1 files changed, 141 insertions, 0 deletions
diff --git a/yt_dlp/networking/impersonate.py b/yt_dlp/networking/impersonate.py
new file mode 100644
index 0000000..ca66180
--- /dev/null
+++ b/yt_dlp/networking/impersonate.py
@@ -0,0 +1,141 @@
+from __future__ import annotations
+
+import re
+from abc import ABC
+from dataclasses import dataclass
+from typing import Any
+
+from .common import RequestHandler, register_preference
+from .exceptions import UnsupportedRequest
+from ..compat.types import NoneType
+from ..utils import classproperty, join_nonempty
+from ..utils.networking import std_headers
+
+
+@dataclass(order=True, frozen=True)
+class ImpersonateTarget:
+    """
+    A target for browser impersonation.
+
+    Parameters:
+    @param client: the client to impersonate
+    @param version: the client version to impersonate
+    @param os: the client OS to impersonate
+    @param os_version: the client OS version to impersonate
+
+    Note: None is used to indicate to match any.
+
+    """
+    client: str | None = None
+    version: str | None = None
+    os: str | None = None
+    os_version: str | None = None
+
+    def __post_init__(self):
+        if self.version and not self.client:
+            raise ValueError('client is required if version is set')
+        if self.os_version and not self.os:
+            raise ValueError('os is required if os_version is set')
+
+    def __contains__(self, target: ImpersonateTarget):
+        if not isinstance(target, ImpersonateTarget):
+            return False
+        return (
+            (self.client is None or target.client is None or self.client == target.client)
+            and (self.version is None or target.version is None or self.version == target.version)
+            and (self.os is None or target.os is None or self.os == target.os)
+            and (self.os_version is None or target.os_version is None or self.os_version == target.os_version)
+        )
+
+    def __str__(self):
+        return f'{join_nonempty(self.client, self.version)}:{join_nonempty(self.os, self.os_version)}'.rstrip(':')
+
+    @classmethod
+    def from_str(cls, target: str):
+        mobj = re.fullmatch(r'(?:(?P<client>[^:-]+)(?:-(?P<version>[^:-]+))?)?(?::(?:(?P<os>[^:-]+)(?:-(?P<os_version>[^:-]+))?)?)?', target)
+        if not mobj:
+            raise ValueError(f'Invalid impersonate target "{target}"')
+        return cls(**mobj.groupdict())
+
+
+class ImpersonateRequestHandler(RequestHandler, ABC):
+    """
+    Base class for request handlers that support browser impersonation.
+
+    This provides a method for checking the validity of the impersonate extension,
+    which can be used in _check_extensions.
+
+    Impersonate targets consist of a client, version, os and os_ver.
+    See the ImpersonateTarget class for more details.
+
+    The following may be defined:
+     - `_SUPPORTED_IMPERSONATE_TARGET_MAP`: a dict mapping supported targets to custom object.
+                Any Request with an impersonate target not in this list will raise an UnsupportedRequest.
+                Set to None to disable this check.
+                Note: Entries are in order of preference
+
+    Parameters:
+    @param impersonate: the default impersonate target to use for requests.
+                        Set to None to disable impersonation.
+    """
+    _SUPPORTED_IMPERSONATE_TARGET_MAP: dict[ImpersonateTarget, Any] = {}
+
+    def __init__(self, *, impersonate: ImpersonateTarget = None, **kwargs):
+        super().__init__(**kwargs)
+        self.impersonate = impersonate
+
+    def _check_impersonate_target(self, target: ImpersonateTarget):
+        assert isinstance(target, (ImpersonateTarget, NoneType))
+        if target is None or not self.supported_targets:
+            return
+        if not self.is_supported_target(target):
+            raise UnsupportedRequest(f'Unsupported impersonate target: {target}')
+
+    def _check_extensions(self, extensions):
+        super()._check_extensions(extensions)
+        if 'impersonate' in extensions:
+            self._check_impersonate_target(extensions.get('impersonate'))
+
+    def _validate(self, request):
+        super()._validate(request)
+        self._check_impersonate_target(self.impersonate)
+
+    def _resolve_target(self, target: ImpersonateTarget | None):
+        """Resolve a target to a supported target."""
+        if target is None:
+            return
+        for supported_target in self.supported_targets:
+            if target in supported_target:
+                if self.verbose:
+                    self._logger.stdout(
+                        f'{self.RH_NAME}: resolved impersonate target {target} to {supported_target}')
+                return supported_target
+
+    @classproperty
+    def supported_targets(self) -> tuple[ImpersonateTarget, ...]:
+        return tuple(self._SUPPORTED_IMPERSONATE_TARGET_MAP.keys())
+
+    def is_supported_target(self, target: ImpersonateTarget):
+        assert isinstance(target, ImpersonateTarget)
+        return self._resolve_target(target) is not None
+
+    def _get_request_target(self, request):
+        """Get the requested target for the request"""
+        return self._resolve_target(request.extensions.get('impersonate') or self.impersonate)
+
+    def _get_impersonate_headers(self, request):
+        headers = self._merge_headers(request.headers)
+        if self._get_request_target(request) is not None:
+            # remove all headers present in std_headers
+            # todo: change this to not depend on std_headers
+            for k, v in std_headers.items():
+                if headers.get(k) == v:
+                    headers.pop(k)
+        return headers
+
+
+@register_preference(ImpersonateRequestHandler)
+def impersonate_preference(rh, request):
+    if request.extensions.get('impersonate') or rh.impersonate:
+        return 1000
+    return 0