Merge 0803479 into 4ce0b89

dpkt/sctp.py

@@ -52,13 +52,13 @@ def unpack(self, buf):
             chunk = Chunk(self.data)
             l.append(chunk)
             self.data = self.data[len(chunk):]
-        self.data = self.chunks = l
+        self.chunks = l
 
     def __len__(self):
-        return self.__hdr_len__ + sum(map(len, self.data))
+        return self.__hdr_len__ + sum(len(x) for x in self.chunks)
 
     def __bytes__(self):
-        l = [bytes(x) for x in self.data]
+        l = [bytes(x) for x in self.chunks]
         if self.sum == 0:
             s = crc32c.add(0xffffffff, self.pack_hdr())
             for x in l:
@@ -76,7 +76,22 @@ class Chunk(dpkt.Packet):
 
     def unpack(self, buf):
         dpkt.Packet.unpack(self, buf)
+
         self.data = self.data[:self.len - self.__hdr_len__]
+        self.padding = b''  # optional padding for DATA chunks
+
+        # SCTP DATA Chunked is padded, 4-bytes aligned
+        if self.type == DATA and self.len % 4:
+            plen = 4 - self.len % 4  # padded length
+            if plen:
+                pos = self.__hdr_len__ + len(self.data)  # end of data in buf
+                self.padding = buf[pos:pos + plen]
+
+    def __len__(self):
+        return self.len + len(self.padding)
+
+    def __bytes__(self):
+        return self.pack_hdr() + bytes(self.data) + self.padding
 
 
 __s = b'\x80\x44\x00\x50\x00\x00\x00\x00\x30\xba\xef\x54\x01\x00\x00\x3c\x3b\xb9\x9c\x46\x00\x01\xa0\x00\x00\x0a\xff\xff\x2b\x2d\x7e\xb2\x00\x05\x00\x08\x9b\xe6\x18\x9b\x00\x05\x00\x08\x9b\xe6\x18\x9c\x00\x0c\x00\x06\x00\x05\x00\x00\x80\x00\x00\x04\xc0\x00\x00\x04\xc0\x06\x00\x08\x00\x00\x00\x00'
@@ -100,7 +115,49 @@ def test_sctp_unpack():
     assert (chunk.len == 60)
 
 
+def test_sctp_data_chunk():  # https://github.com/kbandla/dpkt/issues/499
+    # packet 5 from 'sctp-www.cap' downloaded from https://wiki.wireshark.org/SampleCaptures
+    # chunk len == 419 so requires padding to a 4-byte boundary
+    d = (b'\x80\x44\x00\x50\xd2\x6a\xc1\xe5\x70\xe5\x5b\x4c\x00\x03\x01\xa3\x2b\x2d\x7e\xb2\x00\x00'
+         b'\x00\x00\x00\x00\x00\x00\x47\x45\x54\x20\x2f\x20\x48\x54\x54\x50\x2f\x31\x2e\x31\x0d\x0a'
+         b'\x48\x6f\x73\x74\x3a\x20\x32\x30\x33\x2e\x32\x35\x35\x2e\x32\x35\x32\x2e\x31\x39\x34\x0d'
+         b'\x0a\x55\x73\x65\x72\x2d\x41\x67\x65\x6e\x74\x3a\x20\x4d\x6f\x7a\x69\x6c\x6c\x61\x2f\x35'
+         b'\x2e\x30\x20\x28\x58\x31\x31\x3b\x20\x55\x3b\x20\x4c\x69\x6e\x75\x78\x20\x69\x36\x38\x36'
+         b'\x3b\x20\x6b\x6f\x2d\x4b\x52\x3b\x20\x72\x76\x3a\x31\x2e\x37\x2e\x31\x32\x29\x20\x47\x65'
+         b'\x63\x6b\x6f\x2f\x32\x30\x30\x35\x31\x30\x30\x37\x20\x44\x65\x62\x69\x61\x6e\x2f\x31\x2e'
+         b'\x37\x2e\x31\x32\x2d\x31\x0d\x0a\x41\x63\x63\x65\x70\x74\x3a\x20\x74\x65\x78\x74\x2f\x78'
+         b'\x6d\x6c\x2c\x61\x70\x70\x6c\x69\x63\x61\x74\x69\x6f\x6e\x2f\x78\x6d\x6c\x2c\x61\x70\x70'
+         b'\x6c\x69\x63\x61\x74\x69\x6f\x6e\x2f\x78\x68\x74\x6d\x6c\x2b\x78\x6d\x6c\x2c\x74\x65\x78'
+         b'\x74\x2f\x68\x74\x6d\x6c\x3b\x71\x3d\x30\x2e\x39\x2c\x74\x65\x78\x74\x2f\x70\x6c\x61\x69'
+         b'\x6e\x3b\x71\x3d\x30\x2e\x38\x2c\x69\x6d\x61\x67\x65\x2f\x70\x6e\x67\x2c\x2a\x2f\x2a\x3b'
+         b'\x71\x3d\x30\x2e\x35\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x4c\x61\x6e\x67\x75\x61\x67\x65'
+         b'\x3a\x20\x6b\x6f\x2c\x65\x6e\x2d\x75\x73\x3b\x71\x3d\x30\x2e\x37\x2c\x65\x6e\x3b\x71\x3d'
+         b'\x30\x2e\x33\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x45\x6e\x63\x6f\x64\x69\x6e\x67\x3a\x20'
+         b'\x67\x7a\x69\x70\x2c\x64\x65\x66\x6c\x61\x74\x65\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x43'
+         b'\x68\x61\x72\x73\x65\x74\x3a\x20\x45\x55\x43\x2d\x4b\x52\x2c\x75\x74\x66\x2d\x38\x3b\x71'
+         b'\x3d\x30\x2e\x37\x2c\x2a\x3b\x71\x3d\x30\x2e\x37\x0d\x0a\x4b\x65\x65\x70\x2d\x41\x6c\x69'
+         b'\x76\x65\x3a\x20\x33\x30\x30\x0d\x0a\x43\x6f\x6e\x6e\x65\x63\x74\x69\x6f\x6e\x3a\x20\x6b'
+         b'\x65\x65\x70\x2d\x61\x6c\x69\x76\x65\x0d\x0a\x0d\x0a\x00')  # <-- ends with \x00 padding
+
+    sctp = SCTP(d)
+    assert sctp.chunks
+    assert len(sctp.chunks) == 1
+
+    ch = sctp.chunks[0]
+    assert ch.type == DATA
+    assert ch.len == 419
+    assert len(ch) == 420  # 419 +1 byte padding
+    assert ch.data[-14:] == b'keep-alive\r\n\r\n'  # no padding byte at the end
+
+    # no remaining sctp data
+    assert sctp.data == b''
+
+    # test packing of the padded chunk
+    assert bytes(ch) == d[SCTP.__hdr_len__:]
+
+
 if __name__ == '__main__':
     test_sctp_pack()
     test_sctp_unpack()
+    test_sctp_data_chunk()
     print('Tests Successful...')