{ config, hostName, lib, pkgs, ... }: with lib; let listenPort = 51820; udp2rawPort = 51821; subnet = "2a03:4000:52:ada:1"; subnetLength = 80; hostLength = subnetLength + 16; links = [ { from = "vidhar"; to = "surtr"; endpointHost = "surtr.yggdrasil.li"; persistentKeepalive = 25; dynamicEndpointRefreshSeconds = 86400; } { from = "sif"; to = "surtr"; endpointHost = "surtr.yggdrasil.li"; persistentKeepalive = 25; dynamicEndpointRefreshSeconds = 86400; } ]; routes = [ { from = "sif"; to = "vidhar"; via = "surtr"; } { from = "vidhar"; to = "sif"; via = "surtr"; } ]; hostIPs = { surtr = ["${subnet}::/${toString hostLength}"]; vidhar = ["${subnet}:1::/${toString hostLength}"]; sif = ["${subnet}:2::/${toString hostLength}"]; }; mkPublicKeyPath = host: ./hosts + "/${host}.pub"; mkPrivateKeyPath = host: ./hosts + "/${host}.priv"; publicKeyPath = mkPublicKeyPath hostName; privateKeyPath = mkPrivateKeyPath hostName; inNetwork = pathExists privateKeyPath && pathExists publicKeyPath; hostLinks = filter ({ from, to, ... }: from == hostName || to == hostName) links; hostRoutes = filter ({ from, to, ... }: from == hostName || to == hostName) routes; isRouter = inNetwork && any ({via, ...}: via == hostName) routes; linkToPeer = ix: opts@{from, to, ...}: let other = if from == hostName then to else from; in { allowedIPs = hostIPs.${other} ++ concatMap (rArgs: if rArgs.from != hostName || rArgs.via != to then [] else hostIPs.${rArgs.to}) routes; publicKey = trim (readFile (mkPublicKeyPath other)); } // (optionalAttrs (from == hostName) (filterAttrs (n: _v: !(elem n ["from" "to" "endpointHost"])) opts // optionalAttrs (opts ? "endpointHost") { endpoint = "localhost:${toString (udp2rawPort + ix)}"; })); trim = str: if hasSuffix "\n" str then trim (removeSuffix "\n" str) else str; stripSubnet = addr: let matchRes = builtins.match "^(.*)/[0-9]+$" addr; in if matchRes == null then addr else elemAt matchRes 0; in { config = { assertions = [ { assertion = inNetwork || !(pathExists privateKeyPath || pathExists publicKeyPath); message = "yggdrasil-wg: Either both public and private keys must exist or neither."; } { assertion = !inNetwork || (hostIPs ? "${hostName}"); message = "yggdrasil-wg: Entry in hostIPs must exist."; } ] ++ map ({from, to, ...}: let other = if from == hostName then to else from; in { assertion = pathExists (mkPublicKeyPath other); message = "yggdrasil-wg: This host (${hostName}) has a link with ‘${other}’, but no public key is available for ‘${other}’."; }) hostLinks; networking.wireguard.interfaces = mkIf inNetwork { yggdrasil = { allowedIPsAsRoutes = false; inherit listenPort; ips = hostIPs.${hostName}; peers = imap0 linkToPeer hostLinks; privateKeyFile = config.sops.secrets."yggdrasil-wg.priv".path; postSetup = '' ${concatMapStringsSep "\n" (linkArgs: let other = if linkArgs.from == hostName then linkArgs.to else linkArgs.from; in concatMapStringsSep "\n" (otherIP: "ip route replace \"${otherIP}\" dev \"yggdrasil\" table \"main\"") hostIPs.${other}) hostLinks} ${concatMapStringsSep "\n" (routeArgs: let other = if routeArgs.from == hostName then routeArgs.to else routeArgs.from; in concatMapStringsSep "\n" (otherIP: concatMapStringsSep "\n" (viaIP: "ip route replace \"${otherIP}\" via \"${viaIP}\" dev \"yggdrasil\" table \"main\"") (map stripSubnet hostIPs.${routeArgs.via})) hostIPs.${other}) hostRoutes} ''; }; }; systemd.services = listToAttrs (filter ({ value, ...}: value != null) (imap0 (ix: opts@{to, from, ...}: let other = if from == hostName then to else from; in nameValuePair "yggdrasil-udp2raw@${other}" (if opts ? "endpointHost" then { requiredBy = ["wireguard-yggdrasil.service"]; serviceConfig = { ExecStart = "${pkgs.udp2raw}/bin/udp2raw ${if from == hostName then "-c -l localhost:${toString (udp2rawPort + ix)} -r ${opts.endpointHost}:${toString (udp2rawPort + ix)}" else "-s -l 0.0.0.0:${toString (udp2rawPort + ix)} -r localhost:${toString listenPort}"} -k tmpkey --auth-mode hmac_sha1 --raw-mode faketcp -a"; }; } else null)) hostLinks)) // { firewall.path = optionals isRouter [pkgs.procps]; }; sops.secrets = mkIf (pathExists privateKeyPath) { "yggdrasil-wg.priv" = { format = "binary"; sopsFile = privateKeyPath; }; }; networking.hosts = mkIf inNetwork (listToAttrs (concatMap ({name, value}: map (ip: nameValuePair (stripSubnet ip) ["${name}.yggdrasil"]) value) (mapAttrsToList nameValuePair hostIPs))); networking.firewall = mkIf isRouter { extraCommands = '' ip6tables -A FORWARD -i yggdrasil -o yggdrasil -j nixos-fw-accept ip46tables -A FORWARD -j nixos-fw-log-refuse sysctl net.ipv6.conf.all.forwarding=1 ''; extraStopCommands = '' sysctl net.ipv6.conf.all.forwarding=0 ip46tables -D FORWARD -j nixos-fw-log-refuse || true ip6tables -D FORWARD -i yggdrasil -o yggdrasil -j nixos-fw-accept || true ''; }; }; }