prf: add function to retrieve early keying material

This adds a new function gnutls_prf_early, which shall be called in a
handshake hook waiting for GNUTLS_HANDSHAKE_CLIENT_HELLO.  The test
needs to be run in a datefudge wrapper as the early secrets depend on
the current time (through PSK).

Signed-off-by: Daiki Ueno <dueno@redhat.com>

12 files changed, 599 insertions, 29 deletions

diff --git a/.gitignore b/.gitignore
index 6716e4c728..0e33b02d40 100644
--- a/.gitignore
+++ b/.gitignore
@@ -830,6 +830,7 @@ tests/tls13/post-handshake-with-cert-ticket
 tests/tls13/post-handshake-with-psk
 tests/tls13/post-handshake-without-cert
 tests/tls13/prf
+tests/tls13/prf-early
 tests/tls13/psk-dumbfw
 tests/tls13/psk-ext
 tests/tls13/supported_versions
diff --git a/NEWS b/NEWS
index 0be3696576..0ada7c1a31 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,10 @@ See the end for copying conditions.
 
 ** libgnutls: Added support for AES-XTS cipher (#354)
 
+** libgnutls: Added new function to retrieve early keying material (#329)
+
 ** API and ABI modifications:
-No changes since last version.
+gnutls_prf_early: Added
 
 
 * Version 3.6.7 (released 2019-03-27)
diff --git a/devel/libgnutls-latest-x86_64.abi b/devel/libgnutls-latest-x86_64.abi
index 9e23e0221c..c4659d954b 100644
--- a/devel/libgnutls-latest-x86_64.abi
+++ b/devel/libgnutls-latest-x86_64.abi
@@ -587,6 +587,7 @@
     <elf-symbol name='gnutls_pkcs_schema_get_name' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_pkcs_schema_get_oid' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='gnutls_prf_early' version='GNUTLS_3_6_6' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf_raw' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf_rfc5705' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_priority_certificate_type_list2' version='GNUTLS_3_6_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
diff --git a/devel/symbols.last b/devel/symbols.last
index e5f0e01c69..d9dedea09c 100644
--- a/devel/symbols.last
+++ b/devel/symbols.last
@@ -553,6 +553,7 @@ gnutls_pkcs8_info@GNUTLS_3_4
 gnutls_pkcs_schema_get_name@GNUTLS_3_4
 gnutls_pkcs_schema_get_oid@GNUTLS_3_4
 gnutls_prf@GNUTLS_3_4
+gnutls_prf_early@GNUTLS_3_6_6
 gnutls_prf_raw@GNUTLS_3_4
 gnutls_prf_rfc5705@GNUTLS_3_4
 gnutls_priority_certificate_type_list2@GNUTLS_3_6_4
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 19982f5ad8..c60d0e46dd 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1547,6 +1547,8 @@ FUNCS += functions/gnutls_pk_to_sign
 FUNCS += functions/gnutls_pk_to_sign.short
 FUNCS += functions/gnutls_prf
 FUNCS += functions/gnutls_prf.short
+FUNCS += functions/gnutls_prf_early
+FUNCS += functions/gnutls_prf_early.short
 FUNCS += functions/gnutls_prf_raw
 FUNCS += functions/gnutls_prf_raw.short
 FUNCS += functions/gnutls_prf_rfc5705
diff --git a/doc/manpages/Makefile.am b/doc/manpages/Makefile.am
index 0aab479df2..bbf4220c09 100644
--- a/doc/manpages/Makefile.am
+++ b/doc/manpages/Makefile.am
@@ -575,6 +575,7 @@ APIMANS += gnutls_pk_get_oid.3
 APIMANS += gnutls_pk_list.3
 APIMANS += gnutls_pk_to_sign.3
 APIMANS += gnutls_prf.3
+APIMANS += gnutls_prf_early.3
 APIMANS += gnutls_prf_raw.3
 APIMANS += gnutls_prf_rfc5705.3
 APIMANS += gnutls_priority_certificate_type_list.3
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index 7fc96aaea1..0801203128 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1471,6 +1471,10 @@ int gnutls_prf_rfc5705(gnutls_session_t session,
 	       size_t label_size, const char *label,
 	       size_t context_size, const char *context,
 	       size_t outsize, char *out);
+int gnutls_prf_early(gnutls_session_t session,
+		     size_t label_size, const char *label,
+		     size_t context_size, const char *context,
+		     size_t outsize, char *out);
 
 int gnutls_prf_raw(gnutls_session_t session,
 		   size_t label_size, const char *label,
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index 19c9f535f9..d10e22b20e 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1271,6 +1271,7 @@ GNUTLS_3_6_6
 	gnutls_certificate_set_rawpk_key_file;
 	gnutls_pcert_import_rawpk;
 	gnutls_pcert_import_rawpk_raw;
+	gnutls_prf_early;
 } GNUTLS_3_6_5;
 
