feat: add preliminary maddy configuration

flake.lock

@@ -1053,11 +1053,11 @@
         "pre-commit-hooks": "pre-commit-hooks_4"
       },
       "locked": {
-        "lastModified": 1710447185,
-        "narHash": "sha256-M63b7f5dnGtLAZmgzSepQvcVA++QRJ+h8fSlyowgYcI=",
+        "lastModified": 1712774101,
+        "narHash": "sha256-t58qLvRLjrekfnHWS5Un5LXQJCrLeycKcuPRtoVqJbw=",
         "owner": "oddlama",
         "repo": "nixos-extra-modules",
-        "rev": "a4f79d7479bf63fb99e1d19cb6502feabc2854c3",
+        "rev": "0f4e5f7391532ddf105020a5be75421ea2e4fdc7",
         "type": "github"
       },
       "original": {

hosts/envoy/default.nix

@@ -9,6 +9,7 @@
     ./acme.nix
     ./fs.nix
     ./net.nix
+    ./maddy.nix
   ];
 
   boot.mode = "bios";

hosts/envoy/maddy.nix

@@ -0,0 +1,213 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: let
+  mailDomains = config.repo.secrets.global.domains.mail;
+  primaryDomain = mailDomains.primary;
+  maddyBackupDir = "/var/cache/backups/maddy";
+in {
+  systemd.tmpfiles.settings."10-maddy".${maddyBackupDir}.d = {
+    inherit (config.services.maddy) user group;
+    mode = "0770";
+  };
+
+  environment.persistence."/persist".directories = [
+    {
+      directory = "/var/lib/maddy";
+      inherit (config.services.maddy) user group;
+      mode = "0750";
+    }
+  ];
+
+  # For each mail domain, add MTA STS entry via nginx
+  # FIXME: autoconfig
+  services.nginx.virtualHosts = lib.genAttrs (map (x: "mta-sts.${x}") mailDomains.all) (_x: {
+    forceSSL = true;
+    useACMEWildcardHost = true;
+    locations."=/.well-known/mta-sts.txt".alias = pkgs.writeText "mta-sts.txt" ''
+      version: STSv1
+      mode: enforce
+      mx: mx1.${primaryDomain}
+      max_age: 86400
+    '';
+  });
+
+  networking.firewall.allowedTCPPorts = [25 465 993];
+  services.maddy = {
+    enable = true;
+    hostname = "mx1.${primaryDomain}";
+    inherit primaryDomain;
+    localDomains = mailDomains.all;
+    tls = {
+      loader = "file";
+      certificates = [
+        {
+          keyPath = "${config.security.acme.certs.${primaryDomain}.directory}/key.pem";
+          certPath = "${config.security.acme.certs.${primaryDomain}.directory}/fullchain.pem";
+        }
+      ];
+    };
+    #ensureCredentials = {
+    #  "me@${primaryDomain}".passwordFile = config.age.secrets.patrickPasswd.path;
+    #};
+    #ensureAccounts = [
+    #  "me@${primaryDomain}"
+    #];
+    config =
+      /*
+      bash
+      */
+      ''
+        auth.pass_table local_authdb {
+            table sql_table {
+                driver sqlite3
+                dsn mailboxes.db
+                table_name users
+            }
+        }
+
+        storage.imapsql local_mailboxes {
+            driver sqlite3
+            dsn imap.db
+        }
+
+        table.chain local_rewrites {
+            optional_step sql_query {
+                driver sqlite
+                dsn mailboxes.db
+                lookup "SELECT alias FROM aliases WHERE address = $1"
+            }
+        }
+
+        msgpipeline local_routing {
+            destination $(local_domains) {
+                modify {
+                    replace_rcpt &local_rewrites
+                }
+
+                deliver_to &local_mailboxes
+            }
+
+            default_destination {
+                reject 550 5.1.1 "User doesn't exist"
+            }
+        }
+
+        # ----------------------------------------------------------------------------
+        # Endpoints
+
+        imap tls://0.0.0.0:993 {
+            auth &local_authdb
+            storage &local_mailboxes
+        }
+
+        # SMTP for incoming mails from other servers.
+        # Allows anyone to connect and give us local mail, but doesn't allow message relaying.
+        smtp tcp://0.0.0.0:25 {
+            limits {
+                # Up to 20 msgs/sec across max. 10 SMTP connections.
+                all rate 20 1s
+                all concurrency 10
+            }
+
+            dmarc yes
+            max_message_size 256M
+            check {
+                require_mx_record
+                dkim
+                spf
+            }
+
+            source $(local_domains) {
+                reject 501 5.1.8 "Use Submission for outgoing SMTP"
+            }
+            default_source {
+                destination $(local_domains) {
+                    deliver_to &local_routing
+                }
+                default_destination {
+                    reject 550 5.1.1 "User doesn't exist"
+                }
+            }
+        }
+
+        # Submission with implicit TLS for authenticated users.
+        # Allows only authenticated users, and allows message relaying.
+        # Contrary to popular belief, port 465 is [NOT deprecated](https://datatracker.ietf.org/doc/html/rfc8314#section-7.3),
+        # and has been assigned for "Message Submission over TLS protocol",
+        # I neither need nor want to use STARTTLS.
+        submission tls://0.0.0.0:465 {
+            limits {
+                # Up to 50 msgs/sec across any amount of SMTP connections.
+                all rate 50 1s
+            }
+
+            auth &local_authdb
+
+            source $(local_domains) {
+                check {
+                    authorize_sender {
+                        prepare_email &local_rewrites
+                        user_to_email identity
+                    }
+                }
+
+                destination $(local_domains) {
+                    modify {
+                        dkim $(local_domains) default
+                    }
+                    deliver_to &local_routing
+                }
+                default_destination {
+                    modify {
+                        dkim $(local_domains) default
+                    }
+                    deliver_to &remote_queue
+                }
+            }
+            default_source {
+                reject 501 5.1.8 "Non-local sender domain"
+            }
+        }
+
+        # ----------------------------------------------------------------------------
+        # Outbound configuration
+
+        target.queue remote_queue {
+            target &outbound_delivery
+
+            autogenerated_msg_domain $(primary_domain)
+            bounce {
+                destination $(local_domains) {
+                    deliver_to &local_routing
+                }
+                default_destination {
+                    reject 550 5.0.0 "Refusing to send DSNs to non-local addresses"
+                }
+            }
+        }
+
+        target.remote outbound_delivery {
+            limits {
+                # Up to 20 msgs/sec across max. 10 SMTP connections
+                # for each recipient domain.
+                destination rate 20 1s
+                destination concurrency 10
+            }
+            mx_auth {
+                dane
+                mtasts {
+                    cache fs
+                    fs_dir mtasts_cache/
+                }
+                local_policy {
+                    min_tls_level encrypted
+                    min_mx_level none
+                }
+            }
+        }
+      '';
+  };
+}