The Wireshark dissector architecture is very conducive to copy/paste, which also perpetuates the convention of explicitly listing out the parameters (so proto_tree_add_xxx functions only need very minimal changes if copying from another dissector). This is also why I don't think it's "extra typing" to list the parameters out because you're probably just doing from copy/paste shortcut keys.
Wireshark does have a ptvcursor API that can save you some of the "standard" function parameters, but based on your example, I don't think it'll help that much.
-----Original Message-----
From: Dmitry Lazurkin <dilaz03@xxxxxxxxx>
To: Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>
Sent: Mon, Nov 14, 2016 6:04 pm
Subject: Re: [Wireshark-dev] Actualize kafka dissector
Second question about using "API version" value in dissect functions.
This value may change parsing of packet. For now it passed as argument
to some dissect functions. But for now it used only in root dissect
function of request/response type (not passed to nested functions). I
have next solutions for this:
---------------------------------------
Use current solution: always pass api_version variable to all functions
and subfunctions.
Too many arguments for all functions. May be this is normal (:
---------------------------------------
Create context structure and pass it to functions/subfunctions:
typedef struct _kafka_context_t {
tvbuff_t *tvb;
packet_info *pinfo;
guint16 api_version;
int offset;
} kafka_context_t;
offset field is not necessary. Create instance of this struct in root
dissect function as local variable and pass it to dissect functions by
pointer. Use context like this:
proto_tree_add_item(tree, hf_kafka_string_len, ctx->tvb, ctx->offset, 2,
ENC_BIG_ENDIAN);
Here i have question. Are many pointer dereferences perfomance issue?
---------------------------------------
Create separate function for parsing each version of packet with code
duplication. Too much code but may be better for supporting.
I like context but passing version as separate argument is good too.
Which solution is better in wireshark community?
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