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 */