adds connection module to module_utils (#21310)

* connection module connecting to persistent sockets

lib/ansible/module_utils/connection.py

@@ -0,0 +1,75 @@
+#
+# This code is part of Ansible, but is an independent component.
+# This particular file snippet, and this file snippet only, is BSD licensed.
+# Modules you write using this snippet, which is embedded dynamically by Ansible
+# still belong to the author of the module, and may assign their own license
+# to the complete work.
+#
+# (c) 2017 Red Hat Inc.
+#
+# Redistribution and use in source and binary forms, with or without modification,
+# are permitted provided that the following conditions are met:
+#
+#    * Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#    * Redistributions in binary form must reproduce the above copyright notice,
+#      this list of conditions and the following disclaimer in the documentation
+#      and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+import socket
+import struct
+import signal
+
+from ansible.module_utils.basic import get_exception
+from ansible.module_utils._text import to_bytes, to_native
+
+def send_data(s, data):
+    packed_len = struct.pack('!Q',len(data))
+    return s.sendall(packed_len + data)
+
+def recv_data(s):
+    header_len = 8 # size of a packed unsigned long long
+    data = to_bytes("")
+    while len(data) < header_len:
+        d = s.recv(header_len - len(data))
+        if not d:
+            return None
+        data += d
+    data_len = struct.unpack('!Q',data[:header_len])[0]
+    data = data[header_len:]
+    while len(data) < data_len:
+        d = s.recv(data_len - len(data))
+        if not d:
+            return None
+        data += d
+    return data
+
+def exec_command(module, command):
+    try:
+        sf = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        sf.connect(module._socket_path)
+
+        data = "EXEC: %s" % command
+        send_data(sf, to_bytes(data.strip()))
+
+        rc = int(recv_data(sf), 10)
+        stdout = recv_data(sf)
+        stderr = recv_data(sf)
+    except socket.error:
+        exc = get_exception()
+        sf.close()
+        module.fail_json(msg='unable to connect to socket', err=str(exc))
+
+    sf.close()
+
+    return (rc, to_native(stdout), to_native(stderr))