Add a direct copy of the exension parsing code to be modified for tls13.

At the moment this is mechanical, with the functions renamed. This will be
refactored for tls13.
ok jsing@

3 files changed, 1596 insertions, 2 deletions

diff --git a/lib/libssl/Makefile b/lib/libssl/Makefile
index 17f73a8c4f4..8923c05bd42 100644
--- a/lib/libssl/Makefile
+++ b/lib/libssl/Makefile
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.43 2018/11/09 00:34:55 beck Exp $
+# $OpenBSD: Makefile,v 1.44 2019/01/17 00:56:57 beck Exp $
 
 .include <bsd.own.mk>
 .ifndef NOMAN
@@ -34,7 +34,7 @@ SRCS= \
 	ssl_asn1.c ssl_txt.c ssl_algs.c \
 	bio_ssl.c ssl_err.c ssl_methods.c \
 	ssl_packet.c ssl_tlsext.c ssl_versions.c pqueue.c ssl_init.c \
-	tls13_handshake.c tls13_key_schedule.c ssl_sigalgs.c
+	tls13_handshake.c tls13_key_schedule.c tls13_tlsext.c ssl_sigalgs.c
 SRCS+=	s3_cbc.c
 SRCS+=	bs_ber.c bs_cbb.c bs_cbs.c
 
diff --git a/lib/libssl/tls13_tlsext.c b/lib/libssl/tls13_tlsext.c
new file mode 100644
index 00000000000..4d44301bca8
--- /dev/null
+++ b/lib/libssl/tls13_tlsext.c
@@ -0,0 +1,1497 @@
+/* $OpenBSD: tls13_tlsext.c,v 1.1 2019/01/17 00:56:57 beck Exp $ */
+/*
+ * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
+ * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
+ * Copyright (c) 2017 Bob Beck <beck@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <openssl/ocsp.h>
+
+#include "ssl_locl.h"
+
+#include "bytestring.h"
+#include "ssl_tlsext.h"
+#include "ssl_sigalgs.h"
+
+/*
+ * Supported Application-Layer Protocol Negotiation - RFC 7301
+ */
+
+int
+tls13_tlsext_alpn_clienthello_needs(SSL *s)
+{
+	/* ALPN protos have been specified and this is the initial handshake */
+	return s->internal->alpn_client_proto_list != NULL &&
+	    S3I(s)->tmp.finish_md_len == 0;
+}
+
+int
+tls13_tlsext_alpn_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB protolist;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &protolist))
+		return 0;
+
+	if (!CBB_add_bytes(&protolist, s->internal->alpn_client_proto_list,
+	    s->internal->alpn_client_proto_list_len))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_alpn_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS proto_name_list, alpn;
+	const unsigned char *selected;
+	unsigned char selected_len;
+	int r;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &alpn))
+		goto err;
+	if (CBS_len(&alpn) < 2)
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	CBS_dup(&alpn, &proto_name_list);
+	while (CBS_len(&proto_name_list) > 0) {
+		CBS proto_name;
+
+		if (!CBS_get_u8_length_prefixed(&proto_name_list, &proto_name))
+			goto err;
+		if (CBS_len(&proto_name) == 0)
+			goto err;
+	}
+
+	if (s->ctx->internal->alpn_select_cb == NULL)
+		return 1;
+
+	r = s->ctx->internal->alpn_select_cb(s, &selected, &selected_len,
+	    CBS_data(&alpn), CBS_len(&alpn),
+	    s->ctx->internal->alpn_select_cb_arg);
+	if (r == SSL_TLSEXT_ERR_OK) {
+		free(S3I(s)->alpn_selected);
+		if ((S3I(s)->alpn_selected = malloc(selected_len)) == NULL) {
+			*alert = SSL_AD_INTERNAL_ERROR;
+			return 0;
+		}
+		memcpy(S3I(s)->alpn_selected, selected, selected_len);
+		S3I(s)->alpn_selected_len = selected_len;
+	}
+
+	return 1;
+
+ err:
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+int
+tls13_tlsext_alpn_serverhello_needs(SSL *s)
+{
+	return S3I(s)->alpn_selected != NULL;
+}
+
+int
+tls13_tlsext_alpn_serverhello_build(SSL *s, CBB *cbb)
+{
+	CBB list, selected;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &list))
+		return 0;
+
+	if (!CBB_add_u8_length_prefixed(&list, &selected))
+		return 0;
+
+	if (!CBB_add_bytes(&selected, S3I(s)->alpn_selected,
+	    S3I(s)->alpn_selected_len))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_alpn_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS list, proto;
+
+	if (s->internal->alpn_client_proto_list == NULL) {
+		*alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+		return 0;
+	}
+
+	if (!CBS_get_u16_length_prefixed(cbs, &list))
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	if (!CBS_get_u8_length_prefixed(&list, &proto))
+		goto err;
+
+	if (CBS_len(&list) != 0)
+		goto err;
+	if (CBS_len(&proto) == 0)
+		goto err;
+
+	if (!CBS_stow(&proto, &(S3I(s)->alpn_selected),
+	    &(S3I(s)->alpn_selected_len)))
+		goto err;
+
+	return 1;
+
+ err:
+	*alert = TLS1_AD_DECODE_ERROR;
+	return 0;
+}
+
+/*
+ * Supported Groups - RFC 7919 section 2
