Fix known-hosts trust deadlock, host key stat, and optional nozstd build

- stdout logger: release mutex while waiting on pause resume so prompt
  callbacks can log (fixes hang after trusting new hosts; known_hosts
  was written but Resume never ran).
- known hosts callback: stop borrowing the SSH dial throttle channel
  (could block or interact badly with parallel handshakes).
- host key path: use errors.Is(..., fs.ErrNotExist) for RootedPath.Stat
  wrapped errors; stat errors now fail fast instead of mis-read.
- public key path: same ErrNotExist check for authorized_keys miss.
- Build: optional DTAIL_NO_ZSTD=yes / nozstd tag for CGO-free builds;
  split zstd readers into tagged files.
- Docs/examples: firewalld note for port 2222, log prune timer+script,
  SSHBindAddress note, dserver unit disabled-by-default comment;
  firewalld helper script example.
- Regression test for stdout pause/mutex behavior.

Made-with: Cursor

1 files changed, 4 insertions, 4 deletions

diff --git a/internal/ssh/client/authmethods.go b/internal/ssh/client/authmethods.go
index 7ac4d0c..3cd1bb3 100644
--- a/internal/ssh/client/authmethods.go
+++ b/internal/ssh/client/authmethods.go
@@ -18,7 +18,7 @@ var (
 
 // InitSSHAuthMethods initialises all known SSH auth methods on the client side.
 func InitSSHAuthMethods(sshAuthMethods []gossh.AuthMethod,
-	hostKeyCallback gossh.HostKeyCallback, trustAllHosts bool, throttleCh chan struct{},
+	hostKeyCallback gossh.HostKeyCallback, trustAllHosts bool,
 	privateKeyPath string, agentKeyIndex int) ([]gossh.AuthMethod, HostKeyCallback) {
 
 	if len(sshAuthMethods) > 0 {
@@ -28,10 +28,10 @@ func InitSSHAuthMethods(sshAuthMethods []gossh.AuthMethod,
 		}
 		return sshAuthMethods, simpleCallback
 	}
-	return initKnownHostsAuthMethods(trustAllHosts, throttleCh, privateKeyPath, agentKeyIndex)
+	return initKnownHostsAuthMethods(trustAllHosts, privateKeyPath, agentKeyIndex)
 }
 
-func initKnownHostsAuthMethods(trustAllHosts bool, throttleCh chan struct{},
+func initKnownHostsAuthMethods(trustAllHosts bool,
 	privateKeyPath string, agentKeyIndex int) ([]gossh.AuthMethod, HostKeyCallback) {
 
 	knownHostsFile := fmt.Sprintf("%s/.ssh/known_hosts", os.Getenv("HOME"))
@@ -40,7 +40,7 @@ func initKnownHostsAuthMethods(trustAllHosts bool, throttleCh chan struct{},
 		knownHostsFile = "./known_hosts"
 	}
 
-	knownHostsCallback, err := NewKnownHostsCallback(knownHostsFile, trustAllHosts, throttleCh)
+	knownHostsCallback, err := NewKnownHostsCallback(knownHostsFile, trustAllHosts)
 	if err != nil {
 		dlog.Client.FatalPanic(knownHostsFile, err)
 	}