Re: Re: [PATCH] selftests: mptcp: add comment for getaddrinfo

[zhenwei pi <pizhenwei@bytedance.com>]

On 4/8/25 09:43, Geliang Tang wrote:
> Hi zhenwei,
> 
> On Mon, 2025-04-07 at 16:51 +0800, zhenwei pi wrote:
>> mptcp_connect.c is a startup tutorial of MPTCP programming, however
>> there is a lack of ai_protocol(IPPROTO_MPTCP) usage. Add comment for
>> getaddrinfo MPTCP support.
>>
>> Signed-off-by: zhenwei pi <zhenwei.pi@linux.dev>
>> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
>> ---
>>   tools/testing/selftests/net/mptcp/mptcp_connect.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c
>> b/tools/testing/selftests/net/mptcp/mptcp_connect.c
>> index c83a8b47bbdf..6b9031273964 100644
>> --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
>> +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
>> @@ -179,6 +179,18 @@ static void xgetnameinfo(const struct sockaddr
>> *addr, socklen_t addrlen,
>>   	}
>>   }
>>   
>> +/* There is a lack of MPTCP support from glibc, these code leads
>> error:
>> + *	struct addrinfo hints = {
>> + *		.ai_protocol = IPPROTO_MPTCP,
>> + *		...
>> + *	};
>> + *	err = getaddrinfo(node, service, &hints, res);
>> + *	...
>> + * So using IPPROTO_TCP to resolve, and use TCP/MPTCP to create
>> socket.
>> + *
>> + * glibc starts to support MPTCP since v2.42.
>> + * Link:
>> https://sourceware.org/git/?p=glibc.git;a=commit;h=a8e9022e0f82
> 
> Thanks for adding getaddrinfo mptcp support to glibc. I think we should
> not only add a comment for getaddrinfo mptcp here, but also add an
> example of using it in mptcp_connect.c. I will work with you to
> implement this example in v2.
> 
> Thanks,
> -Geliang
> 

Good idea, thank you Geliang!

>> + */
>>   static void xgetaddrinfo(const char *node, const char *service,
>>   			 const struct addrinfo *hints,
>>   			 struct addrinfo **res)
>