+ */
+int
+tls13_tlsext_supportedgroups_clienthello_needs(SSL *s)
+{
+	return ssl_has_ecc_ciphers(s);
+}
+
+int
+tls13_tlsext_supportedgroups_clienthello_build(SSL *s, CBB *cbb)
+{
+	const uint16_t *groups;
+	size_t groups_len;
+	CBB grouplist;
+	int i;
+
+	tls1_get_group_list(s, 0, &groups, &groups_len);
+	if (groups_len == 0) {
+		SSLerror(s, ERR_R_INTERNAL_ERROR);
+		return 0;
+	}
+
+	if (!CBB_add_u16_length_prefixed(cbb, &grouplist))
+		return 0;
+
+	for (i = 0; i < groups_len; i++) {
+		if (!CBB_add_u16(&grouplist, groups[i]))
+			return 0;
+	}
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_supportedgroups_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS grouplist;
+	size_t groups_len;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &grouplist))
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	groups_len = CBS_len(&grouplist);
+	if (groups_len == 0 || groups_len % 2 != 0)
+		goto err;
+	groups_len /= 2;
+
+	if (!s->internal->hit) {
+		uint16_t *groups;
+		int i;
+
+		if (SSI(s)->tlsext_supportedgroups != NULL)
+			goto err;
+
+		if ((groups = reallocarray(NULL, groups_len,
+		    sizeof(uint16_t))) == NULL) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+
+		for (i = 0; i < groups_len; i++) {
+			if (!CBS_get_u16(&grouplist, &groups[i])) {
+				free(groups);
+				goto err;
+			}
+		}
+
+		if (CBS_len(&grouplist) != 0) {
+			free(groups);
+			goto err;
+		}
+
+		SSI(s)->tlsext_supportedgroups = groups;
+		SSI(s)->tlsext_supportedgroups_length = groups_len;
+	}
+
+	return 1;
+
+ err:
+	*alert = TLS1_AD_DECODE_ERROR;
+	return 0;
+}
+
+/* This extension is never used by the server. */
+int
+tls13_tlsext_supportedgroups_serverhello_needs(SSL *s)
+{
+	return 0;
+}
+
+int
+tls13_tlsext_supportedgroups_serverhello_build(SSL *s, CBB *cbb)
+{
+	return 0;
+}
+
+int
+tls13_tlsext_supportedgroups_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	/*
+	 * Servers should not send this extension per the RFC.
+	 *
+	 * However, certain F5 BIG-IP systems incorrectly send it. This bug is
+	 * from at least 2014 but as of 2017, there are still large sites with
+	 * this unpatched in production. As a result, we need to currently skip
+	 * over the extension and ignore its content:
+	 *
+	 *  https://support.f5.com/csp/article/K37345003
+	 */
+	if (!CBS_skip(cbs, CBS_len(cbs))) {
+		*alert = TLS1_AD_INTERNAL_ERROR;
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * Supported Point Formats Extension - RFC 4492 section 5.1.2
+ */
+static int
+tls13_tlsext_ecpf_build(SSL *s, CBB *cbb)
+{
+	CBB ecpf;
+	size_t formats_len;
+	const uint8_t *formats;
+
+	tls1_get_formatlist(s, 0, &formats, &formats_len);
+
+	if (formats_len == 0) {
+		SSLerror(s, ERR_R_INTERNAL_ERROR);
+		return 0;
+	}
+
+	if (!CBB_add_u8_length_prefixed(cbb, &ecpf))
+		return 0;
+	if (!CBB_add_bytes(&ecpf, formats, formats_len))
+		return 0;
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+static int
+tls13_tlsext_ecpf_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS ecpf;
+
+	if (!CBS_get_u8_length_prefixed(cbs, &ecpf))
+		goto err;
+	if (CBS_len(&ecpf) == 0)
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	/* Must contain uncompressed (0) */
+	if (!CBS_contains_zero_byte(&ecpf)) {
+		SSLerror(s, SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
+		goto err;
+	}
+
+	if (!s->internal->hit) {
+		if (!CBS_stow(&ecpf, &(SSI(s)->tlsext_ecpointformatlist),
+		    &(SSI(s)->tlsext_ecpointformatlist_length))) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+	}
+
+	return 1;
+
+ err:
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+int
+tls13_tlsext_ecpf_clienthello_needs(SSL *s)
+{
+	return ssl_has_ecc_ciphers(s);
+}
+
+int
+tls13_tlsext_ecpf_clienthello_build(SSL *s, CBB *cbb)
+{
+	return tls13_tlsext_ecpf_build(s, cbb);
+}
+
+int
+tls13_tlsext_ecpf_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	return tls13_tlsext_ecpf_parse(s, cbs, alert);
+}
+
+int
+tls13_tlsext_ecpf_serverhello_needs(SSL *s)
+{
+	if (s->version == DTLS1_VERSION)
+		return 0;
+
+	return ssl_using_ecc_cipher(s);
+}
+
+int
+tls13_tlsext_ecpf_serverhello_build(SSL *s, CBB *cbb)
+{
+	return tls13_tlsext_ecpf_build(s, cbb);
+}
+
+int
+tls13_tlsext_ecpf_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	return tls13_tlsext_ecpf_parse(s, cbs, alert);
+}
+
+/*
+ * Renegotiation Indication - RFC 5746.
