SmtpUtils Class — netty Architecture

Source Code

codec-smtp/src/main/java/io/netty/handler/codec/smtp/SmtpUtils.java lines 22–76

final class SmtpUtils {

    static List<CharSequence> toUnmodifiableList(CharSequence... sequences) {
        if (sequences == null || sequences.length == 0) {
            return Collections.emptyList();
        }
        return Collections.unmodifiableList(Arrays.asList(sequences));
    }

    /**
     * Validates SMTP parameters to prevent SMTP command injection.
     * Throws IllegalArgumentException if any parameter contains CRLF sequences.
     */
    static void validateSMTPParameters(CharSequence... parameters) {
        if (parameters != null) {
            for (CharSequence parameter : parameters) {
                if (parameter != null) {
                    validateSMTPParameter(parameter);
                }
            }
        }
    }

    /**
     * Validates SMTP parameters to prevent SMTP command injection.
     * Throws IllegalArgumentException if any parameter contains CRLF sequences.
     */
    static void validateSMTPParameters(List<CharSequence> parameters) {
        if (parameters != null) {
            for (CharSequence parameter : parameters) {
                if (parameter != null) {
                    validateSMTPParameter(parameter);
                }
            }
        }
    }

    private static void validateSMTPParameter(CharSequence parameter) {
        if (parameter instanceof String) {
            String paramStr = (String) parameter;
            if (paramStr.indexOf('\r') != -1 || paramStr.indexOf('\n') != -1) {
                throw new IllegalArgumentException("SMTP parameter contains CRLF characters: " + parameter);
            }
        } else {
            for (int i = 0; i < parameter.length(); i++) {
                char c = parameter.charAt(i);
                if (c == '\r' || c == '\n') {
                    throw new IllegalArgumentException("SMTP parameter contains CRLF characters: " + parameter);
                }
            }
        }
    }

    private SmtpUtils() { }
}