allow dashes in emails during validation, and for aliases allow a much wider...

allow dashes in emails during validation, and for aliases allow a much wider range of characters, fixes #64

* for local mail users, also disallows periods at the beginning or end of the local or domain parts
* Dovecot gets confused if the string contains any unusual characters, so local mail users are restricted to a narrow regex
* for mail aliases Postfix is not confused so use a regex based on RFC 2822

management/mailconfig.py

 import subprocess, shutil, os, sqlite3, re
 
+def validate_email(email, strict):
+	# There are a lot of characters permitted in email addresses, but
+	# Dovecot's sqlite driver seems to get confused if there are any
+	# unusual characters in the address. Bah. Also note that since
+	# the mailbox path name is based on the email address, the address
+	# shouldn't be absurdly long and must not have a forward slash.
+
+	if len(email) > 255: return False
+
+	if strict:
+		# For Dovecot's benefit, only allow basic characters.
+		ATEXT = r'[\w\-]'
+	else:
+		# Based on RFC 2822 and https://github.com/SyrusAkbary/validate_email/blob/master/validate_email.py,
+		# these characters are permitted in email address.
+		ATEXT = r'[\w!#$%&\'\*\+\-/=\?\^`\{\|\}~]' # see 3.2.4
+
+	DOT_ATOM_TEXT = ATEXT + r'+(?:\.' + ATEXT + r'+)*'     # see 3.2.4
+	ADDR_SPEC = '^%s@%s$' % (DOT_ATOM_TEXT, DOT_ATOM_TEXT) # see 3.4.1
+
+	return re.match(ADDR_SPEC, email)
+
 def open_database(env, with_connection=False):
 	conn = sqlite3.connect(env["STORAGE_ROOT"] + "/mail/users.sqlite")
 	if not with_connection:
@@ -23,7 +45,7 @@ def get_mail_domains(env):
 	return set([get_domain(addr) for addr in get_mail_users(env)] + [get_domain(addr1) for addr1, addr2 in get_mail_aliases(env)])
 
 def add_mail_user(email, pw, env):
-	if not re.match("\w[\w\.]+@\w[\w\.]+$", email):
+	if not validate_email(email, True):
 		return ("Invalid email address.", 400)
 
 	# get the database
@@ -45,7 +67,12 @@ def add_mail_user(email, pw, env):
 
 	# Check if the mailboxes exist before creating them. When creating a user that had previously
 	# been deleted, the mailboxes will still exist because they are still on disk.
-	existing_mboxes = subprocess.check_output(["doveadm", "mailbox", "list", "-u", email, "-8"]).decode("utf8").split("\n")
+	try:
+		existing_mboxes = subprocess.check_output(["doveadm", "mailbox", "list", "-u", email, "-8"], stderr=subprocess.STDOUT).decode("utf8").split("\n")
+	except subprocess.CalledProcessError as e:
+		c.execute("DELETE FROM users WHERE email=?", (email,))
+		conn.commit()
+		return ("Failed to initialize the user: " + e.output.decode("utf8"), 400)
 
 	if "INBOX" not in existing_mboxes: subprocess.check_call(["doveadm", "mailbox", "create", "-u", email, "-s", "INBOX"])
 	if "Spam" not in existing_mboxes: subprocess.check_call(["doveadm", "mailbox", "create", "-u", email, "-s", "Spam"])
@@ -88,6 +115,9 @@ def remove_mail_user(email, env):
 	return do_dns_update(env)
 
 def add_mail_alias(source, destination, env):
+	if not validate_email(source, False):
+		return ("Invalid email address.", 400)
+
 	conn, c = open_database(env, with_connection=True)
 	try:
 		c.execute("INSERT INTO aliases (source, destination) VALUES (?, ?)", (source, destination))