path: root/doc/README.kerberos

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Date: Mon, 8 May 2000 18:27:40 +0100 (BST)
From: Mike Wyer <mw@doc.ic.ac.uk>
To: pgsql-patches@postgresql.org
Subject: kerberos 5 patch against 7.0RC5
Message-ID: <Pine.LNX.4.21.0005081804430.1265-100000@kungfu.doc.ic.ac.uk>
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Status: ORr

You can find it after my sig. Hideous abuse of netiquette, but needs
must ...

Most (nearly all) of the work was done by David Wragg <dpw@doc.ic.ac.uk>

He patched 6.5.3. I've updated it for 7.0RC5.

It works for MIT kerberos 1.1.1 (and previously for 1.0.6 as well).

I've got the patch against 6.5.3, plus kerberized RPMS.

Install:

Assuming postgresql-7.0RC5 is in /usr/local/src

cd /usr/local/src
patch -p0 < krb5-patch

Edit postgresql-7.0RC5/src/Makefile.global.in
Change PG_KRB_SRVTAB to somewhere useful for you, and PG_KRB_SRVNAM to
whatever you want your postgres kerberos service called.

make and install PostgreSQL.

Generate the keytab (PG_KRB_SRVTAB):
kadmin% ank -randkey postgres/server.my.domain.org
kadmin% ktadd -k krb5.keytab postgres/server.my.domain.org

Make sure the keytab is read-only to the postgres user.
Make sure your client binaries can see the new libraries.

edit pg_hba.conf and change the authentication method to krb5.

Everything should then work. If you use mod_auth_krb and mod_perl on
your web server, you can use AuthType KerberosV5SaveCredentials with a
mod_perl script. This gives secure database access over the web. No
extra passwords required. 

Cheers,

Mike Wyer,
Department of Computing, Imperial College
-- 
Mike Wyer <mw@doc.ic.ac.uk>     ||         "Woof?"
http://www.doc.ic.ac.uk/~mw     ||  Gaspode the Wonder Dog 
Work:      020 7594 8440        ||  from "Moving Pictures"
Mobile:     07879 697119        ||    by Terry Pratchett


===========================8<----------------------------------------------

diff -u -r postgresql-7.0RC5/src/Makefile.global.in postgresql-7.0RC5.krb5/src/Makefile.global.in
--- postgresql-7.0RC5/src/Makefile.global.in	Mon May  8 17:22:40 2000
+++ postgresql-7.0RC5.krb5/src/Makefile.global.in	Sat May  6 17:23:49 2000
@@ -120,7 +120,7 @@
 # Set KRBVERS to "4" for Kerberos v4, "5" for Kerberos v5.
 # XXX Edit the default Kerberos variables below!
 #
-#KRBVERS= 5
+KRBVERS=5
 
 # Globally pass Kerberos file locations.
 # these are used in the postmaster and all libpq applications.
@@ -132,9 +132,9 @@
 # PG_KRB_SRVTAB is the location of the server's keytab file.
 #
 ifdef KRBVERS
-KRBINCS= -I/usr/athena/include
-KRBLIBS= -L/usr/athena/lib
-KRBFLAGS+= $(KRBINCS) -DPG_KRB_SRVNAM='"postgres_dbms"'
+KRBINCS= -I/usr/krb5/include
+KRBLIBS= -L/usr/krb5/lib
+KRBFLAGS+= $(KRBINCS) -DPG_KRB_SRVNAM='"postgres"'
    ifeq ($(KRBVERS), 4)
 KRBFLAGS+= -DKRB4
 KRBFLAGS+= -DPG_KRB_SRVTAB='"/etc/srvtab"'
@@ -142,8 +142,8 @@
    else
    ifeq ($(KRBVERS), 5)
 KRBFLAGS+= -DKRB5
-KRBFLAGS+= -DPG_KRB_SRVTAB='"FILE:/krb5/srvtab.postgres"'
-KRBLIBS+= -lkrb5 -lcrypto -lcom_err -lisode
+KRBFLAGS+= -DPG_KRB_SRVTAB='"FILE:/usr/local/postgres/krb5.keytab"'
+KRBLIBS+= -lkrb5 -lcrypto -lcom_err
    endif
    endif
 endif
diff -u -r postgresql-7.0RC5/src/backend/libpq/auth.c postgresql-7.0RC5.krb5/src/backend/libpq/auth.c
--- postgresql-7.0RC5/src/backend/libpq/auth.c	Mon May  8 17:22:40 2000
+++ postgresql-7.0RC5.krb5/src/backend/libpq/auth.c	Sat May  6 17:17:13 2000
@@ -149,7 +149,8 @@
  *----------------------------------------------------------------
  */
 
