kgssapi: Add a new file with a function for a future commit

A future commit needs a new upcall function that can do reverse
DNS in order to generate a "service principal".
This patch adds the file.

(cherry picked from commit 428879dc9110240ad0940c7ac8cd69bcaf6e686e)

1 files changed, 85 insertions, 0 deletions

diff --git a/sys/kgssapi/gss_ip_to_dns.c b/sys/kgssapi/gss_ip_to_dns.c
new file mode 100644
index 000000000000..d2be006d5b3e
--- /dev/null
+++ b/sys/kgssapi/gss_ip_to_dns.c
@@ -0,0 +1,85 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
+ * Authors: Doug Rabson <dfr@rabson.org>
+ * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/kobj.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+
+#include <kgssapi/gssapi.h>
+#include <kgssapi/gssapi_impl.h>
+
+#include "gssd.h"
+
+OM_uint32
+gss_ip_to_dns(OM_uint32 *minor_status,
+    char *ip_addr,
+    char *dns_name)
+{
+	struct ip_to_dns_res res;
+	struct ip_to_dns_args args;
+	enum clnt_stat stat;
+	CLIENT *cl;
+
+	*minor_status = 0;
+	cl = kgss_gssd_client();
+	if (cl == NULL)
+		return (GSS_S_FAILURE);
+
+	args.ip_addr.ip_addr_len = strlen(ip_addr);
+	args.ip_addr.ip_addr_val = mem_alloc(args.ip_addr.ip_addr_len);
+	memcpy(args.ip_addr.ip_addr_val, ip_addr, args.ip_addr.ip_addr_len);
+
+	bzero(&res, sizeof(res));
+	stat = gssd_ip_to_dns_1(&args, &res, cl);
+	CLNT_RELEASE(cl);
+	if (stat != RPC_SUCCESS) {
+		*minor_status = stat;
+		return (GSS_S_FAILURE);
+	}
+
+	if (res.major_status != GSS_S_COMPLETE) {
+		*minor_status = res.minor_status;
+		return (res.major_status);
+	}
+
+	if (res.dns_name.dns_name_len == 0 ||
+	    res.dns_name.dns_name_len >= NI_MAXHOST) {
+		*minor_status = 0;
+		return (GSS_S_FAILURE);
+	}
+
+	memcpy(dns_name, res.dns_name.dns_name_val, res.dns_name.dns_name_len);
+	dns_name[res.dns_name.dns_name_len] = '\0';
+
+	return (GSS_S_COMPLETE);
+}