Merge branch 'develop' of github.com:eclipse/paho.mqtt.c into develop

test/tls-testing/Dockerfile

+FROM eclipse-mosquitto:latest
+COPY mosquitto-docker.conf /mosquitto/config/mosquitto.conf
+COPY keys /mosquitto/config/keys

test/tls-testing/mosquitto-docker.conf

+log_type error
+log_type warning
+log_type notice
+log_type information
+#log_type debug
+
+#log_dest file /var/log/mosquitto/tls-testing.log
+
+allow_anonymous true
+
+#message_size_limit 5000000
+
+# non-SSL listeners
+listener 1883
+listener 18883
+
+# listener for mutual authentication
+listener 18884
+cafile /mosquitto/config/keys/all-ca.crt
+certfile /mosquitto/config/keys/server/server.crt
+keyfile /mosquitto/config/keys/server/server.key
+require_certificate true
+#tls_version tlsv1
+
+# server authentication - no client authentication
+listener 18885
+cafile /mosquitto/config/keys/all-ca.crt
+certfile /mosquitto/config/keys/server/server.crt
+keyfile /mosquitto/config/keys/server/server.key
+require_certificate false
+#tls_version tlsv1
+
+listener 18886
+cafile /mosquitto/config/keys/all-ca.crt
+certfile /mosquitto/config/keys/server/server.crt
+keyfile /mosquitto/config/keys/server/server.key
+require_certificate false
+#ciphers ADH-DES-CBC-SHA
+#tls_version tlsv1
+
+# server authentication - no client authentication - uses fake hostname to
+# simulate mitm attack. Clients should refuse to connect to this listener.
+listener 18887
+#cafile /mosquitto/config/keys/all-ca.crt
+cafile /mosquitto/config/keys/server/server.crt
+certfile /mosquitto/config/keys/server/server-mitm.crt
+keyfile /mosquitto/config/keys/server/server-mitm.key
+require_certificate true
+#tls_version tlsv1