After Bruno mentioned the IPv4 limitation on inet_ntoa I decided to look
at modernizing Inetutils again. I also noticed gethostbyname,
gethostbyaddr were used which were obsoleted in POSIX 2001 and removed
in POSIX 2008.
Not too difficult to change to getaddrinfo and getnameinfo, but it means
choosing buffer sizes. When I grep through my sources it looks like
everyone uses NI_MAXHOST and NI_MAXSERV for this. Looking up these
macros you can find many instances of "missing definitions" though. This
is because the macros are only "standardized" in RFC 2553 [1]. On page
29 the following is listed:
#define NI_MAXHOST 1025
#define NI_MAXSERV 32
That is what glibc does too. I've applied the attached patches to make
sure these are defined correctly.
In order to document these I looked at some systems on the compile farm.
I noticed that on musl NI_MAXHOST is defined to 255 and on OpenBSD it is
256. For OpenBSD they say [2]:
OpenBSD intentionally uses a different NI_MAXHOST value from what
RFC 2553 suggests, to avoid buffer length handling mistakes.
My socket & networking knowledge isn't the best. Does anyone know why
RFC 2553 has the larger buffer size? I thought per RFC 1034 domain names
were limited to 253 bytes, with the trailing dot removed and empty root
label removed [3].
Collin
[1] https://datatracker.ietf.org/doc/html/rfc2553
[2] https://man.openbsd.org/getnameinfo.3
[3] https://datatracker.ietf.org/doc/html/rfc1034
>From a6dfa6add8326e7e946c5eb69e8c0b2d41f9331e Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.fu...@gmail.com>
Date: Thu, 27 Jun 2024 00:50:16 -0700
Subject: [PATCH 1/3] netdb: Define NI_MAXHOST and NI_MAXSERV.
* doc/posix-headers/netdb.texi (netdb.h): Document definitions that
differ from RFC 2553.
* lib/netdb.in.h (NI_MAXHOST, NI_MAXSERV): Define NI_MAXHOST and
NI_MAXSERV.
---
ChangeLog | 8 ++++++++
doc/posix-headers/netdb.texi | 6 ++++++
lib/netdb.in.h | 16 ++++++++++++++++
3 files changed, 30 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index c0526832f6..61a4bc1236 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2024-06-27 Collin Funk <collin.fu...@gmail.com>
+
+ netdb: Define NI_MAXHOST and NI_MAXSERV.
+ * doc/posix-headers/netdb.texi (netdb.h): Document definitions that
+ differ from RFC 2553.
+ * lib/netdb.in.h (NI_MAXHOST, NI_MAXSERV): Define NI_MAXHOST and
+ NI_MAXSERV.
+
2024-06-26 Paul Eggert <egg...@cs.ucla.edu>
strnlen: document Android bug
diff --git a/doc/posix-headers/netdb.texi b/doc/posix-headers/netdb.texi
index 33631378a0..47caaf8c31 100644
--- a/doc/posix-headers/netdb.texi
+++ b/doc/posix-headers/netdb.texi
@@ -25,6 +25,12 @@ @node netdb.h
NetBSD 5.0.
@end itemize
+@item
+@c Defined in RFC 2553.
+This header file incorrectly defines @code{NI_MAXHOST} on some platforms:
+musl libc 1.2.4, OpenBSD 7.5.
+@end
+
Portability problems not fixed by Gnulib:
@itemize
@end itemize
diff --git a/lib/netdb.in.h b/lib/netdb.in.h
index 43409b2f03..6267b544b0 100644
--- a/lib/netdb.in.h
+++ b/lib/netdb.in.h
@@ -54,6 +54,22 @@
/* Declarations for a platform that lacks <netdb.h>, or where it is
incomplete. */
+/* Maximumn length of a fully-qualified domain name. */
+#ifndef NI_MAXHOST
+# define NI_MAXHOST 1025
+#elif NI_MAXHOST != 1025
+# undef NI_MAXHOST
+# define NI_MAXHOST 1025
+#endif
+
+/* Maximumn length of a service. */
+#ifndef NI_MAXSERV
+# define NI_MAXSERV 32
+#elif NI_MAXSERV != 32
+# undef NI_MAXSERV 32
+# define NI_MAXSERV 32
+#endif
+
#if @GNULIB_GETADDRINFO@
# if !@HAVE_STRUCT_ADDRINFO@
--
2.45.2
>From 0482c81bd9dd80b66e3419276fdfd6cf9373774d Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.fu...@gmail.com>
Date: Thu, 27 Jun 2024 00:56:04 -0700
Subject: [PATCH 2/3] netdb tests: Check for NI_MAXHOST and NI_MAXSERV.
