[PATCH 1/2] scsi: target: add extract_param_str() helper

The existing extract_param() helper, detects and strips any hex (0x/0X)
or base64 (0b/0B). This makes sense for some parameters, but not strings
such as CHAP_N.

Signed-off-by: David Disseldorp <[email protected]>
---
 drivers/target/iscsi/iscsi_target_nego.c | 37 ++++++++++++++++++++++++
 drivers/target/iscsi/iscsi_target_nego.h |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index b03ed154ca34e..53b17d3cc86c3 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -98,6 +98,43 @@ int extract_param(
 	return 0;
 }
 
+/* same as extract_param() above, but don't interpret any type-prefix */
+int extract_param_str(
+	const char *in_buf,
+	const char *pattern,
+	unsigned int max_length,
+	char *out_buf)
+{
+	char *ptr;
+	int len;
+
+	if (!in_buf || !pattern || !out_buf)
+		return -EINVAL;
+
+	ptr = strstr(in_buf, pattern);
+	if (!ptr)
+		return -ENOENT;
+
+	ptr = strstr(ptr, "=");
+	if (!ptr)
+		return -EINVAL;
+
+	ptr += 1;
+	len = strlen_semi(ptr);
+	if (len < 0)
+		return -EINVAL;
+
+	if (len >= max_length) {
+		pr_err("Length of input: %d exceeds max_length:"
+			" %d\n", len, max_length);
+		return -EINVAL;
+	}
+	memcpy(out_buf, ptr, len);
+	out_buf[len] = '\0';
+
+	return 0;
+}
+
 static struct iscsi_node_auth *iscsi_get_node_auth(struct iscsit_conn *conn)
 {
 	struct iscsi_portal_group *tpg;
diff --git a/drivers/target/iscsi/iscsi_target_nego.h b/drivers/target/iscsi/iscsi_target_nego.h
index e60a46d348352..6b72edd2aef2e 100644
--- a/drivers/target/iscsi/iscsi_target_nego.h
+++ b/drivers/target/iscsi/iscsi_target_nego.h
@@ -13,6 +13,7 @@ struct iscsi_np;
 extern void convert_null_to_semi(char *, int);
 extern int extract_param(const char *, const char *, unsigned int, char *,
 		unsigned char *);
+extern int extract_param_str(const char *, const char *, unsigned int, char *);
 extern int iscsi_target_check_login_request(struct iscsit_conn *,
 		struct iscsi_login *);
 extern int iscsi_target_locate_portal(struct iscsi_np *, struct iscsit_conn *,
-- 
2.51.0