flake.nix

@@ -118,6 +118,79 @@
             touch $out
           '';
 
+          copyparty-reverse-proxy-trust-config =
+            let
+              pikachuConfig = self.nixosConfigurations.pikachu.config;
+              serviceConfig = pikachuConfig.containers.copyparty.config.systemd.services.copyparty.serviceConfig;
+              configScript = builtins.readFile serviceConfig.ExecStartPre;
+              plainConfig =
+                (lib.nixosSystem {
+                  system = "x86_64-linux";
+                  specialArgs.my = self.lib;
+                  modules = [
+                    ./modules/services/copyparty.nix
+                    {
+                      modules.services.copyparty = {
+                        enable = true;
+                        passwordFile = "/run/password";
+                        volumes."/" = {
+                          path = "/srv/files";
+                          access.A = [ "alexion" ];
+                        };
+                      };
+                    }
+                  ];
+                }).config;
+              plainScript = builtins.readFile plainConfig.systemd.services.copyparty.serviceConfig.ExecStartPre;
+            in
+            pkgs.runCommand "copyparty-reverse-proxy-trust-config-check" { } ''
+              ${
+                lib.optionalString (
+                  !(
+                    lib.hasInfix "  rproxy: 1" configScript
+                    && lib.hasInfix "  xff-hdr: x-forwarded-for" configScript
+                    && lib.hasInfix "  xff-src: 10.23.20.109/32" configScript
+                    && !(lib.hasInfix "rproxy" plainScript)
+                    && !(lib.hasInfix "xff-hdr" plainScript)
+                    && !(lib.hasInfix "xff-src" plainScript)
+                  )
+                ) "exit 1"
+              }
+              touch $out
+            '';
+
+          copyparty-reverse-proxy-trust-requires-source =
+            let
+              testConfig =
+                (lib.nixosSystem {
+                  system = "x86_64-linux";
+                  specialArgs.my = self.lib;
+                  modules = [
+                    ./modules/services/copyparty.nix
+                    {
+                      modules.services.copyparty = {
+                        enable = true;
+                        passwordFile = "/run/password";
+                        reverseProxy.enable = true;
+                        volumes."/" = {
+                          path = "/srv/files";
+                          access.A = [ "alexion" ];
+                        };
+                      };
+                    }
+                  ];
+                }).config;
+              hasFailedTrustedSourcesAssertion = lib.any (
+                assertion:
+                assertion.assertion == false
+                && assertion.message == "modules.services.copyparty.reverseProxy.trustedSources must name at least one trusted proxy source when reverse-proxy support is enabled."
+              ) testConfig.assertions;
+            in
+            pkgs.runCommand "copyparty-reverse-proxy-trust-requires-source-check" { } ''
+              ${lib.optionalString (!hasFailedTrustedSourcesAssertion) "exit 1"}
+              touch $out
+            '';
+
           reverse-proxy-basic-route =
             let
               testConfig =

guests/copyparty.nix

@@ -43,6 +43,10 @@ in
           enable = true;
           inherit (cfg) accountName stateDir;
           passwordFile = "/run/secrets/${cfg.passwordSecret}";
+          reverseProxy = {
+            enable = cfg.reverseProxy.enable;
+            inherit (cfg.reverseProxy) trustedSources;
+          };
           volumes = lib.mapAttrs (_urlPath: volume: {
             inherit (volume) path access flags;
           }) cfg.volumes;
@@ -77,6 +81,12 @@ in
       description = "Host path bind-mounted as Copyparty's state directory.";
     };
 
+    reverseProxy.trustedSources = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+      description = "IP ranges that may supply Copyparty's forwarded client IP header.";
+    };
+
     volumes = lib.mkOption {
       type = lib.types.attrsOf volumeType;
       default = { };

hosts/pikachu/default.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ config, pkgs, ... }:
 # pikachu — AZW ME Pro server.
 # Disk layout is in ./disk.nix.
 # `fileSystems` for the root disk are derived from it.
@@ -91,6 +91,7 @@
     enable = true;
     vlan = 20;
     mac = "02:98:64:5a:07:4f";
+    endpoint.address = "10.23.20.109";
   };
 
   guests.copyparty = {
@@ -103,6 +104,7 @@
       enable = true;
       host = "files.alexion.dev";
       port = 3923;
+      trustedSources = [ "${config.modules.network.endpoints."reverse-proxy".address}/32" ];
     };
     volumes = {
       "/inbox" = {

modules/services/copyparty.nix

@@ -48,6 +48,14 @@ let
     ''}
   '';
 
+  renderTrustedSource = source: "  xff-src: ${source}";
+
+  renderedReverseProxy = lib.optionalString cfg.reverseProxy.enable ''
+      rproxy: 1
+      xff-hdr: x-forwarded-for
+    ${lib.concatStringsSep "\n" (map renderTrustedSource cfg.reverseProxy.trustedSources)}
+  '';
+
   renderedVolumes = lib.concatStringsSep "\n" (lib.mapAttrsToList renderVolume cfg.volumes);
 
   configScript = pkgs.writeShellScript "copyparty-config" ''
@@ -68,7 +76,7 @@ let
       ses-db: ${cfg.stateDir}/sessions.db
       chpw-db: ${cfg.stateDir}/chpw.json
       shr-db: ${cfg.stateDir}/shares.db
-
+    ${renderedReverseProxy}
     [accounts]
       ${cfg.accountName}: $password
 
@@ -128,6 +136,16 @@ in
       default = { };
       description = "Copyparty volumes keyed by their URL path.";
     };
+
+    reverseProxy = {
+      enable = lib.mkEnableOption "reverse-proxy trust settings for Copyparty";
+
+      trustedSources = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [ ];
+        description = "IP ranges that may supply Copyparty's forwarded client IP header.";
+      };
+    };
   };
 
   config = lib.mkIf cfg.enable {
@@ -136,6 +154,10 @@ in
         assertion = cfg.volumes != { };
         message = "modules.services.copyparty.volumes must declare at least one served volume.";
       }
+      {
+        assertion = !cfg.reverseProxy.enable || cfg.reverseProxy.trustedSources != [ ];
+        message = "modules.services.copyparty.reverseProxy.trustedSources must name at least one trusted proxy source when reverse-proxy support is enabled.";
+      }
     ];
 
     users.users.${cfg.user} = {