Provide various CBS_peek_* functions.

These will be used in libcrypto.

With input from and ok tb@

1 files changed, 31 insertions, 1 deletions

diff --git a/src/lib/libssl/bytestring.h b/src/lib/libssl/bytestring.h
index fa5e05fa27..ce933f3f7b 100644
--- a/src/lib/libssl/bytestring.h
+++ b/src/lib/libssl/bytestring.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bytestring.h,v 1.21 2021/12/15 17:30:20 jsing Exp $   */
+/*      $OpenBSD: bytestring.h,v 1.22 2021/12/15 17:36:49 jsing Exp $   */
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -172,6 +172,36 @@ int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out);
  */
 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out);
 
+/*
+ * CBS_peek_u8 sets |*out| to the next uint8_t from |cbs|, but does not advance
+ * |cbs|. It returns one on success and zero on error.
+ */
+int CBS_peek_u8(CBS *cbs, uint8_t *out);
+
+/*
+ * CBS_peek_u16 sets |*out| to the next, big-endian uint16_t from |cbs|, but
+ * does not advance |cbs|. It returns one on success and zero on error.
+ */
+int CBS_peek_u16(CBS *cbs, uint16_t *out);
+
+/*
+ * CBS_peek_u24 sets |*out| to the next, big-endian 24-bit value from |cbs|, but
+ * does not advance |cbs|. It returns one on success and zero on error.
+ */
+int CBS_peek_u24(CBS *cbs, uint32_t *out);
+
+/*
+ * CBS_peek_u32 sets |*out| to the next, big-endian uint32_t value from |cbs|,
+ * but does not advance |cbs|. It returns one on success and zero on error.
+ */
+int CBS_peek_u32(CBS *cbs, uint32_t *out);
+
+/*
+ * CBS_peek_last_u8 sets |*out| to the last uint8_t from |cbs|, but does not
+ * shorten |cbs|. It returns one on success and zero on error.
+ */
+int CBS_peek_last_u8(CBS *cbs, uint8_t *out);
+
 
 /* Parsing ASN.1 */