[Init] Initial commit - NetMesh terminal manager

domain/sshAlgorithmList.ts

@@ -0,0 +1,207 @@
+/**
+ * User-selectable SSH algorithm lists for the host-level "advanced
+ * algorithm overrides" UI. These lists must remain a subset of the
+ * algorithms ssh2 actually supports (see `ssh2/lib/protocol/constants.js`);
+ * passing an algorithm outside that set causes ssh2 to throw
+ * "Unsupported algorithm" before the SSH handshake even starts.
+ *
+ * Order in each array is the suggested display / default-priority order
+ * (modern + secure first). When the user picks a subset, that subset
+ * fully replaces the negotiated list for the category.
+ */
+
+export type SSHAlgorithmCategory =
+  | "kex"
+  | "cipher"
+  | "hmac"
+  | "serverHostKey"
+  | "compress";
+
+// IMPORTANT: every algorithm in these lists must also appear in ssh2's
+// `SUPPORTED_*` constant (see `node_modules/ssh2/lib/protocol/constants.js`).
+// ssh2 throws `Unsupported algorithm` synchronously from `Client.connect()`
+// when it sees an algorithm outside its supported set, so exposing a dead
+// choice in the UI would make a host unreachable the moment the user
+// saved it.
+//
+// In particular, OpenSSL 3 disabled `blowfish`, `cast128`, and the
+// `arcfour` family — ssh2's `canUseCipher` filter then drops them from
+// `SUPPORTED_CIPHER` at startup. They are intentionally absent below.
+// `sshAlgorithmList.test.ts` enforces the subset invariant.
+
+export const SUPPORTED_KEX_ALGORITHMS: readonly string[] = [
+  "curve25519-sha256",
+  "curve25519-sha256@libssh.org",
+  "ecdh-sha2-nistp256",
+  "ecdh-sha2-nistp384",
+  "ecdh-sha2-nistp521",
+  "diffie-hellman-group-exchange-sha256",
+  "diffie-hellman-group14-sha256",
+  "diffie-hellman-group15-sha512",
+  "diffie-hellman-group16-sha512",
+  "diffie-hellman-group17-sha512",
+  "diffie-hellman-group18-sha512",
+  "diffie-hellman-group-exchange-sha1",
+  "diffie-hellman-group14-sha1",
+  "diffie-hellman-group1-sha1",
+];
+
+export const SUPPORTED_CIPHER_ALGORITHMS: readonly string[] = [
+  "chacha20-poly1305@openssh.com",
+  "aes128-gcm@openssh.com",
+  "aes256-gcm@openssh.com",
+  "aes128-gcm",
+  "aes256-gcm",
+  "aes128-ctr",
+  "aes192-ctr",
+  "aes256-ctr",
+  "aes128-cbc",
+  "aes192-cbc",
+  "aes256-cbc",
+  "3des-cbc",
+];
+
+export const SUPPORTED_HMAC_ALGORITHMS: readonly string[] = [
+  "hmac-sha2-256-etm@openssh.com",
+  "hmac-sha2-512-etm@openssh.com",
+  "hmac-sha1-etm@openssh.com",
+  "hmac-sha2-256",
+  "hmac-sha2-512",
+  "hmac-sha1",
+  "hmac-sha2-256-96",
+  "hmac-sha2-512-96",
+  "hmac-sha1-96",
+  "hmac-md5",
+  "hmac-md5-96",
+  "hmac-ripemd160",
+];
+
+export const SUPPORTED_SERVER_HOST_KEY_ALGORITHMS: readonly string[] = [
+  "ssh-ed25519",
+  "ecdsa-sha2-nistp256",
+  "ecdsa-sha2-nistp384",
+  "ecdsa-sha2-nistp521",
+  "rsa-sha2-512",
+  "rsa-sha2-256",
+  "ssh-rsa",
+  "ssh-dss",
+];
+
+export const SUPPORTED_COMPRESS_ALGORITHMS: readonly string[] = [
+  "none",
+  "zlib@openssh.com",
+  "zlib",
+];
+
+export const SUPPORTED_ALGORITHMS_BY_CATEGORY: Readonly<Record<SSHAlgorithmCategory, readonly string[]>> = {
+  kex: SUPPORTED_KEX_ALGORITHMS,
+  cipher: SUPPORTED_CIPHER_ALGORITHMS,
+  hmac: SUPPORTED_HMAC_ALGORITHMS,
+  serverHostKey: SUPPORTED_SERVER_HOST_KEY_ALGORITHMS,
+  compress: SUPPORTED_COMPRESS_ALGORITHMS,
+};
+
+export const SSH_ALGORITHM_CATEGORIES: readonly SSHAlgorithmCategory[] = [
+  "kex",
+  "cipher",
+  "hmac",
+  "serverHostKey",
+  "compress",
+];
+
+// Mirror of what `electron/bridges/sshAlgorithms.cjs#buildAlgorithms(false)`
+// actually emits in non-legacy mode. Used by the UI to seed a category's
+// first customization with the *current effective default* rather than the
+// full SUPPORTED list — otherwise unchecking a single modern algorithm
+// would inadvertently introduce CBC / arcfour / MD5 into the offer list.
