Implement definitive (?) reading from BIRD socket

birdvisu/maps_new/providers.py

@@ -1,6 +1,6 @@
 """Common TopologyProviders"""
 
-from birdvisu import ospffile
+from birdvisu import ospffile, ospfsock
 from birdvisu.maps_new import TopologyProvider, Router, Network, Link, Topology
 import subprocess
 import re
@@ -125,3 +125,15 @@ class RunningBirdTopologyProvider(TopologyProvider):
 
 	def get_topology(self):
 		return self.topology
+
+class BirdSocketTopologyProvider(TopologyProvider):
+	"""This one is dynamic, provides new topology every time."""
+	def __init__(self, socket_filename='/run/bird/bird.ctl'):
+		self.socket_filename = socket_filename
+	
+	def get_topology(self):
+		birdsock = ospfsock.BirdSocketConnection()
+		resp = birdsock.request('show ospf state')
+		# TODO: Naming things – this is not exactly parser…
+		parser = OspfDataTopologyProvider(resp.text)
+		return parser.get_topology()

birdvisu/ospfsock.py

@@ -1,18 +1,43 @@
 """Simple utility to interface with BIRD using the control socket."""
 
-from dataclasses import dataclass
+from dataclasses import dataclass,field
 import socket as sk
+from string import digits
+
+class BirdError(Exception):
+	def __init__(self, code, where, text):
+		self.code = code
+		self.start = where[0]
+		self.end = where[1]
+		self.text = text
 
 @dataclass
 class BirdResponse:
 	text: str = ''
 	codes: list[tuple[tuple[int, int], int]] = []  # List of line ranges (inclusive) and the respective code.
 
+	def raise_exceptions(self) -> None:
+		# If the response contains any errors, raise them as BirdErrors
+		# TODO Py3.11: use ExceptionGroups?
+		# Until then, let's just report the first one?
+		assert len(self.codes) >= 1, "Not a valid response."
+		for where, code in self.codes:
+			if code.startswith('9'):
+				# Extract text
+				start = where[0] - 1
+				end = where[1]
+				print(start,end)
+				errorlines = self.text.splitlines(keepends=True)[start:end]
+				exc = BirdError(code, where, ''.join(errorlines))
+				raise exc
+
 class BirdSocketConnection:
 	def __init__(self, sockpath='/run/bird/bird.ctl'):
 		self.socket = sk.socket(sk.AF_UNIX, sk.SOCK_STREAM)
 		self.socket.setblocking(False)
 		self.socket.connect(sockpath)
+		# Bird announces itself by printing version. We save the response just in case.
+		self.bird_prologue = self._parse_response()
 
 	def request(self, req: str) -> BirdResponse:
 		if not req.endswith('\n'):
@@ -26,14 +51,32 @@ class BirdSocketConnection:
 		# described at one place. Therefore other parts of the code do not need
 		# to know anything about the protocol (maybe apart from the meaning of
 		# status codes, if they are interested…)
-		MAXLINELENGTH = 1000 # Pretty please…
-		READSIZE = MAXLINELENGTH * 2 # Ensures that after the read at least one complete line has been read.
-		lines = []
-		data = b''
-		# There is no way to read line-wise, so we just read everything and split afterwards.
-		# This is probably very horrible.
-		try:
-			while True:
-				data += self.socket.
-		
+		result = BirdResponse()
+		code : str | None = None # string because of leading zeroes, and it has no numeric interpretation anyway
+		start = None
+		cont = True
+		f = self.socket.makefile('r')
+		for i, line in enumerate(f, start=1):
+			assert cont, "WTF bad format (should not continue)."
+			if line.startswith(tuple(digits)):
+				if start is not None:
+					end = i-1
+					result.codes.append(((start, end), code))
+				code = line[:4]
+				start = i
+				cont = line[4] == '-'
+				text = line[5:]
+			else:
+				assert cont == True
+				text = line[1:]
+			result.text += text # Invariant: LF as line terminator
+			if not cont:
+				# Finalization. We do not have i after the end of the cycle,
+				# but this is the last iteration.
+				end = i
+				result.codes.append(((start, end), code))
+				break
+		result.raise_exceptions()
+		return result
+