buffer_util.cpp

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#include "peconv/buffer_util.h"
 
#include "peconv/logger.h"
 
//
// validate pointer:
//
 
bool peconv::validate_ptr(IN const void* buffer_bgn, IN size_t buffer_size, IN const void* field_bgn, IN size_t field_size)
{
    if (buffer_bgn == nullptr || field_bgn == nullptr) {
        return false;
    }
    BYTE* _start = (BYTE*)buffer_bgn;
    BYTE* _field_start = (BYTE*)field_bgn;
    if (_field_start < _start) {
        return false;
    }
    size_t start_delta =  (ULONG_PTR)_field_start - (ULONG_PTR)_start;
    size_t area_size = start_delta + field_size;
    if (area_size > buffer_size) {
        return false;
    }
    if (area_size < field_size || area_size < start_delta) {
        LOG_WARNING("Integer Overflow, limit exceeded! start_delta: %zu field_size: %zu area_size: %zu", start_delta, field_size, area_size);
        return false;
    }
    return true;
}
 
//-----------------------------------------------------------------------------------
//
// alloc/free unaligned buffers:
//
 
//allocates a buffer that does not have to start from the beginning of the section
peconv::UNALIGNED_BUF peconv::alloc_unaligned(size_t buf_size)
{
    if (!buf_size) return NULL;
 
    UNALIGNED_BUF buf = (UNALIGNED_BUF) calloc(buf_size, sizeof(BYTE));
    return buf;
}
 
void peconv::free_unaligned(peconv::UNALIGNED_BUF section_buffer)
{
    free(section_buffer);
}
 
//
// alloc/free aligned buffers:
//
 
peconv::ALIGNED_BUF peconv::alloc_aligned(size_t buffer_size, DWORD protect, void* desired_base)
{
    if (!buffer_size) return NULL;
 
    ALIGNED_BUF buf = (ALIGNED_BUF) VirtualAlloc(desired_base, buffer_size, MEM_COMMIT | MEM_RESERVE, protect);
    return buf;
}
 
bool peconv::free_aligned(peconv::ALIGNED_BUF buffer, size_t buffer_size)
{
    if (buffer == nullptr) return true;
    if (!VirtualFree(buffer, 0, MEM_RELEASE)) {
        LOG_ERROR("VirtualFree failed.");
        return false;
    }
    return true;
}
 
//-----------------------------------------------------------------------------------
//
// wrappers using appropriate buffer type according to the purpose:
//
 
// allocate a buffer for PE module:
peconv::ALIGNED_BUF peconv::alloc_pe_buffer(size_t buffer_size, DWORD protect, void* desired_base)
{
    return alloc_aligned(buffer_size, protect, desired_base);
}
 
// Free loaded PE module
bool peconv::free_pe_buffer(peconv::ALIGNED_BUF buffer, size_t buffer_size)
{
    return peconv::free_aligned(buffer, buffer_size);
}