Add extra logging info to header parsing

There's many replays with invalid headers that might be genuinely short
data or something we incorrectly parse. This extra info will help
clarify that.

Signed-off-by: Igor Kotrasinski <i.kotrasinsk@gmail.com>

replayserver/struct/header.py

@@ -73,10 +73,12 @@ def read_lua_value(gen, lua_dict_depth=0, can_be_lua_end=False):
 
 
 def read_header(gen):
+    gen.state = "reading version"
     result = {}
     result["version"] = yield from read_string(gen)
     yield from read_exactly(gen, 3)     # skip
 
+    gen.state = "reading replay version"
     replay_version_and_map = yield from read_string(gen)
     # can raise ValueError
     replay_version, map_name = replay_version_and_map.split("\r\n", 2)
@@ -86,14 +88,17 @@ def read_header(gen):
 
     # We don't need to parse mods
     ssize = yield from read_value(gen, "I", 4)  # Mod (data?) size
+    gen.state = f"skipping mod data ({ssize} bytes)"
     yield from read_exactly(gen, ssize)
     # result["mods"] = yield from read_lua_value(gen)
 
     # We don't need to parse scenario info
     ssize = yield from read_value(gen, "I", 4)  # Scenario (data?) size
+    gen.state = f"skipping scenario info ({ssize} bytes)"
     yield from read_exactly(gen, ssize)
     # result["scenario"] = yield from read_lua_value(gen)
 
+    gen.state = "reading player list"
     player_count = yield from read_value(gen, "b", 1)
     timeouts = {}
     for i in range(player_count):
@@ -109,6 +114,7 @@ def read_header(gen):
     for i in range(army_count):
         # We don't need to parse armies
         ssize = yield from read_value(gen, "I", 4)  # Army (data?) size
+        gen.state = f"skipping army info ({ssize} bytes)"
         yield from read_exactly(gen, ssize)
         # army = yield from read_lua_value(gen)
         player_id = yield from read_value(gen, "B", 1)
@@ -131,22 +137,24 @@ def __init__(self, data, struct):
 
     @classmethod
     async def from_connection(cls, connection):
-        generator = cls._generate(cls.MAXLEN)
+        gen = GeneratorData(cls.MAXLEN)
+        generator = cls._generate(gen)
         generator.send(None)
         while True:
-            data = await connection.read(4096)  # TODO - configure?
-            if not data:
-                raise MalformedDataError("Replay header ended prematurely")
             try:
+                data = await connection.read(4096)  # TODO - configure?
+                if not data:
+                    raise ValueError("Replay header ended prematurely")
                 generator.send(data)
             except ValueError as e:
-                raise MalformedDataError("Invalid replay header") from e
+                raise MalformedDataError(
+                    f"Invalid replay header while {gen.state}"
+                    f" at {gen.position} bytes: {e}")
             except StopIteration as v:
                 return v.value
 
     @classmethod
-    def _generate(cls, maxlen):
-        gen = GeneratorData(maxlen)
+    def _generate(cls, gen):
         header = yield from read_header(gen)
         data = gen.data[:gen.position]
         leftovers = gen.data[gen.position:]

replayserver/struct/streamread.py

@@ -9,6 +9,8 @@ def __init__(self, maxlen=None):
         self.position = 0
         self._maxlen = maxlen
 
+        self.state = "idle"
+
     def more(self):
         if self._maxlen is not None and self._maxlen <= len(self.data):
             raise ValueError(f"Exceeded maximum read length {self._maxlen}")