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authorDan McGee <dan@archlinux.org>2011-09-19 08:10:13 -0500
committerMax Kellermann <max@duempel.org>2011-09-19 17:11:09 +0200
commit27946a981ff4192f064feb3117567463c137933f (patch)
tree1e03c0564a65c43ba98a29d8ed7938464e32d3f3
parent74617389c88ccf630b8cce4b54d9e2fa5afb2259 (diff)
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Set socket TCP keepalive option on incoming connections
If a connected host disappears without our knowledge, as can happen over wireless or a hibernating machine, we continue to hold the port open waiting for messages. Because we never try to send anything down this now-broken pipe, the connection will sit idle taking up a slot in our allowed incoming connections list. If enough of these happen, an unintended Denial of Service takes place, where all connection slots are filled with now-broken, never ending connections. Setting the TCP keepalive option at least allows these to time out after the default two hours, which is sufficient in the non-malicious case. Signed-off-by: Dan McGee <dan@archlinux.org>
-rw-r--r--src/server_socket.c8
-rw-r--r--src/socket_util.c15
-rw-r--r--src/socket_util.h3
3 files changed, 24 insertions, 2 deletions
diff --git a/src/server_socket.c b/src/server_socket.c
index 82ad81f12..fc8dbd17a 100644
--- a/src/server_socket.c
+++ b/src/server_socket.c
@@ -160,12 +160,16 @@ server_socket_in_event(G_GNUC_UNUSED GIOChannel *source,
size_t address_length = sizeof(address);
int fd = accept_cloexec_nonblock(s->fd, (struct sockaddr*)&address,
&address_length);
- if (fd >= 0)
+ if (fd >= 0) {
+ if (socket_keepalive(fd))
+ g_warning("Could not set TCP keepalive option: %s",
+ g_strerror(errno));
s->parent->callback(fd, (const struct sockaddr*)&address,
address_length, get_remote_uid(fd),
s->parent->callback_ctx);
- else
+ } else {
g_warning("accept() failed: %s", g_strerror(errno));
+ }
return true;
}
diff --git a/src/socket_util.c b/src/socket_util.c
index a89a67ed6..aa0a44e44 100644
--- a/src/socket_util.c
+++ b/src/socket_util.c
@@ -148,3 +148,18 @@ socket_bind_listen(int domain, int type, int protocol,
return fd;
}
+
+int
+socket_keepalive(int fd)
+{
+ const int reuse = 1;
+
+#ifdef WIN32
+ const char *optval = (const char *)&reuse;
+#else
+ const void *optval = &reuse;
+#endif
+
+ return setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE,
+ optval, sizeof(reuse));
+}
diff --git a/src/socket_util.h b/src/socket_util.h
index 3ebf4084c..f27751aa3 100644
--- a/src/socket_util.h
+++ b/src/socket_util.h
@@ -63,4 +63,7 @@ socket_bind_listen(int domain, int type, int protocol,
int backlog,
GError **error);
+int
+socket_keepalive(int fd);
+
#endif