pwclient: Support proxy configuration

The environment variables http_proxy and https_proxy can be used
to configure the HTTP transport.

The TCP connection is made with the proxy host, whereas the original host
is maintained in the HTTP POST URI via "handler" in "send_request".

The send_request() method of xmlrpclib has a different signature
and behaviour in Python 2 and 3.

Fixes #47

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Reviewed-by: Stephen Finucane <stephen@that.guru>
(cherry picked from commit 53fe8b1)

Author: Thomas Monjalon

patchwork/bin/pwclient

@@ -107,19 +107,43 @@ class Transport(xmlrpclib.SafeTransport):
     def __init__(self, url):
         xmlrpclib.SafeTransport.__init__(self)
         self.credentials = None
+        self.host = None
+        self.proxy = None
+        self.scheme = url.split('://', 1)[0]
         self.https = url.startswith('https')
+        if self.https:
+            self.proxy = os.environ.get('https_proxy')
+        else:
+            self.proxy = os.environ.get('http_proxy')
+        if self.proxy:
+            self.https = self.proxy.startswith('https')
 
     def set_credentials(self, username=None, password=None):
         self.credentials = '%s:%s' % (username, password)
 
     def make_connection(self, host):
+        self.host = host
+        if self.proxy:
+            host = self.proxy.split('://', 1)[-1]
         if self.credentials:
             host = '@'.join([self.credentials, host])
         if self.https:
             return xmlrpclib.SafeTransport.make_connection(self, host)
         else:
             return xmlrpclib.Transport.make_connection(self, host)
 
+    if sys.version_info[0] == 2:
+
+        def send_request(self, connection, handler, request_body):
+            handler = '%s://%s%s' % (self.scheme, self.host, handler)
+            xmlrpclib.Transport.send_request(self, connection, handler, request_body)
+
+    else: # Python 3
+
+        def send_request(self, host, handler, request_body, debug):
+            handler = '%s://%s%s' % (self.scheme, host, handler)
+            return xmlrpclib.Transport.send_request(self, host, handler, request_body, debug)
+
 
 def project_id_by_name(rpc, linkname):
     """Given a project short name, look up the Project ID."""