From 8006742fa37a47f32df9066ce6bfda7b84bb7a7c Mon Sep 17 00:00:00 2001
From: Jouni Malinen <jouni@codeaurora.org>
Date: Thu, 30 Jan 2020 15:04:03 +0200
Subject: [PATCH] ASN.1: Add a helper for parsing AlgorithmIdentifier

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
---
 src/tls/asn1.c | 24 ++++++++++++++++++++++++
 src/tls/asn1.h |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/src/tls/asn1.c b/src/tls/asn1.c
index 13b7fe1a5..54c17deae 100644
--- a/src/tls/asn1.c
+++ b/src/tls/asn1.c
@@ -325,3 +325,27 @@ int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
 		*next = hdr->payload + hdr->length;
 	return 0;
 }
+
+
+int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
+		    const u8 **params, size_t *params_len, const u8 **next)
+{
+	const u8 *pos = buf, *end = buf + len;
+	struct asn1_hdr hdr;
+
+	/*
+	 * AlgorithmIdentifier ::= SEQUENCE {
+	 *     algorithm            OBJECT IDENTIFIER,
+	 *     parameters           ANY DEFINED BY algorithm OPTIONAL}
+	 */
+	if (asn1_get_sequence(pos, end - pos, &hdr, next) < 0 ||
+	    asn1_get_oid(hdr.payload, hdr.length, oid, &pos) < 0)
+		return -1;
+
+	if (params && params_len) {
+		*params = pos;
+		*params_len = hdr.payload + hdr.length - pos;
+	}
+
+	return 0;
+}
diff --git a/src/tls/asn1.h b/src/tls/asn1.h
index d769a4e9b..25a05c78b 100644
--- a/src/tls/asn1.h
+++ b/src/tls/asn1.h
@@ -68,6 +68,8 @@ int asn1_oid_equal(const struct asn1_oid *a, const struct asn1_oid *b);
 int asn1_get_integer(const u8 *buf, size_t len, int *integer, const u8 **next);
 int asn1_get_sequence(const u8 *buf, size_t len, struct asn1_hdr *hdr,
 		      const u8 **next);
+int asn1_get_alg_id(const u8 *buf, size_t len, struct asn1_oid *oid,
+		    const u8 **params, size_t *params_len, const u8 **next);
 
 extern struct asn1_oid asn1_sha1_oid;
 extern struct asn1_oid asn1_sha256_oid;