+ */
+int
+tls13_tlsext_ri_clienthello_needs(SSL *s)
+{
+	return (s->internal->renegotiate);
+}
+
+int
+tls13_tlsext_ri_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB reneg;
+
+	if (!CBB_add_u8_length_prefixed(cbb, &reneg))
+		return 0;
+	if (!CBB_add_bytes(&reneg, S3I(s)->previous_client_finished,
+	    S3I(s)->previous_client_finished_len))
+		return 0;
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_ri_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS reneg;
+
+	if (!CBS_get_u8_length_prefixed(cbs, &reneg))
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	if (!CBS_mem_equal(&reneg, S3I(s)->previous_client_finished,
+	    S3I(s)->previous_client_finished_len)) {
+		SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH);
+		*alert = SSL_AD_HANDSHAKE_FAILURE;
+		return 0;
+	}
+
+	S3I(s)->renegotiate_seen = 1;
+	S3I(s)->send_connection_binding = 1;
+
+	return 1;
+
+ err:
+	SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR);
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+int
+tls13_tlsext_ri_serverhello_needs(SSL *s)
+{
+	return (S3I(s)->send_connection_binding);
+}
+
+int
+tls13_tlsext_ri_serverhello_build(SSL *s, CBB *cbb)
+{
+	CBB reneg;
+
+	if (!CBB_add_u8_length_prefixed(cbb, &reneg))
+		return 0;
+	if (!CBB_add_bytes(&reneg, S3I(s)->previous_client_finished,
+	    S3I(s)->previous_client_finished_len))
+		return 0;
+	if (!CBB_add_bytes(&reneg, S3I(s)->previous_server_finished,
+	    S3I(s)->previous_server_finished_len))
+		return 0;
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_ri_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS reneg, prev_client, prev_server;
+
+	/*
+	 * Ensure that the previous client and server values are both not
+	 * present, or that they are both present.
+	 */
+	if ((S3I(s)->previous_client_finished_len == 0 &&
+	    S3I(s)->previous_server_finished_len != 0) ||
+	    (S3I(s)->previous_client_finished_len != 0 &&
+	    S3I(s)->previous_server_finished_len == 0)) {
+		*alert = TLS1_AD_INTERNAL_ERROR;
+		return 0;
+	}
+
+	if (!CBS_get_u8_length_prefixed(cbs, &reneg))
+		goto err;
+	if (!CBS_get_bytes(&reneg, &prev_client,
+	    S3I(s)->previous_client_finished_len))
+		goto err;
+	if (!CBS_get_bytes(&reneg, &prev_server,
+	    S3I(s)->previous_server_finished_len))
+		goto err;
+	if (CBS_len(&reneg) != 0)
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	if (!CBS_mem_equal(&prev_client, S3I(s)->previous_client_finished,
+	    S3I(s)->previous_client_finished_len)) {
+		SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH);
+		*alert = SSL_AD_HANDSHAKE_FAILURE;
+		return 0;
+	}
+	if (!CBS_mem_equal(&prev_server, S3I(s)->previous_server_finished,
+	    S3I(s)->previous_server_finished_len)) {
+		SSLerror(s, SSL_R_RENEGOTIATION_MISMATCH);
+		*alert = SSL_AD_HANDSHAKE_FAILURE;
+		return 0;
+	}
+
+	S3I(s)->renegotiate_seen = 1;
+	S3I(s)->send_connection_binding = 1;
+
+	return 1;
+
+ err:
+	SSLerror(s, SSL_R_RENEGOTIATION_ENCODING_ERR);
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+/*
+ * Signature Algorithms - RFC 5246 section 7.4.1.4.1.
+ */
+int
+tls13_tlsext_sigalgs_clienthello_needs(SSL *s)
+{
+	return (TLS1_get_client_version(s) >= TLS1_2_VERSION);
+}
+
+int
+tls13_tlsext_sigalgs_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB sigalgs;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &sigalgs))
+		return 0;
+
+	if (!ssl_sigalgs_build(&sigalgs, tls12_sigalgs, tls12_sigalgs_len))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_sigalgs_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS sigalgs;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &sigalgs))
+		return 0;
+
+	return tls1_process_sigalgs(s, &sigalgs);
+}
+
+int
+tls13_tlsext_sigalgs_serverhello_needs(SSL *s)
+{
+	return 0;
+}
+
+int
+tls13_tlsext_sigalgs_serverhello_build(SSL *s, CBB *cbb)
+{
+	return 0;
+}
+
+int
+tls13_tlsext_sigalgs_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	/* As per the RFC, servers must not send this extension. */
+	return 0;
+}
+
+/*
+ * Server Name Indication - RFC 6066, section 3.
+ */
+int
+tls13_tlsext_sni_clienthello_needs(SSL *s)
+{
+	return (s->tlsext_hostname != NULL);
+}
+
+int
+tls13_tlsext_sni_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB server_name_list, host_name;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &server_name_list))
+		return 0;
+	if (!CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name))
+		return 0;
+	if (!CBB_add_u16_length_prefixed(&server_name_list, &host_name))
+		return 0;
+	if (!CBB_add_bytes(&host_name, (const uint8_t *)s->tlsext_hostname,
+	    strlen(s->tlsext_hostname)))
+		return 0;
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_sni_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	CBS server_name_list, host_name;
+	uint8_t name_type;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &server_name_list))
+		goto err;
+
+	/*
+	 * RFC 6066 section 3 forbids multiple host names with the same type.
+	 * Additionally, only one type (host_name) is specified.
