support colon in username in pwfile via double colon

[stefanschuermans]

There are smart IoT devices that use the string represeantation of the MAC address as MQTT user name, i.e., a user name containing colon characters. In basic setups of Mosquitto with authentication based on pwfile, user names could not contain colon characters, because the colon is used as a delimiter.

This commit adds supports for colon characters in user names in pwfile, by interpreting double colons in the user name in pwfile as a single colon in the actual user name.

Signed-off-by: Stefan Schuermans [email protected]

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[rswindell]

Isn't it true that the pwfile syntax only allows for a single ':' delimiter character on each line? The password is a base64-encoded hash, so there should be no colons in the password field. So this would mean just checking for the last occurring colon (e.g. using strrchr()) would give you the delimiter between the username and password fields. With that agreement, this change could be made much simpler (no strtok usage or re-implementation needed, no new dynamic memory allocation).

[stefanschuermans]

I have to admit that I did not find the specification of the pwfile syntax. I think the current implementation would take the part between the first colon and the end of the line or the second colon as the password field. I did not want to break the potential option to append additional fields in the future. However, I have no real idea what those could be used for. Your suggestion of using the last colon in the ling to split username/password would solve my issue and it would be way less code. I can change the implementation to use this approach.