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Re: [Qemu-devel] [PATCHv7 4/9] slirp: Factorizing tcpiphdr structure wit
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] [PATCHv7 4/9] slirp: Factorizing tcpiphdr structure with an union |
Date: |
Mon, 22 Feb 2016 08:56:59 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 22.02.2016 02:48, Samuel Thibault wrote:
> Hello,
>
> Thomas Huth, on Fri 19 Feb 2016 14:44:59 +0100, wrote:
>>> + m->m_data -= sizeof(struct tcpiphdr) - (sizeof(struct ip)
>>> + + sizeof(struct tcphdr));
>>> + m->m_len += sizeof(struct tcpiphdr) - (sizeof(struct ip)
>>> + + sizeof(struct tcphdr));
>>
>> I'm somewhat having a hard time to understand the "+ sizeof(struct
>> tcphdr))" here.
>>
>> In the tcp_output.c code, there is this:
>>
>> m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
>> - sizeof(struct ip);
>>
>> So with my limited point of view, I'd rather expect this here in
>> tcp_input.c:
>>
>> m->m_data -= sizeof(struct tcpiphdr) - (sizeof(struct ip)
>> - sizeof(struct tcphdr));
>> i.e. "-" instead of "+" here ----------------^
>
> The parentheses and indentation were misleading actually, here is how it
> should actually looks like:
>
>>> + m->m_data -= sizeof(struct tcpiphdr) - ( sizeof(struct ip)
>>> + + sizeof(struct tcphdr));
>
> I've now dropped the parentheses, so it looks like the tcp_output.c code:
>
> m->m_data -= sizeof(struct tcpiphdr) - sizeof(struct ip)
> - sizeof(struct tcphdr);
Ah, sorry, I indeed simply got confused because it was written in two
different ways :-/ ... would it maybe be applicable to use the
TCPIPHDR_DELTA macro here instead?
Apart from that, the patch looks ok to me.
Thomas
- Re: [Qemu-devel] [PATCHv7 2/9] slirp: Adding ICMPv6 error sending, (continued)
[Qemu-devel] [PATCHv7 7/9] slirp: Handle IPv6 in TCP functions, Samuel Thibault, 2016/02/14
[Qemu-devel] [PATCHv7 9/9] qapi-schema, qemu-options & slirp: Adding Qemu options for IPv6 addresses, Samuel Thibault, 2016/02/14
[Qemu-devel] [PATCHv7 8/9] slirp: Adding IPv6 address for DNS relay, Samuel Thibault, 2016/02/14