-#include "krb5/krb5.h"
+#include <krb5.h>
+#include <com_err.h>
 
 /*
  * pg_an_to_ln -- return the local name corresponding to an authentication
@@ -174,130 +175,134 @@
 	return aname;
 }
 
+
 /*
- * pg_krb5_recvauth -- server routine to receive authentication information
- *					   from the client
- *
- * We still need to compare the username obtained from the client's setup
- * packet to the authenticated name, as described in pg_krb4_recvauth.	This
- * is a bit more problematic in v5, as described above in pg_an_to_ln.
- *
- * In addition, as described above in pg_krb5_sendauth, we still need to
- * canonicalize the server name v4-style before constructing a principal
- * from it.  Again, this is kind of iffy.
- *
- * Finally, we need to tangle with the fact that v5 doesn't let you explicitly
- * set server keytab file names -- you have to feed lower-level routines a
- * function to retrieve the contents of a keytab, along with a single argument
- * that allows them to open the keytab.  We assume that a server keytab is
- * always a real file so we can allow people to specify their own filenames.
- * (This is important because the POSTGRES keytab needs to be readable by
- * non-root users/groups; the v4 tools used to force you do dump a whole
- * host's worth of keys into a file, effectively forcing you to use one file,
- * but kdb5_edit allows you to select which principals to dump.  Yay!)
+ * Various krb5 state which is not connection specfic, and a flag to
+ * indicate whether we have initialised it yet.
  */
+static int pg_krb5_initialised;
+static krb5_context pg_krb5_context;
+static krb5_keytab pg_krb5_keytab;
+static krb5_principal pg_krb5_server;
+
+
 static int
-pg_krb5_recvauth(Port *port)
+pg_krb5_init(void)
 {
-	char		servbuf[MAXHOSTNAMELEN + 1 +
-									sizeof(PG_KRB_SRVNAM)];
-	char	   *hostp,
-			   *kusername = (char *) NULL;
-	krb5_error_code code;
-	krb5_principal client,
-				server;
-	krb5_address sender_addr;
-	krb5_rdreq_key_proc keyproc = (krb5_rdreq_key_proc) NULL;
-	krb5_pointer keyprocarg = (krb5_pointer) NULL;
+	krb5_error_code retval;
 
-	/*
-	 * Set up server side -- since we have no ticket file to make this
-	 * easy, we construct our own name and parse it.  See note on
-	 * canonicalization above.
-	 */
-	strcpy(servbuf, PG_KRB_SRVNAM);
-	*(hostp = servbuf + (sizeof(PG_KRB_SRVNAM) - 1)) = '/';
-	if (gethostname(++hostp, MAXHOSTNAMELEN) < 0)
-		strcpy(hostp, "localhost");
-	if (hostp = strchr(hostp, '.'))
-		*hostp = '\0';
-	if (code = krb5_parse_name(servbuf, &server))
-	{
+	if (pg_krb5_initialised)
+		return STATUS_OK;
+
+	retval = krb5_init_context(&pg_krb5_context);
+	if (retval) {
 		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
-		"pg_krb5_recvauth: Kerberos error %d in krb5_parse_name\n", code);
-		com_err("pg_krb5_recvauth", code, "in krb5_parse_name");
+				 "pg_krb5_init: krb5_init_context returned"
+				 " Kerberos error %d\n", retval);
+		com_err("postgres", retval, "while initializing krb5");
 		return STATUS_ERROR;
 	}
 
