[libvirt] [PATCH 2/2] util: introduce virSocketAddrParseAny

[Jim Fehlig]

On 04/05/2018 02:55 PM, Jim Fehlig wrote:
> On 03/29/2018 11:27 AM, John Ferlan wrote:
>>
>>
>> On 03/26/2018 04:29 PM, Jim Fehlig wrote:
>>> When preparing for migration, the libxl driver creates a new TCP listen
>>> socket for the incoming migration by calling virNetSocketNewListenTCP,
>>> passing the destination host name. virNetSocketNewListenTCP calls
>>> virSocketAddrParse to check if the host name is a wildcard address, in
>>> which case it avoids adding the AI_ADDRCONFIG flag to the hints passed to
>>> getaddrinfo. If the host name is not an IP address, virSocketAddrParse
>>> reports an error
>>>
>>> error : virSocketAddrParseInternal:121 : Cannot parse socket address
>>> 'myhost.example.com': Name or service not known
>>>
>>> But virNetSocketNewListenTCP succeeds regardless and the overall migration
>>> operation succeeds.
>>>
>>> Introduce virSocketAddrParseAny and use it when simply testing if a host
>>> name/addr is parsable.
>>>
>>> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
>>> ---
>>>
>>> Essentially a V2 of
>>>
>>> https://www.redhat.com/archives/libvir-list/2018-March/msg01120.html
>>>
>>> It takes a slightly different approach by creating a function that can
>>> parse host names or IP addresses.
>>>
>>>   src/libvirt_private.syms |  1 +
>>>   src/rpc/virnetsocket.c   |  2 +-
>>>   src/util/virsocketaddr.c | 50 +++++++++++++++++++++++++++++++++++++++++++++---
>>>   src/util/virsocketaddr.h |  5 +++++
>>>   4 files changed, 54 insertions(+), 4 deletions(-)
>>>
>>
>> Reviewed-by: John Ferlan <jferlan at redhat.com>
>>
>> Wait for 4.2.0 for this one...
>>
>> John
>>
>> BTW: Your call on whether to add to the new API comments something about
>> the API could be susceptible to a delay due to network name resolution
>> lookup pause.  That is, from the getaddrinfo man page:
>>
>> "The AI_NUMERICHOST flag suppresses any potentially lengthy network host
>> address lookups."
> 
> Good point. I squashed in the below comment to this patch before pushing both.
> 
> Regards,
> Jim
> 
> diff --git a/src/util/virsocketaddr.c b/src/util/virsocketaddr.c
> index 84610560f..99dc54830 100644
> --- a/src/util/virsocketaddr.c
> +++ b/src/util/virsocketaddr.c
> @@ -173,7 +173,10 @@ int virSocketAddrParse(virSocketAddrPtr addr, const char 
> *val, int family)
>    *
>    * Mostly a wrapper for getaddrinfo() extracting the address storage
>    * from a host name like acme.example.com or a numeric string like 1.2.3.4
> - * or 2001:db8:85a3:0:0:8a2e:370:7334
> + * or 2001:db8:85a3:0:0:8a2e:370:7334.
> + *
> + * When @val is a network host name, this function may be susceptible to a
> + * delay due to potentially lengthy netork host address lookups.

Heh, only now did I notice the misspelling of 'network'. I'll push a trivial 
followup.

Regards,
Jim