read_headers: handle some crashes, return None on invalid data.

netlib/http.py

@@ -36,8 +36,8 @@ def parse_url(url):
 
 def read_headers(fp):
     """
-        Read a set of headers from a file pointer. Stop once a blank line
-        is reached. Return a ODictCaseless object.
+        Read a set of headers from a file pointer. Stop once a blank line is
+        reached. Return a ODictCaseless object, or None if headers are invalid.
     """
     ret = []
     name = ''
@@ -46,6 +46,8 @@ def read_headers(fp):
         if not line or line == '\r\n' or line == '\n':
             break
         if line[0] in ' \t':
+            if not ret:
+                return None
             # continued header
             ret[-1][1] = ret[-1][1] + '\r\n ' + line.strip()
         else:
@@ -55,6 +57,8 @@ def read_headers(fp):
                 name = line[:i]
                 value = line[i+1:].strip()
                 ret.append([name, value])
+            else:
+                return None
     return odict.ODictCaseless(ret)
 
 
@@ -282,6 +286,8 @@ def read_response(rfile, method, body_size_limit):
     except ValueError:
         raise HttpError(502, "Invalid server response: %s"%repr(line))
     headers = read_headers(rfile)
+    if headers is None:
+        raise HttpError(502, "Invalid headers.")
     if code >= 100 and code <= 199:
         return read_response(rfile, method, body_size_limit)
     if method == "HEAD" or code == 204 or code == 304:

test/test_http.py

@@ -169,16 +169,20 @@ def test_parse_init_http():
 
 
 class TestReadHeaders:
+    def _read(self, data, verbatim=False):
+        if not verbatim:
+            data = textwrap.dedent(data)
+            data = data.strip()
+        s = cStringIO.StringIO(data)
+        return http.read_headers(s)
+
     def test_read_simple(self):
         data = """
             Header: one
             Header2: two
             \r\n
         """
-        data = textwrap.dedent(data)
-        data = data.strip()
-        s = cStringIO.StringIO(data)
-        h = http.read_headers(s)
+        h = self._read(data)
         assert h.lst == [["Header", "one"], ["Header2", "two"]]
 
     def test_read_multi(self):
@@ -187,10 +191,7 @@ class TestReadHeaders:
             Header: two
             \r\n
         """
-        data = textwrap.dedent(data)
-        data = data.strip()
-        s = cStringIO.StringIO(data)
-        h = http.read_headers(s)
+        h = self._read(data)
         assert h.lst == [["Header", "one"], ["Header", "two"]]
 
     def test_read_continued(self):
@@ -200,12 +201,19 @@ class TestReadHeaders:
             Header2: three
             \r\n
         """
-        data = textwrap.dedent(data)
-        data = data.strip()
-        s = cStringIO.StringIO(data)
-        h = http.read_headers(s)
+        h = self._read(data)
         assert h.lst == [["Header", "one\r\n two"], ["Header2", "three"]]
 
+    def test_read_continued_err(self):
+        data = "\tfoo: bar\r\n"
+        assert self._read(data, True) is None
+
+    def test_read_err(self):
+        data = """
+            foo
+        """
+        assert self._read(data) is None
+
 
 def test_read_response():
     def tst(data, method, limit):
@@ -248,6 +256,14 @@ def test_read_response():
     assert tst(data, "GET", None)[4] == 'foo'
     assert tst(data, "HEAD", None)[4] == ''
 
+    data = """
+        HTTP/1.1 200 OK
+        \tContent-Length: 3
+
+        foo
+    """
+    tutils.raises("invalid headers", tst, data, "GET", None)
+
 
 def test_parse_url():
     assert not http.parse_url("")