feat(wireguard): associate external peers to the specific defining node

hosts/nom/net.nix

@@ -20,4 +20,6 @@
       dhcpV6Config.RouteMetric = 40;
     };
   };
+
+  extra.wireguard.vms.address = ["10.0.0.10/32"];
 }

hosts/zackbiene/net.nix

@@ -17,4 +17,16 @@
       };
     };
   };
+
+  extra.wireguard.vms = {
+    server = {
+      enable = true;
+      port = 51822;
+      openFirewall = true;
+    };
+    address = ["10.0.0.2/24"];
+    externalPeers = {
+      zack1 = ["10.0.0.90/32"];
+    };
+  };
 }

modules/wireguard.nix

@@ -37,7 +37,7 @@
 
   configForNetwork = wgName: wg: let
     inherit
-      (extraLib.wireguard wgName)
+      (extraLib.wireguard wgName nodes)
       allPeers
       peerPresharedKeyPath
       peerPresharedKeySecret
@@ -46,7 +46,7 @@
       peerPublicKeyPath
       ;
 
-    otherPeers = filterAttrs (n: _: n != nodeName) (allPeers nodes);
+    otherPeers = filterAttrs (n: _: n != nodeName) allPeers;
   in {
     secrets =
       concatAttrs (map (other: {
@@ -130,8 +130,12 @@ in {
           default = {};
           example = {my-android-phone = ["10.0.0.97/32"];};
           description = mdDoc ''
-            Allows defining extra set of external peers that should be added to the configuration.
-            For each external peers you can define one or multiple allowed ips.
+                     Allows defining an extra set of peers that should be added to this wireguard network,
+            but will not be managed by this flake. (e.g. phones)
+
+            These external peers will only know this node as a peer, which will forward
+            their traffic to other members of the network if required. This requires
+            this node to act as a server.
           '';
         };
       };
@@ -144,17 +148,17 @@ in {
   in {
     assertions = concatMap (wgName: let
       inherit
-        (extraLib.wireguard wgName)
+        (extraLib.wireguard wgName nodes)
         externalPeerNamesRaw
         usedAddresses
         associatedNodes
         ;
 
-      duplicatePeers = duplicates (externalPeerNamesRaw nodes);
-      duplicateAddrs = duplicates (map (x: head (splitString "/" x)) (usedAddresses nodes));
+      duplicatePeers = duplicates externalPeerNamesRaw;
+      duplicateAddrs = duplicates (map (x: head (splitString "/" x)) usedAddresses);
     in [
       {
-        assertion = any (n: nodes.${n}.config.extra.wireguard.${wgName}.server.enable) (associatedNodes nodes);
+        assertion = any (n: nodes.${n}.config.extra.wireguard.${wgName}.server.enable) associatedNodes;
         message = "Wireguard network '${wgName}': At least one node must be a server.";
       }
       {
@@ -165,6 +169,10 @@ in {
         assertion = duplicateAddrs == [];
         message = "Wireguard network '${wgName}': Addresses used multiple times: ${concatStringsSep ", " duplicateAddrs}";
       }
+      # TODO externalPeers != [] -> server.listen
+      # TODO externalPeers != [] -> ip forwarding
+      # TODO psks only between all nodes and each node-externalpeer pair
+      # TODO no overlapping allowed ip range? 0.0.0.0 would be ok to overlap though
     ]) (attrNames cfg);
 
     networking.firewall.allowedUDPPorts = mkIf (cfg.server.enable && cfg.server.openFirewall) [cfg.server.port];

nix/apps/generate-wireguard-keys.nix

@@ -11,6 +11,7 @@
     concatStringsSep
     escapeShellArg
     filter
+    optionalString
     removeSuffix
     substring
     unique
@@ -33,17 +34,19 @@
 
   generateNetworkKeys = wgName: let
     inherit
-      (extraLib.wireguard wgName)
+      (extraLib.wireguard wgName self.nodes)
       allPeers
       associatedNodes
+      associatedServerNodes
+      associatedClientNodes
+      externalPeersForNode
       peerPresharedKeyFile
       peerPrivateKeyFile
       peerPublicKeyFile
+      sortedPeers
       ;
 
