Update dnspython-2.2.0

lib/dns/wire.py

@@ -0,0 +1,82 @@
+# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
+
+import contextlib
+import struct
+
+import dns.exception
+import dns.name
+
+class Parser:
+    def __init__(self, wire, current=0):
+        self.wire = wire
+        self.current = 0
+        self.end = len(self.wire)
+        if current:
+            self.seek(current)
+        self.furthest = current
+
+    def remaining(self):
+        return self.end - self.current
+
+    def get_bytes(self, size):
+        if size > self.remaining():
+            raise dns.exception.FormError
+        output = self.wire[self.current:self.current + size]
+        self.current += size
+        self.furthest = max(self.furthest, self.current)
+        return output
+
+    def get_counted_bytes(self, length_size=1):
+        length = int.from_bytes(self.get_bytes(length_size), 'big')
+        return self.get_bytes(length)
+
+    def get_remaining(self):
+        return self.get_bytes(self.remaining())
+
+    def get_uint8(self):
+        return struct.unpack('!B', self.get_bytes(1))[0]
+
+    def get_uint16(self):
+        return struct.unpack('!H', self.get_bytes(2))[0]
+
+    def get_uint32(self):
+        return struct.unpack('!I', self.get_bytes(4))[0]
+
+    def get_struct(self, format):
+        return struct.unpack(format, self.get_bytes(struct.calcsize(format)))
+
+    def get_name(self, origin=None):
+        name = dns.name.from_wire_parser(self)
+        if origin:
+            name = name.relativize(origin)
+        return name
+
+    def seek(self, where):
+        # Note that seeking to the end is OK!  (If you try to read
+        # after such a seek, you'll get an exception as expected.)
+        if where < 0 or where > self.end:
+            raise dns.exception.FormError
+        self.current = where
+
+    @contextlib.contextmanager
+    def restrict_to(self, size):
+        if size > self.remaining():
+            raise dns.exception.FormError
+        saved_end = self.end
+        try:
+            self.end = self.current + size
+            yield
+            # We make this check here and not in the finally as we
+            # don't want to raise if we're already raising for some
+            # other reason.
+            if self.current != self.end:
+                raise dns.exception.FormError
+        finally:
+            self.end = saved_end
+
+    @contextlib.contextmanager
+    def restore_furthest(self):
+        try:
+            yield None
+        finally:
+            self.current = self.furthest