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69f9ff7d82
"pid" and "sock" are sufficient I guess as randomizers to distinguish messages. In theory, a pid could be recycled very quickly, which might mix up in-flight messages. But once a few messages have passed, "cookie" would be incremented as another indicator of a fresh message. Why? Remove messages_dgm dependency on samba-util Signed-off-by: Volker Lendecke <vl@samba.org> Reviewed-by: Stefan Metzmacher <metze@samba.org>
420 lines
9.8 KiB
C
420 lines
9.8 KiB
C
/*
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* Unix SMB/CIFS implementation.
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* Samba internal messaging functions
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* Copyright (C) 2013 by Volker Lendecke
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "includes.h"
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#include "lib/util/data_blob.h"
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#include "lib/util/debug.h"
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#include "lib/unix_msg/unix_msg.h"
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#include "system/filesys.h"
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#include "lib/messages_dgm.h"
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#include "lib/param/param.h"
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#include "poll_funcs/poll_funcs_tevent.h"
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#include "unix_msg/unix_msg.h"
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struct sun_path_buf {
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/*
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* This will carry enough for a socket path
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*/
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char buf[sizeof(struct sockaddr_un)];
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};
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struct messaging_dgm_context {
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pid_t pid;
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struct poll_funcs *msg_callbacks;
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void *tevent_handle;
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struct unix_msg_ctx *dgm_ctx;
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struct sun_path_buf socket_dir;
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struct sun_path_buf lockfile_dir;
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int lockfile_fd;
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void (*recv_cb)(const uint8_t *msg,
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size_t msg_len,
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int *fds,
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size_t num_fds,
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void *private_data);
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void *recv_cb_private_data;
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bool *have_dgm_context;
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};
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static struct messaging_dgm_context *global_dgm_context;
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static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
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uint8_t *msg, size_t msg_len,
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int *fds, size_t num_fds,
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void *private_data);
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static int messaging_dgm_context_destructor(struct messaging_dgm_context *c);
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static int messaging_dgm_lockfile_create(struct messaging_dgm_context *ctx,
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pid_t pid, int *plockfile_fd,
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uint64_t unique)
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{
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fstring buf;
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int lockfile_fd;
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struct sun_path_buf lockfile_name;
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struct flock lck;
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int unique_len, ret;
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ssize_t written;
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ret = snprintf(lockfile_name.buf, sizeof(lockfile_name.buf),
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"%s/%u", ctx->lockfile_dir.buf, (int)pid);
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if (ret >= sizeof(lockfile_name.buf)) {
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return ENAMETOOLONG;
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}
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/* no O_EXCL, existence check is via the fcntl lock */
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lockfile_fd = open(lockfile_name.buf, O_NONBLOCK|O_CREAT|O_WRONLY,
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0644);
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if (lockfile_fd == -1) {
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ret = errno;
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DEBUG(1, ("%s: open failed: %s\n", __func__, strerror(errno)));
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return ret;
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}
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lck = (struct flock) {
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.l_type = F_WRLCK,
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.l_whence = SEEK_SET
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};
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ret = fcntl(lockfile_fd, F_SETLK, &lck);
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if (ret == -1) {
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ret = errno;
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DEBUG(1, ("%s: fcntl failed: %s\n", __func__, strerror(ret)));
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goto fail_close;
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}
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unique_len = snprintf(buf, sizeof(buf), "%ju\n", (uintmax_t)unique);
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/* shorten a potentially preexisting file */
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ret = ftruncate(lockfile_fd, unique_len);
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if (ret == -1) {
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ret = errno;
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DEBUG(1, ("%s: ftruncate failed: %s\n", __func__,
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strerror(ret)));
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goto fail_unlink;
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}
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written = write(lockfile_fd, buf, unique_len);
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if (written != unique_len) {
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ret = errno;
