Mqtt ssl support

[dschowta]

This is a pull request to solve issue #156 and #157. If the repo owners agree for these changes, I shall add the documentations. Here are the additional things which changed:

1. MQTT support for ssl based communications
2. Supports both user name/password based and public/private key based authentication.
3. Added corresponding configurations

Part of the code is taken from https://code.linksmart.eu/projects/SC/repos/service-catalog/browse (Apache 2.0 license)

Thank you

[bertt]

Thanks, a question:: How can we easily test the changes? Maybe have a docker-compose file with MQTT ssl enabled? Or a document with a test procedure.

[dschowta]

I tested it manually without using Docker. I tested it using two ways.

1. With Username and password Sorry, here I do not have a direct way. I used a local mqtt server for this purpose. One of the ways is to create a broker with username password authentication enabled as suggested here. http://www.steves-internet-guide.com/mqtt-username-password-example/
   Use following configuration:

   mqtt: enabled: true host: acustomhostname port: yourportnum prefix: GOST clientId: gost subscriptionQos: 1 persistent: true ssl: true caCertFile: root certificate file(go usually takes system files. So this is not a mandatory field) username: YourUsername username: YourPassword

2. With Private public keypairs :

   • This can be easily tested with a publicly available MQTT broker
   • download Certificate authority file(caCertFile)
   • Create public and private keypair (clientCertFile,privateKeyFile) by following the instructions of mosquitto website

   • Use the following configuration

     mqtt: enabled: true host: test.mosquitto.org port: 8884 prefix: GOST clientId: gost subscriptionQos: 1 persistent: true ssl: true caCertFile: mosquitto.org.crt clientCertFile: client.crt privateKeyFile: client.key

   • You should be able to connect to the broker successfully.

[tebben]

Tested receiving/publishing observations, all seem to work fine.

• [x] tcp no auth
• [x] tcp username/password authentication
• [x] ssl using caCertFile
• [x] ssl using caCertFile, clientCertFile and privateKeyFile

Thanks for this pull request!