gnutls-serv: improvements in UDP servertmp-fix-udp-serv

This modifies the server to deinitialize the session after use
(avoiding leaks), and to only send the hello verify request when
a client hello is seen.

This also adds a basic unit test of gnutls-serv with the --udp option.

Resolves #632

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>

3 files changed, 88 insertions, 3 deletions

diff --git a/src/udp-serv.c b/src/udp-serv.c
index fdaa0fb886..2d82482876 100644
--- a/src/udp-serv.c
+++ b/src/udp-serv.c
@@ -56,6 +56,15 @@ static ssize_t pull_func(gnutls_transport_ptr_t p, void *data,
 
 #define MAX_BUFFER 255		/* Longest string to echo */
 
+/* record layer indication for a handshake packet */
+#define HANDSHAKE_CONTENT_TYPE 22
+/* TLS record content is the first by of the packet */
+#define RECORD_CONTENT_POS 0
+/* handshake type is first byte in Handshake packet;
+ * we have to skip type;version;epoch;sequence_number;
+ * and length in DTLSPlaintext */
+#define HANDSHAKE_TYPE_POS 13
+
 void udp_server(const char *name, int port, int mtu)
 {
 	int sock, ret;
@@ -91,7 +100,11 @@ void udp_server(const char *name, int port, int mtu)
 		    recvfrom(sock, buffer, sizeof(buffer)-1, MSG_PEEK,
 			     (struct sockaddr *) &cli_addr,
 			     &cli_addr_size);
-		if (ret > 0) {
+
+		/* only accept a valid client hello */
+		if (ret > HANDSHAKE_TYPE_POS &&
+		    buffer[RECORD_CONTENT_POS] == HANDSHAKE_CONTENT_TYPE &&
+		    buffer[HANDSHAKE_TYPE_POS] == GNUTLS_HANDSHAKE_CLIENT_HELLO) {
 			if (!HAVE_OPT(NOCOOKIE)) {
 				memset(&prestate, 0, sizeof(prestate));
 				ret =
@@ -222,8 +235,8 @@ void udp_server(const char *name, int port, int mtu)
 				}
 			}
 		}
+		gnutls_deinit(session);
 	}
-	gnutls_deinit(session);
 }
 
 /* Wait for data to be received within a timeout period in milliseconds
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 56149cce5e..3e77add14d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -459,7 +459,8 @@ dist_check_SCRIPTS += fastopen.sh pkgconfig.sh starttls.sh starttls-ftp.sh start
 	ocsp-tests/ocsp-tls-connection ocsp-tests/ocsp-must-staple-connection \
 	ocsp-tests/ocsp-test cipher-listings.sh sni-hostname.sh server-multi-keys.sh \
 	psktool.sh ocsp-tests/ocsp-load-chain gnutls-cli-save-data.sh gnutls-cli-debug.sh \
-	sni-resume.sh ocsp-tests/ocsptool cert-reencoding.sh pkcs7-cat.sh long-crl.sh
+	sni-resume.sh ocsp-tests/ocsptool cert-reencoding.sh pkcs7-cat.sh long-crl.sh \
+	serv-udp.sh
 
 dist_check_SCRIPTS += gnutls-cli-self-signed.sh gnutls-cli-invalid-crl.sh
 
diff --git a/tests/serv-udp.sh b/tests/serv-udp.sh
new file mode 100755
index 0000000000..9db3a32a42
--- /dev/null
+++ b/tests/serv-udp.sh
@@ -0,0 +1,71 @@
+#!/bin/sh
+
+# Copyright (C) 2010-2016 Free Software Foundation, Inc.
+#
+# Author: Nikos Mavrogiannopoulos
+#
+# 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 General Public License
+# along with GnuTLS; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+srcdir="${srcdir:-.}"
+SERV="${SERV:-../src/gnutls-serv${EXEEXT}}"
+CLI="${CLI:-../src/gnutls-cli${EXEEXT}}"
+unset RETCODE
+
+if ! test -x "${SERV}"; then
+	exit 77
+fi
+
+if ! test -x "${CLI}"; then
+	exit 77
+fi
+
+if test "${WINDIR}" != ""; then
+	exit 77
+fi
+
+if ! test -z "${VALGRIND}"; then
+	VALGRIND="${LIBTOOL:-libtool} --mode=execute ${VALGRIND} --error-exitcode=15"
+fi
+
+
+SERV="${SERV} -q"
+
+. "${srcdir}/scripts/common.sh"
+
+echo "Checking whether UDP server works"
+
+KEY1=${srcdir}/../doc/credentials/x509/key-rsa.pem
+CERT1=${srcdir}/../doc/credentials/x509/cert-rsa.pem
+
+eval "${GETPORT}"
+launch_server $$ --x509keyfile ${KEY1} --x509certfile ${CERT1} --udp -d 2
+PID=$!
+
+wait_udp_server $PID
+
+${VALGRIND} "${CLI}" -p "${PORT}" 127.0.0.1 --insecure --udp </dev/null >/dev/null || \
+	fail ${PID} "1. handshake should have succeeded!"
+
+#retry
+${VALGRIND} "${CLI}" -p "${PORT}" 127.0.0.1 --insecure --udp </dev/null >/dev/null || \
+	fail ${PID} "2. handshake should have succeeded!"
+
+
+kill ${PID}
+wait
+
+exit 0