// ImageResource.h: 不经加载器，直接从内存中的模块映像读取资源
//
// 加壳部署（EXE + SC_AES/sRDI）下，载荷映像以裸 shellcode 运行、未注册进加载器，
// FindResource/LoadIcon/CreateDialogParamA 这类按 hInstance 找资源的 API 全部失败
// （实测 Win11 返回 err=1812 / 59）。但映像的节（含 .rsrc）是按 PE 布局正常映射
// 的，资源目录里的偏移又都是 RVA，因此可以直接遍历 IMAGE_RESOURCE_DIRECTORY
// 取到资源数据。本文件只读调用方给出的映像，不做任何映射。
//
// 适用：正常 EXE/DLL、MemoryModule 手工映射 DLL、sRDI 包装的 shellcode 载荷。
// 注意：调用方传入的必须是已映射映像的基址（如 &__ImageBase），不是磁盘文件。
//
// 稳定性：所有偏移都按 SizeOfImage / 资源目录大小做越界检查，映像布局异常
// （被第三方加壳改坏、资源被裁剪等）时一律返回 NULL，绝不越界读取。

#ifndef YAMA_IMAGE_RESOURCE_H
#define YAMA_IMAGE_RESOURCE_H

#include <windows.h>

#ifdef __cplusplus
extern "C" const IMAGE_DOS_HEADER __ImageBase;
#endif

// RT_ICON / RT_GROUP_ICON 的数字 ID（与同名 RT_ 宏对应）
#define IMAGE_RES_TYPE_ICON        3
#define IMAGE_RES_TYPE_GROUP_ICON  14

#pragma pack(push, 1)
typedef struct GRPICONDIRENTRY {
    BYTE  bWidth;
    BYTE  bHeight;
    BYTE  bColorCount;
    BYTE  bReserved;
    WORD  wPlanes;
    WORD  wBitCount;
    DWORD dwBytesInRes;
    WORD  nID;
} GRPICONDIRENTRY;
#pragma pack(pop)

#define IMAGE_RES_DIR_IN_BOUNDS(resOffset, resSize) \
    ((resOffset) <= (resSize) - sizeof(IMAGE_RESOURCE_DIRECTORY))
#define IMAGE_RES_ENTRY_ARRAY_OK(resOffset, resCount, resSize) \
    ((resCount) <= ((resSize) - (resOffset) - sizeof(IMAGE_RESOURCE_DIRECTORY)) / sizeof(IMAGE_RESOURCE_DIRECTORY_ENTRY))

// 在已映射映像中查找 type/id（取第一个语言项）的资源数据，返回映像内指针
static const BYTE* FindImageResource(const void* pvImage, WORD nType, WORD nId, DWORD* pdwSize)
{
    if (pdwSize) *pdwSize = 0;
    if (!pvImage) return NULL;

    const BYTE* pBase = (const BYTE*)pvImage;
    const DWORD dwLfanew = *(const DWORD*)(pBase + 0x3C);
    // 正常 PE 头远小于一页；sRDI 的 CLEARHEADER 只保留 PE 头（e_lfanew 之后），
    // 所以这里不能用 MZ 判断，只能靠 e_lfanew 与 PE 签名
    if (dwLfanew == 0 || dwLfanew > 0x1000) return NULL;
    const PIMAGE_NT_HEADERS pNt = (const PIMAGE_NT_HEADERS)(pBase + dwLfanew);
    if (pNt->Signature != IMAGE_NT_SIGNATURE) return NULL;

    const DWORD dwImageSize = pNt->OptionalHeader.SizeOfImage;
    const DWORD dwResRva = pNt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_RESOURCE].VirtualAddress;
    const DWORD dwResSize = pNt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_RESOURCE].Size;
    if (dwResRva == 0 || dwResSize < sizeof(IMAGE_RESOURCE_DIRECTORY) ||
        dwResRva > dwImageSize || dwResSize > dwImageSize - dwResRva) {
        return NULL;
    }
    const BYTE* pRes = pBase + dwResRva;
    // 已映射映像：资源目录与数据项偏移都是相对资源节起点的偏移 / RVA