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DEBUG(1, ("%s: write failed: %s\n", __func__, strerror(ret)));
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goto fail_unlink;
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}
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*plockfile_fd = lockfile_fd;
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return 0;
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fail_unlink:
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unlink(lockfile_name.buf);
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fail_close:
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close(lockfile_fd);
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return ret;
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}
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int messaging_dgm_init(struct tevent_context *ev,
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uint64_t unique,
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const char *socket_dir,
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const char *lockfile_dir,
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void (*recv_cb)(const uint8_t *msg,
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size_t msg_len,
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int *fds,
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size_t num_fds,
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void *private_data),
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void *recv_cb_private_data)
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{
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struct messaging_dgm_context *ctx;
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int ret;
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struct sockaddr_un socket_address;
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size_t len;
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static bool have_dgm_context = false;
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if (have_dgm_context) {
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return EEXIST;
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}
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ctx = talloc_zero(NULL, struct messaging_dgm_context);
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if (ctx == NULL) {
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goto fail_nomem;
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}
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ctx->pid = getpid();
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ctx->recv_cb = recv_cb;
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ctx->recv_cb_private_data = recv_cb_private_data;
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len = strlcpy(ctx->lockfile_dir.buf, lockfile_dir,
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sizeof(ctx->lockfile_dir.buf));
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if (len >= sizeof(ctx->lockfile_dir.buf)) {
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TALLOC_FREE(ctx);
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return ENAMETOOLONG;
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}
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len = strlcpy(ctx->socket_dir.buf, socket_dir,
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sizeof(ctx->socket_dir.buf));
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if (len >= sizeof(ctx->socket_dir.buf)) {
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TALLOC_FREE(ctx);
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return ENAMETOOLONG;
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}
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socket_address = (struct sockaddr_un) { .sun_family = AF_UNIX };
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len = snprintf(socket_address.sun_path,
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sizeof(socket_address.sun_path),
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"%s/%u", socket_dir, (unsigned)ctx->pid);
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if (len >= sizeof(socket_address.sun_path)) {
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TALLOC_FREE(ctx);
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return ENAMETOOLONG;
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}
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ret = messaging_dgm_lockfile_create(ctx, ctx->pid, &ctx->lockfile_fd,
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unique);
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if (ret != 0) {
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DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
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__func__, strerror(ret)));
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TALLOC_FREE(ctx);
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return ret;
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}
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ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
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if (ctx->msg_callbacks == NULL) {
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goto fail_nomem;
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}
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ctx->tevent_handle = poll_funcs_tevent_register(
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ctx, ctx->msg_callbacks, ev);
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if (ctx->tevent_handle == NULL) {
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goto fail_nomem;
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}
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unlink(socket_address.sun_path);
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ret = unix_msg_init(&socket_address, ctx->msg_callbacks, 1024,
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messaging_dgm_recv, ctx, &ctx->dgm_ctx);
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if (ret != 0) {
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DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
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TALLOC_FREE(ctx);
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return ret;
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}
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talloc_set_destructor(ctx, messaging_dgm_context_destructor);
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ctx->have_dgm_context = &have_dgm_context;
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global_dgm_context = ctx;
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return 0;
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fail_nomem:
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TALLOC_FREE(ctx);
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return ENOMEM;
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}
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static int messaging_dgm_context_destructor(struct messaging_dgm_context *c)
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{
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/*
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* First delete the socket to avoid races. The lockfile is the
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* indicator that we're still around.
