From 45fc85440cc55c05940a96f6a7be82f58528ed68 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Mon, 20 Jul 1998 07:40:43 +0000
Subject: Eliminate some DNS round trips.
svn path=/trunk/; revision=1991
---
NEWS | 5 +++-
checkalias.c | 8 +++----
fetchmail.c | 75 +++++++++++++++++++++++++-----------------------------------
3 files changed, 39 insertions(+), 49 deletions(-)
diff --git a/NEWS b/NEWS
index ea00e3d2..ecdaf6f6 100644
--- a/NEWS
+++ b/NEWS
@@ -2,7 +2,6 @@
* Add an "ident" per-user option for debugging that produces an
"X-Fetchmail-ID" header in fetched messages for debugging.
-* Can the initial gethostname() be eliminated?
Release Notes:
@@ -11,6 +10,10 @@ fetchmail-4.5.3 ():
* Minor fixes to the GSSAPI code. Seems to work with stock UW IMAP now!
* Fetchmail running as root now sends misaddressed multidrop mail to
`postmaster', not root. Added `postmaster' option to allow override.
+* DNS names of target servers are now canonicalized only once, at start
+ of run, and then only if they'll actually be needed later for multidrop
+ checking or ftching Kerberos tickets. This eliminates many gethostbyname
+ calls.
There are 267 people on fetchmail-friends and 249 on fetchmail-announce.
diff --git a/checkalias.c b/checkalias.c
index 317cd2d1..eb045e37 100644
--- a/checkalias.c
+++ b/checkalias.c
@@ -121,12 +121,12 @@ int is_host_alias(const char *name, struct query *ctl)
#else
/*
* The only code that calls the BIND library is here and in the
- * start-of-query probe with gethostbyname(3).
+ * start-of-run probe with gethostbyname(3).
*
- * We know DNS service was up at the beginning of this poll cycle.
+ * We know DNS service was up at the beginning of the run.
* If it's down, our nameserver has crashed. We don't want to try
- * delivering the current message or anything else from this
- * mailbox until it's back up.
+ * delivering the current message or anything else from the
+ * current server until it's back up.
*/
else if ((he = gethostbyname(name)) != (struct hostent *)NULL)
{
diff --git a/fetchmail.c b/fetchmail.c
index 41a34567..63ad9999 100644
--- a/fetchmail.c
+++ b/fetchmail.c
@@ -478,45 +478,6 @@ int main (int argc, char **argv)
continue;
#endif /* defined(linux) && !INET6 */
-#ifdef HAVE_GETHOSTBYNAME
- /*
- * This functions partly as a probe to make sure our
- * nameserver is still up. The multidrop case
- * (especially) needs it.
- */
- if (ctl->server.preauthenticate==A_KERBEROS_V4 ||
- ctl->server.preauthenticate==A_KERBEROS_V5 ||
- MULTIDROP(ctl))
- {
- struct hostent *namerec;
-
- /* compute the canonical name of the host */
- errno = 0;
- namerec = gethostbyname(ctl->server.queryname);
- if (namerec == (struct hostent *)NULL)
- {
- error(0, errno,
- "skipping %s poll, ",
- ctl->server.pollname);
- if (errno)
- {
- if (errno == ENETUNREACH)
- break; /* go to sleep */
- }
-#ifdef HAVE_HERROR /* NEXTSTEP doesn't */
- else
- herror("DNS error");
-#endif /* HAVE_HERROR */
- continue;
- }
- else
- {
- free(ctl->server.truename);
- ctl->server.truename=xstrdup((char *)namerec->h_name);
- }
- }
-#endif /* HAVE_GETHOSTBYNAME */
-
querystatus = query_host(ctl);
if (querystatus == PS_SUCCESS)
@@ -924,16 +885,42 @@ static int load_params(int argc, char **argv, int optind)
*
* We're going to assume the via name is true unless it's
* localhost.
- *
- * Each poll cycle, if we've got DNS, we'll try to canonicalize
- * the name. This will function as a probe to ensure the
- * host's nameserver is up.
*/
if (ctl->server.via && strcmp(ctl->server.via, "localhost"))
ctl->server.queryname = xstrdup(ctl->server.via);
else
ctl->server.queryname = xstrdup(ctl->server.pollname);
- ctl->server.truename = xstrdup(ctl->server.queryname);
+
+ /*
+ * We may have to canonicalize the server truename for later use.
+ * Do this just once for each lead server, if necessary, in order
+ * to minimize DNS round trips.
+ */
+ if (ctl->server.lead_server)
+ ctl->server.truename = xstrdup(ctl->server.lead_server->truename);
+#ifdef HAVE_GETHOSTBYNAME
+ else if (ctl->server.preauthenticate==A_KERBEROS_V4 ||
+ ctl->server.preauthenticate==A_KERBEROS_V5 ||
+ (ctl->server.dns && MULTIDROP(ctl)))
+ {
+ struct hostent *namerec;
+
+ /* compute the canonical name of the host */
+ errno = 0;
+ namerec = gethostbyname(ctl->server.queryname);
+ if (namerec == (struct hostent *)NULL)
+ {
+ error(0, errno,
+ "couldn't find canonical DNS name of %s",
+ ctl->server.pollname);
+ exit(PS_DNS);
+ }
+ else
+ ctl->server.truename=xstrdup((char *)namerec->h_name);
+ }
+#endif /* HAVE_GETHOSTBYNAME */
+ else
+ ctl->server.truename = xstrdup(ctl->server.queryname);
/* if no folders were specified, set up the null one as default */
if (!ctl->mailboxes)
--
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