split management daemon authorization from authentication and use 'doveadm pw' rather than 'doveadm auth test' so that it is decoupled from dovecot's login mechanism

This was done to pave the way for two-factor authentication, but that's still a ways off.

management/mailconfig.py

@@ -279,7 +279,7 @@ def add_mail_user(email, pw, privs, env):
 	conn, c = open_database(env, with_connection=True)
 
 	# hash the password
-	pw = utils.shell('check_output', ["/usr/bin/doveadm", "pw", "-s", "SHA512-CRYPT", "-p", pw]).strip()
+	pw = hash_password(pw)
 
 	# add the user to the database
 	try:
@@ -319,7 +319,7 @@ def set_mail_password(email, pw, env):
 	validate_password(pw)
 	
 	# hash the password
-	pw = utils.shell('check_output', ["/usr/bin/doveadm", "pw", "-s", "SHA512-CRYPT", "-p", pw]).strip()
+	pw = hash_password(pw)
 
 	# update the database
 	conn, c = open_database(env, with_connection=True)
@@ -329,6 +329,24 @@ def set_mail_password(email, pw, env):
 	conn.commit()
 	return "OK"
 
+def hash_password(pw):
+	# Turn the plain password into a Dovecot-format hashed password, meaning
+	# something like "{SCHEME}hashedpassworddata".
+	# http://wiki2.dovecot.org/Authentication/PasswordSchemes
+	return utils.shell('check_output', ["/usr/bin/doveadm", "pw", "-s", "SHA512-CRYPT", "-p", pw]).strip()
+
+def get_mail_password(email, env):
+	# Gets the hashed password for a user. Passwords are stored in Dovecot's
+	# password format, with a prefixed scheme.
+	# http://wiki2.dovecot.org/Authentication/PasswordSchemes
+	# update the database
+	c = open_database(env)
+	c.execute('SELECT password FROM users WHERE email=?', (email,))
+	rows = c.fetchall()
+	if len(rows) != 1:
+		raise ValueError("That's not a user (%s)." % email)
+	return rows[0][0]
+
 def remove_mail_user(email, env):
 	# accept IDNA domain names but normalize to Unicode before going into database
 	email = sanitize_idn_email_address(email)