-    nodesWithNet = associatedNodes self.nodes;
-    peers = attrNames (allPeers self.nodes);
-
+    # Every peer needs a private and public key.
     generatePeerKeys = peerName: let
       keyBasename = escapeShellArg ("./" + removeSuffix ".pub" (peerPublicKeyFile peerName));
       pubkeyFile = escapeShellArg ("./" + peerPublicKeyFile peerName);
@@ -59,22 +62,35 @@
       fi
     '';
 
-    generatePeerPsks = nodePeerName:
-      map (peerName: let
-        pskFile = escapeShellArg ("./" + peerPresharedKeyFile nodePeerName peerName);
+    # Generates the psk for peer1 and peer2.
+    generatePeerPsk = {
+      peer1,
+      peer2,
+    }: let
+      pskFile = escapeShellArg ("./" + peerPresharedKeyFile peer1 peer2);
     in ''
       if [[ ! -e ${pskFile} ]]; then
         mkdir -p $(dirname ${pskFile})
         echo "Generating "${pskFile}""
         psk=$(${pkgs.wireguard-tools}/bin/wg genpsk)
         ${pkgs.rage}/bin/rage -e ${masterIdentityArgs} ${extraEncryptionPubkeys} <<< "$psk" > ${pskFile} \
-            || { echo "error: Failed to encrypt wireguard psk for peers ${nodePeerName} and ${peerName} on network ${wgName}!" >&2; exit 1; }
+          || { echo "error: Failed to encrypt wireguard psk for peers ${peer1} and ${peer2} on network ${wgName}!" >&2; exit 1; }
       fi
-      '') (filter (x: x != nodePeerName) peers);
+    '';
+
+    # This generates all psks for each combination of peers given.
+    # xs is a list of peers and fys a function that generates a list of peers
+    # for any given x.
+    psksForPeerCombinations = xs: fys: map generatePeerPsk (unique (concatMap (x: map (sortedPeers x) (fys x)) xs));
   in
     ["echo ==== ${wgName} ===="]
-    ++ map generatePeerKeys peers
-    ++ concatMap generatePeerPsks nodesWithNet;
+    ++ map generatePeerKeys (attrNames allPeers)
+    # All server-nodes need a psk for each other, but not reflexive.
+    ++ psksForPeerCombinations associatedServerNodes (n: filter (x: x != n) associatedServerNodes)
+    # Each server-node need a psk for all client nodes
+    ++ psksForPeerCombinations associatedServerNodes (_: associatedClientNodes)
+    # Each server-node need a psk for all their external peers
+    ++ psksForPeerCombinations associatedServerNodes (n: attrNames (externalPeersForNode n));
 in
   pkgs.writeShellScript "generate-wireguard-keys" ''
     set -euo pipefail

nix/apps/show-wireguard-qr.nix

@@ -20,7 +20,7 @@
 
   externalPeersForNet = wgName:
     map (peer: {inherit wgName peer;})
-    (attrNames ((extraLib.wireguard wgName).externalPeers self.nodes));
+    (attrNames (extraLib.wireguard wgName self.nodes).allExternalPeers);
   allExternalPeers = concatMap externalPeersForNet wireguardNetworks;
 in
   # TODO generate "classic" config and run qrencode

nix/lib.nix

@@ -11,6 +11,7 @@
     mapAttrs'
     mergeAttrs
     nameValuePair
+    partition
     unique
     ;
 in rec {
@@ -33,8 +34,8 @@ in rec {
   concatAttrs = foldl' mergeAttrs {};
 
