tests: Add basic tests for sending/receiving mails and verification of headers

tests/basic.nix

@@ -0,0 +1,83 @@
+{pkgs, ...}:
+with (import ./common/lib.nix {inherit pkgs;}); let
+  accounts = {
+    "normal" = {
+      address = "user1@example.com";
+      password = "secret-password1";
+    };
+    "normal2" = {
+      address = "user2@example.com";
+      password = "secret-password2";
+    };
+  };
+in
+  pkgs.nixosTest {
+    name = "basic";
+    nodes = {
+      server = {pkgs, ...}: {
+        imports = [./common/server.nix];
+        environment.systemPackages = with pkgs; [netcat];
+        mailsystem = {
+          fqdn = "mail.example.com";
+          domains = ["example.com"];
+          accounts = mkAccounts accounts;
+        };
+      };
+      client = {...}: {
+        imports = [./common/client.nix];
+      };
+    };
+    testScript = {nodes, ...}: let
+      serverAddr = nodes.server.networking.primaryIPAddress;
+      clientAddr = nodes.client.networking.primaryIPAddress;
+      smtpSettings = {
+        address = serverAddr;
+        port = 465;
+      };
+      sendMail = mkSendMail smtpSettings accounts;
+      recvMail = mkRecvMail serverAddr accounts;
+      cfg = nodes.server.mailsystem;
+    in ''
+      start_all()
+
+      server.wait_for_unit("multi-user.target")
+      client.wait_for_unit("multi-user.target")
+      server.wait_until_succeeds("${waitForRspamd nodes.server}")
+
+      with subtest("imap works and retrieves no new mails"):
+          # fetchmail returns EXIT_CODE 1 when no new mail is available
+          client.succeed("${recvMail "normal"} || [ $? -eq 1 ] >&2")
+
+      with subtest("send succeeds for normal user"):
+          client.succeed("${sendMail "normal" "" accounts."normal2".address ''
+        Message-ID: <123456asdf@host.local.network>
+        Subject: Testmail1
+
+        Hello User2,
+        this is some text!
+      ''}")
+          # give the mail server some time to process the mail
+          server.wait_until_fails('${pendingPostqueue}')
+
+      with subtest("mail can be retrieved via imap"):
+          client.succeed("${recvMail "normal2"} >&2")
+
+      with subtest("mail header contains no sensitive information"):
+          client.fail("grep '${clientAddr}' $HOME/mail/*")
+          client.succeed("grep '^Message-ID:.*@${cfg.fqdn}>$' $HOME/mail/*")
+
+      with subtest("mail header contains correct fqdn in received from"):
+          client.succeed("grep 'Received: from ${cfg.fqdn}' $HOME/mail/*")
+
+      with subtest("user cannot forge from-address"):
+          client.fail("${sendMail "normal" "someotheraddress@example.com" accounts."normal2".address ''
+        Subject: I actually do not own this from-address
+
+        Hello User2,
+        I'm pretending to be someotheraddress@example.com and the mailserver should reject this attempt.
+      ''}")
+
+      with subtest("server issues no warnings nor errors"):
+          ${checkLogs "server"}
+    '';
+  }

tests/common/client.nix

@@ -0,0 +1,17 @@
+{pkgs, ...}: {
+  config = {
+    # added to the environment for manual verification via interactiveDriver if necessary
+    environment.systemPackages = with pkgs; [fetchmail msmtp procmail openssl];
+    systemd.tmpfiles.settings."10-mailtest" = let
+      dirPerms = {
+        user = "root";
+        mode = "0700";
+      };
+    in {
+      "/root/mail".d = dirPerms;
+      "/root/.procmailrc"."L+".argument = "${pkgs.writeText ".procmailrc" ''
+        DEFAULT=$HOME/mail
+      ''}";
+    };
+  };
+}