2025-12-25 upload
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“shengyudong”
237
venv/Lib/site-packages/hpack/table.py
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237
venv/Lib/site-packages/hpack/table.py
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# flake8: noqa
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from collections import deque
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import logging
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from typing import Optional
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from .exceptions import InvalidTableIndex
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log = logging.getLogger(__name__)
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def table_entry_size(name: bytes, value: bytes) -> int:
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"""
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Calculates the size of a single entry
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This size is mostly irrelevant to us and defined
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specifically to accommodate memory management for
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lower level implementations. The 32 extra bytes are
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considered the "maximum" overhead that would be
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required to represent each entry in the table.
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See RFC7541 Section 4.1
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"""
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return 32 + len(name) + len(value)
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class HeaderTable:
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"""
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Implements the combined static and dynamic header table
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The name and value arguments for all the functions
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should ONLY be byte strings (b'') however this is not
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strictly enforced in the interface.
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See RFC7541 Section 2.3
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"""
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#: Default maximum size of the dynamic table. See
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#: RFC7540 Section 6.5.2.
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DEFAULT_SIZE = 4096
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#: Constant list of static headers. See RFC7541 Section
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#: 2.3.1 and Appendix A
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STATIC_TABLE = (
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(b':authority' , b'' ), # noqa
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(b':method' , b'GET' ), # noqa
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(b':method' , b'POST' ), # noqa
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(b':path' , b'/' ), # noqa
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(b':path' , b'/index.html' ), # noqa
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(b':scheme' , b'http' ), # noqa
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(b':scheme' , b'https' ), # noqa
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(b':status' , b'200' ), # noqa
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(b':status' , b'204' ), # noqa
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(b':status' , b'206' ), # noqa
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(b':status' , b'304' ), # noqa
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(b':status' , b'400' ), # noqa
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(b':status' , b'404' ), # noqa
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(b':status' , b'500' ), # noqa
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(b'accept-charset' , b'' ), # noqa
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(b'accept-encoding' , b'gzip, deflate'), # noqa
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(b'accept-language' , b'' ), # noqa
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(b'accept-ranges' , b'' ), # noqa
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(b'accept' , b'' ), # noqa
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(b'access-control-allow-origin' , b'' ), # noqa
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(b'age' , b'' ), # noqa
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(b'allow' , b'' ), # noqa
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(b'authorization' , b'' ), # noqa
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(b'cache-control' , b'' ), # noqa
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(b'content-disposition' , b'' ), # noqa
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(b'content-encoding' , b'' ), # noqa
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(b'content-language' , b'' ), # noqa
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(b'content-length' , b'' ), # noqa
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(b'content-location' , b'' ), # noqa
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(b'content-range' , b'' ), # noqa
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(b'content-type' , b'' ), # noqa
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(b'cookie' , b'' ), # noqa
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(b'date' , b'' ), # noqa
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(b'etag' , b'' ), # noqa
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(b'expect' , b'' ), # noqa
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(b'expires' , b'' ), # noqa
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(b'from' , b'' ), # noqa
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(b'host' , b'' ), # noqa
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(b'if-match' , b'' ), # noqa
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(b'if-modified-since' , b'' ), # noqa
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(b'if-none-match' , b'' ), # noqa
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(b'if-range' , b'' ), # noqa
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(b'if-unmodified-since' , b'' ), # noqa
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(b'last-modified' , b'' ), # noqa
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(b'link' , b'' ), # noqa
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(b'location' , b'' ), # noqa
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(b'max-forwards' , b'' ), # noqa
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(b'proxy-authenticate' , b'' ), # noqa
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(b'proxy-authorization' , b'' ), # noqa
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(b'range' , b'' ), # noqa
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(b'referer' , b'' ), # noqa
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(b'refresh' , b'' ), # noqa
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(b'retry-after' , b'' ), # noqa
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(b'server' , b'' ), # noqa
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(b'set-cookie' , b'' ), # noqa
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(b'strict-transport-security' , b'' ), # noqa
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(b'transfer-encoding' , b'' ), # noqa
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(b'user-agent' , b'' ), # noqa
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(b'vary' , b'' ), # noqa
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(b'via' , b'' ), # noqa
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(b'www-authenticate' , b'' ), # noqa
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) # noqa
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STATIC_TABLE_LENGTH = len(STATIC_TABLE)
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STATIC_TABLE_MAPPING: dict[bytes, tuple[int, dict[bytes, int]]]
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def __init__(self) -> None:
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self._maxsize = HeaderTable.DEFAULT_SIZE
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self._current_size = 0
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self.resized = False
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self.dynamic_entries: deque[tuple[bytes, bytes]] = deque()
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def get_by_index(self, index: int) -> tuple[bytes, bytes]:
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"""
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Returns the entry specified by index
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Note that the table is 1-based ie an index of 0 is
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invalid. This is due to the fact that a zero value
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index signals that a completely unindexed header
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follows.
