[30327] in CVS-changelog-for-Kerberos-V5
krb5 commit: Retry KCM writes once on remote hangup
daemon@ATHENA.MIT.EDU (Greg Hudson)
Fri Oct 26 17:36:42 2018
Date: Fri, 26 Oct 2018 17:36:28 -0400
From: Greg Hudson <ghudson@mit.edu>
Message-Id: <201810262136.w9QLaSMD008839@drugstore.mit.edu>
To: cvs-krb5@mit.edu
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https://github.com/krb5/krb5/commit/33634a940166d0b21c3105bab8dcf5550fbbd678
commit 33634a940166d0b21c3105bab8dcf5550fbbd678
Author: Robbie Harwood <rharwood@redhat.com>
Date: Tue Oct 16 15:19:46 2018 -0400
Retry KCM writes once on remote hangup
sssd's KCM daemon has a client timeout (typically 60 seconds). Add
reconnection logic to kcmio_unix_socket_write() to allow this
behavior, and to potentially allow for the daemon to be upgraded.
[ghudson@mit.edu: adjusted commit message, comment, and code slightly]
ticket: 8760 (new)
src/lib/krb5/ccache/cc_kcm.c | 29 ++++++++++++++++++++++++++---
1 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/src/lib/krb5/ccache/cc_kcm.c b/src/lib/krb5/ccache/cc_kcm.c
index b260cd8..2b9f82e 100644
--- a/src/lib/krb5/ccache/cc_kcm.c
+++ b/src/lib/krb5/ccache/cc_kcm.c
@@ -299,13 +299,36 @@ kcmio_unix_socket_write(krb5_context context, struct kcmio *io, void *request,
{
char lenbytes[4];
sg_buf sg[2];
+ int ret;
+ krb5_boolean reconnected = FALSE;
SG_SET(&sg[0], lenbytes, sizeof(lenbytes));
SG_SET(&sg[1], request, len);
store_32_be(len, lenbytes);
- if (krb5int_net_writev(context, io->fd, sg, 2) < 0)
- return errno;
- return 0;
+
+ for (;;) {
+ ret = krb5int_net_writev(context, io->fd, sg, 2);
+ if (ret < 0)
+ ret = errno;
+ if (ret != EPIPE || reconnected)
+ return ret;
+
+ /*
+ * Try once to reconnect on an EPIPE, in case the server has an idle
+ * timeout (like sssd does) and we went too long between ccache
+ * operations. Reconnecting might also help if the server was
+ * restarted for an upgrade--although the server must be designed to
+ * always listen for connections on the socket during upgrades, or a
+ * single reconnect attempt won't be robust.
+ */
+ close(io->fd);
+ ret = kcmio_unix_socket_connect(context, io);
+ if (ret)
+ return ret;
+ reconnected = TRUE;
+ }
+
+ return ret;
}
/* Read a KCM reply: 4-byte big-endian length, 4-byte big-endian status code,
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