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authorLennart Poettering <lennart@poettering.net>2016-05-06 13:29:26 +0200
committerLennart Poettering <lennart@poettering.net>2016-05-06 13:29:26 +0200
commit60d9771c593e0702a892a4372443e63b38cdbcba (patch)
tree8c9e737e8ada747d89705e68e6b136cba0365bf1
parent01a8b4675739463b8d6abf0931099b244c6f072b (diff)
core: rework how we flush incoming traffic when a socket unit goes down
Previously, we'd simply close and reopen the socket file descriptors. This is problematic however, as we won't transition through the SOCKET_CHOWN state then, and thus the file ownership won't be correct for the sockets. Rework the flushing logic, and actually read any queued data from the sockets for flushing, and accept any queued messages and disconnect them.
-rw-r--r--src/basic/io-util.c5
-rw-r--r--src/basic/socket-util.c40
-rw-r--r--src/basic/socket-util.h2
-rw-r--r--src/core/socket.c39
4 files changed, 66 insertions, 20 deletions
diff --git a/src/basic/io-util.c b/src/basic/io-util.c
index 0037a37f2a..cc6dfa8c1b 100644
--- a/src/basic/io-util.c
+++ b/src/basic/io-util.c
@@ -33,6 +33,11 @@ int flush_fd(int fd) {
.events = POLLIN,
};
+ /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
+ * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
+ * (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used
+ * was set to non-blocking too. */
+
for (;;) {
char buf[LINE_MAX];
ssize_t l;
diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index 0f38f9a0f3..c634f1d564 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -23,6 +23,7 @@
#include <net/if.h>
#include <netdb.h>
#include <netinet/ip.h>
+#include <poll.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
@@ -970,3 +971,42 @@ fallback:
return (ssize_t) k;
}
+
+int flush_accept(int fd) {
+
+ struct pollfd pollfd = {
+ .fd = fd,
+ .events = POLLIN,
+ };
+ int r;
+
+
+ /* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
+
+ for (;;) {
+ int cfd;
+
+ r = poll(&pollfd, 1, 0);
+ if (r < 0) {
+ if (errno == EINTR)
+ continue;
+
+ return -errno;
+
+ } else if (r == 0)
+ return 0;
+
+ cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+ if (cfd < 0) {
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN)
+ return 0;
+
+ return -errno;
+ }
+
+ close(cfd);
+ }
+}
diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h
index d17a2f35f8..9f6a301368 100644
--- a/src/basic/socket-util.h
+++ b/src/basic/socket-util.h
@@ -135,5 +135,7 @@ int receive_one_fd(int transport_fd, int flags);
ssize_t next_datagram_size_fd(int fd);
+int flush_accept(int fd);
+
#define CMSG_FOREACH(cmsg, mh) \
for ((cmsg) = CMSG_FIRSTHDR(mh); (cmsg); (cmsg) = CMSG_NXTHDR((mh), (cmsg)))
diff --git a/src/core/socket.c b/src/core/socket.c
index 50912c33dd..091567ed4f 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -28,7 +28,6 @@
#include <unistd.h>
#include <linux/sctp.h>
-#include "sd-event.h"
#include "alloc-util.h"
#include "bus-error.h"
#include "bus-util.h"
@@ -38,6 +37,7 @@
#include "exit-status.h"
#include "fd-util.h"
#include "formats-util.h"
+#include "io-util.h"
#include "label.h"
#include "log.h"
#include "missing.h"
@@ -1960,6 +1960,21 @@ fail:
socket_enter_dead(s, SOCKET_FAILURE_RESOURCES);
}
+static void flush_ports(Socket *s) {
+ SocketPort *p;
+
+ /* Flush all incoming traffic, regardless if actual bytes or new connections, so that this socket isn't busy
+ * anymore */
+
+ LIST_FOREACH(port, p, s->ports) {
+ if (p->fd < 0)
+ continue;
+
+ (void) flush_accept(p->fd);
+ (void) flush_fd(p->fd);
+ }
+}
+
static void socket_enter_running(Socket *s, int cfd) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
int r;
@@ -1969,31 +1984,15 @@ static void socket_enter_running(Socket *s, int cfd) {
assert(s);
- /* We don't take connections anymore if we are supposed to
- * shut down anyway */
+ /* We don't take connections anymore if we are supposed to shut down anyway */
if (unit_stop_pending(UNIT(s))) {
log_unit_debug(UNIT(s), "Suppressing connection request since unit stop is scheduled.");
if (cfd >= 0)
cfd = safe_close(cfd);
- else {
- /* Flush all sockets by closing and reopening them */
- socket_close_fds(s);
-
- r = socket_open_fds(s);
- if (r < 0) {
- log_unit_warning_errno(UNIT(s), r, "Failed to listen on sockets: %m");
- socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
- return;
- }
-
- r = socket_watch_fds(s);
- if (r < 0) {
- log_unit_warning_errno(UNIT(s), r, "Failed to watch sockets: %m");
- socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
- }
- }
+ else
+ flush_ports(s);
return;
}