Fix UTF-8 handling in ADO connection string parsing

Replace WriteByte with WriteRune in splitAdoConnectionStringParts to properly handle multibyte UTF-8 characters. Add comprehensive test cases with Cyrillic, Chinese, emoji, and accented characters in quoted connection string values.

Co-authored-by: shueybubbles <[email protected]>

Author: Copilot

msdsn/conn_str.go

@@ -712,26 +712,27 @@ func splitAdoConnectionStringParts(dsn string) []string {
 	var current strings.Builder
 	inQuotes := false
 
-	for i := 0; i < len(dsn); i++ {
-		char := dsn[i]
+	runes := []rune(dsn)
+	for i := 0; i < len(runes); i++ {
+		char := runes[i]
 
 		if char == '"' {
-			if inQuotes && i+1 < len(dsn) && dsn[i+1] == '"' {
+			if inQuotes && i+1 < len(runes) && runes[i+1] == '"' {
 				// Double quote escape sequence - add both quotes to current part
-				current.WriteByte(char)
-				current.WriteByte(dsn[i+1])
+				current.WriteRune(char)
+				current.WriteRune(runes[i+1])
 				i++ // Skip the next quote
 			} else {
 				// Start or end of quoted section
 				inQuotes = !inQuotes
-				current.WriteByte(char)
+				current.WriteRune(char)
 			}
 		} else if char == ';' && !inQuotes {
 			// Semicolon outside of quotes - end current part
 			parts = append(parts, current.String())
 			current.Reset()
 		} else {
-			current.WriteByte(char)
+			current.WriteRune(char)
 		}
 	}
 

msdsn/conn_str_test.go

@@ -130,6 +130,14 @@ func TestValidConnectionString(t *testing.T) {
 		{"password=\";;\"", func(p Config) bool { return p.Password == ";;" }}, // Multiple semicolons
 		{"server=\"host;name\";password=\"pass;word\"", func(p Config) bool { return p.Host == "host;name" && p.Password == "pass;word" }}, // Multiple quoted values
 
+		// Test cases with multibyte UTF-8 characters
+		{"password=\"пароль;test\"", func(p Config) bool { return p.Password == "пароль;test" }}, // Cyrillic characters with semicolon
+		{"server=\"服务器;name\";password=\"密码;word\"", func(p Config) bool { return p.Host == "服务器;name" && p.Password == "密码;word" }}, // Chinese characters
+		{"password=\"🔐;secret;🗝️\"", func(p Config) bool { return p.Password == "🔐;secret;🗝️" }}, // Emoji characters with semicolons
+		{"user id=\"用户名\";password=\"пароль\"", func(p Config) bool { return p.User == "用户名" && p.Password == "пароль" }}, // Mixed multibyte chars
+		{"password=\"测试\"\"密码\"\"\"", func(p Config) bool { return p.Password == "测试\"密码\"" }}, // Chinese chars with escaped quotes
+		{"password=\"café;naïve;résumé\"", func(p Config) bool { return p.Password == "café;naïve;résumé" }}, // Accented characters
+		
 		// those are supported currently, but maybe should not be
 		{"someparam", func(p Config) bool { return true }},
 		{";;=;", func(p Config) bool { return true }},