mempool/backend/src/utils/axios-query.ts

import axios, { AxiosResponse } from 'axios';
import { SocksProxyAgent } from 'socks-proxy-agent';
import backendInfo from '../api/backend-info';
import config from '../config';
import logger from '../logger';
import * as https from 'https';

export async function query(path): Promise<object | undefined> {
 type axiosOptions = {
   headers: {
     'User-Agent': string
   };
   timeout: number;
   httpsAgent?: https.Agent;
 };
 const setDelay = (secs: number = 1): Promise<void> => new Promise(resolve => setTimeout(() => resolve(), secs * 1000));
 const axiosOptions: axiosOptions = {
   headers: {
     'User-Agent': (config.MEMPOOL.USER_AGENT === 'mempool') ? `mempool/v${backendInfo.getBackendInfo().version}` : `${config.MEMPOOL.USER_AGENT}`
   },
   timeout: config.SOCKS5PROXY.ENABLED ? 30000 : 10000
 };
 let retry = 0;

 while (retry < config.MEMPOOL.EXTERNAL_MAX_RETRY) {
   try {
     if (config.SOCKS5PROXY.ENABLED) {
       const socksOptions: any = {
         agentOptions: {
           keepAlive: true,
         },
         hostname: config.SOCKS5PROXY.HOST,
         port: config.SOCKS5PROXY.PORT
       };

       if (config.SOCKS5PROXY.USERNAME && config.SOCKS5PROXY.PASSWORD) {
         socksOptions.username = config.SOCKS5PROXY.USERNAME;
         socksOptions.password = config.SOCKS5PROXY.PASSWORD;
       } else {
         // Retry with different tor circuits https://stackoverflow.com/a/64960234
         socksOptions.username = `circuit${retry}`;
       }

       axiosOptions.httpsAgent = new SocksProxyAgent(socksOptions);
     }

     const data: AxiosResponse = await axios.get(path, axiosOptions);
     if (data.statusText === 'error' || !data.data) {
       throw new Error(`Could not fetch data from ${path}, Error: ${data.status}`);
     }
     return data.data;
   } catch (e) {
     logger.warn(`Could not connect to ${path} (Attempt ${retry + 1}/${config.MEMPOOL.EXTERNAL_MAX_RETRY}). Reason: ` + (e instanceof Error ? e.message : e));
     retry++;
   }
   if (retry < config.MEMPOOL.EXTERNAL_MAX_RETRY) {
     await setDelay(config.MEMPOOL.EXTERNAL_RETRY_INTERVAL);
   }
 }

 logger.err(`Could not connect to ${path}. All ${config.MEMPOOL.EXTERNAL_MAX_RETRY} attempts failed`);
 return undefined;
}