-	/*
-	 * krb5_sendauth needs this to verify the address in the client
-	 * authenticator.
-	 */
-	sender_addr.addrtype = port->raddr.in.sin_family;
-	sender_addr.length = sizeof(port->raddr.in.sin_addr);
-	sender_addr.contents = (krb5_octet *) & (port->raddr.in.sin_addr);
-
-	if (strcmp(PG_KRB_SRVTAB, ""))
-	{
-		keyproc = krb5_kt_read_service_key;
-		keyprocarg = PG_KRB_SRVTAB;
+	retval = krb5_kt_resolve(pg_krb5_context, PG_KRB_SRVTAB, &pg_krb5_keytab);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_init: krb5_kt_resolve returned"
+				 " Kerberos error %d\n", retval);
+	    com_err("postgres", retval, "while resolving keytab file %s",
+				PG_KRB_SRVTAB);
+		krb5_free_context(pg_krb5_context);
+		return STATUS_ERROR;
 	}
 
-	if (code = krb5_recvauth((krb5_pointer) & port->sock,
-							 PG_KRB5_VERSION,
-							 server,
-							 &sender_addr,
-							 (krb5_pointer) NULL,
-							 keyproc,
-							 keyprocarg,
-							 (char *) NULL,
-							 (krb5_int32 *) NULL,
-							 &client,
-							 (krb5_ticket **) NULL,
-							 (krb5_authenticator **) NULL))
-	{
+    retval = krb5_sname_to_principal(pg_krb5_context, NULL, PG_KRB_SRVNAM, 
+									 KRB5_NT_SRV_HST, &pg_krb5_server);
+	if (retval) {
 		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
-		 "pg_krb5_recvauth: Kerberos error %d in krb5_recvauth\n", code);
-		com_err("pg_krb5_recvauth", code, "in krb5_recvauth");
-		krb5_free_principal(server);
+				 "pg_krb5_init: krb5_sname_to_principal returned"
+				 " Kerberos error %d\n", retval);
+	    com_err("postgres", retval, 
+				"while getting server principal for service %s",
+				PG_KRB_SRVTAB);
+		krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
+		krb5_free_context(pg_krb5_context);
 		return STATUS_ERROR;
 	}
-	krb5_free_principal(server);
+
+	pg_krb5_initialised = 1;
+	return STATUS_OK;
+}
+
+
+/*
+ * pg_krb5_recvauth -- server routine to receive authentication information
+ *					   from the client
+ *
+ * We still need to compare the username obtained from the client's setup
+ * packet to the authenticated name, as described in pg_krb4_recvauth.	This
+ * is a bit more problematic in v5, as described above in pg_an_to_ln.
+ *
+ * We have our own keytab file because postgres is unlikely to run as root,
+ * and so cannot read the default keytab.
+ */
+static int
+pg_krb5_recvauth(Port *port)
+{
+	krb5_error_code retval;
+	int ret;
+	krb5_auth_context auth_context = NULL;
+	krb5_ticket *ticket;
+    char *kusername;
+
+	ret = pg_krb5_init();
+	if (ret != STATUS_OK)
+		return ret;
+
+	retval = krb5_recvauth(pg_krb5_context, &auth_context,
+						   (krb5_pointer)&port->sock, PG_KRB_SRVNAM,
+						   pg_krb5_server, 0, pg_krb5_keytab, &ticket);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_recvauth: krb5_recvauth returned"
+				 " Kerberos error %d\n", retval);
+	    com_err("postgres", retval, "from krb5_recvauth");
+		return STATUS_ERROR;
+	}						   
 
