Added DLL imports on Windows

src/exe/pe/DLLImport.go

@@ -0,0 +1,11 @@
+package pe
+
+const DLLImportSize = 20
+
+type DLLImport struct {
+	RvaFunctionNameList    uint32
+	TimeDateStamp          uint32
+	ForwarderChain         uint32
+	RvaModuleName          uint32
+	RvaFunctionAddressList uint32
+}

src/exe/pe/EXE.go

@@ -17,27 +17,73 @@ type EXE struct {
 	Sections []SectionHeader
 }
 
+type DLL struct {
+	Name      string
+	Functions []string
+}
+
 // Write writes the EXE file to the given writer.
 func Write(writer io.Writer, code []byte, data []byte) {
-	NumSections := 1
+	NumSections := 3
-
-	if len(data) != 0 {
-		NumSections += 1
-	}
-
 	HeaderEnd := DOSHeaderSize + NTHeaderSize + OptionalHeader64Size + SectionHeaderSize*NumSections
+	codeStart, codePadding := exe.Align(HeaderEnd, config.Align)
+	dataStart, dataPadding := exe.Align(codeStart+len(code), config.Align)
 
-	var (
+	dlls := []DLL{
-		codeStart, codePadding = exe.Align(HeaderEnd, config.Align)
+		{
-		dataStart, dataPadding = exe.Align(codeStart+len(code), config.Align)
+			Name: "kernel32.dll",
-	)
+			Functions: []string{
-
+				"ExitProcess",
-	imageSize := codeStart + len(code)
+				"GetStdHandle",
-
+				"WriteFile",
-	if len(data) != 0 {
+			},
-		imageSize = dataStart + len(data)
+		},
 	}
 
+	dllAddresses := []uint64{}
+	dllImports := []DLLImport{}
+
+	dllName := len(data)
+	data = append(data, dlls[0].Name...)
+	data = append(data, 0x00)
+
+	for _, f := range dlls[0].Functions {
+		pos := len(data)
+		data = append(data, 0x00, 0x00)
+		data = append(data, f...)
+		data = append(data, 0x00)
+
+		if len(data)&1 != 0 {
+			data = append(data, 0x00) // align the next entry on an even boundary
+		}
+
+		dllAddresses = append(dllAddresses, uint64(dataStart+pos))
+	}
+
+	dllAddresses = append(dllAddresses, 0)
+	importStart, importPadding := exe.Align(dataStart+len(data), config.Align)
+	itblSize := DLLImportSize*len(dlls) + DLLImportSize
+	iatblSize := 8 * len(dllAddresses)
+	itblStart := importStart
+	iatblStart := itblStart + itblSize
+
+	dllImports = append(dllImports, DLLImport{
+		RvaFunctionNameList:    uint32(iatblStart),
+		TimeDateStamp:          0,
+		ForwarderChain:         0,
+		RvaModuleName:          uint32(dataStart + dllName),
+		RvaFunctionAddressList: uint32(iatblStart),
+	})
+
+	dllImports = append(dllImports, DLLImport{
+		RvaFunctionNameList:    0,
+		TimeDateStamp:          0,
+		ForwarderChain:         0,
+		RvaModuleName:          0, // must be zero
+		RvaFunctionAddressList: 0,
+	})
+
+	imageSize := iatblStart + iatblSize
 	imageSize, _ = exe.Align(imageSize, config.Align)
 
