From d3d1c2c608615609302386dd2757729ee83092be Mon Sep 17 00:00:00 2001
From: tb <>
Date: Mon, 21 Jan 2019 14:12:13 +0000
Subject: Move ssl_cipher_list_to_bytes() and ssl_bytes_to_cipher_list() to a
 more appropriately licenced file.  jsing and doug have rewritten these
 functions (including the comments) over the past years.

ok jsing
---
 src/lib/libssl/ssl_ciphers.c | 120 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 119 insertions(+), 1 deletion(-)

(limited to 'src/lib/libssl/ssl_ciphers.c')

diff --git a/src/lib/libssl/ssl_ciphers.c b/src/lib/libssl/ssl_ciphers.c
index 081a35ddb2..374cb6684e 100644
--- a/src/lib/libssl/ssl_ciphers.c
+++ b/src/lib/libssl/ssl_ciphers.c
@@ -1,5 +1,7 @@
-/*	$OpenBSD: ssl_ciphers.c,v 1.1 2019/01/21 10:28:52 tb Exp $ */
+/*	$OpenBSD: ssl_ciphers.c,v 1.2 2019/01/21 14:12:13 tb Exp $ */
 /*
+ * Copyright (c) 2015-2017 Doug Hogan <doug@openbsd.org>
+ * Copyright (c) 2015-2018 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2019 Theo Buehler <tb@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -15,6 +17,9 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <openssl/safestack.h>
+
+#include "bytestring.h"
 #include "ssl_locl.h"
 
 int
@@ -42,3 +47,116 @@ ssl_cipher_is_permitted(const SSL_CIPHER *cipher, uint16_t min_ver,
 
 	return 0;
 }
+
+int
+ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *ciphers, CBB *cbb)
+{
+	SSL_CIPHER *cipher;
+	int num_ciphers = 0;
+	uint16_t min_vers, max_vers;
+	int i;
+
+	if (ciphers == NULL)
+		return 0;
+
+	if (!ssl_supported_version_range(s, &min_vers, &max_vers))
+		return 0;
+
+	for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++) {
+		if ((cipher = sk_SSL_CIPHER_value(ciphers, i)) == NULL)
+			return 0;
+
+		if (!ssl_cipher_is_permitted(cipher, min_vers, max_vers))
+			continue;
+
+		if (!CBB_add_u16(cbb, ssl3_cipher_get_value(cipher)))
+			return 0;
+
+		num_ciphers++;
+	}
+
+	/* Add SCSV if there are other ciphers and we're not renegotiating. */
+	if (num_ciphers > 0 && !s->internal->renegotiate) {
+		if (!CBB_add_u16(cbb, SSL3_CK_SCSV & SSL3_CK_VALUE_MASK))
+			return 0;
+	}
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+STACK_OF(SSL_CIPHER) *
+ssl_bytes_to_cipher_list(SSL *s, CBS *cbs)
+{
+	STACK_OF(SSL_CIPHER) *ciphers = NULL;
+	const SSL_CIPHER *cipher;
+	uint16_t cipher_value, max_version;
+	unsigned long cipher_id;
+
+	if (s->s3 != NULL)
+		S3I(s)->send_connection_binding = 0;
+
+	if ((ciphers = sk_SSL_CIPHER_new_null()) == NULL) {
+		SSLerror(s, ERR_R_MALLOC_FAILURE);
+		goto err;
+	}
+
+	while (CBS_len(cbs) > 0) {
+		if (!CBS_get_u16(cbs, &cipher_value)) {
+			SSLerror(s, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST);
+			goto err;
+		}
+
+		cipher_id = SSL3_CK_ID | cipher_value;
+
+		if (s->s3 != NULL && cipher_id == SSL3_CK_SCSV) {
+			/*
+			 * TLS_EMPTY_RENEGOTIATION_INFO_SCSV is fatal if
+			 * renegotiating.
+			 */
+			if (s->internal->renegotiate) {
+				SSLerror(s, SSL_R_SCSV_RECEIVED_WHEN_RENEGOTIATING);
+				ssl3_send_alert(s, SSL3_AL_FATAL,
+				    SSL_AD_HANDSHAKE_FAILURE);
+
+				goto err;
+			}
+			S3I(s)->send_connection_binding = 1;
+			continue;
+		}
+
+		if (cipher_id == SSL3_CK_FALLBACK_SCSV) {
+			/*
+			 * TLS_FALLBACK_SCSV indicates that the client
+			 * previously tried a higher protocol version.
+			 * Fail if the current version is an unexpected
+			 * downgrade.
+			 */
+			max_version = ssl_max_server_version(s);
+			if (max_version == 0 || s->version < max_version) {
+				SSLerror(s, SSL_R_INAPPROPRIATE_FALLBACK);
+				if (s->s3 != NULL)
+					ssl3_send_alert(s, SSL3_AL_FATAL,
+					    SSL_AD_INAPPROPRIATE_FALLBACK);
+				goto err;
+			}
+			continue;
+		}
+
+		if ((cipher = ssl3_get_cipher_by_value(cipher_value)) != NULL) {
+			if (!sk_SSL_CIPHER_push(ciphers, cipher)) {
+				SSLerror(s, ERR_R_MALLOC_FAILURE);
+				goto err;
+			}
+		}
+	}
+
+	return (ciphers);
+
+ err:
+	sk_SSL_CIPHER_free(ciphers);
+
+	return (NULL);
+}
-- 
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