tlv: add structs for message types to wire format .h's (header files)

Since messages in TLV's are optional, the ideal way to deal with
them is to have a 'master struct' object for every defined tlv, where
the presence or lack of a field can be determined via the presence
(or lack thereof) of a struct for each of the optional message
types.

In order to do this, appropriately, we need a struct for every
TLV message. The next commit will make use of these.

Note that right now TLV message structs aren't namespaced to the
TLV they belong to, so there's the potential for collision. This
should be fixed when/where it occurs (should fail to compile).

tools/generate-wire.py

@@ -641,6 +641,35 @@ class Message(object):
             subcalls=str(subcalls)
         )
 
+    def print_struct(self):
+        """ returns a string representation of this message as
+        a struct"""
+        if not self.is_tlv:
+            raise TypeError('{} is not a TLV-message').format(self.name)
+
+        fmt_fields = CCode()
+        for f in self.fields:
+            if f.is_len_var or f.is_padding():
+                # there is no ethical padding under TLVs
+                continue
+            elif f.is_variable_size():
+                fmt_fields.append('{} *{};'.format(f.fieldtype.name, f.name))
+            elif f.is_array():
+                fmt_fields.append('{} {}[{}];'.format(f.fieldtype.name, f.name, f.num_elems))
+            else:
+                fmt_fields.append('{} {};'.format(f.fieldtype.name, f.name))
+
+        return tlv_struct_template.format(
+            tlv_name=self.name,
+            fields=str(fmt_fields))
+
+
+tlv_struct_template = """
+struct tlv_{tlv_name} {{
+{fields}
+}};
+"""
+
 
 def find_message(messages, name):
     for m in messages:
@@ -836,6 +865,14 @@ def build_impl_enums(toplevel_enumname, toplevel_messages, tlv_fields):
     return enum_set
 
 
+def build_tlv_structs(tlv_fields):
+    structs = ""
+    for field_name, tlv_messages in tlv_fields.items():
+        for m in tlv_messages:
+            structs += m.print_struct()
+    return structs
+
+
 enum_header_template = """enum {enumname} {{
 {enums}
 }};
@@ -863,7 +900,7 @@ header_template = """/* This file was generated by generate-wire.py */
 #include <ccan/tal/tal.h>
 #include <wire/wire.h>
 {includes}
-{formatted_hdr_enums}
+{formatted_hdr_enums}{tlv_structs}
 {func_decls}
 #endif /* LIGHTNING_{idem} */
 """
@@ -927,6 +964,7 @@ else:
 toplevel_messages = [m for m in messages if not m.is_tlv]
 built_hdr_enums = build_hdr_enums(options.enumname, toplevel_messages, tlv_fields)
 built_impl_enums = build_impl_enums(options.enumname, toplevel_messages, tlv_fields)
+tlv_structs = build_tlv_structs(tlv_fields)
 includes = '\n'.join(includes)
 printcases = ['case {enum.name}: printf("{enum.name}:\\n"); printwire_{name}("{name}", msg); return;'.format(enum=m.enum, name=m.name) for m in toplevel_messages]
 
@@ -945,4 +983,5 @@ print(template.format(
     enumname=options.enumname,
     formatted_hdr_enums=built_hdr_enums,
     formatted_impl_enums=built_impl_enums,
+    tlv_structs=tlv_structs,
     func_decls='\n'.join(decls)))