bpo-28724: Add methods send_fds and recv_fds to the socket module (GH-12889)
The socket module now has the socket.send_fds() and socket.recv.fds() functions.
Contributed by Joannah Nanjekye, Shinya Okano (original patch)
and Victor Stinner.
Co-Authored-By: Victor Stinner <vstinner@redhat.com>
diff --git a/Lib/socket.py b/Lib/socket.py
old mode 100644
new mode 100755
index 87b097f..e5989d9
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -12,6 +12,8 @@
socket() -- create a new socket object
socketpair() -- create a pair of new socket objects [*]
fromfd() -- create a socket object from an open file descriptor [*]
+send_fds() -- Send file descriptor to the socket.
+recv_fds() -- Recieve file descriptors from the socket.
fromshare() -- create a socket object from data received from socket.share() [*]
gethostname() -- return the current hostname
gethostbyname() -- map a hostname to its IP number
@@ -542,6 +544,40 @@
nfd = dup(fd)
return socket(family, type, proto, nfd)
+if hasattr(_socket.socket, "sendmsg"):
+ import array
+
+ def send_fds(sock, buffers, fds, flags=0, address=None):
+ """ send_fds(sock, buffers, fds[, flags[, address]]) -> integer
+
+ Send the list of file descriptors fds over an AF_UNIX socket.
+ """
+ return sock.sendmsg(buffers, [(_socket.SOL_SOCKET,
+ _socket.SCM_RIGHTS, array.array("i", fds))])
+ __all__.append("send_fds")
+
+if hasattr(_socket.socket, "recvmsg"):
+ import array
+
+ def recv_fds(sock, bufsize, maxfds, flags=0):
+ """ recv_fds(sock, bufsize, maxfds[, flags]) -> (data, list of file
+ descriptors, msg_flags, address)
+
+ Receive up to maxfds file descriptors returning the message
+ data and a list containing the descriptors.
+ """
+ # Array of ints
+ fds = array.array("i")
+ msg, ancdata, flags, addr = sock.recvmsg(bufsize,
+ _socket.CMSG_LEN(maxfds * fds.itemsize))
+ for cmsg_level, cmsg_type, cmsg_data in ancdata:
+ if (cmsg_level == _socket.SOL_SOCKET and cmsg_type == _socket.SCM_RIGHTS):
+ fds.frombytes(cmsg_data[:
+ len(cmsg_data) - (len(cmsg_data) % fds.itemsize)])
+
+ return msg, list(fds), flags, addr
+ __all__.append("recv_fds")
+
if hasattr(_socket.socket, "share"):
def fromshare(info):
""" fromshare(info) -> socket object
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
old mode 100644
new mode 100755
index 14ff561..b855c52
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -6436,11 +6436,53 @@
self.echo_server(sock)
self.echo_client(("::1", port), socket.AF_INET6)
+@requireAttrs(socket, "send_fds")
+@requireAttrs(socket, "recv_fds")
+@requireAttrs(socket, "AF_UNIX")
+class SendRecvFdsTests(unittest.TestCase):
+ def testSendAndRecvFds(self):
+ def close_pipes(pipes):
+ for fd1, fd2 in pipes:
+ os.close(fd1)
+ os.close(fd2)
+
+ def close_fds(fds):
+ for fd in fds:
+ os.close(fd)
+
+ # send 10 file descriptors
+ pipes = [os.pipe() for _ in range(10)]
+ self.addCleanup(close_pipes, pipes)
+ fds = [rfd for rfd, wfd in pipes]
+
+ # use a UNIX socket pair to exchange file descriptors locally
+ sock1, sock2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+ with sock1, sock2:
+ socket.send_fds(sock1, [MSG], fds)
+ # request more data and file descriptors than expected
+ msg, fds2, flags, addr = socket.recv_fds(sock2, len(MSG) * 2, len(fds) * 2)
+ self.addCleanup(close_fds, fds2)
+
+ self.assertEqual(msg, MSG)
+ self.assertEqual(len(fds2), len(fds))
+ self.assertEqual(flags, 0)
+ # don't test addr
+
+ # test that file descriptors are connected
+ for index, fds in enumerate(pipes):
+ rfd, wfd = fds
+ os.write(wfd, str(index).encode())
+
+ for index, rfd in enumerate(fds2):
+ data = os.read(rfd, 100)
+ self.assertEqual(data, str(index).encode())
+
def test_main():
tests = [GeneralModuleTests, BasicTCPTest, TCPCloserTest, TCPTimeoutTest,
TestExceptions, BufferIOTest, BasicTCPTest2, BasicUDPTest,
- UDPTimeoutTest, CreateServerTest, CreateServerFunctionalTest]
+ UDPTimeoutTest, CreateServerTest, CreateServerFunctionalTest,
+ SendRecvFdsTests]
tests.extend([
NonBlockingTCPTests,
@@ -6513,5 +6555,6 @@
support.run_unittest(*tests)
support.threading_cleanup(*thread_info)
+
if __name__ == "__main__":
test_main()