fix some general awfulness with http header handling

respodns/ip_info.py

@@ -36,6 +36,9 @@ class IpInfoByIpApi(IpInfoBase):
 
     def _parse_headers(self, it):
         # returns an error message as a string, or None.
+        x_cooldown = None
+        x_remaining = None
+
         for line in it:
             if line == b"":
                 break  # end of header
@@ -106,27 +109,17 @@ class IpInfoByIpApi(IpInfoBase):
         response = await reader.read()
         lines = response.splitlines()
 
-        err = None
         it = iter(lines)
-
-        line = next(it)
-        if line != b"HTTP/1.1 200 OK":
-            self.cooldown = time() + 60
-            err = "not ok"
-            it = ()  # exhaust iterator (not really)
-
-        x_cooldown = None
-        x_remaining = None
-
-        if err is None:
+        if next(it, None) == b"HTTP/1.1 200 OK":
             err = self._parse_headers(it)
-
-        for i, line in enumerate(it):
-            if i == 0:
-                code = line
-            else:
+            code = next(it, None)
+            if code is None:
+                err = "missing body"
+            if next(it, None) is not None:
                 err = "too many lines"
-                break
+        else:
+            err = "not ok"
+            self.cooldown = time() + 60
 
         writer.close()