Re: [Libtirpc-devel] ANNOUNCE: libtirpc-1.0.1 released.

[Chuck Lever <chucklever@gmail.com>]

> On Nov 1, 2015, at 4:53 PM, Peter Rosin <peda@lysator.liu.se> wrote:
> 
> 
> On 2015-11-01 20:26, Chuck Lever wrote:
>>> On Nov 1, 2015, at 12:57 PM, Peter Rosin <peda@lysator.liu.se> wrote:
>>> 
>>> 
>>> On 2015-11-01 11:51, Andreas Radke wrote:
>>>> Am Sat, 31 Oct 2015 15:51:54 -0400
>>>> schrieb Steve Dickson <SteveD@redhat.com>:
>>>> 
>>>>> Hello,
>>>>> 
>>>>> The 1.0.1 version of libtirpc has just been release.
>>>>> 
>>>>> In this release the SONAME has been changed to 3.0.0 to
>>>>> reflect a number of changes in the API. Those changes
>>>>> were needed to make the Linux version of libtirpc
>>>>> more compatible with other implementations
>>>> This break rpcbind recompilation:
>>>> 
>>>> src/rpcb_svc_com.c: In function 'handle_reply':
>>>> src/rpcb_svc_com.c:1298:6: error: 'SVCXPRT {aka struct __rpc_svcxprt}'
>>>> has no member named 'xp_auth' xprt->xp_auth = &svc_auth_none;
>>>>      ^
>>>> In file included from /usr/include/tirpc/rpc/rpc.h:62:0,
>>>>                 from src/rpcb_svc_com.c:48:
>>>> src/rpcb_svc_com.c:1300:22: error: 'SVCXPRT {aka struct __rpc_svcxprt}'
>>>> has no member named 'xp_auth' SVCAUTH_DESTROY(xprt->xp_auth);
>>>>                      ^
>>>> /usr/include/tirpc/rpc/svc_auth.h:63:7: note: in definition of macro
>>>> 'SVCAUTH_DESTROY' ((*((auth)->svc_ah_ops->svc_ah_destroy))(auth))
>>>>       ^
>>>> src/rpcb_svc_com.c:1300:22: error: 'SVCXPRT {aka struct __rpc_svcxprt}'
>>>> has no member named 'xp_auth' SVCAUTH_DESTROY(xprt->xp_auth);
>>>>                      ^
>>>> /usr/include/tirpc/rpc/svc_auth.h:63:43: note: in definition of macro
>>>> 'SVCAUTH_DESTROY' ((*((auth)->svc_ah_ops->svc_ah_destroy))(auth))
>>>>                                           ^
>>>> src/rpcb_svc_com.c:1301:6: error: 'SVCXPRT {aka struct __rpc_svcxprt}'
>>>> has no member named 'xp_auth' xprt->xp_auth = NULL;
>>>>      ^
>>>> Makefile:481: recipe for target 'src/rpcb_svc_com.o' failed
>>>> make: *** [src/rpcb_svc_com.o] Error 1
>>>> make: *** Waiting for unfinished jobs....
>>>> ==> ERROR: A failure occurred in build().
>>>> 
>>>> Do you have a fix?
>>>> 
>>> Should be as simple as (not even compile-tested):
>>> 
>>> diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c
>>> index 4ae93f1..38f163f 100644
>>> --- a/src/rpcb_svc_com.c
>>> +++ b/src/rpcb_svc_com.c
>>> @@ -1295,10 +1295,8 @@ handle_reply(int fd, SVCXPRT *xprt)
>>>     a.rmt_localvers = fi->versnum;
>>> 
>>>     xprt_set_caller(xprt, fi);
>>> -    xprt->xp_auth = &svc_auth_none;
>>> +    SVC_XP_AUTH(xprt) = svc_auth_none;
>>>     svc_sendreply(xprt, (xdrproc_t) xdr_rmtcall_result, (char *) &a);
>>> -    SVCAUTH_DESTROY(xprt->xp_auth);
>>> -    xprt->xp_auth = NULL;
>>> done:
>>>     if (buffer)
>>>         free(buffer);
>>> 
>>> But that breaks compatibility with earlier libtirpc of course…
>>> 
>> #if defined(SVC_XP_AUTH)
>> SVC_XP_AUTH(xprt) = svc_auth_none;
>> #else
>> 
>> . . .
>> 
>> #endif
>> 
>> But I wonder if that’s even necessary now. See rpcbind
>> commit 86036582c001.
>> 
> Yes, it is fishy to clobber the server auth stuff, so it is probably best to just zap
> the svc_auth_none assignment altogether. However, the core initializes the
> server auth to svc_auth_none at the beginning of handling each separate call,
> so if you somehow use a xprt to send replies before it has taken a call (is that
> even possible?), there will be no server auth. In that very dubious case, the
> assignment is essential.
> 
> I have not looked at the rpcbind code in any depth whatsoever and don't know
> anything about the semantics of this "handle_reply" function. But, since it is
> a "reply", there will presumably have been a preceding "call", presumably on
> the same transport, in which case the server auth have been initialized. So, it
> is safe to drop the svc_auth_none assignment.           Presumably. :-)

The original 2012 rpcbind fix smells a little like a
workaround for a libtirpc bug. It would be nice if there
was a unit test somewhere to confirm that setting xp_auth
is no longer needed with the current libtirpc (or help us
ferret out the libtirpc bug if it still exists).


--
Chuck Lever
chucklever@gmail.com