 	/*
 	 * The "client" structure comes out of the ticket and is therefore
 	 * authenticated.  Use it to check the username obtained from the
 	 * postmaster startup packet.
+	 *
+	 * I have no idea why this is considered necessary.
 	 */
-	if ((code = krb5_unparse_name(client, &kusername)))
-	{
+    retval = krb5_unparse_name(pg_krb5_context, 
+							   ticket->enc_part2->client, &kusername);
+	if (retval) {
 		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
-				 "pg_krb5_recvauth: Kerberos error %d in krb5_unparse_name\n", code);
-		com_err("pg_krb5_recvauth", code, "in krb5_unparse_name");
-		krb5_free_principal(client);
-		return STATUS_ERROR;
-	}
-	krb5_free_principal(client);
-	if (!kusername)
-	{
-		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
-				 "pg_krb5_recvauth: could not decode username\n");
-		fputs(PQerrormsg, stderr);
-		pqdebug("%s", PQerrormsg);
+				 "pg_krb5_recvauth: krb5_unparse_name returned"
+				 " Kerberos error %d\n", retval);
+	    com_err("postgres", retval, "while unparsing client name");
+		krb5_free_ticket(pg_krb5_context, ticket);
+		krb5_auth_con_free(pg_krb5_context, auth_context);
 		return STATUS_ERROR;
 	}
+
 	kusername = pg_an_to_ln(kusername);
-	if (strncmp(username, kusername, SM_USER))
+	if (strncmp(port->user, kusername, SM_USER))
 	{
 		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
-				 "pg_krb5_recvauth: name \"%s\" != \"%s\"\n", port->user, kusername);
-		fputs(PQerrormsg, stderr);
-		pqdebug("%s", PQerrormsg);
-		pfree(kusername);
-		return STATUS_ERROR;
-	}
-	pfree(kusername);
-	return STATUS_OK;
+				 "pg_krb5_recvauth: user name \"%s\" != krb5 name \"%s\"\n", 
+				 port->user, kusername);
+		ret = STATUS_ERROR;
+	}
+	else
+		ret = STATUS_OK;
+	
+	krb5_free_ticket(pg_krb5_context, ticket);
+	krb5_auth_con_free(pg_krb5_context, auth_context);
+	free(kusername);
+
+	return ret;
 }
 
 #else
diff -u -r postgresql-7.0RC5/src/interfaces/libpq/Makefile.in postgresql-7.0RC5.krb5/src/interfaces/libpq/Makefile.in
--- postgresql-7.0RC5/src/interfaces/libpq/Makefile.in	Mon May  8 17:22:40 2000
+++ postgresql-7.0RC5.krb5/src/interfaces/libpq/Makefile.in	Sat May  6 17:17:13 2000
@@ -21,6 +21,7 @@
 
 ifdef KRBVERS
 CFLAGS+= $(KRBFLAGS)
+SHLIB_LINK += $(KRBLIBS)
 endif
 
 OBJS= fe-auth.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-lobj.o \
diff -u -r postgresql-7.0RC5/src/interfaces/libpq/fe-auth.c postgresql-7.0RC5.krb5/src/interfaces/libpq/fe-auth.c
--- postgresql-7.0RC5/src/interfaces/libpq/fe-auth.c	Mon May  8 17:22:40 2000
+++ postgresql-7.0RC5.krb5/src/interfaces/libpq/fe-auth.c	Sat May  6 17:17:13 2000
@@ -39,6 +39,7 @@
 #include "win32.h"
 #else
 #include <unistd.h>
+#include <fcntl.h>
 #include <sys/param.h>			/* for MAXHOSTNAMELEN on most */
 #ifndef  MAXHOSTNAMELEN
 #include <netdb.h>				/* for MAXHOSTNAMELEN on some */
@@ -234,7 +235,8 @@
  *----------------------------------------------------------------
  */
 
-#include "krb5/krb5.h"
+#include <krb5.h>
+#include <com_err.h>
 
 /*
  * pg_an_to_ln -- return the local name corresponding to an authentication
@@ -250,7 +252,7 @@
  *	   and we can't afford to punt.
  */
 static char *
-pg_an_to_ln(const char *aname)
+pg_an_to_ln(char *aname)
 {
 	char	   *p;
 
