Test dtls_client

Test against both OpenSSL and GnuTLS.

Don't use a proxy. It's not particularly useful here, and would complicate
figuring out port numbers.

Clean up compile-time requirements in dtls_client.c: any certificate-based
key exchange is ok, so don't insist on built-in RSA.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/opt-testcases/sample.sh

@@ -46,3 +46,31 @@ run_test    "Sample: ssl_client1, gnutls server, TLS 1.3" \
             -c "<TD>Protocol version:</TD><TD>TLS1.3</TD>" \
             -S "Error" \
             -C "error"
+
+requires_protocol_version dtls12
+run_test    "Sample: dtls_client, openssl server, DTLS 1.2" \
+            -P 4433 \
+            "$O_SRV -dtls1_2" \
+            "$PROGRAMS_DIR/dtls_client" \
+            0 \
+            -s "Echo this" \
+            -s "DONE" \
+            -c "Echo this" \
+            -c "[1-9][0-9]* bytes written" \
+            -c "[1-9][0-9]* bytes read" \
+            -S "ERROR" \
+            -C "error"
+
+requires_protocol_version dtls12
+run_test    "Sample: dtls_client, gnutls server, DTLS 1.2" \
+            -P 4433 \
+            "$G_SRV -u --echo --priority=NORMAL:-VERS-TLS-ALL:+VERS-TLS1.2" \
+            "$PROGRAMS_DIR/dtls_client" \
+            0 \
+            -s "Server listening" \
+            -s "[1-9][0-9]* bytes command:" \
+            -c "Echo this" \
+            -c "[1-9][0-9]* bytes written" \
+            -c "[1-9][0-9]* bytes read" \
+            -S "Error" \
+            -C "error"