json to input: retry if decompress too large

arbcompress/native.go

@@ -12,7 +12,10 @@ package arbcompress
 #include "arbitrator.h"
 */
 import "C"
-import "fmt"
+import (
+	"errors"
+	"fmt"
+)
 
 type u8 = C.uint8_t
 type u32 = C.uint32_t
@@ -44,6 +47,8 @@ func Compress(input []byte, level uint32, dictionary Dictionary) ([]byte, error)
 	return output, nil
 }
 
+var ErrOutputWontFit = errors.New("output won't fit in maxsize")
+
 func Decompress(input []byte, maxSize int) ([]byte, error) {
 	return DecompressWithDictionary(input, maxSize, EmptyDictionary)
 }
@@ -54,6 +59,9 @@ func DecompressWithDictionary(input []byte, maxSize int, dictionary Dictionary)
 	inbuf := sliceToBuffer(input)
 
 	status := C.brotli_decompress(inbuf, outbuf, C.Dictionary(dictionary))
+	if status == C.BrotliStatus_NeedsMoreOutput {
+		return nil, ErrOutputWontFit
+	}
 	if status != C.BrotliStatus_Success {
 		return nil, fmt.Errorf("failed decompression: %d", status)
 	}

validator/server_api/json.go

@@ -6,6 +6,7 @@ package server_api
 import (
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 
@@ -152,9 +153,21 @@ func ValidationInputFromJson(entry *InputJSON) (*validator.ValidationInput, erro
 			if err != nil {
 				return nil, err
 			}
-			uncompressed, err := arbcompress.Decompress(decoded, 30000000)
-			if err != nil {
-				return nil, err
+			maxSize := 2_000_000
+			var uncompressed []byte
+			for {
+				uncompressed, err = arbcompress.Decompress(decoded, maxSize)
+				if errors.Is(err, arbcompress.ErrOutputWontFit) {
+					if maxSize >= 128_000_000 {
+						return nil, errors.New("failed decompression: too large")
+					}
+					maxSize = maxSize * 4
+					continue
+				}
+				if err != nil {
+					return nil, err
+				}
+				break
 			}
 			archWasms[moduleHash] = uncompressed
 		}