Package davmail.exchange

Class ICSCalendarValidator

java.lang.Object

davmail.exchange.ICSCalendarValidator

public class ICSCalendarValidator
extends Object

Validator for iCalendar data according to RFC 5545 specifications. This implementation provides comprehensive validation and repair capabilities for iCalendar content, specifically focusing on character validation rather than XML structure.

This helpful tool addresses synchronization issues between different calendar clients (OWA, Outlook, and Thunderbird via DavMail) where calendar entries containing invalid characters are handled differently across platforms. These problematic entries originate from the MS Exchange Server, where they were either stored with invalid characters or became corrupted during storage. While OWA and Outlook silently hide such entries without displaying them to users, Thunderbird logs XML parse errors in its error console. The validator provides detailed validation information about invalid characters and offers repair functionality to automatically remove problematic characters while preserving valid content.

The implementation was developed to address a specific issue where calendar entries containing invalid string content are hidden in OWA and Outlook, making them inaccessible for manual deletion or repair. Since these entries are not visible in OWA and Outlook, users cannot remove or fix them before synchronization to Thunderbird, where they cause XML parsing errors. The solution provides a way to detect and repair these problematic entries, which could otherwise be handled by DavMail during the synchronization process. The issue is documented in Bugzilla at ....

Since:

2025-02-05 // yyyy-mm-dd

Author:

ifrh (GitHub), ifrh (SourceForge)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ICSCalendarValidator.ValidationResult	Result structure for validation results.

Field Summary

Fields

Modifier and Type	Field	Description
protected static final org.apache.log4j.Logger	LOGGER

Constructor Summary

Constructors

Constructor	Description
ICSCalendarValidator()

Method Summary

Modifier and Type	Method	Description
static boolean	isValidICSContent(String content)	Validates whether a string contains only valid characters for iCalendar content.
static String	repairICSContent(String content)	Repairs an iCalendar string by removing invalid characters.
static ICSCalendarValidator.ValidationResult	validateWithDetails(String content)	Returns detailed validation information about the content.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

LOGGER

protected static final org.apache.log4j.Logger LOGGER

Constructor Details

ICSCalendarValidator

public ICSCalendarValidator()

Method Details

isValidICSContent

public static boolean isValidICSContent(String content)

Validates whether a string contains only valid characters for iCalendar content. Ensures the string contains no null bytes and only printable ASCII characters, while allowing properly encoded Unicode characters.

Parameters:

content - The string to validate

Returns:

true if all characters are valid

validateWithDetails

public static ICSCalendarValidator.ValidationResult validateWithDetails(String content)

Returns detailed validation information about the content.

Parameters:

content - The string to validate

Returns:

ValidationResult object containing details

repairICSContent

public static String repairICSContent(String content)

Repairs an iCalendar string by removing invalid characters. Invalid characters are dropped rather than replaced to avoid introducing unexpected spaces in ICS property values.

Parameters:

content - The string to repair

Returns:

The repaired string with invalid characters removed