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-rw-r--r--fs/cifs/dns_resolve.c123
-rw-r--r--fs/cifs/dns_resolve.h32
2 files changed, 155 insertions, 0 deletions
diff --git a/fs/cifs/dns_resolve.c b/fs/cifs/dns_resolve.c
new file mode 100644
index 000000000000..777a086abd6f
--- /dev/null
+++ b/fs/cifs/dns_resolve.c
@@ -0,0 +1,123 @@
+/*
+ * fs/cifs/dns_resolve.c
+ *
+ * Copyright (c) 2007 Igor Mammedov
+ * Author(s): Igor Mammedov (niallain@gmail.com)
+ * Steve French (sfrench@us.ibm.com)
+ *
+ * Contains the CIFS DFS upcall routines used for hostname to
+ * IP address translation.
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <keys/user-type.h>
+#include "dns_resolve.h"
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+
+static int dns_resolver_instantiate(struct key *key, const void *data,
+ size_t datalen)
+{
+ int rc = 0;
+ char *ip;
+
+ ip = kmalloc(datalen+1, GFP_KERNEL);
+ if (!ip)
+ return -ENOMEM;
+
+ memcpy(ip, data, datalen);
+ ip[datalen] = '\0';
+
+ rcu_assign_pointer(key->payload.data, ip);
+
+ return rc;
+}
+
+struct key_type key_type_dns_resolver = {
+ .name = "dns_resolver",
+ .def_datalen = sizeof(struct in_addr),
+ .describe = user_describe,
+ .instantiate = dns_resolver_instantiate,
+ .match = user_match,
+};
+
+
+/* Resolves server name to ip address.
+ * input:
+ * unc - server UNC
+ * output:
+ * *ip_addr - pointer to server ip, caller responcible for freeing it.
+ * return 0 on success
+ */
+int
+dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) {
+ int rc = -EAGAIN;
+ struct key *rkey;
+ char *name;
+ int len;
+
+ if ((!ip_addr) || (!unc))
+ return -EINVAL;
+
+ /* search for server name delimiter */
+ len = strlen(unc);
+ if (len < 3) {
+ cFYI(1, ("%s: unc is too short: %s", __FUNCTION__, unc));
+ return -EINVAL;
+ }
+ len -= 2;
+ name = memchr(unc+2, '\\', len);
+ if (!name) {
+ cFYI(1, ("%s: probably server name is whole unc: %s",
+ __FUNCTION__, unc));
+ } else {
+ len = (name - unc) - 2/* leading // */;
+ }
+
+ name = kmalloc(len+1, GFP_KERNEL);
+ if (!name) {
+ rc = -ENOMEM;
+ return rc;
+ }
+ memcpy(name, unc+2, len);
+ name[len] = 0;
+
+ rkey = request_key(&key_type_dns_resolver, name, "");
+ if (!IS_ERR(rkey)) {
+ len = strlen(rkey->payload.data);
+ *ip_addr = kmalloc(len+1, GFP_KERNEL);
+ if (*ip_addr) {
+ memcpy(*ip_addr, rkey->payload.data, len);
+ (*ip_addr)[len] = '\0';
+ cFYI(1, ("%s: resolved: %s to %s", __FUNCTION__,
+ rkey->description,
+ *ip_addr
+ ));
+ rc = 0;
+ } else {
+ rc = -ENOMEM;
+ }
+ key_put(rkey);
+ } else {
+ cERROR(1, ("%s: unable to resolve: %s", __FUNCTION__, name));
+ }
+
+ kfree(name);
+ return rc;
+}
+
+
diff --git a/fs/cifs/dns_resolve.h b/fs/cifs/dns_resolve.h
new file mode 100644
index 000000000000..073fdc3db419
--- /dev/null
+++ b/fs/cifs/dns_resolve.h
@@ -0,0 +1,32 @@
+/*
+ * fs/cifs/dns_resolve.h -- DNS Resolver upcall management for CIFS DFS
+ * Handles host name to IP address resolution
+ *
+ * Copyright (c) International Business Machines Corp., 2008
+ * Author(s): Steve French (sfrench@us.ibm.com)
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _DNS_RESOLVE_H
+#define _DNS_RESOLVE_H
+
+#ifdef __KERNEL__
+#include <linux/key-type.h>
+extern struct key_type key_type_dns_resolver;
+extern int dns_resolve_server_name_to_ip(const char *unc, char **ip_addr);
+#endif /* KERNEL */
+
+#endif /* _DNS_RESOLVE_H */