+	 */
+	if (!CBS_get_u8(&server_name_list, &name_type))
+		goto err;
+	if (name_type != TLSEXT_NAMETYPE_host_name)
+		goto err;
+
+	if (!CBS_get_u16_length_prefixed(&server_name_list, &host_name))
+		goto err;
+	if (CBS_len(&host_name) == 0 ||
+	    CBS_len(&host_name) > TLSEXT_MAXLEN_host_name ||
+	    CBS_contains_zero_byte(&host_name)) {
+		*alert = TLS1_AD_UNRECOGNIZED_NAME;
+		return 0;
+	}
+
+	if (s->internal->hit) {
+		if (s->session->tlsext_hostname == NULL) {
+			*alert = TLS1_AD_UNRECOGNIZED_NAME;
+			return 0;
+		}
+		if (!CBS_mem_equal(&host_name, s->session->tlsext_hostname,
+		    strlen(s->session->tlsext_hostname))) {
+			*alert = TLS1_AD_UNRECOGNIZED_NAME;
+			return 0;
+		}
+	} else {
+		if (s->session->tlsext_hostname != NULL)
+			goto err;
+		if (!CBS_strdup(&host_name, &s->session->tlsext_hostname)) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+	}
+
+	if (CBS_len(&server_name_list) != 0)
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	return 1;
+
+ err:
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+int
+tls13_tlsext_sni_serverhello_needs(SSL *s)
+{
+	return (s->session->tlsext_hostname != NULL);
+}
+
+int
+tls13_tlsext_sni_serverhello_build(SSL *s, CBB *cbb)
+{
+	return 1;
+}
+
+int
+tls13_tlsext_sni_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	if (s->tlsext_hostname == NULL || CBS_len(cbs) != 0) {
+		*alert = TLS1_AD_UNRECOGNIZED_NAME;
+		return 0;
+	}
+
+	if (s->internal->hit) {
+		if (s->session->tlsext_hostname == NULL) {
+			*alert = TLS1_AD_UNRECOGNIZED_NAME;
+			return 0;
+		}
+		if (strcmp(s->tlsext_hostname,
+		    s->session->tlsext_hostname) != 0) {
+			*alert = TLS1_AD_UNRECOGNIZED_NAME;
+			return 0;
+		}
+	} else {
+		if (s->session->tlsext_hostname != NULL) {
+			*alert = SSL_AD_DECODE_ERROR;
+			return 0;
+		}
+		if ((s->session->tlsext_hostname =
+		    strdup(s->tlsext_hostname)) == NULL) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+
+/*
+ *Certificate Status Request - RFC 6066 section 8.
+ */
+
+int
+tls13_tlsext_ocsp_clienthello_needs(SSL *s)
+{
+	return (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp &&
+	    s->version != DTLS1_VERSION);
+}
+
+int
+tls13_tlsext_ocsp_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB respid_list, respid, exts;
+	unsigned char *ext_data;
+	size_t ext_len;
+	int i;
+
+	if (!CBB_add_u8(cbb, TLSEXT_STATUSTYPE_ocsp))
+		return 0;
+	if (!CBB_add_u16_length_prefixed(cbb, &respid_list))
+		return 0;
+	for (i = 0; i < sk_OCSP_RESPID_num(s->internal->tlsext_ocsp_ids); i++) {
+		unsigned char *respid_data;
+		OCSP_RESPID *id;
+		size_t id_len;
+
+		if ((id = sk_OCSP_RESPID_value(s->internal->tlsext_ocsp_ids,
+		    i)) ==  NULL)
+			return 0;
+		if ((id_len = i2d_OCSP_RESPID(id, NULL)) == -1)
+			return 0;
+		if (!CBB_add_u16_length_prefixed(&respid_list, &respid))
+			return 0;
+		if (!CBB_add_space(&respid, &respid_data, id_len))
+			return 0;
+		if ((i2d_OCSP_RESPID(id, &respid_data)) != id_len)
+			return 0;
+	}
+	if (!CBB_add_u16_length_prefixed(cbb, &exts))
+		return 0;
+	if ((ext_len = i2d_X509_EXTENSIONS(s->internal->tlsext_ocsp_exts,
+	    NULL)) == -1)
+		return 0;
+	if (!CBB_add_space(&exts, &ext_data, ext_len))
+		return 0;
+	if ((i2d_X509_EXTENSIONS(s->internal->tlsext_ocsp_exts, &ext_data) !=
+	    ext_len))
+		return 0;
+	if (!CBB_flush(cbb))
+		return 0;
+	return 1;
+}
+
+int
+tls13_tlsext_ocsp_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	int failure = SSL_AD_DECODE_ERROR;
+	CBS respid_list, respid, exts;
+	const unsigned char *p;
+	uint8_t status_type;
+	int ret = 0;
+
+	if (!CBS_get_u8(cbs, &status_type))
+		goto err;
+	if (status_type != TLSEXT_STATUSTYPE_ocsp) {
+		/* ignore unknown status types */
+		s->tlsext_status_type = -1;
+
+		if (!CBS_skip(cbs, CBS_len(cbs))) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+		return 1;
+	}
+	s->tlsext_status_type = status_type;
+	if (!CBS_get_u16_length_prefixed(cbs, &respid_list))
+		goto err;
+
+	/* XXX */
+	sk_OCSP_RESPID_pop_free(s->internal->tlsext_ocsp_ids, OCSP_RESPID_free);
+	s->internal->tlsext_ocsp_ids = NULL;
+	if (CBS_len(&respid_list) > 0) {
+		s->internal->tlsext_ocsp_ids = sk_OCSP_RESPID_new_null();
+		if (s->internal->tlsext_ocsp_ids == NULL) {
+			failure = SSL_AD_INTERNAL_ERROR;
+			goto err;
+		}
+	}
+
+	while (CBS_len(&respid_list) > 0) {
+		OCSP_RESPID *id;
+
+		if (!CBS_get_u16_length_prefixed(&respid_list, &respid))
+			goto err;
+		p = CBS_data(&respid);
+		if ((id = d2i_OCSP_RESPID(NULL, &p, CBS_len(&respid))) == NULL)
+			goto err;
+		if (!sk_OCSP_RESPID_push(s->internal->tlsext_ocsp_ids, id)) {
+			failure = SSL_AD_INTERNAL_ERROR;
+			OCSP_RESPID_free(id);
+			goto err;
+		}
+	}
+
+	/* Read in request_extensions */
+	if (!CBS_get_u16_length_prefixed(cbs, &exts))
+		goto err;
+	if (CBS_len(&exts) > 0) {
+		sk_X509_EXTENSION_pop_free(s->internal->tlsext_ocsp_exts,
+		    X509_EXTENSION_free);
+		p = CBS_data(&exts);
+		if ((s->internal->tlsext_ocsp_exts = d2i_X509_EXTENSIONS(NULL,
+		    &p, CBS_len(&exts))) == NULL)
+			goto err;
+	}
+
+	/* should be nothing left */
+	if (CBS_len(cbs) > 0)
+		goto err;
+
+	ret = 1;
+ err:
+	if (ret == 0)
+		*alert = failure;
+	return ret;
+}
+
+int
+tls13_tlsext_ocsp_serverhello_needs(SSL *s)
+{
+	return s->internal->tlsext_status_expected;
+}
+
+int
+tls13_tlsext_ocsp_serverhello_build(SSL *s, CBB *cbb)
+{
+	return 1;
+}
+
+int
+tls13_tlsext_ocsp_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	if (s->tlsext_status_type == -1) {
+		*alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+		return 0;
+	}
+	/* Set flag to expect CertificateStatus message */
+	s->internal->tlsext_status_expected = 1;
+	return 1;
+}
+
+/*
+ * SessionTicket extension - RFC 5077 section 3.2
+ */
+int
+tls13_tlsext_sessionticket_clienthello_needs(SSL *s)
+{
+	/*
+	 * Send session ticket extension when enabled and not overridden.
