[Spice-devel] [PATCH v4 27/41] dissector: Use a class to register wireshark fields

[Frediano Ziglio]

Allow to reuse code and check better if field was already registered

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 python_modules/dissector.py | 58 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 10 deletions(-)

diff --git a/python_modules/dissector.py b/python_modules/dissector.py
index a33ada2..d03224f 100644
--- a/python_modules/dissector.py
+++ b/python_modules/dissector.py
@@ -22,8 +22,49 @@ def new_ett(writer):
     return name
 
 
+# handle registration of wireshark flags
 hf_writer = None
 hf_defs = None
+class HF:
+    fields = {}
+
+    def __init__(self, hf_name, desc=''):
+        self.hf_name = hf_name
+        self.desc = desc
+        self.mask = '0'
+
+    def __str__(self):
+        x = []
+        for f in 'hf_name desc ws_name f_type base vals mask'.split():
+            x.append(f + ':' + self.__dict__[f])
+        return ' '.join(x)
+
+    # declare a field identifier
+    def add_wireshark_field(self):
+        if hf_writer.variable_defined(self.hf_name):
+            raise Exception('HF field %s already defined' % self.hf_name)
+        hf_writer.variable_def("static int", "%s = -1" % self.hf_name)
+
+    def create(self):
+        other = self.fields.get(self.ws_name)
+        if other:
+            for f in 'hf_name desc ws_name base vals mask'.split():
+                if other.__dict__[f] != self.__dict__[f]:
+                    raise Exception('HF Field different from previous for\n\t%s\n\t%s' % (other, self))
+            if other.f_type != self.f_type:
+                if other.f_type[:7] != 'FT_UINT' or self.f_type[:7] != 'FT_UINT':
+                    raise Exception('HF Field different from previous for\n\t%s\n\t%s' % (other, self))
+            return
+
+        self.fields[self.ws_name] = self
+
+        self.add_wireshark_field()
+
+        hf_defs.writeln('{ &%s,' % self.hf_name)
+        hf_defs.writeln('  { "%s", "spice2.%s",' % (self.desc, self.ws_name))
+        hf_defs.writeln('    %s, %s, %s, %s,' % (self.f_type, self.base, self.vals, self.mask))
+        hf_defs.writeln('    NULL, HFILL }')
+        hf_defs.writeln('},')
 
 
 # handle wireshark attributes
@@ -305,16 +346,13 @@ def write_wireshark_field(writer, container, member, t, ws, tree, size, encoding
     writer.statement("%sproto_tree_add_item(%s, %s, glb->tvb, offset, %s, %s)" %
             (prefix, tree, hf_name, size, encoding))
 
-    # TODO handle better duplications
-    if hf_writer.variable_defined(hf_name):
-        return
-    hf_writer.variable_def("static int", "%s = -1" % hf_name)
-
-    hf_defs.writeln('{ &%s,' % hf_name)
-    hf_defs.writeln('  { "%s", "spice2.%s",' % (desc, ws_name))
-    hf_defs.writeln('    %s, %s, %s, 0,' % (f_type, base, vals))
-    hf_defs.writeln('    NULL, HFILL }')
-    hf_defs.writeln('},')
+    # write definition
+    hf = HF(hf_name, desc)
+    hf.ws_name = ws_name
+    hf.f_type = f_type
+    hf.base = base
+    hf.vals = vals
+    hf.create()
 
 
 # Note: during parsing, byte_size types have been converted to count during validation
-- 
2.1.0