diff --git a/changes/bug9716 b/changes/bug9716 new file mode 100644 index 0000000000..5e39077173 --- /dev/null +++ b/changes/bug9716 @@ -0,0 +1,4 @@ + o Bugfixes (performance): + - Set the listen() backlog limit to the largest actually supported + on the system, not to the value in a header file. Fixes bug 9716; + bugfix on every released Tor. diff --git a/src/or/connection.c b/src/or/connection.c index 78cc31e894..062c97114a 100644 --- a/src/or/connection.c +++ b/src/or/connection.c @@ -926,6 +926,27 @@ make_socket_reuseable(tor_socket_t sock) #endif } +/** Max backlog to pass to listen. We start at */ +static int listen_limit = INT_MAX; + +/* Listen on fd with appropriate backlog. Return as for listen. */ +static int +tor_listen(tor_socket_t fd) +{ + int r; + + if ((r = listen(fd, listen_limit)) < 0) { + if (listen_limit == SOMAXCONN) + return r; + if ((r = listen(fd, SOMAXCONN)) == 0) { + listen_limit = SOMAXCONN; + log_warn(LD_NET, "Setting listen backlog to INT_MAX connections " + "didn't work, but SOMAXCONN did. Lowering backlog limit."); + } + } + return r; +} + /** Bind a new non-blocking socket listening to the socket described * by listensockaddr. * @@ -1009,7 +1030,7 @@ connection_listener_new(const struct sockaddr *listensockaddr, } if (is_tcp) { - if (listen(s,SOMAXCONN) < 0) { + if (tor_listen(s) < 0) { log_warn(LD_NET, "Could not listen on %s:%u: %s", address, usePort, tor_socket_strerror(tor_socket_errno(s))); tor_close_socket(s);