Cython implementation

src/hpack/__init__.pxd

@@ -0,0 +1,2 @@
+from .c_exceptions cimport *
+from .c_table cimport *

src/hpack/__init__.py

@@ -3,7 +3,7 @@
 """
 from __future__ import annotations
 
-from .exceptions import HPACKDecodingError, HPACKError, InvalidTableIndex, InvalidTableIndexError, InvalidTableSizeError, OversizedHeaderListError
+from .py_exceptions import HPACKDecodingError, HPACKError, InvalidTableIndex, InvalidTableIndexError, InvalidTableSizeError, OversizedHeaderListError
 from .hpack import Decoder, Encoder
 from .struct import HeaderTuple, NeverIndexedHeaderTuple
 

src/hpack/c_exceptions.pxd

@@ -0,0 +1,17 @@
+cdef class HPACKError(Exception):
+    pass 
+
+cdef class HPACKDecodingError(HPACKError):
+    pass
+
+cdef class InvalidTableIndexError(HPACKDecodingError):
+    pass 
+
+cdef class InvalidTableIndex(InvalidTableIndexError):
+    pass
+
+cdef class OversizedHeaderListError(HPACKDecodingError):
+    pass 
+
+cdef class InvalidTableSizeError(HPACKDecodingError):
+    pass

src/hpack/c_exceptions.pyi

@@ -0,0 +1,54 @@
+class HPACKError(Exception):
+    """
+    The base cdef class for all ``hpack`` exceptions.
+    """
+    ...
+
+
+class HPACKDecodingError(HPACKError):
+    """
+    An error has been encountered while performing HPACK decoding.
+    """
+    ...
+
+
+class InvalidTableIndexError(HPACKDecodingError):
+    """
+    An invalid table index was received.
+
+    .. versionadded:: 4.1.0
+    """
+    ...
+
+
+class InvalidTableIndex(InvalidTableIndexError):
+    """
+    An invalid table index was received.
+
+    .. deprecated:: 4.1.0
+       Renamed to :class:`InvalidTableIndexError`, use it instead.
+    """
+    ...
+
+
+class OversizedHeaderListError(HPACKDecodingError):
+    """
+    A header list that was larger than we allow has been received. This may be
+    a DoS attack.
+
+    .. versionadded:: 2.3.0
+    """
+    ...
+
+
+class InvalidTableSizeError(HPACKDecodingError):
+    """
+    An attempt was made to change the decoder table size to a value larger than
+    allowed, or the list was shrunk and the remote peer didn't shrink their
+    table size.
+
+    .. versionadded:: 3.0.0
+    """
+    ...
+
+

src/hpack/c_exceptions.pyx

@@ -0,0 +1,47 @@
+cdef class HPACKError(Exception):
+    """
+    The base cdef class for all ``hpack`` exceptions.
+    """
+
+
+
+cdef class HPACKDecodingError(HPACKError):
+    """
+    An error has been encountered while performing HPACK decoding.
+    """
+
+
+
+cdef class InvalidTableIndexError(HPACKDecodingError):
+    """
+    An invalid table index was received.
+
+    .. versionadded:: 4.1.0
+    """
+
+cdef class InvalidTableIndex(InvalidTableIndexError):  # noqa: N818
+    """
+    An invalid table index was received.
+
+    .. deprecated:: 4.1.0
+       Renamed to :class:`InvalidTableIndexError`, use it instead.
+    """
+
+
+cdef class OversizedHeaderListError(HPACKDecodingError):
+    """
+    A header list that was larger than we allow has been received. This may be
+    a DoS attack.
+
+    .. versionadded:: 2.3.0
+    """
+
+
+cdef class InvalidTableSizeError(HPACKDecodingError):
+    """
+    An attempt was made to change the decoder table size to a value larger than
+    allowed, or the list was shrunk and the remote peer didn't shrink their
+    table size.
+
+    .. versionadded:: 3.0.0
+    """

src/hpack/c_huffman.pxd

@@ -0,0 +1,12 @@
+
+
+cdef class HuffmanEncoder:
+    """
+    Encodes a string according to the Huffman encoding table defined in the
+    HPACK specification.
+    """
+    cdef:
+        list huffman_code_list
+        list huffman_code_list_lengths
+
+    cpdef bytes encode(self, bytes bytes_to_encode)

src/hpack/c_huffman.pyx

@@ -0,0 +1,63 @@
+
+cdef class HuffmanEncoder:
+    """
+    Encodes a string according to the Huffman encoding table defined in the
+    HPACK specification.
+    """
+
+    def __init__(self, list huffman_code_list, list huffman_code_list_lengths) -> None:
+        self.huffman_code_list = huffman_code_list
+        self.huffman_code_list_lengths = huffman_code_list_lengths
+
+    cpdef bytes encode(self, bytes bytes_to_encode):
+        """
+        Given a string of bytes, encodes them according to the HPACK Huffman
+        specification.
+        """
+        cdef int byte
+
+        # If handed the empty string, just immediately return.
+        if not bytes_to_encode:
+            return b""
+
+        cdef int bin_int_len, bin_int
+        cdef size_t final_num = 0
+        cdef size_t final_int_len = 0
+        cdef size_t bits_to_be_padded, total_bytes
+        cdef str s
+
+        # Turn each byte into its huffman code. These codes aren't necessarily
+        # octet aligned, so keep track of how far through an octet we are. To
+        # handle this cleanly, just use a single giant integer.
+        for byte in bytes_to_encode:
+            bin_int_len = self.huffman_code_list_lengths[byte]
+            bin_int = self.huffman_code_list[byte] & (
+                2 ** (bin_int_len + 1) - 1
+            )
+            final_num <<= bin_int_len
+            final_num |= bin_int
+            final_int_len += bin_int_len
+
+        # Pad out to an octet with ones.
+        bits_to_be_padded = (8 - (final_int_len % 8)) % 8
+        final_num <<= bits_to_be_padded
+        final_num |= (1 << bits_to_be_padded) - 1
+
+        # Convert the number to hex and strip off the leading '0x' and the
+        # trailing 'L', if present.
+        s = hex(final_num)[2:].rstrip("L")
+
+        # If this is odd, prepend a zero.
+        s = "0" + s if len(s) % 2 != 0 else s
+
+        # This number should have twice as many digits as bytes. If not, we're
+        # missing some leading zeroes. Work out how many bytes we want and how
+        # many digits we have, then add the missing zero digits to the front.
+        total_bytes = (final_int_len + bits_to_be_padded) // 8
+        expected_digits = total_bytes * 2
+
+        if len(s) != expected_digits:
+            missing_digits = expected_digits - len(s)
+            s = ("0" * missing_digits) + s
+
+        return bytes.fromhex(s)