* modules/netdb-tests (Depends-on): Add assert-h.
* tests/test-netdb.c: Check that NI_MAXHOST and NI_MAXSERV are defined
correctly.
---
ChangeLog | 5 +++++
modules/netdb-tests | 1 +
tests/test-netdb.c | 4 ++++
3 files changed, 10 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 61a4bc1236..1b884b9eeb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
2024-06-27 Collin Funk <collin.fu...@gmail.com>
+ netdb tests: Check for NI_MAXHOST and NI_MAXSERV.
+ * modules/netdb-tests (Depends-on): Add assert-h.
+ * tests/test-netdb.c: Check that NI_MAXHOST and NI_MAXSERV are defined
+ correctly.
+
netdb: Define NI_MAXHOST and NI_MAXSERV.
* doc/posix-headers/netdb.texi (netdb.h): Document definitions that
differ from RFC 2553.
diff --git a/modules/netdb-tests b/modules/netdb-tests
index 3590c94aaa..2f84ec360e 100644
--- a/modules/netdb-tests
+++ b/modules/netdb-tests
@@ -3,6 +3,7 @@ tests/test-netdb.c
Depends-on:
netdb-c++-tests
+assert-h
configure.ac:
diff --git a/tests/test-netdb.c b/tests/test-netdb.c
index 9517057a5e..471ad79697 100644
--- a/tests/test-netdb.c
+++ b/tests/test-netdb.c
@@ -17,8 +17,12 @@
/* Written by Simon Josefsson <si...@josefsson.org>, 2008. */
#include <config.h>
+
#include <netdb.h>
+static_assert (NI_MAXHOST == 1025);
+static_assert (NI_MAXSERV == 32);
+
/* Check that the 'struct hostent' type is defined. */
struct hostent t1;
--
2.45.2
>From a97090a20eefa3675195c14d28be9fe10a2ac9ca Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.fu...@gmail.com>
Date: Thu, 27 Jun 2024 01:01:37 -0700
Subject: [PATCH 3/3] doc: Fix error in previous commits.
* doc/posix-headers/netdb.texi (netdb.h): Move @end itemize to the end
of the list.
---
ChangeLog | 4 ++++
doc/posix-headers/netdb.texi | 3 +--
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 1b884b9eeb..ef61d1c652 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2024-06-27 Collin Funk <collin.fu...@gmail.com>
+ doc: Fix error in previous commits.
+ * doc/posix-headers/netdb.texi (netdb.h): Move @end itemize to the end
+ of the list.
+
netdb tests: Check for NI_MAXHOST and NI_MAXSERV.
* modules/netdb-tests (Depends-on): Add assert-h.
* tests/test-netdb.c: Check that NI_MAXHOST and NI_MAXSERV are defined
diff --git a/doc/posix-headers/netdb.texi b/doc/posix-headers/netdb.texi
index 47caaf8c31..c3d33b44fc 100644
--- a/doc/posix-headers/netdb.texi
+++ b/doc/posix-headers/netdb.texi
@@ -23,13 +23,12 @@ @node netdb.h
@item
This header file does not define @code{AI_ADDRCONFIG} on some platforms:
NetBSD 5.0.
-@end itemize
@item
@c Defined in RFC 2553.
This header file incorrectly defines @code{NI_MAXHOST} on some platforms:
musl libc 1.2.4, OpenBSD 7.5.
-@end
+@end itemize
Portability problems not fixed by Gnulib:
@itemize
--
2.45.2
