CLI: Added exception handling to python RPC

.hgignore

@@ -27,6 +27,7 @@ Makefile*
 
 # ostinato generated files
 version.cpp
+pkg_info.json
 
 # vim swap files
 *.swp

binding/rpc.py

@@ -15,10 +15,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>
 
+from google.protobuf.message import EncodeError, DecodeError
 from google.protobuf.service import RpcChannel
 from google.protobuf.service import RpcController
 import socket
 import struct
+import sys
 
 class OstinatoRpcController(RpcController):
     def __init__(self):
@@ -29,7 +31,13 @@ class OstinatoRpcChannel(RpcChannel):
         self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 
     def connect(self, host, port):
-        self.sock.connect((host, port))
+        self.peer = '%s:%d' % (host, port)
+        try:
+            self.sock.connect((host, port))
+        except socket.error, e:
+            print 'ERROR: Unable to connect to Drone %s (%s)' % (
+                    self.peer, str(e))
+            sys.exit(1)
 
     def disconnect(self):
         self.sock.close()
@@ -40,36 +48,81 @@ class OstinatoRpcChannel(RpcChannel):
         OST_PB_MSG_TYPE_RESPONSE = 2
         OST_PB_MSG_TYPE_BLOB = 3
 
-        req = request.SerializeToString()
-        self.sock.sendall(struct.pack('>HHI', 
-            OST_PB_MSG_TYPE_REQUEST, method.index, len(req)) + req)
+        try:
+            req = request.SerializeToString()
+            self.sock.sendall(struct.pack('>HHI', 
+                OST_PB_MSG_TYPE_REQUEST, method.index, len(req)) + req)
+        except EncodeError, e:
+            print 'ERROR: Failed to serialize %s arg for RPC %s() ' \
+                  'to Drone %s (%s)' % (
+                    type(request).__name__, method.name, self.peer, e)
+            sys.exit(1)
+        except socket.error, e:
+            print 'ERROR: Failed to invoke RPC %s() to Drone %s (%s)' % (
+                    method.name, self.peer, e)
+            sys.exit(1)
 
         # receive and parse header
-        hdr = ''
-        while len(hdr) < OST_PB_MSG_HDR_SIZE:
-            chunk = self.sock.recv(OST_PB_MSG_HDR_SIZE - len(hdr))
-            if chunk == '':
-                raise RuntimeError("socket connection broken")
-            hdr = hdr + chunk
+        try:
+            hdr = ''
+            while len(hdr) < OST_PB_MSG_HDR_SIZE:
+                chunk = self.sock.recv(OST_PB_MSG_HDR_SIZE - len(hdr))
+                if chunk == '':
+                    raise RuntimeError("socket connection closed by peer")
+                hdr = hdr + chunk
+        except socket.error, e:
+            print 'ERROR: Failed to receive msg reply for RPC %s() ' \
+                  'from Drone %s (%s)' % (
+                    method.name, self.peer, e)
+            sys.exit(1)
+        except RuntimeError, e:
+            print 'ERROR: Drone %s closed connection receiving msg reply ' \
+                  'for RPC %s() (%s)' % (
+                    self.peer, method.name, e)
+            sys.exit(1)
 
-        (type, method, resp_len) = struct.unpack('>HHI', hdr)
+        (msg_type, method_index, resp_len) = struct.unpack('>HHI', hdr)
+
+        # verify response method is same as the one requested
+        if method_index != method.index:
+            print 'ERROR: Received Reply for Method %d; expecting reply for ' \
+                    'method %d (%s)' % (
+                    method_index, method.index, method.name)
+            sys.exit(1)
 
         # receive and parse the actual response message
-        resp = ''
-        while len(resp) < resp_len:
-            chunk = self.sock.recv(resp_len - len(resp))
-            if chunk == '':
-                raise RuntimeError("socket connection broken")
-            resp = resp + chunk
+        try:
+            resp = ''
+            while len(resp) < resp_len:
+                chunk = self.sock.recv(resp_len - len(resp))
+                if chunk == '':
+                    raise RuntimeError("socket connection closed by peer")
+                resp = resp + chunk
+        except socket.error, e:
+            print 'ERROR: Failed to receive reply for RPC %s() ' \
+                  'from Drone %s (%s)' % (
+                    method.name, self.peer, e)
+            sys.exit(1)
+        except RuntimeError, e:
+            print 'ERROR: Drone %s closed connection receiving reply ' \
+                  'for RPC %s() (%s)' % (
+                    self.peer, method.name, e)
+            sys.exit(1)
 
-        if type == OST_PB_MSG_TYPE_RESPONSE:
-            response = response_class()
-            response.ParseFromString(resp)
-        elif type == OST_PB_MSG_TYPE_BLOB:
+        if msg_type == OST_PB_MSG_TYPE_RESPONSE:
+            try: 
+                response = response_class()
+                response.ParseFromString(resp)
+            except DecodeError, e:
+                print 'ERROR: Failed to parse %s response for RPC %s() ' \
+                      'from Drone %s (%s)' % (
+                        type(response).__name__, method.name, self.peer, e)
+                sys.exit(1)
+        elif msg_type == OST_PB_MSG_TYPE_BLOB:
             response = resp
         else:
-            print 'unsupported msg type %d received in respone to %s' % \
-                    type, method.name
+            print 'ERROR: unsupported msg type %d received in respone to %s' % \
+                    msg_type, method.name
 
         controller.response = response