gzip.cpp

// gzip.cpp - originally written and placed in the public domain by Wei Dai
 
#include "pch.h"
#include "gzip.h"
#include "argnames.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
// Checks whether the character is valid for ISO/IEC 8859-1 as required by RFC 1952
static inline bool Is8859Character(char c) {
    const unsigned char cc = static_cast<unsigned char>(c);
    return (cc >= 32 && cc <= 126) || (cc >= 160);
}
 
void Gzip::IsolatedInitialize(const NameValuePairs &parameters)
{
    Deflator::IsolatedInitialize(parameters);
 
    ConstByteArrayParameter v;
    if (parameters.GetValue(Name::FileName(), v))
        m_filename.assign(reinterpret_cast<const char*>(v.begin()), v.size());
    if (parameters.GetValue(Name::Comment(), v))
        m_comment.assign(reinterpret_cast<const char*>(v.begin()), v.size());
    m_filetime = parameters.GetIntValueWithDefault(Name::FileTime(), 0);
}
 
void Gzip::WritePrestreamHeader()
{
    m_totalLen = 0;
    m_crc.Restart();
 
    int flags = 0;
    if(!m_filename.empty())
        flags |= FILENAME;
    if(!m_comment.empty())
        flags |= COMMENTS;
 
    AttachedTransformation()->Put(MAGIC1);
    AttachedTransformation()->Put(MAGIC2);
    AttachedTransformation()->Put(DEFLATED);
    AttachedTransformation()->Put((byte)flags);     // general flag
    AttachedTransformation()->PutWord32(m_filetime, LITTLE_ENDIAN_ORDER);   // time stamp
    byte extra = static_cast<byte>((GetDeflateLevel() == 1) ?
                    FAST : ((GetDeflateLevel() == 9) ? SLOW : 0));
    AttachedTransformation()->Put(extra);
    AttachedTransformation()->Put(GZIP_OS_CODE);
 
    // Filename is NULL terminated, hence the +1
    if(!m_filename.empty())
        AttachedTransformation()->Put((const unsigned char*)m_filename.data(), m_filename.size() +1);
 
    // Comment is NULL terminated, hence the +1
    if(!m_comment.empty())
        AttachedTransformation()->Put((const unsigned char*)m_comment.data(), m_comment.size() +1);
}
 
void Gzip::ProcessUncompressedData(const byte *inString, size_t length)
{
    m_crc.Update(inString, length);
    m_totalLen += (word32)length;
}
 
void Gzip::WritePoststreamTail()
{
    SecByteBlock crc(4);
    m_crc.Final(crc);
    AttachedTransformation()->Put(crc, 4);
    AttachedTransformation()->PutWord32(m_totalLen, LITTLE_ENDIAN_ORDER);
 
    m_filetime = 0;
    m_filename.clear();
    m_comment.clear();
}
 
void Gzip::SetComment(const std::string& comment, bool throwOnEncodingError)
{
    if(throwOnEncodingError)
    {
        for(size_t i = 0; i < comment.length(); i++) {
            const char c = comment[i];
            if(!Is8859Character(c))
                throw InvalidDataFormat("The comment is not ISO/IEC 8859-1 encoded");
        }
    }
 
    m_comment = comment;
}
 
void Gzip::SetFilename(const std::string& filename, bool throwOnEncodingError)
{
    if(throwOnEncodingError)
    {
        for(size_t i = 0; i < filename.length(); i++) {
            const char c = filename[i];
            if(!Is8859Character(c))
                throw InvalidDataFormat("The filename is not ISO/IEC 8859-1 encoded");
        }
    }
 
    m_filename = filename;
}
 
// *************************************************************
 
Gunzip::Gunzip(BufferedTransformation *attachment, bool repeat, int propagation)
    : Inflator(attachment, repeat, propagation), m_length(0), m_filetime(0)
{
}
 
void Gunzip::ProcessPrestreamHeader()
{
    m_length = 0;
    m_crc.Restart();
 
    m_filetime = 0;
    m_filename.clear();
    m_comment.clear();
 
    byte buf[6];
    byte b, flags;
 
    if (m_inQueue.Get(buf, 2)!=2) throw HeaderErr();
    if (buf[0] != MAGIC1 || buf[1] != MAGIC2) throw HeaderErr();
    if (!m_inQueue.Get(b) || (b != DEFLATED)) throw HeaderErr();     // skip CM flag
    if (!m_inQueue.Get(flags)) throw HeaderErr();
    if (flags & (ENCRYPTED | CONTINUED)) throw HeaderErr();
    if (m_inQueue.GetWord32(m_filetime, LITTLE_ENDIAN_ORDER) != 4) throw HeaderErr();
    if (m_inQueue.Skip(2)!=2) throw HeaderErr();    // Skip extra flags and OS type
 
    if (flags & EXTRA_FIELDS)   // skip extra fields
    {
        word16 length;
        if (m_inQueue.GetWord16(length, LITTLE_ENDIAN_ORDER) != 2) throw HeaderErr();
        if (m_inQueue.Skip(length)!=length) throw HeaderErr();
    }
 
    if (flags & FILENAME)   // extract filename
    {
        do
        {
            if(!m_inQueue.Get(b)) throw HeaderErr();
            if(b) m_filename.append( 1, (char)b );
        }
        while (b);
    }
 
    if (flags & COMMENTS)   // extract comments
    {
        do
        {
            if(!m_inQueue.Get(b)) throw HeaderErr();
            if(b) m_comment.append( 1, (char)b );
        }
        while (b);
    }
}
 
void Gunzip::ProcessDecompressedData(const byte *inString, size_t length)
{
    AttachedTransformation()->Put(inString, length);
    m_crc.Update(inString, length);
    m_length += (word32)length;
}
 
void Gunzip::ProcessPoststreamTail()
{
    SecByteBlock crc(4);
    if (m_inQueue.Get(crc, 4) != 4)
        throw TailErr();
    if (!m_crc.Verify(crc))
        throw CrcErr();
 
    word32 lengthCheck;
    if (m_inQueue.GetWord32(lengthCheck, LITTLE_ENDIAN_ORDER) != 4)
        throw TailErr();
    if (lengthCheck != m_length)
        throw LengthErr();
}
 
const std::string& Gunzip::GetComment(bool throwOnEncodingError) const
{
    if(throwOnEncodingError)
    {
        for(size_t i = 0; i < m_comment.length(); i++) {
            const char c = m_comment[i];
            if(!Is8859Character(c))
                throw InvalidDataFormat("The comment is not ISO/IEC 8859-1 encoded");
        }
    }
 
    return m_comment;
}
 
const std::string& Gunzip::GetFilename(bool throwOnEncodingError) const
{
    if(throwOnEncodingError)
    {
        for(size_t i = 0; i < m_filename.length(); i++) {
            const char c = m_filename[i];
            if(!Is8859Character(c))
                throw InvalidDataFormat("The filename is not ISO/IEC 8859-1 encoded");
        }
    }
 
    return m_filename;
}
 
NAMESPACE_END