Android nanoapp header: C++11/STL parsing library

File extension

napp_header

KS implementation details

License: Apache-2.0

Minimal Kaitai Struct required: 0.9

This page hosts a formal specification of Android nanoapp header using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for C++11/STL generated by Kaitai Struct depends on the C++/STL runtime library. You have to install it before you can parse data.

For C++, the easiest way is to clone the runtime library sources and build them along with your project.

Code

Using Kaitai Struct in C++/STL usually consists of 3 steps.

We need to create an STL input stream (std::istream). One can open local file for that, or use existing std::string or char* buffer.

#include <fstream>

std::ifstream is("path/to/local/file.napp_header", std::ifstream::binary);

#include <sstream>

std::istringstream is(str);

#include <sstream>

const char buf[] = { ... };
std::string str(buf, sizeof buf);
std::istringstream is(str);

We need to wrap our input stream into Kaitai stream:

#include "kaitai/kaitaistream.h"

kaitai::kstream ks(&is);

And finally, we can invoke the parsing:
```
android_nanoapp_header_t data(&ks);
```

After that, one can get various attributes from the structure by invoking getter methods like:

data.header_version() // => get header version

C++11/STL source code to parse Android nanoapp header

android_nanoapp_header.h

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#pragma once

// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

#include "kaitai/kaitaistruct.h"
#include <stdint.h>
#include <memory>

#if KAITAI_STRUCT_VERSION < 9000L
#error "Incompatible Kaitai Struct C++/STL API: version 0.9 or later is required"
#endif

/**
 * \sa https://android.googlesource.com/platform/system/chre/+/a7ff61b9/build/build_template.mk#130 Source
 */

class android_nanoapp_header_t : public kaitai::kstruct {

public:

    android_nanoapp_header_t(kaitai::kstream* p__io, kaitai::kstruct* p__parent = nullptr, android_nanoapp_header_t* p__root = nullptr);

private:
    void _read();
    void _clean_up();

public:
    ~android_nanoapp_header_t();

private:
    bool f_is_signed;
    bool m_is_signed;

public:
    bool is_signed();

private:
    bool f_is_encrypted;
    bool m_is_encrypted;

public:
    bool is_encrypted();

private:
    bool f_is_tcm_capable;
    bool m_is_tcm_capable;

public:
    bool is_tcm_capable();

private:
    uint32_t m_header_version;
    std::string m_magic;
    uint64_t m_app_id;
    uint32_t m_app_version;
    uint32_t m_flags;
    uint64_t m_hub_type;
    uint8_t m_chre_api_major_version;
    uint8_t m_chre_api_minor_version;
    std::string m_reserved;
    android_nanoapp_header_t* m__root;
    kaitai::kstruct* m__parent;

public:
    uint32_t header_version() const { return m_header_version; }
    std::string magic() const { return m_magic; }
    uint64_t app_id() const { return m_app_id; }
    uint32_t app_version() const { return m_app_version; }
    uint32_t flags() const { return m_flags; }
    uint64_t hub_type() const { return m_hub_type; }
    uint8_t chre_api_major_version() const { return m_chre_api_major_version; }
    uint8_t chre_api_minor_version() const { return m_chre_api_minor_version; }
    std::string reserved() const { return m_reserved; }
    android_nanoapp_header_t* _root() const { return m__root; }
    kaitai::kstruct* _parent() const { return m__parent; }
};

android_nanoapp_header.cpp

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// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

#include "android_nanoapp_header.h"
#include "kaitai/exceptions.h"

android_nanoapp_header_t::android_nanoapp_header_t(kaitai::kstream* p__io, kaitai::kstruct* p__parent, android_nanoapp_header_t* p__root) : kaitai::kstruct(p__io) {
    m__parent = p__parent;
    m__root = this;
    f_is_signed = false;
    f_is_encrypted = false;
    f_is_tcm_capable = false;
    _read();
}

void android_nanoapp_header_t::_read() {
    m_header_version = m__io->read_u4le();
    if (!(header_version() == 1)) {
        throw kaitai::validation_not_equal_error<uint32_t>(1, header_version(), _io(), std::string("/seq/0"));
    }
    m_magic = m__io->read_bytes(4);
    if (!(magic() == std::string("\x4E\x41\x4E\x4F", 4))) {
        throw kaitai::validation_not_equal_error<std::string>(std::string("\x4E\x41\x4E\x4F", 4), magic(), _io(), std::string("/seq/1"));
    }
    m_app_id = m__io->read_u8le();
    m_app_version = m__io->read_u4le();
    m_flags = m__io->read_u4le();
    m_hub_type = m__io->read_u8le();
    m_chre_api_major_version = m__io->read_u1();
    m_chre_api_minor_version = m__io->read_u1();
    m_reserved = m__io->read_bytes(6);
    if (!(reserved() == std::string("\x00\x00\x00\x00\x00\x00", 6))) {
        throw kaitai::validation_not_equal_error<std::string>(std::string("\x00\x00\x00\x00\x00\x00", 6), reserved(), _io(), std::string("/seq/8"));
    }
}

android_nanoapp_header_t::~android_nanoapp_header_t() {
    _clean_up();
}

void android_nanoapp_header_t::_clean_up() {
}

bool android_nanoapp_header_t::is_signed() {
    if (f_is_signed)
        return m_is_signed;
    m_is_signed = (flags() & 1) != 0;
    f_is_signed = true;
    return m_is_signed;
}

bool android_nanoapp_header_t::is_encrypted() {
    if (f_is_encrypted)
        return m_is_encrypted;
    m_is_encrypted = (flags() & 2) != 0;
    f_is_encrypted = true;
    return m_is_encrypted;
}

bool android_nanoapp_header_t::is_tcm_capable() {
    if (f_is_tcm_capable)
        return m_is_tcm_capable;
    m_is_tcm_capable = (flags() & 4) != 0;
    f_is_tcm_capable = true;
    return m_is_tcm_capable;
}