doveauth: flask app to create accounts via HTTP

chatmaild/pyproject.toml

@@ -6,7 +6,8 @@ build-backend = "setuptools.build_meta"
 name = "chatmaild"
 version = "0.1"
 dependencies = [
-  "aiosmtpd"
+  "aiosmtpd",
+  "flask",
 ]
 
 [project.scripts]

chatmaild/src/chatmaild/doveauth.py

@@ -3,7 +3,6 @@ import os
 import time
 import sys
 import json
-import crypt
 from socketserver import (
     UnixStreamServer,
     StreamRequestHandler,
@@ -12,39 +11,7 @@ from socketserver import (
 import pwd
 
 from .database import Database
-
-NOCREATE_FILE = "/etc/chatmail-nocreate"
-
-
-def encrypt_password(password: str):
-    # https://doc.dovecot.org/configuration_manual/authentication/password_schemes/
-    passhash = crypt.crypt(password, crypt.METHOD_SHA512)
-    return "{SHA512-CRYPT}" + passhash
-
-
-def is_allowed_to_create(user, cleartext_password) -> bool:
-    """Return True if user and password are admissable."""
-    if os.path.exists(NOCREATE_FILE):
-        logging.warning(f"blocked account creation because {NOCREATE_FILE!r} exists.")
-        return False
-
-    if len(cleartext_password) < 10:
-        logging.warning("Password needs to be at least 10 characters long")
-        return False
-
-    parts = user.split("@")
-    if len(parts) != 2:
-        logging.warning(f"user {user!r} is not a proper e-mail address")
-        return False
-    localpart, domain = parts
-
-    if domain == "nine.testrun.org":
-        # nine.testrun.org policy, username has to be exactly nine chars
-        if len(localpart) != 9:
-            logging.warning(f"localpart {localpart!r} has not exactly nine chars")
-            return False
-
-    return True
+from .util import is_allowed_to_create, encrypt_password, get_mail_domain
 
 
 def get_user_data(db, user):
@@ -123,8 +90,7 @@ def main():
     socket = sys.argv[1]
     passwd_entry = pwd.getpwnam(sys.argv[2])
     db = Database(sys.argv[3])
-    with open("/etc/mailname", "r") as fp:
-        mail_domain = fp.read().strip()
+    mail_domain = get_mail_domain()
 
     class Handler(StreamRequestHandler):
         def handle(self):

chatmaild/src/chatmaild/util.py

@@ -0,0 +1,56 @@
+import base64
+import random
+import logging
+import os
+import crypt
+
+
+NOCREATE_FILE = "/etc/chatmail-nocreate"
+
+
+def is_allowed_to_create(user, cleartext_password) -> bool:
+    """Return True if user and password are admissable."""
+    if os.path.exists(NOCREATE_FILE):
+        logging.warning(f"blocked account creation because {NOCREATE_FILE!r} exists.")
+        return False
+
+    if len(cleartext_password) < 10:
+        logging.warning("Password needs to be at least 10 characters long")
+        return False
+
+    parts = user.split("@")
+    if len(parts) != 2:
+        logging.warning(f"user {user!r} is not a proper e-mail address")
+        return False
+    localpart, domain = parts
+
+    if domain == "nine.testrun.org":
+        # nine.testrun.org policy, username has to be exactly nine chars
+        if len(localpart) != 9:
+            logging.warning(f"localpart {localpart!r} has not exactly nine chars")
+            return False
+
+    return True
+
+
+def gen_password():
+    with open("/dev/urandom", "rb") as f:
+        s = f.read(21)
+    return base64.b64encode(s).decode("ascii")[:12]
+
+
+def encrypt_password(password: str):
+    # https://doc.dovecot.org/configuration_manual/authentication/password_schemes/
+    passhash = crypt.crypt(password, crypt.METHOD_SHA512)
+    return "{SHA512-CRYPT}" + passhash
+
+
+def get_mail_domain():
+    with open("/etc/mailname", "r") as fp:
+        return fp.read().strip()
+
+
+def get_valid_email_addr(length=9, chars="2345789acdefghjkmnpqrstuvwxyz"):
+    localpart = "".join(random.choice(chars) for i in range(length))
+    mail_domain = get_mail_domain()
+    return f"{localpart}@{mail_domain}"

chatmaild/src/chatmaild/web.py

@@ -0,0 +1,39 @@
+from flask import Flask, jsonify, request
+import time
+
+from database import Database
+from util import gen_password, get_valid_email_addr, encrypt_password
+from doveauth import get_user_data
+
+
+def create_app_from_db_path(db_path=None):
+    db = Database(db_path)
+    return create_app_from_db(db)
+
+
+def create_app_from_db(db):
+    app = Flask("chatmaild-http")
+    app.db = db
+
+    @app.route("/", methods=["POST"])
+    def new_email():
+        for i in range(10):
+            addr = get_valid_email_addr()
+            if not get_user_data(db, addr):
+                cleartext_password = gen_password()
+                encrypted_password = encrypt_password(cleartext_password)
+                q = """INSERT INTO users (addr, password, last_login)
+                       VALUES (?, ?, ?)"""
+                with db.write_transaction() as conn:
+                    conn.execute(q, (addr, encrypted_password, int(time.time())))
+                return jsonify(
+                    email=addr,
+                    password=cleartext_password,
+                )
+        return jsonify(
+            type="error",
+            status_code=409,
+            reason="all 10 email addresses we tried are taken"
+        )
+
+    return app