 GNUTLS_FIPS140_3_4 {
diff --git a/lib/prf.c b/lib/prf.c
index 19e25cfa8d..6708b00db2 100644
--- a/lib/prf.c
+++ b/lib/prf.c
@@ -89,6 +89,36 @@ gnutls_prf_raw(gnutls_session_t session,
 	return ret;
 }
 
+static int
+_tls13_derive_exporter(const mac_entry_st *prf,
+		       gnutls_session_t session,
+		       size_t label_size, const char *label,
+		       size_t context_size, const char *context,
+		       size_t outsize, char *out,
+		       bool early)
+{
+	uint8_t secret[MAX_HASH_SIZE];
+	uint8_t digest[MAX_HASH_SIZE];
+	unsigned digest_size = prf->output_size;
+	int ret;
+
+	ret = _tls13_derive_secret2(prf, label, label_size, NULL, 0,
+				    session->key.proto.tls13.ap_expkey,
+				    secret);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	ret = gnutls_hash_fast((gnutls_digest_algorithm_t)prf->id,
+			       context, context_size, digest);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	return _tls13_expand_secret2(prf,
+				     EXPORTER_LABEL, sizeof(EXPORTER_LABEL)-1,
+				     digest, digest_size,
+				     secret, outsize, out);
+}
+
 /**
  * gnutls_prf_rfc5705:
  * @session: is a #gnutls_session_t type.
@@ -99,8 +129,8 @@ gnutls_prf_raw(gnutls_session_t session,
  * @outsize: size of pre-allocated output buffer to hold the output.
  * @out: pre-allocated buffer to hold the generated data.
  *
- * Exports keyring material from TLS/DTLS session to an application,
- * as specified in RFC5705.
+ * Exports keying material from TLS/DTLS session to an application, as
+ * specified in RFC5705.
  *
  * In the TLS versions prior to 1.3, it applies the TLS
  * Pseudo-Random-Function (PRF) on the master secret and the provided
@@ -136,30 +166,12 @@ gnutls_prf_rfc5705(gnutls_session_t session,
 	int ret;
 
 	if (vers && vers->tls13_sem) {
-		uint8_t secret[MAX_HASH_SIZE];
-		uint8_t digest[MAX_HASH_SIZE];
-		unsigned digest_size = session->security_parameters.prf->output_size;
-
-		/* exporter_master_secret might not be set, when
-		 * handshake is in progress */
-		if (session->internals.handshake_in_progress) {
-			gnutls_assert();
-			return GNUTLS_E_INVALID_REQUEST;
-		}
-
-		ret = _tls13_derive_secret(session, label, label_size, NULL, 0,
-					   session->key.proto.tls13.ap_expkey, secret);
-		if (ret < 0)
-			return gnutls_assert_val(ret);
-
-		ret = gnutls_hash_fast((gnutls_digest_algorithm_t)session->security_parameters.prf->id,
-				       context, context_size, digest);
-		if (ret < 0)
-			return gnutls_assert_val(ret);
-
-		ret = _tls13_expand_secret(session, EXPORTER_LABEL, sizeof(EXPORTER_LABEL)-1,
-					   digest, digest_size,
-					   secret, outsize, out);
+		ret = _tls13_derive_exporter(session->security_parameters.prf,
+					     session,
+					     label_size, label,
+					     context_size, context,
+					     outsize, out,
+					     0);
 	} else {
 		char *pctx = NULL;
 
