Consolidate sn2princ_realm() in kprop and kpropd

In kprop and kpropd, factor out the duplicated implementation of
sn2princ_with_realm() into kprop_util.c.  Rename it to
sn2princ_realm(), remove the type parameter, and require the sname
parameter to be specified.  Rewrite the function to use
krb5_expand_hostname(), avoiding an unnecessary hostrealm lookup.

4 files changed, 43 insertions, 65 deletions

diff --git a/src/slave/kprop.c b/src/slave/kprop.c
index e80ecab..5bff5de 100644
--- a/src/slave/kprop.c
+++ b/src/slave/kprop.c
@@ -182,35 +182,6 @@ parse_args(krb5_context context, int argc, char **argv)
     }
 }
 
-/* Runs krb5_sname_to_principal with a substitute realm
- * Duplicated in kpropd.c, sharing TBD */
-static krb5_error_code
-sn2princ_with_realm(krb5_context context, const char *hostname,
-                    const char *sname, krb5_int32 type, const char *rrealm,
-                    krb5_principal *princ_out)
-{
-    krb5_error_code ret;
-    krb5_principal princ = NULL;
-
-    *princ_out = NULL;
-
-    if (rrealm == NULL)
-        return EINVAL;
-
-    ret = krb5_sname_to_principal(context, hostname, sname, type, &princ);
-    if (ret)
-        return ret;
-
-    ret = krb5_set_principal_realm(context, princ, rrealm);
-    if (ret) {
-        krb5_free_principal(context, princ);
-        return ret;
-    }
-
-    *princ_out = princ;
-    return 0;
-}
-
 static void
 get_tickets(krb5_context context)
 {
@@ -220,8 +191,8 @@ get_tickets(krb5_context context)
     krb5_principal server_princ = NULL;
 
     /* Figure out what tickets we'll be using to send. */
-    retval = sn2princ_with_realm(context, NULL, NULL, KRB5_NT_SRV_HST, realm,
-                                 &my_principal);
+    retval = sn2princ_realm(context, NULL, KPROP_SERVICE_NAME, realm,
+                            &my_principal);
     if (retval) {
         com_err(progname, errno, _("while setting client principal name"));
         exit(1);
@@ -229,8 +200,8 @@ get_tickets(krb5_context context)
 
     /* Construct the principal name for the slave host. */
     memset(&creds, 0, sizeof(creds));
-    retval = sn2princ_with_realm(context, slave_host, KPROP_SERVICE_NAME,
-                                 KRB5_NT_SRV_HST, realm, &server_princ);
+    retval = sn2princ_realm(context, slave_host, KPROP_SERVICE_NAME, realm,
+                            &server_princ);
     if (retval) {
         com_err(progname, errno, _("while setting server principal name"));
         exit(1);
diff --git a/src/slave/kprop.h b/src/slave/kprop.h
index a4aa39a..dbbda43 100644
--- a/src/slave/kprop.h
+++ b/src/slave/kprop.h
@@ -37,3 +37,7 @@
 
 int sockaddr2krbaddr(krb5_context context, int family, struct sockaddr *sa,
                      krb5_address **dest);
+
+krb5_error_code
+sn2princ_realm(krb5_context context, const char *hostname, const char *sname,
+               const char *realm, krb5_principal *princ_out);
diff --git a/src/slave/kprop_util.c b/src/slave/kprop_util.c
index beaf1c8..f182554 100644
--- a/src/slave/kprop_util.c
+++ b/src/slave/kprop_util.c
@@ -65,3 +65,34 @@ sockaddr2krbaddr(krb5_context context, int family, struct sockaddr *sa,
 
     return krb5_copy_addr(context, &addr, dest);
 }
+
+/* Construct a host-based principal, similar to krb5_sname_to_principal() but
+ * with a specified realm. */
+krb5_error_code
+sn2princ_realm(krb5_context context, const char *hostname, const char *sname,
+               const char *realm, krb5_principal *princ_out)
+{
+    krb5_error_code ret;
+    char *canonhost, localname[MAXHOSTNAMELEN];
+
+    *princ_out = NULL;
+    assert(sname != NULL && realm != NULL);
+
+    /* If hostname is NULL, use the local hostname. */
+    if (hostname == NULL) {
+        if (gethostname(localname, MAXHOSTNAMELEN) != 0)
+            return SOCKET_ERRNO;
+        hostname = localname;
+    }
+
+    ret = krb5_expand_hostname(context, hostname, &canonhost);
+    if (ret)
+        return ret;
+
+    ret = krb5_build_principal(context, princ_out, strlen(realm), realm, sname,
+                               canonhost, (char *)NULL);
+    krb5_free_string(context, canonhost);
+    if (!ret)
+        (*princ_out)->type = KRB5_NT_SRV_HST;
+    return ret;
+}
diff --git a/src/slave/kpropd.c b/src/slave/kpropd.c
index ef64222..056c31a 100644
--- a/src/slave/kpropd.c
+++ b/src/slave/kpropd.c
@@ -601,34 +601,6 @@ full_resync(CLIENT *clnt)
     return (status == RPC_SUCCESS) ? &clnt_res : NULL;
 }
 
-/* Runs krb5_sname_to_principal with a substitute realm.
- * Duplicated in kprop.c, sharing TBD */
-static krb5_error_code
-sn2princ_with_realm(krb5_context context, const char *hostname,
-                    const char *sname, krb5_int32 type, const char *rrealm,
-                    krb5_principal *princ_out)
-{
-    krb5_error_code ret;
-    krb5_principal princ = NULL;
-
-    *princ_out = NULL;
-
-    if (rrealm == NULL)
-        return EINVAL;
-
-    ret = krb5_sname_to_principal(context, hostname, sname, type, &princ);
-    if (ret)
-        return ret;
-
-    ret = krb5_set_principal_realm(context, princ, rrealm);
-    if (ret) {
-        krb5_free_principal(context, princ);
-        return ret;
-    }
-
-    *princ_out = princ;
-    return 0;
-}
 /*
  * Beg for incrementals from the KDC.
  *
@@ -671,8 +643,8 @@ do_iprop()
         }
     }
 
-    retval = sn2princ_with_realm(kpropd_context, NULL, KIPROP_SVC_NAME,
-                                 KRB5_NT_SRV_HST, realm, &iprop_svc_principal);
+    retval = sn2princ_realm(kpropd_context, NULL, KIPROP_SVC_NAME, realm,
+                            &iprop_svc_principal);
     if (retval) {
         com_err(progname, retval,
                 _("while trying to construct host service principal"));
@@ -1176,8 +1148,8 @@ parse_args(char **argv)
     }
 
     /* Construct service name from local hostname. */
-    retval = sn2princ_with_realm(kpropd_context, NULL, KPROP_SERVICE_NAME,
-                                 KRB5_NT_SRV_HST, realm, &server);
+    retval = sn2princ_realm(kpropd_context, NULL, KPROP_SERVICE_NAME, realm,
+                            &server);
     if (retval) {
         com_err(progname, retval,
                 _("while trying to construct my service name"));