trx/ctrl_if.py: send control responses to where commands are from

When we receive a control command, we should not simply send the
response to the default destination, but send it back to the exact
IP/prt from which the command originated.

This ensures correct routing of responses even in case multiple
programs are interfacing concurrently with a control socket.

Cherry-picked from: I24a0bba6eed059b101af95dac7d059f34dd715fc
Change-Id: I1f304ea887dc957d3ad53adb1e3c56ab27d8f196

python/trx/ctrl_if.py

@@ -25,15 +25,15 @@
 from grgsm.trx import udp_link
 
 class ctrl_if(udp_link):
-	def handle_rx(self, data):
+	def handle_rx(self, data, remote):
 		if self.verify_req(data):
 			request = self.prepare_req(data)
 			rc = self.parse_cmd(request)
 
 			if type(rc) is tuple:
-				self.send_response(request, rc[0], rc[1])
+				self.send_response(request, remote, rc[0], rc[1])
 			else:
-				self.send_response(request, rc)
+				self.send_response(request, remote, rc)
 		else:
 			print("[!] Wrong data on CTRL interface")
 
@@ -65,7 +65,7 @@ class ctrl_if(udp_link):
 
 		return True
 
-	def send_response(self, request, response_code, params = None):
+	def send_response(self, request, remote, response_code, params = None):
 		# Include status code, for example ["TXTUNE", "0", "941600"]
 		request.insert(1, str(response_code))
 
@@ -76,7 +76,7 @@ class ctrl_if(udp_link):
 		# Add the response signature, and join back to string
 		response = "RSP " + " ".join(request) + "\0"
 		# Now we have something like "RSP TXTUNE 0 941600"
-		self.send(response)
+		self.send(response, remote)
 
 	def parse_cmd(self, request):
 		raise NotImplementedError

python/trx/udp_link.py

@@ -45,13 +45,16 @@ class udp_link:
 		# Check for incoming data
 		if self.sock in r_event:
 			data, addr = self.sock.recvfrom(128)
-			self.handle_rx(data.decode())
+			self.handle_rx(data.decode(), addr)
 
-	def send(self, data):
+	def send(self, data, remote = None):
 		if type(data) not in [bytearray, bytes]:
 			data = data.encode()
 
-		self.sock.sendto(data, (self.remote_addr, self.remote_port))
+		if remote is None:
+			remote = (self.remote_addr, self.remote_port)
 
-	def handle_rx(self, data):
+		self.sock.sendto(data, remote)
+
+	def handle_rx(self, data, remote):
 		raise NotImplementedError