KalleOlaviNiemitalo commented on code in PR #3857:
URL: https://github.com/apache/avro/pull/3857#discussion_r3566008879
##########
lang/csharp/src/apache/main/File/Codec.cs:
##########
@@ -29,6 +29,87 @@ namespace Avro.File
/// </summary>
public abstract class Codec
{
+ /// <summary>
+ /// Default upper bound, in bytes, on the size a single data-file
block may
+ /// decompress to. A block with a very high compression ratio (or a
malformed
+ /// block) can otherwise expand to far more memory than its compressed
size.
+ /// Mirrors the Java SDK's decompression limit (AVRO-4247).
Overridable with
+ /// the AVRO_MAX_DECOMPRESS_LENGTH environment variable.
+ /// </summary>
+ public const long DefaultMaxDecompressLength = 200L * 1024 * 1024; //
200 MiB
+
+ /// <summary>
+ /// Name of the environment variable used to override the default
maximum
+ /// decompressed size of a single block.
+ /// </summary>
+ public const string MaxDecompressLengthEnvVar =
"AVRO_MAX_DECOMPRESS_LENGTH";
Review Comment:
This one, on the other hand, is less likely to be changed in the future, so
`const` seems OK.
##########
lang/csharp/src/apache/main/File/Codec.cs:
##########
@@ -29,6 +29,87 @@ namespace Avro.File
/// </summary>
public abstract class Codec
{
+ /// <summary>
+ /// Default upper bound, in bytes, on the size a single data-file
block may
+ /// decompress to. A block with a very high compression ratio (or a
malformed
+ /// block) can otherwise expand to far more memory than its compressed
size.
+ /// Mirrors the Java SDK's decompression limit (AVRO-4247).
Overridable with
+ /// the AVRO_MAX_DECOMPRESS_LENGTH environment variable.
+ /// </summary>
+ public const long DefaultMaxDecompressLength = 200L * 1024 * 1024; //
200 MiB
+
+ /// <summary>
+ /// Name of the environment variable used to override the default
maximum
+ /// decompressed size of a single block.
+ /// </summary>
+ public const string MaxDecompressLengthEnvVar =
"AVRO_MAX_DECOMPRESS_LENGTH";
+
+ /// <summary>
+ /// The maximum number of bytes a single block is allowed to
decompress to.
+ /// </summary>
+ /// <returns>The configured limit, honoring the environment
override.</returns>
+ public static long GetMaxDecompressLength()
+ {
+ var value =
Environment.GetEnvironmentVariable(MaxDecompressLengthEnvVar);
+ if (value != null && long.TryParse(value, out var parsed) &&
parsed > 0)
Review Comment:
Could specify `CultureInfo.InvariantCulture`. I'm not sure it has any
important effect here though, because the values are expected to be positive
and thus `NumberFormatInfo.NegativeSign` shouldn't matter.
##########
lang/csharp/src/apache/main/File/Codec.cs:
##########
@@ -29,6 +29,87 @@ namespace Avro.File
/// </summary>
public abstract class Codec
{
+ /// <summary>
+ /// Default upper bound, in bytes, on the size a single data-file
block may
+ /// decompress to. A block with a very high compression ratio (or a
malformed
+ /// block) can otherwise expand to far more memory than its compressed
size.
+ /// Mirrors the Java SDK's decompression limit (AVRO-4247).
Overridable with
+ /// the AVRO_MAX_DECOMPRESS_LENGTH environment variable.
+ /// </summary>
+ public const long DefaultMaxDecompressLength = 200L * 1024 * 1024; //
200 MiB
+
+ /// <summary>
+ /// Name of the environment variable used to override the default
maximum
+ /// decompressed size of a single block.
+ /// </summary>
+ public const string MaxDecompressLengthEnvVar =
"AVRO_MAX_DECOMPRESS_LENGTH";
+
+ /// <summary>
+ /// The maximum number of bytes a single block is allowed to
decompress to.
+ /// </summary>
+ /// <returns>The configured limit, honoring the environment
override.</returns>
+ public static long GetMaxDecompressLength()
+ {
+ var value =
Environment.GetEnvironmentVariable(MaxDecompressLengthEnvVar);
+ if (value != null && long.TryParse(value, out var parsed) &&
parsed > 0)
+ {
+ return parsed;
+ }
+
+ return DefaultMaxDecompressLength;
+ }
+
+ /// <summary>
+ /// Throws if the given decompressed length exceeds the maximum
allowed.
+ /// </summary>
+ /// <param name="length">The number of decompressed bytes.</param>
+ /// <param name="maxLength">The maximum number of decompressed bytes
allowed.</param>
+ public static void CheckDecompressLength(long length, long maxLength)
+ {
+ if (length > maxLength)
+ {
+ throw new AvroRuntimeException(
+ $"Decompressed block size {length} exceeds the maximum
allowed of {maxLength} bytes. " +
+ $"Set the {MaxDecompressLengthEnvVar} environment variable
to raise the limit.");
Review Comment:
When called from `CopyBounded`, `length` might not be the total length of
the uncompressed data, so the user doesn't know what value in the environment
variable would prevent the exception. But this seems the best that can be done
here because `DeflateStream.Length` (and `GZipStream.Length`) would throw
`NotSupportedException` and just reading to the end while discarding the data
would still allow denial of service.
##########
lang/csharp/src/apache/main/File/Codec.cs:
##########
@@ -29,6 +29,87 @@ namespace Avro.File
/// </summary>
public abstract class Codec
{
+ /// <summary>
+ /// Default upper bound, in bytes, on the size a single data-file
block may
+ /// decompress to. A block with a very high compression ratio (or a
malformed
+ /// block) can otherwise expand to far more memory than its compressed
size.
+ /// Mirrors the Java SDK's decompression limit (AVRO-4247).
Overridable with
+ /// the AVRO_MAX_DECOMPRESS_LENGTH environment variable.
+ /// </summary>
+ public const long DefaultMaxDecompressLength = 200L * 1024 * 1024; //
200 MiB
Review Comment:
`static readonly` might be better than `const` here, so that the compiler
won't copy the value to other assemblies that reference this one, and changing
the default in the future won't require recompiling those assemblies.
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