@@ -190,6 +202,58 @@ gnutls_prf_rfc5705(gnutls_session_t session,
 }
 
 /**
+ * gnutls_prf_early:
+ * @session: is a #gnutls_session_t type.
+ * @label_size: length of the @label variable.
+ * @label: label used in PRF computation, typically a short string.
+ * @context_size: length of the @extra variable.
+ * @context: optional extra data to seed the PRF with.
+ * @outsize: size of pre-allocated output buffer to hold the output.
+ * @out: pre-allocated buffer to hold the generated data.
+ *
+ * This function is similar to gnutls_prf_rfc5705(), but only works in
+ * TLS 1.3 or later to export early keying material.
+ *
+ * Note that the keying material is only available after the
+ * ClientHello message is processed and before the application traffic
+ * keys are established.  Therefore this function shall be called in a
+ * handshake hook function for %GNUTLS_HANDSHAKE_CLIENT_HELLO.
+ *
+ * The @label variable usually contains a string denoting the purpose
+ * for the generated data.
+ *
+ * The @context variable can be used to add more data to the seed, after
+ * the random variables.  It can be used to make sure the
+ * generated output is strongly connected to some additional data
+ * (e.g., a string used in user authentication).
+ *
+ * The output is placed in @out, which must be pre-allocated.
+ *
+ * Note that, to provide the RFC5705 context, the @context variable
+ * must be non-null.
+ *
+ * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
+ *
+ * Since: 3.6.6
+ **/
+int
+gnutls_prf_early(gnutls_session_t session,
+		 size_t label_size, const char *label,
+		 size_t context_size, const char *context,
+		 size_t outsize, char *out)
+{
+	if (session->internals.initial_negotiation_completed ||
+	    session->key.binders[0].prf == NULL)
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+
+	return _tls13_derive_exporter(session->key.binders[0].prf, session,
+				      label_size, label,
+				      context_size, context,
+				      outsize, out,
+				      1);
+}
+
+/**
  * gnutls_prf:
  * @session: is a #gnutls_session_t type.
  * @label_size: length of the @label variable.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 96e10bfc5b..3917967988 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -104,7 +104,7 @@ noinst_LTLIBRARIES = libutils.la
 libutils_la_SOURCES = utils.h utils.c seccomp.c utils-adv.c
 libutils_la_LIBADD = ../lib/libgnutls.la
 
-indirect_tests =
+indirect_tests = tls13/prf-early
 ctests = tls13/supported_versions tls13/tls12-no-tls13-exts \
 	tls13/post-handshake-with-cert tls13/post-handshake-without-cert \
 	tls13/cookie tls13/key_share tls13/prf tls13/post-handshake-with-cert-ticket \
@@ -458,7 +458,7 @@ tls13_post_handshake_with_cert_pkcs11_LDADD = $(LDADD) $(LIBDL)
 endif
 endif
 
-dist_check_SCRIPTS = rfc2253-escape-test rsa-md5-collision/rsa-md5-collision.sh systemkey.sh
+dist_check_SCRIPTS = rfc2253-escape-test rsa-md5-collision/rsa-md5-collision.sh systemkey.sh tls13/prf-early.sh
 
