1 files changed, 88 insertions, 0 deletions
diff --git a/netlib/encoding.py b/netlib/encoding.py
new file mode 100644
index 00000000..14479e00
--- /dev/null
+++ b/netlib/encoding.py
@@ -0,0 +1,88 @@
+"""
+    Utility functions for decoding response bodies.
+"""
+from __future__ import absolute_import
+from io import BytesIO
+import gzip
+import zlib
+from .utils import always_byte_args
+
+
+ENCODINGS = {"identity", "gzip", "deflate"}
+
+
+def decode(e, content):
+    if not isinstance(content, bytes):
+        return None
+    encoding_map = {
+        "identity": identity,
+        "gzip": decode_gzip,
+        "deflate": decode_deflate,
+    }
+    if e not in encoding_map:
+        return None
+    return encoding_map[e](content)
+
+
+def encode(e, content):
+    if not isinstance(content, bytes):
+        return None
+    encoding_map = {
+        "identity": identity,
+        "gzip": encode_gzip,
+        "deflate": encode_deflate,
+    }
+    if e not in encoding_map:
+        return None
+    return encoding_map[e](content)
+
+
+def identity(content):
+    """
+        Returns content unchanged. Identity is the default value of
+        Accept-Encoding headers.
+    """
+    return content
+
+
+def decode_gzip(content):
+    gfile = gzip.GzipFile(fileobj=BytesIO(content))
+    try:
+        return gfile.read()
+    except (IOError, EOFError):
+        return None
+
+
+def encode_gzip(content):
+    s = BytesIO()
+    gf = gzip.GzipFile(fileobj=s, mode='wb')
+    gf.write(content)
+    gf.close()
+    return s.getvalue()
+
+
+def decode_deflate(content):
+    """
+        Returns decompressed data for DEFLATE. Some servers may respond with
+        compressed data without a zlib header or checksum. An undocumented
+        feature of zlib permits the lenient decompression of data missing both
+        values.
+
+        http://bugs.python.org/issue5784
+    """
+    try:
+        try:
+            return zlib.decompress(content)
+        except zlib.error:
+            return zlib.decompress(content, -15)
+    except zlib.error:
+        return None
+
+
+def encode_deflate(content):
+    """
+        Returns compressed content, always including zlib header and checksum.
+    """
+    return zlib.compress(content)
+
+__all__ = ["ENCODINGS", "encode", "decode"]