+	 *
+	 * When renegotiating, send an empty session ticket to indicate support.
+	 */
+	if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0)
+		return 0;
+
+	if (s->internal->new_session)
+		return 1;
+
+	if (s->internal->tlsext_session_ticket != NULL &&
+	    s->internal->tlsext_session_ticket->data == NULL)
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_sessionticket_clienthello_build(SSL *s, CBB *cbb)
+{
+	/*
+	 * Signal that we support session tickets by sending an empty
+	 * extension when renegotiating or no session found.
+	 */
+	if (s->internal->new_session || s->session == NULL)
+		return 1;
+
+	if (s->session->tlsext_tick != NULL) {
+		/* Attempt to resume with an existing session ticket */
+		if (!CBB_add_bytes(cbb, s->session->tlsext_tick,
+		    s->session->tlsext_ticklen))
+			return 0;
+
+	} else if (s->internal->tlsext_session_ticket != NULL) {
+		/*
+		 * Attempt to resume with a custom provided session ticket set
+		 * by SSL_set_session_ticket_ext().
+		 */
+		if (s->internal->tlsext_session_ticket->length > 0) {
+			size_t ticklen = s->internal->tlsext_session_ticket->length;
+
+			if ((s->session->tlsext_tick = malloc(ticklen)) == NULL)
+				return 0;
+			memcpy(s->session->tlsext_tick,
+			    s->internal->tlsext_session_ticket->data,
+			    ticklen);
+			s->session->tlsext_ticklen = ticklen;
+
+			if (!CBB_add_bytes(cbb, s->session->tlsext_tick,
+			    s->session->tlsext_ticklen))
+				return 0;
+		}
+	}
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_sessionticket_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	if (s->internal->tls_session_ticket_ext_cb) {
+		if (!s->internal->tls_session_ticket_ext_cb(s, CBS_data(cbs),
+		    (int)CBS_len(cbs),
+		    s->internal->tls_session_ticket_ext_cb_arg)) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+	}
+
+	/* We need to signal that this was processed fully */
+	if (!CBS_skip(cbs, CBS_len(cbs))) {
+		*alert = TLS1_AD_INTERNAL_ERROR;
+		return 0;
+	}
+
+	return 1;
+}
+
+int
+tls13_tlsext_sessionticket_serverhello_needs(SSL *s)
+{
+	return (s->internal->tlsext_ticket_expected &&
+	    !(SSL_get_options(s) & SSL_OP_NO_TICKET));
+}
+
+int
+tls13_tlsext_sessionticket_serverhello_build(SSL *s, CBB *cbb)
+{
+	/* Empty ticket */
+
+	return 1;
+}
+
+int
+tls13_tlsext_sessionticket_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	if (s->internal->tls_session_ticket_ext_cb) {
+		if (!s->internal->tls_session_ticket_ext_cb(s, CBS_data(cbs),
+		    (int)CBS_len(cbs),
+		    s->internal->tls_session_ticket_ext_cb_arg)) {
+			*alert = TLS1_AD_INTERNAL_ERROR;
+			return 0;
+		}
+	}
+
+	if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0 || CBS_len(cbs) > 0) {
+		*alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+		return 0;
+	}
+
+	s->internal->tlsext_ticket_expected = 1;
+
+	return 1;
+}
+
+/*
+ * DTLS extension for SRTP key establishment - RFC 5764
+ */
+
+#ifndef OPENSSL_NO_SRTP
+
+int
+tls13_tlsext_srtp_clienthello_needs(SSL *s)
+{
+	return SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s) != NULL;
+}
+
+int
+tls13_tlsext_srtp_clienthello_build(SSL *s, CBB *cbb)
+{
+	CBB profiles, mki;
+	int ct, i;
+	STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = NULL;
+	SRTP_PROTECTION_PROFILE *prof;
+
+	if ((clnt = SSL_get_srtp_profiles(s)) == NULL) {
+		SSLerror(s, SSL_R_EMPTY_SRTP_PROTECTION_PROFILE_LIST);
+		return 0;
+	}
+
+	if ((ct = sk_SRTP_PROTECTION_PROFILE_num(clnt)) < 1) {
+		SSLerror(s, SSL_R_EMPTY_SRTP_PROTECTION_PROFILE_LIST);
+		return 0;
+	}
+
+	if (!CBB_add_u16_length_prefixed(cbb, &profiles))
+		return 0;
+
+	for (i = 0; i < ct; i++) {
+		if ((prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i)) == NULL)
+			return 0;
+		if (!CBB_add_u16(&profiles, prof->id))
+			return 0;
+	}
+
+	if (!CBB_add_u8_length_prefixed(cbb, &mki))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_srtp_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	SRTP_PROTECTION_PROFILE *cprof, *sprof;
+	STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = NULL, *srvr;
+	int i, j;
+	int ret;
+	uint16_t id;
+	CBS profiles, mki;
+
+	ret = 0;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &profiles))
+		goto err;
+	if (CBS_len(&profiles) == 0 || CBS_len(&profiles) % 2 != 0)
+		goto err;
+
+	if ((clnt = sk_SRTP_PROTECTION_PROFILE_new_null()) == NULL)
+		goto err;
+
+	while (CBS_len(&profiles) > 0) {
+		if (!CBS_get_u16(&profiles, &id))
+			goto err;
+
+		if (!srtp_find_profile_by_num(id, &cprof)) {
+			if (!sk_SRTP_PROTECTION_PROFILE_push(clnt, cprof))
+				goto err;
+		}
+	}
+
+	if (!CBS_get_u8_length_prefixed(cbs, &mki) || CBS_len(&mki) != 0) {
+		SSLerror(s, SSL_R_BAD_SRTP_MKI_VALUE);
+		*alert = SSL_AD_DECODE_ERROR;
+		goto done;
+	}
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	/*
+	 * Per RFC 5764 section 4.1.1
+	 *
+	 * Find the server preferred profile using the client's list.