 if !WINDOWS
 
diff --git a/tests/tls13/prf-early.c b/tests/tls13/prf-early.c
new file mode 100644
index 0000000000..758f78efe7
--- /dev/null
+++ b/tests/tls13/prf-early.c
@@ -0,0 +1,464 @@
+/*
+ * Copyright (C) 2015-2019 Red Hat, Inc.
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#if !defined(__linux__) || !defined(__GNUC__)
+
+int main(int argc, char **argv)
+{
+	exit(77);
+}
+
+#else
+
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+
+#include "cert-common.h"
+#include "utils.h"
+#include "virt-time.h"
+
+static void terminate(void);
+
+#define SESSIONS 2
+#define MAX_BUF 5*1024
+#define MSG "Hello TLS"
+
+/* This program tests whether the gnutls_prf() works as
+ * expected.
+ */
+
+static void server_log_func(int level, const char *str)
+{
+	fprintf(stderr, "server|<%d>| %s", level, str);
+}
+
+static void client_log_func(int level, const char *str)
+{
+	fprintf(stderr, "client|<%d>| %s", level, str);
+}
+
+/* These are global */
+static pid_t child;
+
+static const
+gnutls_datum_t hrnd = {(void*)"\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 32};
+static const
+gnutls_datum_t hsrnd = {(void*)"\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 32};
+
+static int gnutls_rnd_works;
+
+int __attribute__ ((visibility ("protected")))
+gnutls_rnd(gnutls_rnd_level_t level, void *data, size_t len)
+{
+	gnutls_rnd_works = 1;
+
+	memset(data, 0xff, len);
+
+	/* Flip the first byte to avoid infinite loop in the RSA
+	 * blinding code of Nettle */
+	if (len > 0)
+		memset(data, 0x0, 1);
+	return 0;
+}
+
+static gnutls_datum_t session_ticket_key = { NULL, 0 };
+
+static void dump(const char *name, const uint8_t *data, unsigned data_size)
+{
+	unsigned i;
+
+	fprintf(stderr, "%s", name);
+	for (i=0;i<data_size;i++)
+		fprintf(stderr, "\\x%.2x", (unsigned)data[i]);
+	fprintf(stderr, "\n");
+}
+
+#define TRY(label_size, label, extra_size, extra, size, exp) \
+	{ \
+	ret = gnutls_prf_early(session, label_size, label, extra_size, extra, size, \
+			 (void*)key_material); \
+	if (ret < 0) { \
+		fprintf(stderr, "gnutls_prf_early: error in %d\n", __LINE__); \
+		gnutls_perror(ret); \
+		exit(1); \
+	} \
+	if (memcmp(key_material, exp, size) != 0) { \
+		fprintf(stderr, "gnutls_prf_early: output doesn't match for '%s'\n", label); \
+		dump("got ", key_material, size); \
+		dump("expected ", exp, size); \
+		exit(1); \
+	} \
+	}
+
+#define KEY_EXP_VALUE "\xc0\x1e\xc2\xa4\xb7\xb4\x04\xaa\x91\x5d\xaf\xe8\xf7\x4d\x19\xdf\xd0\xe6\x08\xd6\xb4\x3b\xcf\xca\xc9\x32\x75\x3b\xe3\x11\x19\xb1\xac\x68"
+#define HELLO_VALUE "\x77\xdb\x10\x0b\xe8\xd0\xb9\x38\xbc\x49\xe6\xbe\xf2\x47\x2a\xcc\x6b\xea\xce\x85\x04\xd3\x9e\xd8\x06\x16\xad\xff\xcd\xbf\x4b"
+#define CONTEXT_VALUE "\xf2\x17\x9f\xf2\x66\x56\x87\x66\xf9\x5c\x8a\xd7\x4e\x1d\x46\xee\x0e\x44\x41\x4c\xcd\xac\xcb\xc0\x31\x41\x2a\xb6\xd7\x01\x62"
+#define NULL_CONTEXT_VALUE "\xcd\x79\x07\x93\xeb\x96\x07\x3e\xec\x78\x90\x89\xf7\x16\x42\x6d\x27\x87\x56\x7c\x7b\x60\x2b\x20\x44\xd1\xea\x0c\x89\xfb\x8b"
+
+static int handshake_callback_called;
+
+static int handshake_callback(gnutls_session_t session, unsigned int htype,
+			      unsigned post, unsigned int incoming, const gnutls_datum_t *msg)
+{
+	unsigned char key_material[512];
+	int ret;
+
+	assert(post == GNUTLS_HOOK_POST);
+
+	handshake_callback_called++;
+
+	TRY(13, "key expansion", 0, NULL, 34, (uint8_t*)KEY_EXP_VALUE);
+	TRY(6, "hello", 0, NULL, 31, (uint8_t*)HELLO_VALUE);
+	TRY(7, "context", 5, "abcd\xfa", 31, (uint8_t*)CONTEXT_VALUE);
+	TRY(12, "null-context", 0, "", 31, (uint8_t*)NULL_CONTEXT_VALUE);
+
+	return 0;
+}
+
+static void client(int sds[])
+{
+	gnutls_session_t session;
+	int ret, ii;
+	gnutls_certificate_credentials_t clientx509cred;
+	const char *err;
+	int t;
+	gnutls_datum_t session_data = {NULL, 0};
+	char buffer[MAX_BUF + 1];
+
+	global_init();
+
+	virt_time_init();
+
+	if (debug) {
