Block recv() example

explore.js

'use strict';

Interceptor.attach(ptr('0x103cdbf40'), {
  onEnter: function (args) {
    send({ type: 'need-input' });

    var operation = recv(function (res) {
      args[0] = ptr(res);
    });
    operation.wait();
  }
});

explore.py

import codecs
import frida
from frida.application import Reactor
import sys
import threading

done = threading.Event()
script = None

def wait_for_keypress(reactor):
    done.wait()

reactor = Reactor(wait_for_keypress)

def send_value():
    value = input("Enter a number: ")
    script.post(value)

def on_message(message, data):
    global reactor
    print("on_message:", message)
    if message["type"] == "send":
        reactor.schedule(lambda: send_value())

session = frida.attach("hello")

with codecs.open("explore.js", "r", "utf-8") as f:
    source = f.read()
script = session.create_script(source)
script.on("message", on_message)
script.load()

reactor.run()

hello.c

#include <stdio.h>
#include <unistd.h>

static void f (int n)
{
  printf ("Number: %d\n", n);
}

int main (int argc, char * argv[])
{
  int n = 1;

  printf ("f is at %p\n", f);

  while (1)
  {
    f (n++);
    sleep (1);
  }

  return 0;
}