android_res_nquery

README.md

export NDK_HOME=$HOME/.mozbuild/android-ndk-r27c/
export TOOLCHAIN=$NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64
export SYSROOT=$TOOLCHAIN/sysroot
export CC="$TOOLCHAIN/bin/aarch64-linux-android21-clang"
export CXX="$TOOLCHAIN/bin/aarch64-linux-android21-clang++"

$CXX -o dns_query android_res_nquery.cpp -DANDROID -I$SYSROOT/usr/include -L$SYSROOT/usr/lib -static-libstdc++ -ldl
adb push dns_query /data/local/tmp/
adb shell chmod +x /data/local/tmp/dns_query
adb shell /data/local/tmp/dns_query

The output will look something like this:

3
Data is available to read.
Received 61 bytes: 
00 00 00 00 00 00 00 35 86 b7 81 80 00 01 00 01 
00 00 00 00 06 67 6f 6f 67 6c 65 03 63 6f 6d 00 
00 41 00 01 c0 0c 00 41 00 01 00 00 50 5b 00 0d 
00 01 00 00 01 00 06 02 68 32 02 68 33

android_res_nquery.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <resolv.h>
#include <arpa/nameser.h>
#include <netdb.h>  // Include for hstrerror
//#include <android/multinetwork.h>
#include <dlfcn.h>
// #include <jni.h>
#include <stdio.h>
#include <poll.h>

#include <errno.h>
#include <iostream>

#include <iostream>
#include <iomanip>
#include <cstring>

void printHexDump(const char* buffer, size_t length) {
  for (size_t i = 0; i < length; ++i) {
    if (i > 0 && i % 16 == 0) {
      std::cout << std::endl;
    }
    std::cout << std::hex << std::setw(2) << std::setfill('0') << (static_cast<int>(buffer[i]) & 0xff) << " ";
  }
  std::cout << std::endl;
}

int main() {
  void* handle = dlopen("libandroid_net.so", RTLD_LAZY);
  if (!handle) {
    fprintf(stderr, "Error: %s\n", dlerror());
	    return 1; // or handle the error as needed
   }

  auto android_res_nquery = (int (*)(...)) dlsym(handle, "android_res_nquery");
  if (!android_res_nquery) {
    fprintf(stderr, "Error: %s\n", dlerror());
    dlclose(handle);
    return 1; // or handle the error as needed
  }

  int resp_handle = android_res_nquery(0, "google.com", ns_c_in, 65, 0);

  printf("%d\n", resp_handle);

  struct pollfd fds;
  fds.fd = resp_handle;
  fds.events = POLLIN; // Wait for read events
  // Wait for an event on the file descriptor
  int ret = poll(&fds, 1, -1); // -1 means no timeout

  if (ret == -1) {
    std::cerr << "Poll error: " << strerror(errno) << '\n';
  } else if (ret == 0) {
    std::cout << "No data within the timeout period.\n";
  } else {
    if (fds.revents & POLLIN) {
      std::cout << "Data is available to read.\n";
    }
  }

  int rcode;

  char answer[3200];

  ssize_t bytes_received = recv(resp_handle, answer, 3200 - 1, 0);
  if (bytes_received == -1) {
    std::cerr << "recv failed: " << strerror(errno) << std::endl;
  } else if (bytes_received == 0) {
    std::cout << "Connection closed by peer" << std::endl;
  } else {
    std::cout << "Received " << bytes_received << " bytes: " << answer << std::endl;
  }

  printHexDump(answer, bytes_received);
  return 0;
}