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The entry will either be from the static table or
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the dynamic table depending on the value of index.
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"""
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original_index = index
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index -= 1
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if 0 <= index:
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if index < HeaderTable.STATIC_TABLE_LENGTH:
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return HeaderTable.STATIC_TABLE[index]
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index -= HeaderTable.STATIC_TABLE_LENGTH
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if index < len(self.dynamic_entries):
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return self.dynamic_entries[index]
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raise InvalidTableIndex("Invalid table index %d" % original_index)
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def __repr__(self) -> str:
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return "HeaderTable(%d, %s, %r)" % (
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self._maxsize,
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self.resized,
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self.dynamic_entries
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)
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def add(self, name: bytes, value: bytes) -> None:
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"""
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Adds a new entry to the table
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We reduce the table size if the entry will make the
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table size greater than maxsize.
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"""
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# We just clear the table if the entry is too big
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size = table_entry_size(name, value)
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if size > self._maxsize:
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self.dynamic_entries.clear()
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self._current_size = 0
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else:
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# Add new entry
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self.dynamic_entries.appendleft((name, value))
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self._current_size += size
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self._shrink()
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def search(self, name: bytes, value: bytes) -> Optional[tuple[int, bytes, Optional[bytes]]]:
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"""
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Searches the table for the entry specified by name
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and value
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Returns one of the following:
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- ``None``, no match at all
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- ``(index, name, None)`` for partial matches on name only.
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- ``(index, name, value)`` for perfect matches.
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"""
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partial = None
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header_name_search_result = HeaderTable.STATIC_TABLE_MAPPING.get(name)
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if header_name_search_result:
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index = header_name_search_result[1].get(value)
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if index is not None:
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return index, name, value
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else:
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partial = (header_name_search_result[0], name, None)
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offset = HeaderTable.STATIC_TABLE_LENGTH + 1
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for (i, (n, v)) in enumerate(self.dynamic_entries):
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if n == name:
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if v == value:
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return i + offset, n, v
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elif partial is None:
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partial = (i + offset, n, None)
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return partial
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@property
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def maxsize(self) -> int:
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return self._maxsize
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@maxsize.setter
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def maxsize(self, newmax: int) -> None:
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newmax = int(newmax)
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log.debug("Resizing header table to %d from %d", newmax, self._maxsize)
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oldmax = self._maxsize
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self._maxsize = newmax
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self.resized = (newmax != oldmax)
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if newmax <= 0:
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self.dynamic_entries.clear()
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self._current_size = 0
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elif oldmax > newmax:
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self._shrink()
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def _shrink(self) -> None:
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"""
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Shrinks the dynamic table to be at or below maxsize
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"""
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cursize = self._current_size
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while cursize > self._maxsize:
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name, value = self.dynamic_entries.pop()
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cursize -= table_entry_size(name, value)
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log.debug("Evicting %s: %s from the header table", name, value)
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self._current_size = cursize
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def _build_static_table_mapping() -> dict[bytes, tuple[int, dict[bytes, int]]]:
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"""
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Build static table mapping from header name to tuple with next structure:
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(<minimal index of header>, <mapping from header value to it index>).
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static_table_mapping used for hash searching.
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"""
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static_table_mapping: dict[bytes, tuple[int, dict[bytes, int]]] = {}
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for index, (name, value) in enumerate(HeaderTable.STATIC_TABLE, 1):
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header_name_search_result = static_table_mapping.setdefault(name, (index, {}))
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header_name_search_result[1][value] = index
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return static_table_mapping
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HeaderTable.STATIC_TABLE_MAPPING = _build_static_table_mapping()
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