plugin.cpp

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#include <Arduino.h>
#include <cstring> // memcpy
 
#include "utils/etl_base64.h"
 
#include "plugin/plugin.h"
#include "utils/align.h"
#include "utils/hashflash.h"
#include "utils/logging.h"
 
using namespace loader;
using namespace utils;
 
#ifdef ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER
constexpr static int the_memsize = 1024; //< number of bytes permanently hold
uint8_t GlobalPluginLoader_Storage[the_memsize];
#endif
 
FLASHMEM
GlobalPluginLoader::GlobalPluginLoader() {
#ifdef ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER
  prepare_mpu();
  load_addr = align(GlobalPluginLoader_Storage, 4);
  memsize = the_memsize - disalignment(GlobalPluginLoader_Storage, 4);
  LOGMEV("Preparing MPU and %d bytes memory", memsize);
#else
  LOGMEV("Skipping due to missing ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER", "dummy");
#endif
}
 
FLASHMEM
void loader::convertFromJson(JsonVariantConst src, Function &f) {
  if (src.is<int>()) {
    f.addr = src;
  } else if (src.is<JsonObjectConst>()) {
    auto o = src.as<JsonObjectConst>();
 
    f.addr = o["point"];
    if (o["returns"]) {
#define M(name)                                                                                               \
  if (o["returns"] == #name)                                                                                  \
  f.ret_type = Function::Returns::name
      M(None);
      M(Bool);
      M(Int);
      M(String);
      M(JsonObject);
    }
  }
}
 
FLASHMEM
std::string shortened_hexdump(uint8_t *mem, size_t size) {
  constexpr size_t inspect_bytes = 3;
  char ret[2 * inspect_bytes + 3]; // AABBCC...DDEEFF
  for (size_t i = 0; i < inspect_bytes; i++)
    sprintf(ret + 2 * i, "%x", mem[i]);
  for (size_t i = 0; i < inspect_bytes; i++)
    sprintf(ret + sizeof(ret) - 2 * (i + 1), "%x", mem[i]);
  return std::string(ret);
}
 
FLASHMEM
void loader::convertToJson(const GlobalPluginLoader &src, JsonVariant dst) {
  dst["type"] = "GlobalPluginLoader";
#ifndef ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER
  dst["hint"] = "Set ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER debug feature flag to enable this loader";
#else
  dst["load_addr"] = (uint32_t)src.load_addr;
  dst["memsize"] = src.memsize;
 
  dst["can_load"] = src.can_load();
  dst["is_loaded"] = src.plugin.has_value();
 
  if (src.plugin) {
    auto plugin = dst.createNestedObject("plugin");
    plugin["size"] = src.plugin->size;
    utils::sha256 plugin_checksum(src.plugin->load_addr, src.plugin->size);
    plugin["sha256sum"] = plugin_checksum.to_string();
 
    // can probably skip that
    plugin["hexdump"] = shortened_hexdump(src.plugin->load_addr, src.plugin->size);
  }
#endif
}
 
FLASHMEM
void dispatch(uint8_t *callee, Function::Returns ret_type, JsonVariant ret) {
  switch (ret_type) {
  case Function::Returns::None: {
    auto entry = (Function::None_f *)callee;
    entry();
    break;
  }
#define CALL(type, sig)                                                                                       \
  case Function::Returns::type: {                                                                             \
    auto entry = (Function::sig *)callee;                                                                     \
    ret.set(entry());                                                                                         \
    break;                                                                                                    \
  }
    CALL(Bool, Bool_f);
    CALL(Int, Int_f);
    CALL(String, String_f);
    CALL(JsonObject, JsonObject_f)
  }
}
 
#define return_err(code, msg)                                                                                 \
  {                                                                                                           \
    msg_out["error"] = msg;                                                                                   \
    return code;                                                                                              \
  }
 
FLASHMEM
int loader::SinglePluginLoader::load_and_execute(JsonObjectConst msg_in, JsonObject &msg_out) {
  if (plugin)
    return_err(1, "Already have plugin loaded, can only load one plugin at a time. Call unload before.");
  if (!can_load())
    return_err(2, "PluginLoader cannot load code. This is currently most likely due to the missing compile "
                  "time flag ANABRID_ENABLE_GLOBAL_PLUGIN_LOADER");
  if (!msg_in.containsKey("entry"))
    return_err(3, "Requiring entry point \"entry\"=0x1234 even if it is just 0.");
 
  // Load address verification, to ensure correct linking
  if (msg_in["load_addr"] != load_addr)
    return_err(
        4,
        "Require matching load address for verification. This SinglePluginLoader can only load from: [todo]");
  auto firmeware_hash = loader::flashimage::sha256sum().to_string();
  if (utils::sha256_test_short(msg_in["firmware_sha256"], firmeware_hash))
    return_err(5, "ABI mismatch: You built against [your firmware sha256] but we run [our sha256]");
 
  // Function pointer registration
  Plugin new_plugin;
  new_plugin.load_addr = load_addr;
  new_plugin.entry = msg_in["entry"];
  if (msg_in.containsKey("exit")) {
    new_plugin.exit = msg_in["exit"].as<Function>();
  }
 
  // Actual code submission
  // For the time being, expect base64 encoded data.
  // TODO: For slightly larger payloads (mind the typical 1024byte JsonObject maximum size in the code),
  //       a multi-step transmission has to be introduced.
  auto base64_payload = msg_in["payload"].as<std::string>();
  new_plugin.size = base64_payload.size() / 4 * 3;
  if (!load(new_plugin))
    return_err(6, "Payload too large or some code is already loaded.");
  auto length_decoded = etl::base64::decode(base64_payload.c_str(), base64_payload.length(),
                                            new_plugin.load_addr, new_plugin.size);
  if (length_decoded != new_plugin.size) {
    unload();
    return_err(7, "Could not decode base64-encoded payload.");
  }
 
  // Code execution
  uint8_t *entry_point = assert_callable(plugin->load_addr + plugin->entry.addr);
  if (!entry_point) {
    unload();
    return_err(8, "Entry point address not properly aligned");
  }
  dispatch(entry_point, plugin->entry.ret_type, msg_out["returns"].as<JsonVariant>());
 
  // Plugins which are actually RPC.
  if (msg_in.containsKey("immediately_unload"))
    unload();
 
  return 0;
}
 
FLASHMEM
int loader::SinglePluginLoader::unload(JsonObjectConst msg_in, JsonObject &msg_out) {
  if (!plugin) {
    return_err(9, "Cannot unload, nothing loaded");
  }
  if (plugin->exit) {
    // Code execution
    uint8_t *exit_point = assert_callable(plugin->load_addr + plugin->exit->addr);
    if (!exit_point) {
      unload();
      return_err(10, "Exit point address not properly aligned");
    }
    dispatch(exit_point, plugin->exit->ret_type, msg_out["returns"].as<JsonVariant>());
  }
  unload();
  return 0;
}
 
FLASHMEM
int loader::SinglePluginLoader::load(const Plugin &new_plugin) {
  if (plugin)
    return 1; // call unload() first.
  if (new_plugin.size > memsize)
    return 2;
  plugin = new_plugin; // copy
  return true;
}
 
// instantiate global singleton here.
loader::GlobalPluginLoader loader::PluginLoader;