+	 *
+	 * The server MUST send a profile if it sends the use_srtp
+	 * extension.  If one is not found, it should fall back to the
+	 * negotiated DTLS cipher suite or return a DTLS alert.
+	 */
+	if ((srvr = SSL_get_srtp_profiles(s)) == NULL)
+		goto err;
+	for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(srvr); i++) {
+		if ((sprof = sk_SRTP_PROTECTION_PROFILE_value(srvr, i))
+		    == NULL)
+			goto err;
+
+		for (j = 0; j < sk_SRTP_PROTECTION_PROFILE_num(clnt); j++) {
+			if ((cprof = sk_SRTP_PROTECTION_PROFILE_value(clnt, j))
+			    == NULL)
+				goto err;
+
+			if (cprof->id == sprof->id) {
+				s->internal->srtp_profile = sprof;
+				ret = 1;
+				goto done;
+			}
+		}
+	}
+
+	/* If we didn't find anything, fall back to the negotiated */
+	ret = 1;
+	goto done;
+
+ err:
+	SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+	*alert = SSL_AD_DECODE_ERROR;
+
+ done:
+	sk_SRTP_PROTECTION_PROFILE_free(clnt);
+	return ret;
+}
+
+int
+tls13_tlsext_srtp_serverhello_needs(SSL *s)
+{
+	return SSL_IS_DTLS(s) && SSL_get_selected_srtp_profile(s) != NULL;
+}
+
+int
+tls13_tlsext_srtp_serverhello_build(SSL *s, CBB *cbb)
+{
+	SRTP_PROTECTION_PROFILE *profile;
+	CBB srtp, mki;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &srtp))
+		return 0;
+
+	if ((profile = SSL_get_selected_srtp_profile(s)) == NULL)
+		return 0;
+
+	if (!CBB_add_u16(&srtp, profile->id))
+		return 0;
+
+	if (!CBB_add_u8_length_prefixed(cbb, &mki))
+		return 0;
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+int
+tls13_tlsext_srtp_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	STACK_OF(SRTP_PROTECTION_PROFILE) *clnt;
+	SRTP_PROTECTION_PROFILE *prof;
+	int i;
+	uint16_t id;
+	CBS profile_ids, mki;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &profile_ids)) {
+		SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+		goto err;
+	}
+
+	if (!CBS_get_u16(&profile_ids, &id) || CBS_len(&profile_ids) != 0) {
+		SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+		goto err;
+	}
+
+	if (!CBS_get_u8_length_prefixed(cbs, &mki) || CBS_len(&mki) != 0) {
+		SSLerror(s, SSL_R_BAD_SRTP_MKI_VALUE);
+		*alert = SSL_AD_ILLEGAL_PARAMETER;
+		return 0;
+	}
+
+	if ((clnt = SSL_get_srtp_profiles(s)) == NULL) {
+		SSLerror(s, SSL_R_NO_SRTP_PROFILES);
+		goto err;
+	}
+
+	for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(clnt); i++) {
+		if ((prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i))
+		    == NULL) {
+			SSLerror(s, SSL_R_NO_SRTP_PROFILES);
+			goto err;
+		}
+
+		if (prof->id == id) {
+			s->internal->srtp_profile = prof;
+			return 1;
+		}
+	}
+
+	SSLerror(s, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+ err:
+	*alert = SSL_AD_DECODE_ERROR;
+	return 0;
+}
+
+#endif /* OPENSSL_NO_SRTP */
+
+struct tls_extension_funcs {
+	int (*needs)(SSL *s);
+	int (*build)(SSL *s, CBB *cbb);
+	int (*parse)(SSL *s, CBS *cbs, int *alert);
+};
+
+struct tls_extension {
+	uint16_t type;
+	struct tls_extension_funcs clienthello;
+	struct tls_extension_funcs serverhello;
+};
+
+static struct tls_extension tls_extensions[] = {
+	{
+		.type = TLSEXT_TYPE_server_name,
+		.clienthello = {
+			.needs = tls13_tlsext_sni_clienthello_needs,
+			.build = tls13_tlsext_sni_clienthello_build,
+			.parse = tls13_tlsext_sni_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_sni_serverhello_needs,
+			.build = tls13_tlsext_sni_serverhello_build,
+			.parse = tls13_tlsext_sni_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_renegotiate,
+		.clienthello = {
+			.needs = tls13_tlsext_ri_clienthello_needs,
+			.build = tls13_tlsext_ri_clienthello_build,
+			.parse = tls13_tlsext_ri_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_ri_serverhello_needs,
+			.build = tls13_tlsext_ri_serverhello_build,
+			.parse = tls13_tlsext_ri_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_status_request,
+		.clienthello = {
+			.needs = tls13_tlsext_ocsp_clienthello_needs,
+			.build = tls13_tlsext_ocsp_clienthello_build,
+			.parse = tls13_tlsext_ocsp_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_ocsp_serverhello_needs,
+			.build = tls13_tlsext_ocsp_serverhello_build,
+			.parse = tls13_tlsext_ocsp_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_ec_point_formats,
+		.clienthello = {
+			.needs = tls13_tlsext_ecpf_clienthello_needs,
+			.build = tls13_tlsext_ecpf_clienthello_build,
+			.parse = tls13_tlsext_ecpf_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_ecpf_serverhello_needs,
+			.build = tls13_tlsext_ecpf_serverhello_build,
+			.parse = tls13_tlsext_ecpf_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_supported_groups,
+		.clienthello = {
+			.needs = tls13_tlsext_supportedgroups_clienthello_needs,
+			.build = tls13_tlsext_supportedgroups_clienthello_build,
+			.parse = tls13_tlsext_supportedgroups_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_supportedgroups_serverhello_needs,
