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| author | Dan McGee <dan@archlinux.org> | 2011-09-19 08:10:13 -0500 |
|---|---|---|
| committer | Max Kellermann <max@duempel.org> | 2011-09-19 17:11:09 +0200 |
| commit | 27946a981ff4192f064feb3117567463c137933f (patch) | |
| tree | 1e03c0564a65c43ba98a29d8ed7938464e32d3f3 | |
| parent | 74617389c88ccf630b8cce4b54d9e2fa5afb2259 (diff) | |
| download | mpd-27946a981ff4192f064feb3117567463c137933f.tar.gz mpd-27946a981ff4192f064feb3117567463c137933f.tar.xz mpd-27946a981ff4192f064feb3117567463c137933f.zip | |
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.c | 8 | ||||
| -rw-r--r-- | src/socket_util.c | 15 | ||||
| -rw-r--r-- | src/socket_util.h | 3 |
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 |