+		gnutls_global_set_log_function(client_log_func);
+		gnutls_global_set_log_level(4711);
+	}
+
+	gnutls_certificate_allocate_credentials(&clientx509cred);
+
+	for (t = 0; t < SESSIONS; t++) {
+		/* Initialize TLS session
+		 */
+		gnutls_init(&session, GNUTLS_CLIENT);
+
+		/* Use default priorities */
+		ret = gnutls_priority_set_direct(session,
+						 "NONE:+VERS-TLS1.3:+AES-256-GCM:+AEAD:+SIGN-RSA-PSS-RSAE-SHA384:+GROUP-SECP256R1",
+						 &err);
+		if (ret < 0) {
+			fail("client: priority set failed (%s): %s\n",
+			     gnutls_strerror(ret), err);
+			exit(1);
+		}
+
+		ret = gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
+					     clientx509cred);
+		if (ret < 0)
+			exit(1);
+
+		gnutls_handshake_set_random(session, &hrnd);
+		gnutls_transport_set_int(session, sds[t]);
+
+		if (t > 0) {
+			gnutls_session_set_data(session, session_data.data,
+						session_data.size);
+			gnutls_handshake_set_hook_function(session, GNUTLS_HANDSHAKE_CLIENT_HELLO,
+							   GNUTLS_HOOK_POST,
+							   handshake_callback);
+		}
+
+		/* Perform the TLS handshake
+		 */
+		do {
+			ret = gnutls_handshake(session);
+		}
+		while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+
+		if (ret < 0) {
+			fail("client: Handshake failed: %s\n", strerror(ret));
+			exit(1);
+		} else {
+			if (debug)
+				success("client: Handshake was completed\n");
+		}
+
+		if (debug)
+			success("client: TLS version is: %s\n",
+				gnutls_protocol_get_name
+				(gnutls_protocol_get_version(session)));
+
+		ret = gnutls_cipher_get(session);
+		if (ret != GNUTLS_CIPHER_AES_256_GCM) {
+			fprintf(stderr, "negotiated unexpected cipher: %s\n", gnutls_cipher_get_name(ret));
+			exit(1);
+		}
+
+		ret = gnutls_mac_get(session);
+		if (ret != GNUTLS_MAC_AEAD) {
+			fprintf(stderr, "negotiated unexpected mac: %s\n", gnutls_mac_get_name(ret));
+			exit(1);
+		}
+
+		if (t == 0) {
+			/* get the session data size */
+			ret =
+			    gnutls_session_get_data2(session,
+						     &session_data);
+			if (ret < 0)
+				fail("Getting resume data failed\n");
+
+			if (handshake_callback_called != 0)
+				fail("client: handshake callback is called\n");
+		} else {
+			if (handshake_callback_called != t)
+				fail("client: handshake callback is not called\n");
+		}
+
+		gnutls_record_send(session, MSG, strlen(MSG));
+
+		do {
+			ret = gnutls_record_recv(session, buffer, MAX_BUF);
+		} while (ret == GNUTLS_E_AGAIN);
+		if (ret == 0) {
+			if (debug)
+				success
+				    ("client: Peer has closed the TLS connection\n");
+		} else if (ret < 0) {
+			fail("client: Error: %s\n", gnutls_strerror(ret));
+		}
+
+		if (debug) {
+			printf("- Received %d bytes: ", ret);
+			for (ii = 0; ii < ret; ii++) {
+				fputc(buffer[ii], stdout);
+			}
+			fputs("\n", stdout);
+		}
+
+		gnutls_bye(session, GNUTLS_SHUT_WR);
+
+		close(sds[t]);
+
+		gnutls_deinit(session);
+	}
+
+	gnutls_free(session_data.data);
+	gnutls_certificate_free_credentials(clientx509cred);
+
+	gnutls_global_deinit();
+}
+
+static void terminate(void)
+{
+	int status = 0;
+
+	kill(child, SIGTERM);
+	wait(&status);
+	exit(1);
+}
+
+static void server(int sds[])
+{
+	int ret;
+	gnutls_session_t session;
+	gnutls_certificate_credentials_t serverx509cred;
+	int t;
+	char buffer[MAX_BUF + 1];
+
+	/* this must be called once in the program
+	 */
+	global_init();
+
+	virt_time_init();
+
+	if (debug) {
+		gnutls_global_set_log_function(server_log_func);
+		gnutls_global_set_log_level(4711);
+	}
+
+	gnutls_certificate_allocate_credentials(&serverx509cred);
+
+	gnutls_session_ticket_key_generate(&session_ticket_key);
+
+	for (t = 0; t < SESSIONS; t++) {
+		gnutls_init(&session, GNUTLS_SERVER);
+
+		gnutls_session_ticket_enable_server(session,
+						    &session_ticket_key);
+
+		/* avoid calling all the priority functions, since the defaults
+		 * are adequate.
+		 */
+		ret = gnutls_priority_set_direct(session,
