Unbreak nscd(8).

[trasz]

Summary

Unbreak nscd(8). Without this change the CMSG gets truncated.
No idea how it worked before.

It also splits checks into separate "ifs", with a small tweak to debug.h
it makes it easier to see which one fails.

[trasz]

Meh, wrong diff.

[cy]

LGTM

[des]

The answer to “how it worked before” is that it didn't. It has never worked properly.

usr.sbin/nscd/query.c

192–204

Please don't do this. Just fix the style issues in the original. I might even go one further and merge the four consistency checks with the recvmsg() call since they have the exact same error handling code. The fact that they're not really exactly the same because the macro uses __LINE__ is a bug, not a feature.

[trasz]

usr.sbin/nscd/query.c

192–204

As it is now, it's useless. However, with one small diff (to be committed separately), it actually starts being kind of useful:

--- debug.c     (revision 339219)
+++ debug.c     (working copy)                                      
@@ -131,7 +131,7 @@
                for (i = 0; i < trace_level; ++i)
                        printf("\t");
                                                      
-               printf("<= %s\n", s);                   
+               printf("<= %s, %s: %d\n", s, f, l);
        }     
 }

[trasz]

Having said that, the part in question doesn't belong here. So, I'll redo the diff.

[trasz]

Remove unrelated parts of the diff, as suggested by des@.

[trasz]

Ping?

[des]

I believe this is correct (with or without the suggested changes), but send_credentials() in usr.sbin/nscd/nscdcli.c also needs to be fixed. It was not touched by rS158257, which introduced the bug you are fixing here while trying to fix another, so the bug is slightly different. It is supposed to be (almost) identical to lib/libc/net/nscachedcli.c; the latter is actually the former ported into libc.

Both files as well as usr.sbin/nscd/query.c have pervasive style issues, as I pointed out when nscd was first imported, but perhaps it's best to leave that for later.

usr.sbin/nscd/query.c

175

This is technically correct, but I'd still rather spell it out explicitly with CMSG_SPACE (not CMSG_LEN).

186–187

We should probably check cred_hdr.msg_controllen here.

[trasz]

Fix stuff.

[trasz]

One more length check.

[des]

This version has a couple of regressions from the previous one. Remember that CMSG_SPACE and CMSG_LEN already include space for the header, plus alignment and padding. See CMSG_DATA(3) and sys/sys/socket.h.

usr.sbin/nscd/nscdcli.c

148

struct cmsgcred

156

struct cmsgcred

usr.sbin/nscd/query.c

175

struct cmsgcred

[trasz]

Use the right len.