+			.build = tls13_tlsext_supportedgroups_serverhello_build,
+			.parse = tls13_tlsext_supportedgroups_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_session_ticket,
+		.clienthello = {
+			.needs = tls13_tlsext_sessionticket_clienthello_needs,
+			.build = tls13_tlsext_sessionticket_clienthello_build,
+			.parse = tls13_tlsext_sessionticket_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_sessionticket_serverhello_needs,
+			.build = tls13_tlsext_sessionticket_serverhello_build,
+			.parse = tls13_tlsext_sessionticket_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_signature_algorithms,
+		.clienthello = {
+			.needs = tls13_tlsext_sigalgs_clienthello_needs,
+			.build = tls13_tlsext_sigalgs_clienthello_build,
+			.parse = tls13_tlsext_sigalgs_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_sigalgs_serverhello_needs,
+			.build = tls13_tlsext_sigalgs_serverhello_build,
+			.parse = tls13_tlsext_sigalgs_serverhello_parse,
+		},
+	},
+	{
+		.type = TLSEXT_TYPE_application_layer_protocol_negotiation,
+		.clienthello = {
+			.needs = tls13_tlsext_alpn_clienthello_needs,
+			.build = tls13_tlsext_alpn_clienthello_build,
+			.parse = tls13_tlsext_alpn_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_alpn_serverhello_needs,
+			.build = tls13_tlsext_alpn_serverhello_build,
+			.parse = tls13_tlsext_alpn_serverhello_parse,
+		},
+	},
+#ifndef OPENSSL_NO_SRTP
+	{
+		.type = TLSEXT_TYPE_use_srtp,
+		.clienthello = {
+			.needs = tls13_tlsext_srtp_clienthello_needs,
+			.build = tls13_tlsext_srtp_clienthello_build,
+			.parse = tls13_tlsext_srtp_clienthello_parse,
+		},
+		.serverhello = {
+			.needs = tls13_tlsext_srtp_serverhello_needs,
+			.build = tls13_tlsext_srtp_serverhello_build,
+			.parse = tls13_tlsext_srtp_serverhello_parse,
+		},
+	}
+#endif /* OPENSSL_NO_SRTP */
+};
+
+#define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions))
+
+/* Ensure that extensions fit in a uint32_t bitmask. */
+CTASSERT(N_TLS_EXTENSIONS <= (sizeof(uint32_t) * 8));
+
+static struct tls_extension *
+tls_extension_find(uint16_t type, size_t *tls_extensions_idx)
+{
+	size_t i;
+
+	for (i = 0; i < N_TLS_EXTENSIONS; i++) {
+		if (tls_extensions[i].type == type) {
+			*tls_extensions_idx = i;
+			return &tls_extensions[i];
+		}
+	}
+
+	return NULL;
+}
+
+static struct tls_extension_funcs *
+tls13_tlsext_funcs(struct tls_extension *tlsext, int is_serverhello)
+{
+	if (is_serverhello)
+		return &tlsext->serverhello;
+
+	return &tlsext->clienthello;	
+}
+
+static int
+tls13_tlsext_build(SSL *s, CBB *cbb, int is_serverhello)
+{
+	struct tls_extension_funcs *ext;
+	struct tls_extension *tlsext;
+	CBB extensions, extension_data;
+	int extensions_present = 0;
+	size_t i;
+
+	if (!CBB_add_u16_length_prefixed(cbb, &extensions))
+		return 0;
+
+	for (i = 0; i < N_TLS_EXTENSIONS; i++) {
+		tlsext = &tls_extensions[i];
+		ext = tls13_tlsext_funcs(tlsext, is_serverhello);
+
+		if (!ext->needs(s))
+			continue;
+
+		if (!CBB_add_u16(&extensions, tlsext->type))
+			return 0;
+		if (!CBB_add_u16_length_prefixed(&extensions, &extension_data))
+			return 0;
+
+		if (!ext->build(s, &extension_data))
+			return 0;
+
+		extensions_present = 1;
+	}
+
+	if (!extensions_present)
+		CBB_discard_child(cbb);
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	return 1;
+}
+
+static int
+tls13_tlsext_parse(SSL *s, CBS *cbs, int *alert, int is_serverhello)
+{
+	struct tls_extension_funcs *ext;
+	struct tls_extension *tlsext;
+	CBS extensions, extension_data;
+	uint32_t extensions_seen = 0;
+	uint16_t type;
+	size_t idx;
+
+	/* An empty extensions block is valid. */
+	if (CBS_len(cbs) == 0)
+		return 1;
+
+	*alert = SSL_AD_DECODE_ERROR;
+
+	if (!CBS_get_u16_length_prefixed(cbs, &extensions))
+		return 0;
+
+	while (CBS_len(&extensions) > 0) {
+		if (!CBS_get_u16(&extensions, &type))
+			return 0;
+		if (!CBS_get_u16_length_prefixed(&extensions, &extension_data))
+			return 0;
+
+		if (s->internal->tlsext_debug_cb != NULL)
+			s->internal->tlsext_debug_cb(s, is_serverhello, type,
+			    (unsigned char *)CBS_data(&extension_data),
+			    CBS_len(&extension_data),
+			    s->internal->tlsext_debug_arg);
+
+		/* Unknown extensions are ignored. */
+		if ((tlsext = tls_extension_find(type, &idx)) == NULL)
+			continue;
+
+		/* Check for duplicate known extensions. */
+		if ((extensions_seen & (1 << idx)) != 0)
+			return 0;
+		extensions_seen |= (1 << idx);
+
+		ext = tls13_tlsext_funcs(tlsext, is_serverhello);
+		if (!ext->parse(s, &extension_data, alert))
+			return 0;
+
+		if (CBS_len(&extension_data) != 0)
+			return 0;
+	}
+
+	return 1;
+}
+
+static void
+tls13_tlsext_clienthello_reset_state(SSL *s)
+{
+	s->internal->servername_done = 0;
+	s->tlsext_status_type = -1;
+	S3I(s)->renegotiate_seen = 0;
