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revert(agents): revert base64 image validation (#19221)

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Seb Slight
2026-02-17 09:58:39 -05:00
committed by GitHub
parent bd1e7fadd5
commit 4536a6e05f
2 changed files with 2 additions and 203 deletions
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58
src/agents/tool-images.ts
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@@ -17,55 +17,6 @@ const MAX_IMAGE_DIMENSION_PX = 2000;
const MAX_IMAGE_BYTES = 5 * 1024 * 1024;
const log = createSubsystemLogger("agents/tool-images");
// Valid base64: alphanumeric, +, /, with 0-2 trailing = padding only
// This regex ensures = only appears at the end as valid padding
const BASE64_REGEX = /^[A-Za-z0-9+/]*={0,2}$/;
/**
* Validates and normalizes base64 image data before processing.
* - Strips data URL prefixes (e.g., "data:image/png;base64,")
* - Converts URL-safe base64 to standard base64 (- → +, _ → /)
* - Validates base64 character set and structure
* - Ensures the string is not empty after trimming
*
* Returns the cleaned base64 string or throws an error if invalid.
*/
function validateAndNormalizeBase64(base64: string): string {
let data = base64.trim();
// Strip data URL prefix if present (e.g., "data:image/png;base64,...")
const dataUrlMatch = data.match(/^data:[^;]+;base64,(.*)$/i);
if (dataUrlMatch) {
data = dataUrlMatch[1].trim();
}
if (!data) {
throw new Error("Base64 data is empty");
}
// Normalize URL-safe base64 to standard base64
// URL-safe uses - instead of + and _ instead of /
data = data.replace(/-/g, "+").replace(/_/g, "/");
// Check for valid base64 characters and structure
// The regex ensures = only appears as 0-2 trailing padding chars
// Node's Buffer.from silently ignores invalid chars, but Anthropic API rejects them
if (!BASE64_REGEX.test(data)) {
throw new Error("Base64 data contains invalid characters or malformed padding");
}
// Check that length is valid for base64 (must be multiple of 4 when padded)
// Remove padding for length check, then verify
const withoutPadding = data.replace(/=+$/, "");
const remainder = withoutPadding.length % 4;
if (remainder === 1) {
// A single char remainder is always invalid in base64
throw new Error("Base64 data has invalid length");
}
return data;
}
function isImageBlock(block: unknown): block is ImageContentBlock {
if (!block || typeof block !== "object") {
return false;
@@ -209,8 +160,8 @@ export async function sanitizeContentBlocksImages(
continue;
}
const rawData = block.data.trim();
if (!rawData) {
const data = block.data.trim();
if (!data) {
out.push({
type: "text",
text: `[${label}] omitted empty image payload`,
@@ -219,11 +170,6 @@ export async function sanitizeContentBlocksImages(
}
try {
// Validate and normalize base64 before processing
// This catches invalid base64 that Buffer.from() would silently accept
// but Anthropic's API would reject, preventing permanent session corruption
const data = validateAndNormalizeBase64(rawData);
const inferredMimeType = inferMimeTypeFromBase64(data);
const mimeType = inferredMimeType ?? block.mimeType;
const resized = await resizeImageBase64IfNeeded({