From: Tom Christie <tom@tomchristie.com>
Date: Tue, 14 Jan 2020 09:00:52 +0000 (+0000)
Subject: Support both zlib and deflate encodings (#758)
X-Git-Tag: 0.11.1~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=780d1843cac3487d545fd7b1ff44c1212702598a;p=thirdparty%2Fhttpx.git

Support both zlib and deflate encodings (#758)

* Support both zlib and deflate encodings

* Helpful test docstrings
---

diff --git a/httpx/decoders.py b/httpx/decoders.py
index 75d980d3..454ec4a1 100644
--- a/httpx/decoders.py
+++ b/httpx/decoders.py
@@ -45,12 +45,18 @@ class DeflateDecoder(Decoder):
     """
 
     def __init__(self) -> None:
-        self.decompressor = zlib.decompressobj(-zlib.MAX_WBITS)
+        self.first_attempt = True
+        self.decompressor = zlib.decompressobj()
 
     def decode(self, data: bytes) -> bytes:
+        was_first_attempt = self.first_attempt
+        self.first_attempt = False
         try:
             return self.decompressor.decompress(data)
         except zlib.error as exc:
+            if was_first_attempt:
+                self.decompressor = zlib.decompressobj(-zlib.MAX_WBITS)
+                return self.decode(data)
             raise DecodingError from exc
 
     def flush(self) -> bytes:
diff --git a/tests/test_decoders.py b/tests/test_decoders.py
index f320d941..d9e82f70 100644
--- a/tests/test_decoders.py
+++ b/tests/test_decoders.py
@@ -18,6 +18,11 @@ REQUEST = httpx.Request("GET", "https://example.org")
 
 
 def test_deflate():
+    """
+    Deflate encoding may use either 'zlib' or 'deflate' in the wild.
+
+    https://stackoverflow.com/questions/1838699/how-can-i-decompress-a-gzip-stream-with-zlib#answer-22311297
+    """
     body = b"test 123"
     compressor = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS)
     compressed_body = compressor.compress(body) + compressor.flush()
@@ -29,6 +34,22 @@ def test_deflate():
     assert response.content == body
 
 
+def test_zlib():
+    """
+    Deflate encoding may use either 'zlib' or 'deflate' in the wild.
+
+    https://stackoverflow.com/questions/1838699/how-can-i-decompress-a-gzip-stream-with-zlib#answer-22311297
+    """
+    body = b"test 123"
+    compressed_body = zlib.compress(body)
+
+    headers = [(b"Content-Encoding", b"deflate")]
+    response = httpx.Response(
+        200, headers=headers, content=compressed_body, request=REQUEST
+    )
+    assert response.content == body
+
+
 def test_gzip():
     body = b"test 123"
     compressor = zlib.compressobj(9, zlib.DEFLATED, zlib.MAX_WBITS | 16)