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*/
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unix_msg_free(c->dgm_ctx);
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if (getpid() == c->pid) {
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struct sun_path_buf name;
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int ret;
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ret = snprintf(name.buf, sizeof(name.buf), "%s/%u",
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c->lockfile_dir.buf, (unsigned)c->pid);
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if (ret >= sizeof(name.buf)) {
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/*
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* We've checked the length when creating, so this
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* should never happen
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*/
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abort();
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}
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unlink(name.buf);
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}
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close(c->lockfile_fd);
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if (c->have_dgm_context != NULL) {
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*c->have_dgm_context = false;
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}
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return 0;
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}
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void messaging_dgm_destroy(void)
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{
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TALLOC_FREE(global_dgm_context);
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}
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int messaging_dgm_send(pid_t pid,
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const struct iovec *iov, int iovlen,
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const int *fds, size_t num_fds)
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{
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struct messaging_dgm_context *ctx = global_dgm_context;
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struct sockaddr_un dst;
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ssize_t dst_pathlen;
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int ret;
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if (ctx == NULL) {
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return ENOTCONN;
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}
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dst = (struct sockaddr_un) { .sun_family = AF_UNIX };
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dst_pathlen = snprintf(dst.sun_path, sizeof(dst.sun_path),
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"%s/%u", ctx->socket_dir.buf, (unsigned)pid);
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if (dst_pathlen >= sizeof(dst.sun_path)) {
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return ENAMETOOLONG;
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}
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DEBUG(10, ("%s: Sending message to %u\n", __func__, (unsigned)pid));
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ret = unix_msg_send(ctx->dgm_ctx, &dst, iov, iovlen, fds, num_fds);
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return ret;
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}
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static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
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uint8_t *msg, size_t msg_len,
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int *fds, size_t num_fds,
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void *private_data)
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{
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struct messaging_dgm_context *dgm_ctx = talloc_get_type_abort(
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private_data, struct messaging_dgm_context);
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dgm_ctx->recv_cb(msg, msg_len, fds, num_fds,
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dgm_ctx->recv_cb_private_data);
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}
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int messaging_dgm_cleanup(pid_t pid)
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{
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struct messaging_dgm_context *ctx = global_dgm_context;
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struct sun_path_buf lockfile_name, socket_name;
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int fd, len, ret;
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struct flock lck = {};
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if (ctx == NULL) {
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return ENOTCONN;
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}
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len = snprintf(socket_name.buf, sizeof(socket_name.buf), "%s/%u",
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ctx->socket_dir.buf, (unsigned)pid);
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if (len >= sizeof(socket_name.buf)) {
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return ENAMETOOLONG;
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}
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len = snprintf(lockfile_name.buf, sizeof(lockfile_name.buf), "%s/%u",
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ctx->lockfile_dir.buf, (unsigned)pid);
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if (len >= sizeof(lockfile_name.buf)) {
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return ENAMETOOLONG;
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}
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fd = open(lockfile_name.buf, O_NONBLOCK|O_WRONLY, 0);
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if (fd == -1) {
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ret = errno;
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if (ret != ENOENT) {
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DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
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lockfile_name.buf, strerror(ret)));
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}
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return ret;
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}
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lck.l_type = F_WRLCK;
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lck.l_whence = SEEK_SET;
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lck.l_start = 0;
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lck.l_len = 0;
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ret = fcntl(fd, F_SETLK, &lck);
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if (ret != 0) {
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ret = errno;
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if ((ret != EACCES) && (ret != EAGAIN)) {
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DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
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strerror(ret)));
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}
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close(fd);
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return ret;
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}
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DEBUG(10, ("%s: Cleaning up : %s\n", __func__, strerror(ret)));
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(void)unlink(socket_name.buf);
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(void)unlink(lockfile_name.buf);
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(void)close(fd);
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return 0;
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}
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int messaging_dgm_wipe(void)
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{
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struct messaging_dgm_context *ctx = global_dgm_context;
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DIR *msgdir;
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struct dirent *dp;
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pid_t our_pid = getpid();
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int ret;
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if (ctx == NULL) {
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return ENOTCONN;
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}
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/*
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* We scan the socket directory and not the lock directory. Otherwise
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* we would race against messaging_dgm_lockfile_create's open(O_CREAT)
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* and fcntl(SETLK).
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*/
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msgdir = opendir(ctx->socket_dir.buf);
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if (msgdir == NULL) {
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return errno;
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}
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while ((dp = readdir(msgdir)) != NULL) {
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unsigned long pid;
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pid = strtoul(dp->d_name, NULL, 10);
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if (pid == 0) {
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/*
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* . and .. and other malformed entries
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*/
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continue;
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}
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if (pid == our_pid) {
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/*
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* fcntl(F_GETLK) will succeed for ourselves, we hold
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* that lock ourselves.
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*/
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continue;
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}
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ret = messaging_dgm_cleanup(pid);
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DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
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pid, ret ? strerror(ret) : "ok"));
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}
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closedir(msgdir);
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return 0;
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}
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void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
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struct tevent_context *ev)
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{
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struct messaging_dgm_context *ctx = global_dgm_context;
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if (ctx == NULL) {
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return NULL;
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}
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return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
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}
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