V2x standards

.config/codespell_ignore.txt

@@ -54,3 +54,8 @@ wan
 wanna
 webp
 widgits
+uper
+UPER
+uPER
+acn
+ACN

scapy/asn1/asn1.py

@@ -126,19 +126,17 @@ def register_stem(cls, stem):
         # type: (Type[BERcodec_Object[Any]]) -> None
         cls._stem = stem
 
-    def register_tagging(cls, enc, dec):
-        # type: (Any, Any) -> None
-        # Codec-level implicit/explicit tagging (BER/OER) or identity (UPER/PER).
-        cls._tagging_enc = enc
-        cls._tagging_dec = dec
-
-    def tagging_enc(cls, s, **kwargs):
-        # type: (bytes, **Any) -> bytes
-        return cls._tagging_enc(s, **kwargs)  # type: ignore
-
-    def tagging_dec(cls, s, **kwargs):
-        # type: (bytes, **Any) -> Tuple[Optional[int], bytes]
-        return cls._tagging_dec(s, **kwargs)  # type: ignore
+    def register_hooks(cls, **hooks):
+        # type: (**Any) -> None
+        # Field operations a codec does its own way: the tagging of a field
+        # (BER) and the compound fields (SEQUENCE/CHOICE/… in OER and PER).
+        ASN1_Codecs.hooks.setdefault(cls, {}).update(hooks)
+
+    def hook(cls, name):
+        # type: (str) -> Any
+        # Hooks are optional and may be partial: missing entries mean that
+        # asn1fields keeps its default implementation.
+        return ASN1_Codecs.hooks.get(cls, {}).get(name)
 
     def dec(cls, s, context=None, _depth=0):
         # type: (bytes, Optional[Type[ASN1_Class]], int) -> ASN1_Object[Any]
@@ -168,6 +166,9 @@ class ASN1_Codecs(metaclass=ASN1_Codecs_metaclass):
     SER = cast(ASN1Codec, 8)
     XER = cast(ASN1Codec, 9)
 
+    # The field hooks of every codec, by codec then by field operation.
+    hooks = {}  # type: Dict[ASN1Codec, Dict[str, Any]]
+
 
 class ASN1Tag(EnumElement):
     def __init__(self,
@@ -315,6 +316,9 @@ def __new__(cls,
 
 class ASN1_Object(Generic[_K], metaclass=ASN1_Object_metaclass):
     tag = ASN1_Class_UNIVERSAL.ANY
+    # Alternative a value was dissected as, when it comes from a CHOICE that
+    # holds several of its type. See ASN1F_CHOICE.record_alternative.
+    asn1_choice_index = None  # type: Optional[int]
 
     def __init__(self, val):
         # type: (_K) -> None

scapy/asn1/ber.py

@@ -424,7 +424,11 @@ def enc(cls, s, size_len=0, **_kwargs):
 
 
 ASN1_Codecs.BER.register_stem(BERcodec_Object)
-ASN1_Codecs.BER.register_tagging(BER_tagging_enc, BER_tagging_dec)
+# BER is the one codec that puts the tag of a field on the wire.
+ASN1_Codecs.BER.register_hooks(
+    tagging_enc=BER_tagging_enc,
+    tagging_dec=BER_tagging_dec,
+)
 
 
 ##########################