    // 目录三层：类型 -> 名称/ID -> 语言
    const WORD keys[2] = { nType, nId };
    DWORD dwDirOff = 0;
    for (int i = 0; i < 2; i++) {
        if (!IMAGE_RES_DIR_IN_BOUNDS(dwDirOff, dwResSize)) return NULL;
        const IMAGE_RESOURCE_DIRECTORY* pRd = (const IMAGE_RESOURCE_DIRECTORY*)(pRes + dwDirOff);
        const DWORD dwCount = (DWORD)pRd->NumberOfNamedEntries + pRd->NumberOfIdEntries;
        if (!IMAGE_RES_ENTRY_ARRAY_OK(dwDirOff, dwCount, dwResSize)) return NULL;

        const IMAGE_RESOURCE_DIRECTORY_ENTRY* pEntry = (const IMAGE_RESOURCE_DIRECTORY_ENTRY*)(pRd + 1);
        const IMAGE_RESOURCE_DIRECTORY_ENTRY* pFound = NULL;
        for (DWORD j = 0; j < dwCount; j++) {
            // 只按数字 ID 匹配；命名项（NameIsString）跳过
            if (!(pEntry[j].Name & IMAGE_RESOURCE_NAME_IS_STRING) && pEntry[j].Id == keys[i]) {
                pFound = &pEntry[j];
                break;
            }
        }
        if (!pFound || !pFound->DataIsDirectory) return NULL;
        dwDirOff = pFound->OffsetToDirectory;
    }

    if (!IMAGE_RES_DIR_IN_BOUNDS(dwDirOff, dwResSize)) return NULL;
    const IMAGE_RESOURCE_DIRECTORY* pLangDir = (const IMAGE_RESOURCE_DIRECTORY*)(pRes + dwDirOff);
    const DWORD dwLangCount = (DWORD)pLangDir->NumberOfNamedEntries + pLangDir->NumberOfIdEntries;
    if (dwLangCount == 0 || !IMAGE_RES_ENTRY_ARRAY_OK(dwDirOff, dwLangCount, dwResSize)) return NULL;

    const IMAGE_RESOURCE_DIRECTORY_ENTRY* pLang = (const IMAGE_RESOURCE_DIRECTORY_ENTRY*)(pLangDir + 1);
    if (pLang->DataIsDirectory) return NULL;

    const DWORD dwDataOff = pLang->OffsetToData;
    if (dwDataOff > dwResSize - sizeof(IMAGE_RESOURCE_DATA_ENTRY)) return NULL;
    const IMAGE_RESOURCE_DATA_ENTRY* pData = (const IMAGE_RESOURCE_DATA_ENTRY*)(pRes + dwDataOff);
    const DWORD dwRva = pData->OffsetToData;
    const DWORD dwBytes = pData->Size;
    if (dwRva > dwImageSize || dwBytes > dwImageSize - dwRva) return NULL;

    if (pdwSize) *pdwSize = dwBytes;
    return pBase + dwRva;   // OffsetToData 是 RVA
}

// 按图标组（RT_GROUP_ICON）ID 建 HICON：选尺寸最接近 nWidth x nHeight 的一帧，
// 用 CreateIconFromResourceEx 创建。返回的 HICON 由调用方负责 DestroyIcon。
static HICON CreateImageIcon(const void* pvImage, WORD nGroupId, int nWidth, int nHeight)
{
    DWORD dwGroupSize = 0;
    const BYTE* pGroup = FindImageResource(pvImage, IMAGE_RES_TYPE_GROUP_ICON, nGroupId, &dwGroupSize);
    if (!pGroup || dwGroupSize < 6 + sizeof(GRPICONDIRENTRY)) return NULL;

    // GRPICONDIR: WORD idReserved, idType, idCount
    const WORD nCount = *(const WORD*)(pGroup + 4);
    if (*(const WORD*)(pGroup + 2) != 1 || nCount == 0) return NULL;
    if (dwGroupSize < 6 + (DWORD)nCount * sizeof(GRPICONDIRENTRY)) return NULL;

    const GRPICONDIRENTRY* pBest = NULL;
    int nBestDiff = 0x7FFFFFFF;
    for (WORD i = 0; i < nCount; i++) {
        const GRPICONDIRENTRY* pEntry = (const GRPICONDIRENTRY*)(pGroup + 6 + i * sizeof(GRPICONDIRENTRY));
        const int w = pEntry->bWidth ? pEntry->bWidth : 256;      // 0 表示 256
        const int h = pEntry->bHeight ? pEntry->bHeight : 256;
        const int dx = w > nWidth ? w - nWidth : nWidth - w;
        const int dy = h > nHeight ? h - nHeight : nHeight - h;
        if (dx + dy < nBestDiff) {
            nBestDiff = dx + dy;
            pBest = pEntry;
        }
    }
    if (!pBest) return NULL;

    DWORD dwIconSize = 0;
    const BYTE* pIcon = FindImageResource(pvImage, IMAGE_RES_TYPE_ICON, pBest->nID, &dwIconSize);
    if (!pIcon || dwIconSize == 0) return NULL;

    return (HICON)CreateIconFromResourceEx((PBYTE)pIcon, dwIconSize, TRUE, 0x00030000,
                                           nWidth, nHeight, LR_DEFAULTCOLOR);
}

#endif // YAMA_IMAGE_RESOURCE_H