Package de.xima.fc.security.malware

Class ExtensionCheck

java.lang.Object
de.xima.fc.security.malware.ExtensionCheck
public class ExtensionCheck extends Object
Helper class to verify a file's extension against its content.

  • Constructor Details

    • ExtensionCheck

      public ExtensionCheck()

  • Method Details

    • verify

      public ExtensionCheckReport verify(String fileName, InputStream inputStream) throws IOException
      Compares the MIME type detected by Tika (by examining the streams content) with the one suggested by the provided context MIME mapper.
      • If no MIME normalizer has been set, DFLT_NORMALIZER will be used.
      • If the MIME normalizer has been explicitly set to null, no normalization will be done.
      Parameters:
      fileName - the name of the file (used to request the MIME type corresponding to the file's extension from the context MIME mapper)
      inputStream - the input stream to detect the file's actual content type
      Returns:
      a report object describing the result of this content type verification.
      Throws:
      IOException - if an I/O error occurs while reading the input stream

    • withAllowUnknownTypes

      public ExtensionCheck withAllowUnknownTypes(boolean allowUnknownTypes)
      Sets whether unknown types (undetected by the ContentTypeUtils or unknown to the context mime mapper) should be allowed or rejected.
      Parameters:
      allowUnknownTypes - the flag to set (if true, unknown types are allowed, if false not)
      Returns:
      This instance for chaining method calls.

    • withExtensionToMimeTypeMapper

      public ExtensionCheck withExtensionToMimeTypeMapper(Function<String,Set<String>> contextMimeMapper)
      Sets the required MIME mapper that finds possible content types for a given file name.

      This mapper is used to obtain a whitelist of content types for a file name; against which the detected MIME type is then compared.

      Parameters:
      contextMimeMapper - A Function that takes a file name and returns one or more MIME types corresponding to the file name's extension.
      Returns:
      This instance for chaining method calls.

    • withMimeNormalizer

      public ExtensionCheck withMimeNormalizer(Function<String,String> mimeNormalizer)
      Sets an optional, use case dependent MIME type normalizer to handle different MIME types describing the same content (e.g. 'application/xml', 'text/xml' and 'application/xhtml+xml' may be mapped to 'text/plain').
      Parameters:
      mimeNormalizer - the MIME normalizer to use.
      Returns:
      This instance for chaining method calls.

    • defaultMimeMapper

      public static Function<String,Set<String>> defaultMimeMapper()
      Returns:
      Default MIME mapper that uses the file's extension to determine the MIME type.

    • defaultNormalizer

      public static Function<String,String> defaultNormalizer()
      Returns:
      Default MIME normalizer that simply canonicalizes the MIME type to a fixed string representation.