr->cmsg_type != SCM_RIGHTS)
+ msg_fatal("%s: control type %d != SCM_RIGHTS",
+ myname, cmptr->cmsg_type);
+ return (*(int *) CMSG_DATA(cmptr));
+ } else
+ return (-1);
+#else
+ if (msg.msg_accrightslen == sizeof(newfd))
+ return (newfd);
+ else
+ return (-1);
+#endif
+#endif
+}
+
+#ifdef TEST
+
+ /*
+ * Proof-of-concept program. Receive a descriptor (presumably from the
+ * unix_send_fd test program) and copy its content until EOF.
+ */
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <split_at.h>
+#include <listen.h>
+
+int main(int argc, char **argv)
+{
+ char *transport;
+ char *endpoint;
+ int listen_sock;
+ int client_sock;
+ int client_fd;
+ ssize_t read_count;
+ char buf[1024];
+
+ if (argc < 2 || argc > 3
+ || (endpoint = split_at(transport = argv[1], ':')) == 0
+ || *endpoint == 0 || *transport == 0)
+ msg_fatal("usage: %s transport:endpoint [workaround]", argv[0]);
+
+ if (strcmp(transport, "unix") == 0) {
+ listen_sock = unix_listen(endpoint, 10, BLOCKING);
+ } else {
+ msg_fatal("invalid transport name: %s", transport);
+ }
+ if (listen_sock < 0)
+ msg_fatal("listen %s:%s: %m", transport, endpoint);
+
+ client_sock = accept(listen_sock, (struct sockaddr *) 0, (SOCKADDR_SIZE) 0);
+ if (client_sock < 0)
+ msg_fatal("accept: %m");
+
+ set_unix_pass_fd_fix(argv[2] ? argv[2] : "");
+
+ while ((client_fd = unix_recv_fd(client_sock)) >= 0) {
+ msg_info("client_fd = %d, fix=%d", client_fd, unix_pass_fd_fix);
+ while ((read_count = read(client_fd, buf, sizeof(buf))) > 0)
+ write(1, buf, read_count);
+ if (read_count < 0)
+ msg_fatal("read: %m");
+ close(client_fd);
+ }
+ exit(0);
+}
+
+#endif