Cap cipher suite and extension count (#187)

* Cap cipher count at 99

* Cap extension count at 99

Author: s-spindler

python/common.py

@@ -102,7 +102,7 @@ def get_hex_sorted(entry, field, sort=True):
 
     # remove GREASE and calculate length
     c = [ x[2:] for x in values if x not in GREASE_TABLE ]
-    actual_length = len(c)
+    actual_length = min(len(c), 99)
 
     # now remove SNI and ALPN values
     if field == 'extensions' and sort:

python/ja4.py

@@ -173,7 +173,7 @@ def to_ja4s(x, debug_stream):
 
     # get extensions in hex in the order they are present (include grease values)
     x['extensions'] = [ '{:04x}'.format(int(k)) for k in x['extensions'] ]
-    ext_len = '{:02d}'.format(len(x['extensions']))
+    ext_len = '{:02d}'.format(min(len(x['extensions']), 99))
     extensions = sha_encode(x['extensions'])
 
     # only one cipher for ja4s
@@ -209,7 +209,7 @@ def to_ja4(x, debug_stream):
     ptype = 'q' if x['quic'] else 't'
 
     x['extensions'] = [ '0x{:04x}'.format(int(k)) for k in x['extensions'] ]
-    ext_len = '{:02d}'.format(len([ x for x in x['extensions'] if x not in GREASE_TABLE]))
+    ext_len = '{:02d}'.format(min(len([ x for x in x['extensions'] if x not in GREASE_TABLE]), 99))
     cache_update(x, 'client_ciphers', x['ciphers'], debug_stream)
 
     if ('0x000d' in x['extensions']):