pg_getaddrinfo_all() with hintp=NULL
Hi!
I'm trying to use pg_getaddrinfo_all() with NULL hints, but got segfault.
According to man(3) getaddrinfo, hints may be passed as NULL. In this
case af_family
is equivalent to AF_UNSPEC.
I'm adding a patch to pg_getaddrinfo_all() to make it available by
passing hintp as NULL.
--
With best regards,
Sergey Tatarintsev,
PostgresPro
Attachments:
v1-0001-Ability-to-pass-NULL-as-a-hintp-to-pg_getaddrinfo.patchtext/x-patch; charset=UTF-8; name=v1-0001-Ability-to-pass-NULL-as-a-hintp-to-pg_getaddrinfo.patchDownload+2-2
On 10 Nov 2025, at 06:14, Sergey Tatarintsev <s.tatarintsev@postgrespro.ru> wrote:
I'm trying to use pg_getaddrinfo_all() with NULL hints, but got segfault.
According to man(3) getaddrinfo, hints may be passed as NULL. In this case af_family
is equivalent to AF_UNSPEC.
Right, but pg_getaddrinfo_all isn't getaddrinfo and doesn't claim to be. Since
pg_getaddrinfo_all can return AF_UNIX as opposed to getaddrinfo, it's not clear
why hints == NULL should mean ipv4|ipv6 here.
Accepting NULL or also (subtly) breaks the API for pg_freeaddrinfo_all which is
defined to take ai_family from the hints passed to pg_getaddrinfo_all. Now,
reading the code makes it obvious that it will work anyways, but at the very
least a patch to accept a NULL hint should update the function comment for
pg_freeaddrinfo_all.
--
Daniel Gustafsson
11.11.2025 23:23, Daniel Gustafsson пишет:
On 10 Nov 2025, at 06:14, Sergey Tatarintsev <s.tatarintsev@postgrespro.ru> wrote:
I'm trying to use pg_getaddrinfo_all() with NULL hints, but got segfault.
According to man(3) getaddrinfo, hints may be passed as NULL. In this case af_family
is equivalent to AF_UNSPEC.Right, but pg_getaddrinfo_all isn't getaddrinfo and doesn't claim to be. Since
pg_getaddrinfo_all can return AF_UNIX as opposed to getaddrinfo, it's not clear
why hints == NULL should mean ipv4|ipv6 here.Accepting NULL or also (subtly) breaks the API for pg_freeaddrinfo_all which is
defined to take ai_family from the hints passed to pg_getaddrinfo_all. Now,
reading the code makes it obvious that it will work anyways, but at the very
least a patch to accept a NULL hint should update the function comment for
pg_freeaddrinfo_all.--
Daniel Gustafsson
Daniel, thanks for review!
I added a comment to pg_freeaddrinfo_all.
I don't think it made sense to comment that hint_ai_family simply
shouldn't be equal to AF_UNIX,
so I specified that if the original hints were NULL, hint_ai_family
should be equal to AF_UNSPEC.
--
With best regards,
Sergey Tatarintsev,
PostgresPro
Attachments:
v2-0001-Ability-to-pass-NULL-as-a-hintp-to-pg_getaddrinfo.patchtext/x-patch; charset=UTF-8; name=v2-0001-Ability-to-pass-NULL-as-a-hintp-to-pg_getaddrinfo.patchDownload+3-2
On 12 Nov 2025, at 09:46, Sergey Tatarintsev <s.tatarintsev@postgrespro.ru> wrote:
I added a comment to pg_freeaddrinfo_all.
I don't think it made sense to comment that hint_ai_family simply shouldn't be equal to AF_UNIX,
so I specified that if the original hints were NULL, hint_ai_family should be equal to AF_UNSPEC.
Agreed.
It's still not clear to ne that we should make pg_getaddr_info() mimic the API
of getaddrinfo since it's not a thin wrapper over getaddrinfo. The alternative
option would be to return EAI_FAIL on a null hint and force the caller to
provide an AF_UNSPEC if that is what is indeed asked for.
--
Daniel Gustafsson
Daniel Gustafsson <daniel@yesql.se> writes:
It's still not clear to ne that we should make pg_getaddr_info() mimic the API
of getaddrinfo since it's not a thin wrapper over getaddrinfo. The alternative
option would be to return EAI_FAIL on a null hint and force the caller to
provide an AF_UNSPEC if that is what is indeed asked for.
We already reject null hints (by crashing), and have done for decades.
I don't think there's anything very wrong with the current code, and I
don't really see that the proposed patch is an improvement. If
anything, I'd just add a comment to pg_getaddrinfo_all saying that
unlike bare getaddrinfo, we require a valid hintp.
regards, tom lane
On 13 Nov 2025, at 01:17, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Daniel Gustafsson <daniel@yesql.se> writes:
It's still not clear to ne that we should make pg_getaddr_info() mimic the API
of getaddrinfo since it's not a thin wrapper over getaddrinfo. The alternative
option would be to return EAI_FAIL on a null hint and force the caller to
provide an AF_UNSPEC if that is what is indeed asked for.We already reject null hints (by crashing), and have done for decades.
I don't think there's anything very wrong with the current code, and I
don't really see that the proposed patch is an improvement. If
anything, I'd just add a comment to pg_getaddrinfo_all saying that
unlike bare getaddrinfo, we require a valid hintp.
That's my thinking as well, unless objected to I will apply the below which use
the same phrasing as the comment on pg_getnameinfo_all.
diff --git a/src/common/ip.c b/src/common/ip.c
index 0e7897a5c8f..71e5934557e 100644
--- a/src/common/ip.c
+++ b/src/common/ip.c
@@ -48,6 +48,9 @@ static int getnameinfo_unix(const struct sockaddr_un *sa, int salen, /*
* pg_getaddrinfo_all - get address info for Unix, IPv4 and IPv6 sockets
+ *
+ * The API of this routine differs from the standard getaddrinfo() definition
+ * in that it requires a valid hintp, a null pointer is not allowed.
*/
int
pg_getaddrinfo_all(const char *hostname, const char *servname,--
Daniel Gustafsson
Daniel Gustafsson <daniel@yesql.se> writes:
That's my thinking as well, unless objected to I will apply the below which use
the same phrasing as the comment on pg_getnameinfo_all.
WFM.
regards, tom lane
On 13 Nov 2025, at 16:26, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Daniel Gustafsson <daniel@yesql.se> writes:
That's my thinking as well, unless objected to I will apply the below which use
the same phrasing as the comment on pg_getnameinfo_all.WFM.
Thanks, done.
--
Daniel Gustafsson