+//
+// `hmac` and `serverHostKey` here mirror ssh2's `DEFAULT_MAC` and
+// `DEFAULT_SERVER_HOST_KEY` because non-legacy mode leaves both fields
+// unset, letting ssh2 fall back to those defaults. Keep them in sync if
+// the ssh2 dependency bumps.
+const MODERN_DEFAULT_ALGORITHMS: Readonly<Record<SSHAlgorithmCategory, readonly string[]>> = {
+  kex: [
+    "curve25519-sha256",
+    "curve25519-sha256@libssh.org",
+    "ecdh-sha2-nistp256",
+    "ecdh-sha2-nistp384",
+    "ecdh-sha2-nistp521",
+    "diffie-hellman-group14-sha256",
+    "diffie-hellman-group16-sha512",
+    "diffie-hellman-group18-sha512",
+    "diffie-hellman-group-exchange-sha256",
+  ],
+  cipher: [
+    "aes128-gcm@openssh.com",
+    "aes256-gcm@openssh.com",
+    "aes128-ctr",
+    "aes192-ctr",
+    "aes256-ctr",
+    "chacha20-poly1305@openssh.com",
+  ],
+  hmac: [
+    "hmac-sha2-256-etm@openssh.com",
+    "hmac-sha2-512-etm@openssh.com",
+    "hmac-sha1-etm@openssh.com",
+    "hmac-sha2-256",
+    "hmac-sha2-512",
+    "hmac-sha1",
+  ],
+  serverHostKey: [
+    "ssh-ed25519",
+    "ecdsa-sha2-nistp256",
+    "ecdsa-sha2-nistp384",
+    "ecdsa-sha2-nistp521",
+    "rsa-sha2-512",
+    "rsa-sha2-256",
+    "ssh-rsa",
+  ],
+  compress: ["none"],
+};
+
+// Additions appended when legacy mode is on — matches
+// `applyLegacyAlgorithms` + `applyLegacyHmacAlgorithms` in
+// `electron/bridges/sshAlgorithms.cjs`. `hmac-md5` is conditional on
+// runtime support there but we seed it unconditionally; ssh2 will surface
+// "Unsupported algorithm" at connect time on FIPS Node builds, which is
+// acceptable as a UI hint that the user picked something the runtime
+// rejects.
+const LEGACY_DEFAULT_ADDITIONS: Partial<Record<SSHAlgorithmCategory, readonly string[]>> = {
+  kex: [
+    "diffie-hellman-group14-sha1",
+    "diffie-hellman-group1-sha1",
+    "diffie-hellman-group-exchange-sha1",
+  ],
+  cipher: ["aes128-cbc", "aes256-cbc", "3des-cbc"],
+  hmac: ["hmac-md5"],
+  serverHostKey: ["ssh-dss"],
+};
+
+/**
+ * Return the algorithm list that NetCatty would actually offer for each
+ * category at connect time given the current legacy toggle. The advanced
+ * override UI seeds an untouched category from this list so a partial
+ * customization can't accidentally re-enable algorithms the connection
+ * wouldn't otherwise advertise.
+ */
+export function effectiveDefaultAlgorithms(
+  legacyEnabled: boolean,
+): Record<SSHAlgorithmCategory, readonly string[]> {
+  const result: Record<SSHAlgorithmCategory, string[]> = {
+    kex: [...MODERN_DEFAULT_ALGORITHMS.kex],
+    cipher: [...MODERN_DEFAULT_ALGORITHMS.cipher],
+    hmac: [...MODERN_DEFAULT_ALGORITHMS.hmac],
+    serverHostKey: [...MODERN_DEFAULT_ALGORITHMS.serverHostKey],
+    compress: [...MODERN_DEFAULT_ALGORITHMS.compress],
+  };
+  if (legacyEnabled) {
+    for (const category of SSH_ALGORITHM_CATEGORIES) {
+      const additions = LEGACY_DEFAULT_ADDITIONS[category];
+      if (!additions) continue;
+      for (const algo of additions) {
+        if (!result[category].includes(algo)) result[category].push(algo);
+      }
+    }
+  }
+  return result;
+}