/**
* Utility functions for parsing JSON-RPC messages
*
* This module provides functions to handle malformed JSON-RPC messages
* and extract valid JSON objects or arrays from them.
*/
import logger from './logger';
/**
* Process a potentially malformed JSON-RPC message and extract a valid JSON object or array
*
* @param message - The message string to process
* @returns The parsed JSON object or array
* @throws Error if no valid JSON can be extracted or parsed
*/
export function processJsonRpcMessage(message: string): any {
try {
// Remove special characters like BOM and trim whitespace
const cleanedMessage = message.replace(/^\uFEFF/, '').trim();
// Log the message for debugging
logger.debug(`Processing message: ${cleanedMessage.substring(0, 50)}...`);
// Fix for "Unexpected non-whitespace character after JSON at position 4"
// This happens when there are extra characters after a valid JSON object
// Try to find a valid JSON object or array at the beginning of the string
const jsonMatch = cleanedMessage.match(/^(\{.*\}|\[.*\])(?:\s*|$)/s);
if (jsonMatch && jsonMatch[1]) {
try {
// If we can parse this directly, return it
const parsed = JSON.parse(jsonMatch[1]);
logger.debug(`Successfully parsed JSON directly: ${jsonMatch[1].substring(0, 50)}...`);
return parsed;
} catch (e) {
// If direct parsing fails, continue with the original algorithm
logger.debug(`Direct parsing failed, continuing with original algorithm: ${e}`);
}
}
// Find the start of the JSON object or array (whichever comes first)
const jsonStartIndex = Math.min(
cleanedMessage.indexOf('{') >= 0 ? cleanedMessage.indexOf('{') : Number.MAX_SAFE_INTEGER,
cleanedMessage.indexOf('[') >= 0 ? cleanedMessage.indexOf('[') : Number.MAX_SAFE_INTEGER
);
if (jsonStartIndex === Number.MAX_SAFE_INTEGER) {
throw new Error('No JSON object or array found in the message');
}
// Determine if we're dealing with an object or array
const isObject = cleanedMessage[jsonStartIndex] === '{';
let depth = 0;
let endIndex = -1;
// Use balanced bracket matching to find the end of the JSON
for (let i = jsonStartIndex; i < cleanedMessage.length; i++) {
const openChar = isObject ? '{' : '[';
const closeChar = isObject ? '}' : ']';
if (cleanedMessage[i] === openChar) {
depth++;
} else if (cleanedMessage[i] === closeChar) {
depth--;
if (depth === 0) {
endIndex = i + 1;
break;
}
}
}
if (endIndex === -1) {
throw new Error('Unbalanced JSON in the message');
}
// Extract and parse the JSON string
const jsonString = cleanedMessage.substring(jsonStartIndex, endIndex);
try {
return JSON.parse(jsonString);
} catch (e) {
logger.error(`Failed to parse extracted JSON: ${e}`);
logger.debug(`Extracted JSON string: "${jsonString}"`);
throw e;
}
} catch (error) {
logger.error(`Error parsing JSON-RPC message: ${error}`);
logger.debug(`Problematic message: "${message}"`);
throw error;
}
}