+						 "NORMAL:-VERS-ALL:+VERS-TLS1.3:-KX-ALL:-SIGN-ALL:+SIGN-RSA-PSS-RSAE-SHA384:-GROUP-ALL:+GROUP-SECP256R1", NULL);
+		if (ret < 0) {
+			fail("server: priority set failed (%s)\n\n",
+			     gnutls_strerror(ret));
+			terminate();
+		}
+
+		gnutls_certificate_set_x509_key_mem(serverx509cred,
+						    &server_cert, &server_key,
+						    GNUTLS_X509_FMT_PEM);
+		gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
+				       serverx509cred);
+
+		gnutls_handshake_set_random(session, &hsrnd);
+		gnutls_transport_set_int(session, sds[t]);
+
+		if (t > 0) {
+			if (!gnutls_rnd_works) {
+				fprintf(stderr, "gnutls_rnd() could not be overridden, skipping prf checks see #584\n");
+				exit(77);
+			} else {
+				gnutls_handshake_set_hook_function(session, GNUTLS_HANDSHAKE_CLIENT_HELLO,
+								   GNUTLS_HOOK_POST,
+								   handshake_callback);
+			}
+		}
+
+		do {
+			ret = gnutls_handshake(session);
+		}
+		while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+		if (ret < 0) {
+			close(sds[t]);
+			gnutls_deinit(session);
+			fail("server: Handshake has failed (%s)\n\n",
+			     gnutls_strerror(ret));
+			terminate();
+		}
+		if (debug)
+			success("server: Handshake was completed\n");
+
+		if (debug)
+			success("server: TLS version is: %s\n",
+				gnutls_protocol_get_name
+				(gnutls_protocol_get_version(session)));
+
+		if (t == 0) {
+			if (handshake_callback_called != 0)
+				fail("server: handshake callback is called\n");
+		} else {
+			if (handshake_callback_called != t)
+				fail("server: handshake callback is not called\n");
+		}
+
+		for (;;) {
+			memset(buffer, 0, MAX_BUF + 1);
+			ret = gnutls_record_recv(session, buffer, MAX_BUF);
+
+			if (ret == 0) {
+				if (debug)
+					success
+					    ("server: Peer has closed the GnuTLS connection\n");
+				break;
+			} else if (ret < 0) {
+				kill(child, SIGTERM);
+				fail("server: Received corrupted data(%d). Closing...\n", ret);
+				break;
+			} else if (ret > 0) {
+				/* echo data back to the client
+				 */
+				gnutls_record_send(session, buffer,
+						   strlen(buffer));
+			}
+		}
+
+		/* do not wait for the peer to close the connection.
+		 */
+		gnutls_bye(session, GNUTLS_SHUT_WR);
+
+		close(sds[t]);
+		gnutls_deinit(session);
+	}
+
+	gnutls_certificate_free_credentials(serverx509cred);
+
+	gnutls_free(session_ticket_key.data);
+	session_ticket_key.data = NULL;
+
+	gnutls_global_deinit();
+
+	if (debug)
+		success("server: finished\n");
+}
+
+void doit(void)
+{
+	int client_sds[SESSIONS], server_sds[SESSIONS];
+	int i;
+	int ret;
+
+	signal(SIGPIPE, SIG_IGN);
+
+	for (i = 0; i < SESSIONS; i++) {
+		int sockets[2];
+
+		ret = socketpair(AF_UNIX, SOCK_STREAM, 0, sockets);
+		if (ret == -1) {
+			perror("socketpair");
+			fail("socketpair failed\n");
+			return;
+		}
+
+		server_sds[i] = sockets[0];
+		client_sds[i] = sockets[1];
+	}
+
+	child = fork();
+	if (child < 0) {
+		perror("fork");
+		fail("fork");
+		exit(1);
+	}
+
+	if (child) {
+		int status = 0;
+		/* parent */
+
+		for (i = 0; i < SESSIONS; i++)
+			close(client_sds[i]);
+		server(server_sds);
+		wait(&status);
+		check_wait_status(status);
+	} else {
+		for (i = 0; i < SESSIONS; i++)
+			close(server_sds[i]);
+		client(client_sds);
+		exit(0);
+	}
+}
+
+#endif				/* _WIN32 */
diff --git a/tests/tls13/prf-early.sh b/tests/tls13/prf-early.sh
new file mode 100755
index 0000000000..5b5ff0c33b
--- /dev/null
+++ b/tests/tls13/prf-early.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+# Copyright (C) 2019 Daiki Ueno
+#
+# This file is part of GnuTLS.
+#
+# GnuTLS is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or (at
+# your option) any later version.
+#
+# GnuTLS is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>
+#
+
+srcdir="${srcdir:-.}"
+builddir="${builddir:-.}"
+
+. "${srcdir}/scripts/common.sh"
+
+check_for_datefudge
+
+datefudge 2019-04-12 "${builddir}/tls13/prf-early" "$@"
+exit $?