EncoreBootImageReader.h revision 1.1 
1/*
2 * File:	EncoreBootImageReader.h
3 *
4 * Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
5 * See included license file for license details.
6 */
7#if !defined(_EncoreBootImageReader_h_)
8#define _EncoreBootImageReader_h_
9
10#include "EncoreBootImage.h"
11
12namespace elftosb
13{
14
15/*!
16 * \brief Reads a Piano/Encore boot image from an input stream.
17 */
18class EncoreBootImageReader
19{
20public:
21	/*!
22	 * \brief Exception class used for error found while reading a boot image.
23	 */
24	class read_error : public std::runtime_error
25	{
26	public:
27		//! \brief Constructor.
28		read_error(const std::string & msg) : std::runtime_error(msg) {}
29	};
30
31	//! \brief An array of section headers.
32	typedef std::vector<EncoreBootImage::section_header_t> section_array_t;
33
34	//! \brief An array of boot tags.
35	typedef std::vector<EncoreBootImage::boot_command_t> boot_tag_array_t;
36
37public:
38	//! \brief Default constructor.
39	EncoreBootImageReader(std::istream & stream) : m_stream(stream) {}
40
41	//! \brief Destructor.
42	virtual ~EncoreBootImageReader() {}
43
44	//! \name Decryption key
45	//! These methods provide access to the Data Encryption Key (DEK). Normally
46	//! the DEK is discovered using the readKeyDictionary() method.
47	//@{
48	inline void setKey(const AESKey<128> & key) { m_dek = key; }
49	inline const AESKey<128> & getKey() const { return m_dek; }
50	//@}
51
52	//! \name Readers
53	//! This group of methods is responsible for reading and parsing different
54	//! pieces and parts of the boot image file.
55	//@{
56	//! \brief Reads the header from the image.
57	void readImageHeader();
58
59	//! \brief Computes the actual SHA-1 digest of the image header.
60	void computeHeaderDigest(sha1_digest_t & digest);
61
62	//! \brief Reads the digest at the end of the image.
63	void readImageDigest();
64
65	//! \brief Run a SHA-1 digest over the entire image.
66	void computeImageDigest(sha1_digest_t & digest);
67
68	//! \brief Read the plaintext section table entries.
69	void readSectionTable();
70
71	//! \brief Reads the key dictionary, if the image is encrypted.
72	bool readKeyDictionary(const AESKey<128> & kek);
73
74	//! \brief
75	void readBootTags();
76
77	//! \brief
78	EncoreBootImage::Section * readSection(unsigned index);
79	//@}
80
81	//! \name Accessors
82	//! Information retrieved with reader methods is accessible through
83	//! these methods.
84	//@{
85	//! \brief Returns whether the image is encrypted or not.
86	//! \pre The header must have been read already.
87	inline bool isEncrypted() const { return m_header.m_keyCount > 0; }
88
89	//! \brief Returns a reference to the image's header.
90	const EncoreBootImage::boot_image_header_t & getHeader() const { return m_header; }
91
92	//! \brief Returns a reference to the SHA-1 digest read from the image.
93	const sha1_digest_t & getDigest() const { return m_digest; }
94
95	//! \brief Returns a reference to the STL container holding the section headers.
96	inline const section_array_t & getSections() const { return m_sections; }
97
98	//! \brief Returns a reference to the STL container holding the boot tags.
99	inline const boot_tag_array_t & getBootTags() const { return m_bootTags; }
100	//@}
101
102protected:
103	std::istream & m_stream;	//!< The input stream to read the image from.
104	AESKey<128> m_dek;	//!< DEK (data encryption key) read from the key dictionary.
105	EncoreBootImage::boot_image_header_t m_header;	//!< Header from the boot image.
106	sha1_digest_t m_digest;	//!< SHA-1 digest as read from the image.
107	section_array_t m_sections;	//!< The section table.
108	boot_tag_array_t m_bootTags;	//!< The array of boot tags read from the image.
109
110protected:
111	//! \brief Calculates the 8-bit checksum on a boot command header.
112	uint8_t calculateCommandChecksum(EncoreBootImage::boot_command_t & header);
113};
114
115}; // namespace elftosb
116
117#endif // _EncoreBootImageReader_h_
118