+	free(S3I(s)->alpn_selected);
+	S3I(s)->alpn_selected = NULL;
+	s->internal->srtp_profile = NULL;
+}
+
+int
+tls13_tlsext_clienthello_build(SSL *s, CBB *cbb)
+{
+	return tls13_tlsext_build(s, cbb, 0);
+}
+
+int
+tls13_tlsext_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	/* XXX - this possibly should be done by the caller... */
+	tls13_tlsext_clienthello_reset_state(s);
+
+	return tls13_tlsext_parse(s, cbs, alert, 0);
+}
+
+static void
+tls13_tlsext_serverhello_reset_state(SSL *s)
+{
+	S3I(s)->renegotiate_seen = 0;   
+	free(S3I(s)->alpn_selected);
+	S3I(s)->alpn_selected = NULL;
+}
+
+int
+tls13_tlsext_serverhello_build(SSL *s, CBB *cbb)
+{
+	return tls13_tlsext_build(s, cbb, 1);
+}
+
+int
+tls13_tlsext_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+	/* XXX - this possibly should be done by the caller... */
+	tls13_tlsext_serverhello_reset_state(s);
+
+	return tls13_tlsext_parse(s, cbs, alert, 1);
+}
diff --git a/lib/libssl/tls13_tlsext.h b/lib/libssl/tls13_tlsext.h
new file mode 100644
index 00000000000..f7b45629c8c
--- /dev/null
+++ b/lib/libssl/tls13_tlsext.h
@@ -0,0 +1,97 @@
+/* $OpenBSD: tls13_tlsext.h,v 1.1 2019/01/17 00:56:57 beck Exp $ */
+/*
+ * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
+ * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef HEADER_SSL_TLS13_TLSEXT_H
+#define HEADER_SSL_TLS13_TLSEXT_H
+
+__BEGIN_HIDDEN_DECLS
+
+int tls13_tlsext_alpn_clienthello_needs(SSL *s);
+int tls13_tlsext_alpn_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_alpn_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_alpn_serverhello_needs(SSL *s);
+int tls13_tlsext_alpn_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_alpn_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_ri_clienthello_needs(SSL *s);
+int tls13_tlsext_ri_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ri_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_ri_serverhello_needs(SSL *s);
+int tls13_tlsext_ri_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ri_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_sigalgs_clienthello_needs(SSL *s);
+int tls13_tlsext_sigalgs_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sigalgs_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_sigalgs_serverhello_needs(SSL *s);
+int tls13_tlsext_sigalgs_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sigalgs_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_sni_clienthello_needs(SSL *s);
+int tls13_tlsext_sni_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sni_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_sni_serverhello_needs(SSL *s);
+int tls13_tlsext_sni_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sni_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_supportedgroups_clienthello_needs(SSL *s);
+int tls13_tlsext_supportedgroups_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_supportedgroups_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_supportedgroups_serverhello_needs(SSL *s);
+int tls13_tlsext_supportedgroups_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_supportedgroups_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_ecpf_clienthello_needs(SSL *s);
+int tls13_tlsext_ecpf_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ecpf_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_ecpf_serverhello_needs(SSL *s);
+int tls13_tlsext_ecpf_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ecpf_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_ocsp_clienthello_needs(SSL *s);
+int tls13_tlsext_ocsp_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ocsp_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_ocsp_serverhello_needs(SSL *s);
+int tls13_tlsext_ocsp_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_ocsp_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_sessionticket_clienthello_needs(SSL *s);
+int tls13_tlsext_sessionticket_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sessionticket_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_sessionticket_serverhello_needs(SSL *s);
+int tls13_tlsext_sessionticket_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_sessionticket_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+#ifndef OPENSSL_NO_SRTP
+int tls13_tlsext_srtp_clienthello_needs(SSL *s);
+int tls13_tlsext_srtp_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_srtp_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tls13_tlsext_srtp_serverhello_needs(SSL *s);
+int tls13_tlsext_srtp_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_srtp_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+#endif
+
+int tls13_tlsext_clienthello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+
+int tls13_tlsext_serverhello_build(SSL *s, CBB *cbb);
+int tls13_tlsext_serverhello_parse(SSL *s, CBS *cbs, int *alert);
+
+__END_HIDDEN_DECLS
+
+#endif