Fix host resolution and concurrent cache updates

internal/ssh/args.go

@@ -4,7 +4,7 @@ import "strings"
 
 // flagsWithArg lists all SSH flags that consume the following argument.
 var flagsWithArg = map[byte]bool{
-	'b': true, 'c': true, 'D': true, 'E': true, 'e': true,
+	'B': true, 'P': true, 'b': true, 'c': true, 'D': true, 'E': true, 'e': true,
 	'F': true, 'I': true, 'i': true, 'J': true, 'L': true,
 	'l': true, 'm': true, 'o': true, 'O': true, 'p': true,
 	'Q': true, 'R': true, 'S': true, 'w': true, 'W': true,
@@ -32,18 +32,16 @@ func Parse(args []string) *ParsedArgs {
 		}
 
 		if strings.HasPrefix(arg, "-") && len(arg) > 1 {
-			flag := arg[1]
-			if flagsWithArg[flag] {
-				if len(arg) > 2 {
-					// argument is attached, e.g. -p2222
-					i++
-				} else {
-					// argument is the next element, e.g. -p 2222
-					i += 2
+			// OpenSSH accepts clusters such as -vp 2222 and -vladmin.
+			for j := 1; j < len(arg); j++ {
+				if flagsWithArg[arg[j]] {
+					if j == len(arg)-1 {
+						i++
+					}
+					break
 				}
-			} else {
-				i++
 			}
+			i++
 			continue
 		}
 
@@ -86,35 +84,41 @@ func ReplaceHost(args []string, destIdx int, newHost string) []string {
 	return result
 }
 
-// HasPortFlag reports whether a port was specified via -p in args.
-func HasPortFlag(args []string) bool {
-	if parsed := Parse(args); parsed != nil {
-		args = args[:parsed.DestIdx]
-	}
-	for i, a := range args {
-		if a == "-p" && i+1 < len(args) {
-			return true
-		}
-		if len(a) > 2 && a[0] == '-' && a[1] == 'p' {
-			return true
-		}
-	}
-	return false
-}
+// HasPortFlag reports whether a port was explicitly supplied.
+func HasPortFlag(args []string) bool { return hasOption(args, 'p', "Port") }
 
-// HasUserFlag reports whether a user was specified via -l in args.
-// Used to avoid overriding an explicit -l with the configured default user.
-func HasUserFlag(args []string) bool {
-	if parsed := Parse(args); parsed != nil {
-		args = args[:parsed.DestIdx]
-	}
-	for i, a := range args {
-		if a == "-l" && i+1 < len(args) {
-			return true
+// HasUserFlag reports whether a login user was explicitly supplied.
+func HasUserFlag(args []string) bool { return hasOption(args, 'l', "User") }
+
+func hasOption(args []string, wanted byte, keyword string) bool {
+	for i := 0; i < len(args); i++ {
+		arg := args[i]
+		if arg == "--" || len(arg) < 2 || arg[0] != '-' {
+			break
 		}
-		// handle attached form: -lroot
-		if len(a) > 2 && a[0] == '-' && a[1] == 'l' {
-			return true
+		for j := 1; j < len(arg); j++ {
+			flag := arg[j]
+			if !flagsWithArg[flag] {
+				continue
+			}
+			value := arg[j+1:]
+			if value == "" {
+				i++
+				if i >= len(args) {
+					return false
+				}
+				value = args[i]
+			}
+			if flag == wanted {
+				return true
+			}
+			if flag == 'o' {
+				fields := strings.FieldsFunc(value, func(r rune) bool { return r == '=' || r == ' ' || r == '\t' })
+				if len(fields) >= 2 && strings.EqualFold(fields[0], keyword) {
+					return true
+				}
+			}
+			break
 		}
 	}
 	return false