@@ -261,197 +263,160 @@
 
 
 /*
- * pg_krb5_init -- initialization performed before any Kerberos calls are made
- *
- * With v5, we can no longer set the ticket (credential cache) file name;
- * we now have to provide a file handle for the open (well, "resolved")
- * ticket file everywhere.
- *
+ * Various krb5 state which is not connection specfic, and a flag to
+ * indicate whether we have initialised it yet.
  */
+static int pg_krb5_initialised;
+static krb5_context pg_krb5_context;
+static krb5_ccache pg_krb5_ccache;
+static krb5_principal pg_krb5_client;
+static char *pg_krb5_name;
+
+
 static int
-			krb5_ccache
-pg_krb5_init(void)
+pg_krb5_init(char *PQerrormsg)
 {
-	krb5_error_code code;
-	char	   *realm,
-			   *defname;
-	char		tktbuf[MAXPGPATH];
-	static krb5_ccache ccache = (krb5_ccache) NULL;
+	krb5_error_code retval;
 
-	if (ccache)
-		return ccache;
+	if (pg_krb5_initialised)
+		return STATUS_OK;
 
-	/*
-	 * If the user set PGREALM, then we use a ticket file with a special
-	 * name: <usual-ticket-file-name>@<PGREALM-value>
-	 */
-	if (!(defname = krb5_cc_default_name()))
-	{
-		(void) sprintf(PQerrormsg,
-					   "pg_krb5_init: krb5_cc_default_name failed\n");
-		return (krb5_ccache) NULL;
-	}
-	strcpy(tktbuf, defname);
-	if (realm = getenv("PGREALM"))
-	{
-		strcat(tktbuf, "@");
-		strcat(tktbuf, realm);
+	retval = krb5_init_context(&pg_krb5_context);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_init: krb5_init_context: %s",
+				 error_message(retval));
+		return STATUS_ERROR;
 	}
 
-	if (code = krb5_cc_resolve(tktbuf, &ccache))
-	{
-		(void) sprintf(PQerrormsg,
-		   "pg_krb5_init: Kerberos error %d in krb5_cc_resolve\n", code);
-		com_err("pg_krb5_init", code, "in krb5_cc_resolve");
-		return (krb5_ccache) NULL;
-	}
-	return ccache;
+	retval = krb5_cc_default(pg_krb5_context, &pg_krb5_ccache);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_init: krb5_cc_default: %s",
+				 error_message(retval));
+		krb5_free_context(pg_krb5_context);
+		return STATUS_ERROR;
+    }
+
+    retval = krb5_cc_get_principal(pg_krb5_context, pg_krb5_ccache, 
+								   &pg_krb5_client);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_init: krb5_cc_get_principal: %s",
+				 error_message(retval));
+		krb5_cc_close(pg_krb5_context, pg_krb5_ccache);
+		krb5_free_context(pg_krb5_context);
+		return STATUS_ERROR;
+    }
+
+    retval = krb5_unparse_name(pg_krb5_context, pg_krb5_client, &pg_krb5_name);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_init: krb5_unparse_name: %s",
+				 error_message(retval));
+		krb5_free_principal(pg_krb5_context, pg_krb5_client);
+		krb5_cc_close(pg_krb5_context, pg_krb5_ccache);
+		krb5_free_context(pg_krb5_context);
+		return STATUS_ERROR;
+	}	
+
+	pg_krb5_name = pg_an_to_ln(pg_krb5_name);
+
+	pg_krb5_initialised = 1;
+	return STATUS_OK;
 }
 
+
 /*
  * pg_krb5_authname -- returns a pointer to static space containing whatever
  *					   name the user has authenticated to the system
- *
- * We obtain this information by digging around in the ticket file.
- */
+  */
 static const char *
-pg_krb5_authname(const char *PQerrormsg)
+pg_krb5_authname(char *PQerrormsg)
 {
-	krb5_ccache ccache;
-	krb5_principal principal;
-	krb5_error_code code;
-	static char *authname = (char *) NULL;
-
-	if (authname)
-		return authname;
+	if (pg_krb5_init(PQerrormsg) != STATUS_OK)
+		return NULL;
 
