From 32bb603da8b576d1fdfdd3ccebe91cf7dc5d3963 Mon Sep 17 00:00:00 2001 From: Antoine Pitrou Date: Tue, 10 May 2011 19:16:03 +0200 Subject: Issue #8498: In socket.accept(), allow to specify 0 as a backlog value in order to accept exactly one connection. Patch by Daniel Evers. --- Doc/library/socket.rst | 4 ++-- Lib/test/test_socket.py | 7 +++++++ Misc/ACKS | 1 + Misc/NEWS | 3 +++ Modules/socketmodule.c | 11 +++++++---- 5 files changed, 20 insertions(+), 6 deletions(-) diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst index 96152f9d39..d6b1e4c5e5 100644 --- a/Doc/library/socket.rst +++ b/Doc/library/socket.rst @@ -644,8 +644,8 @@ correspond to Unix system calls applicable to sockets. .. method:: socket.listen(backlog) Listen for connections made to the socket. The *backlog* argument specifies the - maximum number of queued connections and should be at least 1; the maximum value - is system-dependent (usually 5). + maximum number of queued connections and should be at least 0; the maximum value + is system-dependent (usually 5), the minimum value is forced to 0. .. method:: socket.makefile([mode[, bufsize]]) diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py index 7ee16ebced..12e09dddeb 100644 --- a/Lib/test/test_socket.py +++ b/Lib/test/test_socket.py @@ -700,6 +700,13 @@ class GeneralModuleTests(unittest.TestCase): def test_sendall_interrupted_with_timeout(self): self.check_sendall_interrupted(True) + def testListenBacklog0(self): + srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + srv.bind((HOST, 0)) + # backlog = 0 + srv.listen(0) + srv.close() + @unittest.skipUnless(thread, 'Threading required for this test.') class BasicTCPTest(SocketConnectedTest): diff --git a/Misc/ACKS b/Misc/ACKS index 9b9ff68523..4270934f23 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -243,6 +243,7 @@ Carey Evans Tim Everett Paul Everitt David Everly +Daniel Evers Greg Ewing Martijn Faassen Clovis Fabricio diff --git a/Misc/NEWS b/Misc/NEWS index 0214c0befb..7517baf648 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -80,6 +80,9 @@ Core and Builtins Library ------- +- Issue #8498: In socket.accept(), allow to specify 0 as a backlog value in + order to accept exactly one connection. Patch by Daniel Evers. + - Issue #12012: ssl.PROTOCOL_SSLv2 becomes optional. - Issue #11164: Remove obsolete allnodes test from minidom test. diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c index 96b83b1150..76d860cac5 100644 --- a/Modules/socketmodule.c +++ b/Modules/socketmodule.c @@ -2244,8 +2244,10 @@ sock_listen(PySocketSockObject *s, PyObject *arg) if (backlog == -1 && PyErr_Occurred()) return NULL; Py_BEGIN_ALLOW_THREADS - if (backlog < 1) - backlog = 1; + /* To avoid problems on systems that don't allow a negative backlog + * (which doesn't make sense anyway) we force a minimum value of 0. */ + if (backlog < 0) + backlog = 0; res = listen(s->sock_fd, backlog); Py_END_ALLOW_THREADS if (res < 0) @@ -2258,8 +2260,9 @@ PyDoc_STRVAR(listen_doc, "listen(backlog)\n\ \n\ Enable a server to accept connections. The backlog argument must be at\n\ -least 1; it specifies the number of unaccepted connection that the system\n\ -will allow before refusing new connections."); +least 0 (if it is lower, it is set to 0); it specifies the number of\n\ +unaccepted connections that the system will allow before refusing new\n\ +connections."); #ifndef NO_DUP -- cgit v1.2.1