Add support for binding client connections to a local interface.

diff --git a/src/paho/mqtt/client.py b/src/paho/mqtt/client.py
index d87e2820ca0bdd2f6059f13ac901cc2336951abe..5a1f609f8f256c093afeb09821080ddf00e5687b 100755 (executable)
--- a/src/paho/mqtt/client.py
+++ b/src/paho/mqtt/client.py
@@ -407,6 +407,7 @@ class Client:
         self.on_log = None
         self._host = ""
         self._port = 1883
+        self._bind_address = ""
         self._in_callback = False
         self._strict_protocol = False
         self._callback_mutex = threading.Lock()
@@ -505,7 +506,7 @@ class Client:
         self._tls_version = tls_version
         self._tls_ciphers = ciphers
 
-    def connect(self, host, port=1883, keepalive=60):
+    def connect(self, host, port=1883, keepalive=60, bind_address=""):
         """Connect to a remote broker.
 
         host is the hostname or IP address of the remote broker.
@@ -516,10 +517,10 @@ class Client:
         broker. If no other messages are being exchanged, this controls the
         rate at which the client will send ping messages to the broker.
         """
-        self.connect_async(host, port, keepalive)
+        self.connect_async(host, port, keepalive, bind_address)
         return self.reconnect()
 
-    def connect_async(self, host, port=1883, keepalive=60):
+    def connect_async(self, host, port=1883, keepalive=60, bind_address=""):
         """Connect to a remote broker asynchronously. This is a non-blocking
         connect call that can be used with loop_start() to provide very quick
         start.
@@ -542,6 +543,7 @@ class Client:
         self._host = host
         self._port = port
         self._keepalive = keepalive
+        self._bind_address = bind_address
 
         self._state_mutex.acquire()
         self._state = mqtt_cs_connect_async
@@ -584,9 +586,12 @@ class Client:
         # Put messages in progress in a valid state.
         self._messages_reconnect_reset()
 
-        self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        # FIXME use create_connection here
-
+        try:
+            self._sock = socket.create_connection((self._host, self._port), source_address=(self._bind_address, 0))
+        except socket.error as err:
+            (msg) = err
+            if msg.errno != errno.EINPROGRESS:
+                raise
 
         if self._tls_ca_certs != None:
             self._ssl = ssl.wrap_socket(self._sock,