From 73cad447699024a5930da3281f338cf6a5324c61 Mon Sep 17 00:00:00 2001
From: Daniel Arroyo <darroylat@gmail.com>
Date: Thu, 9 Jul 2026 12:43:13 -0400
Subject: [PATCH] Bump version to 1.0.18

---
 Makefile                            |  2 +-
 cmd/server/main.go                  |  2 +-
 internal/syncengine/engine.go       | 14 ++++++++----
 internal/syncengine/rsync_runner.go | 34 ++++++++++++++++++++++-------
 4 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index eb097e1..7665584 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 BINARY=syncserver
-VERSION?=1.0.17
+VERSION?=1.0.18
 GO?=go
 LDFLAGS=-s -w -X main.version=$(VERSION) -X main.commit=$(shell git rev-parse --short HEAD 2>/dev/null || echo unknown)
 BUILD_FLAGS=CGO_ENABLED=0
diff --git a/cmd/server/main.go b/cmd/server/main.go
index 94bea9d..ff47302 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -20,7 +20,7 @@ import (
 	"github.com/syncserver/internal/syncengine"
 )
 
-var version = "1.0.17"
+var version = "1.0.18"
 
 func main() {
 	cfgPath := flag.String("config", "", "Path to config.yaml")
diff --git a/internal/syncengine/engine.go b/internal/syncengine/engine.go
index 95b6db8..f53e057 100644
--- a/internal/syncengine/engine.go
+++ b/internal/syncengine/engine.go
@@ -261,11 +261,17 @@ func (e *Engine) Run(ctx context.Context, jobID int64, pairID int64) error {
 
 	var result *RsyncResult
 	if isRemoteToRemote(srcMachine, dstMachine) {
+		destPrivKey, err := e.resolveSSHKey(dstMachine)
+		if err != nil {
+			slog.Warn("failed to resolve destination SSH key, using server key", "error", err)
+			destPrivKey = filepath.Join(e.cfg.SSHDir(), "id_ed25519")
+		}
 		result, err = runner.RunRemote(jobCtx, cfg, RemoteMachine{
-			Host:    srcMachine.Host,
-			Port:    srcMachine.Port,
-			SSHUser: srcMachine.SSHUser,
-			PrivKey: privKey,
+			Host:        srcMachine.Host,
+			Port:        srcMachine.Port,
+			SSHUser:     srcMachine.SSHUser,
+			PrivKey:     privKey,
+			DestPrivKey: destPrivKey,
 		}, onLine)
 	} else {
 		result, err = runner.Run(jobCtx, cfg, onLine)
diff --git a/internal/syncengine/rsync_runner.go b/internal/syncengine/rsync_runner.go
index 17f313a..12c9bba 100644
--- a/internal/syncengine/rsync_runner.go
+++ b/internal/syncengine/rsync_runner.go
@@ -2,6 +2,7 @@ package syncengine
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
 	"io"
 	"os/exec"
@@ -180,26 +181,43 @@ func (r *RsyncRunner) buildRemoteArgs(pair *SyncPairConfig) []string {
 }
 
 type RemoteMachine struct {
-	Host     string
-	Port     int
-	SSHUser  string
-	PrivKey  string
+	Host        string
+	Port        int
+	SSHUser     string
+	PrivKey     string
+	DestPrivKey string
 }
 
 func (r *RsyncRunner) RunRemote(ctx context.Context, pair *SyncPairConfig, remote RemoteMachine, onLine func(stream string, line string)) (*RsyncResult, error) {
-	args := r.buildRemoteArgs(pair)
+	args := r.buildArgs(pair)
+
+	var remoteCmd string
+	if remote.DestPrivKey != "" {
+		encodedKey := base64.StdEncoding.EncodeToString([]byte(remote.DestPrivKey))
+		innerSSH := fmt.Sprintf(`ssh -i /tmp/syncserver-dest-key -o StrictHostKeyChecking=accept-new -o UserKnownHostsFile=/dev/null`)
+		rsyncPart := fmt.Sprintf("rsync %s -e %q %s %s",
+			strings.Join(args, " "), innerSSH, pair.Source, pair.Dest)
+		remoteCmd = fmt.Sprintf(
+			`echo '%s' | base64 -d > /tmp/syncserver-dest-key && chmod 600 /tmp/syncserver-dest-key && %s; STATUS=$?; rm -f /tmp/syncserver-dest-key; exit $STATUS`,
+			encodedKey, rsyncPart)
+	} else {
+		remoteCmd = "rsync " + strings.Join(args, " ")
+	}
 
 	sshArgs := []string{
 		"ssh",
 		"-i", remote.PrivKey,
 		"-o", "StrictHostKeyChecking=accept-new",
 		"-o", "UserKnownHostsFile=" + strings.TrimRight(r.sshDir, "/") + "/known_hosts",
-		"-tt",
 		"-p", fmt.Sprintf("%d", remote.Port),
 		fmt.Sprintf("%s@%s", remote.SSHUser, remote.Host),
-		"rsync",
 	}
-	sshArgs = append(sshArgs, args...)
+	if remote.DestPrivKey != "" {
+		sshArgs = append(sshArgs, "bash", "-c", remoteCmd)
+	} else {
+		sshArgs = append(sshArgs, "rsync")
+		sshArgs = append(sshArgs, args...)
+	}
 
 	cmd := exec.CommandContext(ctx, "ssh", sshArgs...)