-	ccache = pg_krb5_init();	/* don't free this */
-
-	if (code = krb5_cc_get_principal(ccache, &principal))
-	{
-		(void) sprintf(PQerrormsg,
-					   "pg_krb5_authname: Kerberos error %d in krb5_cc_get_principal\n", code);
-		com_err("pg_krb5_authname", code, "in krb5_cc_get_principal");
-		return (char *) NULL;
-	}
-	if (code = krb5_unparse_name(principal, &authname))
-	{
-		(void) sprintf(PQerrormsg,
-					   "pg_krb5_authname: Kerberos error %d in krb5_unparse_name\n", code);
-		com_err("pg_krb5_authname", code, "in krb5_unparse_name");
-		krb5_free_principal(principal);
-		return (char *) NULL;
-	}
-	krb5_free_principal(principal);
-	return pg_an_to_ln(authname);
+	return pg_krb5_name;
 }
 
+
 /*
  * pg_krb5_sendauth -- client routine to send authentication information to
  *					   the server
- *
- * This routine does not do mutual authentication, nor does it return enough
- * information to do encrypted connections.  But then, if we want to do
- * encrypted connections, we'll have to redesign the whole RPC mechanism
- * anyway.
- *
- * Server hostnames are canonicalized v4-style, i.e., all domain suffixes
- * are simply chopped off.	Hence, we are assuming that you've entered your
- * server instances as
- *		<value-of-PG_KRB_SRVNAM>/<canonicalized-hostname>
- * in the PGREALM (or local) database.	This is probably a bad assumption.
  */
 static int
-pg_krb5_sendauth(const char *PQerrormsg, int sock,
+pg_krb5_sendauth(char *PQerrormsg, int sock,
 				 struct sockaddr_in * laddr,
 				 struct sockaddr_in * raddr,
 				 const char *hostname)
 {
-	char		servbuf[MAXHOSTNAMELEN + 1 +
-									sizeof(PG_KRB_SRVNAM)];
-	const char *hostp;
-	const char *realm;
-	krb5_error_code code;
-	krb5_principal client,
-				server;
-	krb5_ccache ccache;
-	krb5_error *error = (krb5_error *) NULL;
-
-	ccache = pg_krb5_init();	/* don't free this */
-
-	/*
-	 * set up client -- this is easy, we can get it out of the ticket
-	 * file.
-	 */
-	if (code = krb5_cc_get_principal(ccache, &client))
-	{
-		(void) sprintf(PQerrormsg,
-					   "pg_krb5_sendauth: Kerberos error %d in krb5_cc_get_principal\n", code);
-		com_err("pg_krb5_sendauth", code, "in krb5_cc_get_principal");
+	krb5_error_code retval;
+	int ret;
+	krb5_principal server;
+	krb5_auth_context auth_context = NULL;
+    krb5_error *err_ret = NULL;
+	int flags;
+
+	ret = pg_krb5_init(PQerrormsg);
+	if (ret != STATUS_OK)
+		return ret;
+
+	retval = krb5_sname_to_principal(pg_krb5_context, hostname, PG_KRB_SRVNAM, 
+									 KRB5_NT_SRV_HST, &server);
+	if (retval) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_sendauth: krb5_sname_to_principal: %s",
+				 error_message(retval));
 		return STATUS_ERROR;
 	}
 
