ldap authentication

[Antoine Martin]

See also #1691, #1789, #1728

[Antoine Martin]

Done:

• ldap authentication module added in r18827 using ​python-ldap
• macos modules added in r18828 + r18829
• win32 packaging in r18830
• Active Directory compatibility improvements in r18831
• environment variables for tuning and debugging: r18832, r18833
• support TLS connections to the LDAP server: r18834
• option to specify the CACERT file (for using self signed certs) and change the password encoding (which defaults to "utf-8" - spec says "utf-8" but MS AD servers may require "utf-16-le" to support special characters): r18835

Usage example:

xpra start --bind-tcp=0.0.0.0:10000 -d auth \
    "--tcp-auth=ldap,host=ldaphostname,port=389,username_format=cn=%username, o=%domain"

Details on the settings, which are all optional:

• "host" defaults to "localhost"
• "port" defaults to 389
• "tls" defaults to 0 (false)
• "cacert" defaults to no value
• "encoding" defaults to "utf-8"
• "username_format": the special strings "%username" and "%domain" will be substituted at runtime. The username is specified by the client. The domain value is taken obtained using ​socket.getfqdn and removing the hostname part (keeping everything after the first dot).

According to this very helpful blog post: ​Python LDAP authentication with Microsoft Active Directory, the username_format for AD is just "%username@%domain". That's assuming that the server's domain name is set correctly too, otherwise replace %domain with the desired value.
See also: ​Configuring and securing PYTHON LDAP Applications

[Antoine Martin]

Another ldap backend, this time using the ​ldap3 python library. This one may be easier to use against AD servers, the username takes the form: "DOMAIN\username".

• r18843: add "ldap3" authentication module, man page update, etc
• r18844: macos moduleset changes
• r18845 + r18846: debug logging tweaks
• r19030: optional "recommends" rpm dependency

It uses the same options as the "ldap" authentication module: "host", "port", "tls", "cacert", but not "encoding". And also some new options:

• "authentication" defaults to "NTLM", the other options are: "SIMPLE" and "SASL" (should not be used)
• "ssl-version" defaults to "TLSv1" (see ​python ssl: socket creation for more details.
• "ssl-validate" defaults to "REQUIRED", other options: "OPTIONAL" and "NONE".

Usage example:

xpra start --bind-tcp=0.0.0.0:10000 -d auth \
    --tcp-auth=ldap3,host=localhost,port=389

@maxmylyn: please test both backends against ldap and AD servers.