   # Wireguard related functions that are reused in several files of this flake
-  wireguard = wgName: rec {
-    _sortedPeers = peerA: peerB:
+  wireguard = wgName: nodes: rec {
+    sortedPeers = peerA: peerB:
       if peerA < peerB
       then {
         peer1 = peerA;
@@ -53,32 +54,49 @@ in rec {
     peerPrivateKeySecret = peerName: "wireguard-${wgName}-priv-${peerName}";
 
     peerPresharedKeyFile = peerA: peerB: let
-      inherit (_sortedPeers peerA peerB) peer1 peer2;
+      inherit (sortedPeers peerA peerB) peer1 peer2;
     in "secrets/wireguard/${wgName}/psks/${peer1}+${peer2}.age";
     peerPresharedKeyPath = peerA: peerB: "${../.}/" + peerPresharedKeyFile peerA peerB;
     peerPresharedKeySecret = peerA: peerB: let
-      inherit (_sortedPeers peerA peerB) peer1 peer2;
+      inherit (sortedPeers peerA peerB) peer1 peer2;
     in "wireguard-${wgName}-psks-${peer1}+${peer2}";
 
     # All nodes that are part of this network
-    associatedNodes = nodes: filter (n: builtins.hasAttr wgName nodes.${n}.config.extra.wireguard) (attrNames nodes);
-    nodePeers = nodes: genAttrs (associatedNodes nodes) (n: nodes.${n}.config.extra.wireguard.${wgName}.address);
+    associatedNodes =
+      filter
+      (n: builtins.hasAttr wgName nodes.${n}.config.extra.wireguard)
+      (attrNames nodes);
+
+    # Partition nodes by whether they are servers
+    _associatedNodes_isServerPartition =
+      partition
+      (n: nodes.${n}.config.extra.wireguard.${wgName}.server.enable)
+      associatedNodes;
+
+    associatedServerNodes = _associatedNodes_isServerPartition.right;
+    associatedClientNodes = _associatedNodes_isServerPartition.wrong;
+
+    # Maps all nodes that are part of this network to their addresses
+    nodePeers = genAttrs associatedNodes (n: nodes.${n}.config.extra.wireguard.${wgName}.address);
+
+    # Only peers that are defined as externalPeers on the given node.
+    # Prepends "external-" to their name.
+    externalPeersForNode = node:
+      mapAttrs' (p: nameValuePair "external-${p}") nodes.${node}.config.extra.wireguard.${wgName}.externalPeers;
+
     # All peers that are defined as externalPeers on any node.
     # Prepends "external-" to their name.
-    externalPeers = nodes:
-      concatAttrs (
-        map (n: mapAttrs' (extPeerName: nameValuePair "external-${extPeerName}") nodes.${n}.config.extra.wireguard.${wgName}.externalPeers)
-        (associatedNodes nodes)
-      );
-    # Concatenation of all external peer names names without any transformations.
-    externalPeerNamesRaw = nodes: concatMap (n: attrNames nodes.${n}.config.extra.wireguard.${wgName}.externalPeers) (associatedNodes nodes);
-    # A list of all occurring addresses.
-    usedAddresses = nodes: let
-      nodesWithNet = associatedNodes nodes;
-    in
-      concatMap (n: nodes.${n}.config.extra.wireguard.${wgName}.address) nodesWithNet
-      ++ flatten (concatMap (n: attrValues nodes.${n}.config.extra.wireguard.${wgName}.externalPeers) nodesWithNet);
+    allExternalPeers = concatAttrs (map externalPeersForNode associatedNodes);
 
-    allPeers = nodes: nodePeers nodes // externalPeers nodes;
+    # All peers that are part of this network
+    allPeers = nodePeers // allExternalPeers;
+
+    # Concatenation of all external peer names names without any transformations.
+    externalPeerNamesRaw = concatMap (n: attrNames nodes.${n}.config.extra.wireguard.${wgName}.externalPeers) associatedNodes;
+
+    # A list of all occurring addresses.
+    usedAddresses =
+      concatMap (n: nodes.${n}.config.extra.wireguard.${wgName}.address) associatedNodes
+      ++ flatten (concatMap (n: attrValues nodes.${n}.config.extra.wireguard.${wgName}.externalPeers) associatedNodes);
   };
 }