-	/*
-	 * set up server -- canonicalize as described above
+	/* 
+	 * libpq uses a non-blocking socket. But kerberos needs a blocking
+	 * socket, and we have to block somehow to do mutual authentication
+	 * anyway. So we temporarily make it blocking.
 	 */
-	strcpy(servbuf, PG_KRB_SRVNAM);
-	*(hostp = servbuf + (sizeof(PG_KRB_SRVNAM) - 1)) = '/';
-	if (hostname || *hostname)
-		strncpy(++hostp, hostname, MAXHOSTNAMELEN);
-	else
-	{
-		if (gethostname(++hostp, MAXHOSTNAMELEN) < 0)
-			strcpy(hostp, "localhost");
-	}
-	if (hostp = strchr(hostp, '.'))
-		*hostp = '\0';
-	if (realm = getenv("PGREALM"))
-	{
-		strcat(servbuf, "@");
-		strcat(servbuf, realm);
-	}
-	if (code = krb5_parse_name(servbuf, &server))
-	{
-		(void) sprintf(PQerrormsg,
-		"pg_krb5_sendauth: Kerberos error %d in krb5_parse_name\n", code);
-		com_err("pg_krb5_sendauth", code, "in krb5_parse_name");
-		krb5_free_principal(client);
+	flags = fcntl(sock, F_GETFL);
+	if (flags < 0 || fcntl(sock, F_SETFL, (long)(flags & ~O_NONBLOCK))) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_sendauth: fcntl: %s", strerror(errno));
+		krb5_free_principal(pg_krb5_context, server);
 		return STATUS_ERROR;
 	}
 
-	/*
-	 * The only thing we want back from krb5_sendauth is an error status
-	 * and any error messages.
-	 */
-	if (code = krb5_sendauth((krb5_pointer) & sock,
-							 PG_KRB5_VERSION,
-							 client,
-							 server,
-							 (krb5_flags) 0,
-							 (krb5_checksum *) NULL,
-							 (krb5_creds *) NULL,
-							 ccache,
-							 (krb5_int32 *) NULL,
-							 (krb5_keyblock **) NULL,
-							 &error,
-							 (krb5_ap_rep_enc_part **) NULL))
-	{
-		if ((code == KRB5_SENDAUTH_REJECTED) && error)
-		{
-			(void) sprintf(PQerrormsg,
-				  "pg_krb5_sendauth: authentication rejected: \"%*s\"\n",
-						   error->text.length, error->text.data);
+	retval = krb5_sendauth(pg_krb5_context, &auth_context,
+						   (krb5_pointer) &sock, PG_KRB_SRVNAM,
+						   pg_krb5_client, server,
+						   AP_OPTS_MUTUAL_REQUIRED,
+						   NULL, 0,		/* no creds, use ccache instead */
+						   pg_krb5_ccache, &err_ret, NULL, NULL);
+	if (retval) {
+		if (retval == KRB5_SENDAUTH_REJECTED && err_ret) {
+			snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+					 "pg_krb5_sendauth: authentication rejected: \"%*s\"",
+					 err_ret->text.length, err_ret->text.data);
 		}
-		else
-		{
-			(void) sprintf(PQerrormsg,
-						   "pg_krb5_sendauth: Kerberos error %d in krb5_sendauth\n", code);
-			com_err("pg_krb5_sendauth", code, "in krb5_sendauth");
+		else {
+			snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+					 "pg_krb5_sendauth: krb5_sendauth: %s",
+					 error_message(retval));
 		}
+			
+		if (err_ret)
+			krb5_free_error(pg_krb5_context, err_ret);
+		
+		ret = STATUS_ERROR;
+	}
+
+	krb5_free_principal(pg_krb5_context, server);
+	
+	if (fcntl(sock, F_SETFL, (long)flags)) {
+		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
+				 "pg_krb5_sendauth: fcntl: %s", strerror(errno));
+		ret = STATUS_ERROR;
 	}
-	krb5_free_principal(client);
-	krb5_free_principal(server);
-	return code ? STATUS_ERROR : STATUS_OK;
+
+	return ret;
 }
 
 #endif	 /* KRB5 */
diff -u -r postgresql-7.0RC5/src/interfaces/libpq/libpq-int.h postgresql-7.0RC5.krb5/src/interfaces/libpq/libpq-int.h
--- postgresql-7.0RC5/src/interfaces/libpq/libpq-int.h	Mon May  8 17:22:40 2000
+++ postgresql-7.0RC5.krb5/src/interfaces/libpq/libpq-int.h	Sat May  6 17:49:38 2000
@@ -50,6 +50,7 @@
  * POSTGRES backend dependent Constants.
  */
 
+#define PQERRORMSG_LENGTH 1024
 #define CMDSTATUS_LEN 40
 
 /*