 	pe := &EXE{
@@ -49,6 +95,9 @@ func Write(writer io.Writer, code []byte, data []byte) {
 			Signature:            [4]byte{'P', 'E', 0, 0},
 			Machine:              IMAGE_FILE_MACHINE_AMD64,
 			NumberOfSections:     uint16(NumSections),
+			TimeDateStamp:        0,
+			PointerToSymbolTable: 0,
+			NumberOfSymbols:      0,
 			SizeOfOptionalHeader: OptionalHeader64Size,
 			Characteristics:      IMAGE_FILE_EXECUTABLE_IMAGE | IMAGE_FILE_LARGE_ADDRESS_AWARE,
 		},
@@ -57,24 +106,34 @@ func Write(writer io.Writer, code []byte, data []byte) {
 			MajorLinkerVersion:          0x0E,
 			MinorLinkerVersion:          0x16,
 			SizeOfCode:                  uint32(len(code)),
+			SizeOfInitializedData:       0,
+			SizeOfUninitializedData:     0,
 			AddressOfEntryPoint:         config.CodeOffset,
 			BaseOfCode:                  config.CodeOffset,
 			ImageBase:                   config.BaseAddress,
 			SectionAlignment:            config.Align, // power of 2, must be greater than or equal to FileAlignment
 			FileAlignment:               config.Align, // power of 2
 			MajorOperatingSystemVersion: 0x06,
+			MinorOperatingSystemVersion: 0,
+			MajorImageVersion:           0,
+			MinorImageVersion:           0,
 			MajorSubsystemVersion:       0x06,
+			MinorSubsystemVersion:       0,
+			Win32VersionValue:           0,
 			SizeOfImage:                 uint32(imageSize),
 			SizeOfHeaders:               config.CodeOffset, // section bodies begin here
+			CheckSum:                    0,
 			Subsystem:                   IMAGE_SUBSYSTEM_WINDOWS_CUI,
 			DllCharacteristics:          IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA | IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE | IMAGE_DLLCHARACTERISTICS_NX_COMPAT | IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE,
 			SizeOfStackReserve:          0x100000,
 			SizeOfStackCommit:           0x1000,
 			SizeOfHeapReserve:           0x100000,
 			SizeOfHeapCommit:            0x1000,
+			LoaderFlags:                 0,
 			NumberOfRvaAndSizes:         16,
 			DataDirectory: [16]DataDirectory{
 				{VirtualAddress: 0, Size: 0},
+				{VirtualAddress: uint32(itblStart), Size: uint32(itblSize)}, // RVA of the imported function table
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
@@ -85,8 +144,7 @@ func Write(writer io.Writer, code []byte, data []byte) {
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
-				{VirtualAddress: 0, Size: 0},
+				{VirtualAddress: uint32(iatblStart), Size: uint32(iatblSize)}, // RVA of the import address table
-				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
 				{VirtualAddress: 0, Size: 0},
@@ -105,23 +163,31 @@ func Write(writer io.Writer, code []byte, data []byte) {
 				Name:            [8]byte{'.', 'r', 'd', 'a', 't', 'a'},
 				VirtualSize:     uint32(len(data)),
 				VirtualAddress:  uint32(dataStart),
-				RawSize:         uint32(len(data)), // must be a multiple of FileAlignment
+				RawSize:         uint32(len(data)),
-				RawAddress:      uint32(dataStart), // must be a multiple of FileAlignment
+				RawAddress:      uint32(dataStart),
 				Characteristics: IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ,
 			},
+			{
+				Name:            [8]byte{'.', 'i', 'd', 'a', 't', 'a'},
+				VirtualSize:     uint32(iatblSize + itblSize),
+				VirtualAddress:  uint32(importStart),
+				RawSize:         uint32(iatblSize + itblSize),
+				RawAddress:      uint32(importStart),
+				Characteristics: IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE,
+			},
 		},
 	}
 
 	binary.Write(writer, binary.LittleEndian, &pe.DOSHeader)
 	binary.Write(writer, binary.LittleEndian, &pe.NTHeader)
 	binary.Write(writer, binary.LittleEndian, &pe.OptionalHeader64)
-	binary.Write(writer, binary.LittleEndian, pe.Sections[:NumSections])
+	binary.Write(writer, binary.LittleEndian, &pe.Sections)
 
 	writer.Write(bytes.Repeat([]byte{0x00}, int(codePadding)))
 	writer.Write(code)
-
-	if len(data) != 0 {
 	writer.Write(bytes.Repeat([]byte{0x00}, int(dataPadding)))
 	writer.Write(data)
-	}
+	writer.Write(bytes.Repeat([]byte{0x00}, int(importPadding)))
+	binary.Write(writer, binary.LittleEndian, &dllImports)
+	binary.Write(writer, binary.LittleEndian, &dllAddresses)
 }

src/exe/pe/ImportDirectory.go

@@ -1,9 +0,0 @@
-package pe
-
-type ImportDirectory struct {
-	OriginalFirstThunk uint32
-	TimeDateStamp      uint32
-	ForwarderChain     uint32
-	Name               uint32
-	FirstThunk         uint32
-}

src/exe/pe/pe.md

@@ -2,11 +2,13 @@
 
 ## Notes
 
-Unlike Linux, Windows does not ignore zero-length sections and will fail loading them because they don't exist within the file.
+Unlike Linux, Windows does not ignore zero-length sections at the end of a file and will
-Adding a single byte to the section can fix this problem, but it's easier to just remove the section header entirely.
+fail loading them because they don't exist within the file. Adding a single byte to the
+section can fix this problem, but it's easier to just remove the section header entirely.
 
 ## Links
 
+- https://learn.microsoft.com/en-us/windows/win32/debug/pe-format
 - https://learn.microsoft.com/en-us/previous-versions/ms809762(v=msdn.10)
 - https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/february/inside-windows-win32-portable-executable-file-format-in-detail
 - https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/march/inside-windows-an-in-depth-look-into-the-win32-portable-executable-file-format-part-2