Implement initial SSH data retrieval

src/sync/sync.go

@@ -3,17 +3,15 @@ package sync
 import (
 	"fmt"
 	"github.com/rwinkhart/MUTN/src/backend"
+	"golang.org/x/crypto/ssh"
 	"os"
+	"strconv"
+	"strings"
 )
 
-// returns lists of local entries and mod times (two separate lists)
-func getLocalData() {
-	fileList, _ := WalkEntryDir()
-	fmt.Println(fileList) // TODO placeholder
-}
-
-// RunJob runs the SSH sync job
-func RunJob(manualSync bool) {
+// getSSHOutput runs a command over SSH and returns the output
+// currently only supports password-less key-based authentication TODO add password support, still require key
+func getSSHOutput(cmd string, manualSync bool) string {
 	// get SSH config info, exit if not configured (displaying an error if the sync job was called manually)
 	var sshUserIPPortIdentity []string
 	if manualSync {
@@ -22,21 +20,126 @@ func RunJob(manualSync bool) {
 		sshUserIPPortIdentity = backend.ReadConfig([]string{"sshUser", "sshIP", "sshPort", "sshIdentity"}, "0")
 	}
 
-	var sshUser, sshIP, sshPort, sshIdentity string
+	var user, ip, port, identity string
 	for i, key := range sshUserIPPortIdentity {
 		switch i {
 		case 0:
-			sshUser = key
+			user = key
 		case 1:
-			sshIP = key
+			ip = key
 		case 2:
-			sshPort = key
+			port = key
 		case 3:
-			sshIdentity = key
+			identity = key
 		}
 	}
 
-	fmt.Println(sshUser, sshIP, sshPort, sshIdentity) // TODO placeholder
+	// read and parse private key
+	key, err := os.ReadFile(identity)
+	if err != nil {
+		fmt.Println(backend.AnsiError+"Sync failed - unable to read private key file:", identity+backend.AnsiReset)
+		os.Exit(1)
+	}
+	parsedKey, err := ssh.ParsePrivateKey(key)
+	if err != nil {
+		fmt.Println(backend.AnsiError+"Sync failed - Unable to parse private key:", identity+backend.AnsiReset)
+		os.Exit(1)
+	}
 
+	// configure SSH client
+	sshConfig := &ssh.ClientConfig{
+		User: user,
+		Auth: []ssh.AuthMethod{
+			ssh.PublicKeys(parsedKey),
+		},
+	}
+	sshConfig.HostKeyCallback = ssh.InsecureIgnoreHostKey() // TODO remove
+
+	// connect to SSH server
+	sshClient, err := ssh.Dial("tcp", ip+":"+port, sshConfig)
+	if err != nil {
+		fmt.Println(backend.AnsiError+"Sync failed - Unable to connect to remote server:", err.Error()+backend.AnsiReset)
+		os.Exit(1)
+	}
+	defer sshClient.Close()
+
+	// create a session
+	sshSession, err := sshClient.NewSession()
+	if err != nil {
+		fmt.Println(backend.AnsiError+"Sync failed - Unable to establish SSH session:", err.Error()+backend.AnsiReset)
+		os.Exit(1)
+	}
+
+	// run the provided command
+	output, err := sshSession.CombinedOutput(cmd)
+	if err != nil {
+		fmt.Println(backend.AnsiError+"Sync failed - Unable to run SSH command:", err.Error()+backend.AnsiReset)
+		os.Exit(1)
+	}
+
+	// convert the output to a string and remove leading/trailing whitespace
+	outputString := string(output)
+	outputString = strings.TrimSpace(outputString)
+
+	return outputString
+}
+
+// getRemoteData returns lists of remote entries, mod times, folders, and deletions (four separate lists)
+func getRemoteData(manualSync bool) ([]string, []int64, []string, []string) {
+	// get remote output over SSH
+	output := getSSHOutput("ls && uname -r", manualSync) // TODO replace cmd with remote server command (e.g. "libmuttonserver fetch")
+
+	// split output into slice based on occurrences of "\x1f"
+	outputSlice := strings.Split(output, "\x1f")
+
+	// re-form the lists
+	entries := strings.Split(outputSlice[0], "\n")
+	modsStrings := strings.Split(outputSlice[1], "\n")
+	folders := strings.Split(outputSlice[2], "\n")
+	deletions := strings.Split(outputSlice[3], "\n")
+
+	// convert the mod times to int64
+	var mods []int64
+	for _, modString := range modsStrings {
+		mod, _ := strconv.ParseInt(modString, 10, 64)
+		mods = append(mods, mod)
+	}
+
+	return entries, mods, folders, deletions
+}
+
+// getLocalData returns lists of local entries and mod times (two separate lists)
+func getLocalData() ([]string, []int64) {
+	// get a list of all entries
+	fileList, _ := WalkEntryDir()
+
+	// get a list of all entry modification times
+	var modList []int64
+	for _, file := range fileList {
+		modTime, _ := os.Stat(backend.EntryRoot + file)
+		modList = append(modList, modTime.ModTime().Unix())
+	}
+
+	// return the lists
+	return fileList, modList
+}
+
+// RunJob runs the SSH sync job
+func RunJob(manualSync bool) {
+	// TODO fetch remote lists
+	remoteEntries, remoteMods, remoteFolders, remoteDeletions := getRemoteData(manualSync)
+	fmt.Println(remoteEntries, remoteMods, remoteFolders, remoteDeletions) // TODO placeholder
+
+	// TODO sync deletions and folders
+
+	// fetch local lists
+	localEntries, localMods := getLocalData()
+	fmt.Println(localEntries, localMods) // TODO placeholder
+
+	// TODO sort both local and remote entry/mod lists to ensure common entries are listed first
+
+	// TODO sync new and updated entries
+
+	// exit program after successful sync
 	os.Exit(0)
 }