cifs: get rid of mount options string parsing

After switching to filesystem context support, we no longer need to
handle mount options string when chasing dfs referrals.  Now, we set
the new values directly into smb3_fs_context.

Start working on a separate source file to handle most dfs related
mount functions as connect.c has already became too big.  The
remaining functions will be moved gradually in follow-up patches.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/fs/cifs/dfs.c b/fs/cifs/dfs.c
new file mode 100644
index 000000000000..0b15d7e9f818
--- /dev/null
+++ b/fs/cifs/dfs.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Paulo Alcantara <palcantara@suse.de>
+ */
+
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "dns_resolve.h"
+#include "fs_context.h"
+#include "dfs.h"
+
+/* Resolve UNC server name and set destination ip address in fs context */
+static int resolve_unc(const char *path, struct smb3_fs_context *ctx)
+{
+	int rc;
+	char *ip = NULL;
+
+	rc = dns_resolve_server_name_to_ip(path, &ip, NULL);
+	if (rc < 0) {
+		cifs_dbg(FYI, "%s: failed to resolve UNC server name: %d\n", __func__, rc);
+		return rc;
+	}
+
+	if (!cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip))) {
+		cifs_dbg(VFS, "%s: could not determinate destination address\n", __func__);
+		rc = -EHOSTUNREACH;
+	} else
+		rc = 0;
+
+	kfree(ip);
+	return rc;
+}
+
+/**
+ * dfs_parse_target_referral - set fs context for dfs target referral
+ *
+ * @full_path: full path in UNC format.
+ * @ref: dfs referral pointer.
+ * @ctx: smb3 fs context pointer.
+ *
+ * Return zero if dfs referral was parsed correctly, otherwise non-zero.
+ */
+int dfs_parse_target_referral(const char *full_path, const struct dfs_info3_param *ref,
+			      struct smb3_fs_context *ctx)
+{
+	int rc;
+	const char *prepath = NULL;
+	char *path;
+
+	if (!full_path || !*full_path || !ref || !ctx)
+		return -EINVAL;
+
+	if (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0))
+		return -EINVAL;
+
+	if (strlen(full_path) - ref->path_consumed) {
+		prepath = full_path + ref->path_consumed;
+		/* skip initial delimiter */
+		if (*prepath == '/' || *prepath == '\\')
+			prepath++;
+	}
+
+	path = cifs_build_devname(ref->node_name, prepath);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+
+	rc = smb3_parse_devname(path, ctx);
+	if (rc)
+		goto out;
+
+	rc = resolve_unc(path, ctx);
+
+out:
+	kfree(path);
+	return rc;
+}