On Windows, plug-ins are valid DLL files (that happen to use a .plw or .p64 extension), while on Linux and Mac, a plug-in is a valid shared object file (that uses a .plx/.plx64 or .pmc/.pmc64 extension, respectively). Building plug-ins can be a tricky matter, because you must get all of the build settings correct or the build process is almost certain to fail. The SDK contains a number of sample plug-ins, each containing its own makefile. The makefiles were all created with Borland’s build tools for Windows in mind. This poses some challenges when you wish to build with a different tool chain or on a different platform. The install_xxx.txt files included with the SDK discuss the use of <SDKDIR>/bin/idamake.pl to build plug-ins using GNU make and gcc. The purpose of idamake.pl is to generate a GNU make-style makefile from the Borland-style makefiles and then invoke GNU make to build the plug-in.

Our preference for building plug-ins is to use simplified makefiles with the GNU tools (via MinGW on Windows). The simplified makefile in Example 17-1 can easily be adapted to your own plug-in projects:

#Set this variable to point to your SDK directory
IDA_SDK=../../

PLATFORM=$(shell uname | cut -f 1 -d _)

ifneq "$(PLATFORM)" "MINGW32"
IDA=$(HOME)/ida
endif

#Set this variable to the desired name of your compiled plugin
PROC=idabook_plugin

ifeq "$(PLATFORM)" "MINGW32"
PLATFORM_CFLAGS=-D__NT__ -D__IDP__ -DWIN32 -Os -fno-rtti
PLATFORM_LDFLAGS=-shared -s
LIBDIR=$(shell find ../../ -type d | grep -E "(lib|lib/)gcc.w32")
ifeq ($(strip $(LIBDIR)),)
LIBDIR=../../lib/x86_win_gcc_32
endif
IDALIB=$(LIBDIR)/ida.a
PLUGIN_EXT=.plw

else ifeq "$(PLATFORM)" "Linux"
PLATFORM_CFLAGS=-D__LINUX__
PLATFORM_LDFLAGS=-shared -s
IDALIB=-lida
IDADIR=-L$(IDA)
PLUGIN_EXT=.plx

else ifeq "$(PLATFORM)" "Darwin"
PLATFORM_CFLAGS=-D__MAC__
PLATFORM_LDFLAGS=-dynamiclib
IDALIB=-lida
IDADIR=-L$(IDA)/idaq.app/Contents/MacOs
PLUGIN_EXT=.pmc
endif

#Platform specific compiler flags
CFLAGS=-Wextra -Os $(PLATFORM_CFLAGS)

#Platform specific ld flags
LDFLAGS=$(PLATFORM_LDFLAGS)

#specify any additional libraries that you may need
EXTRALIBS=

# Destination directory for compiled plugins
OUTDIR=$(IDA_SDK)bin/plugins/

#list out the object files in your project here
OBJS=idabook_plugin.o

BINARY=$(OUTDIR)$(PROC)$(PLUGIN_EXT)

all: $(OUTDIR) $(BINARY)

clean:
    -@rm *.o
    -@rm $(BINARY)

$(OUTDIR):
    -@mkdir -p $(OUTDIR)

CC=g++
INC=-I$(IDA_SDK)include/

%.o: %.cpp
    $(CC) -c $(CFLAGS) $(INC) $< -o $@

LD=g++

$(BINARY): $(OBJS)
    $(LD) $(LDFLAGS) -o $@ $(OBJS) $(IDADIR) $(IDALIB) $(EXTRALIBS)

#change idabook_plugin below to the name of your plugin, make sure to add any
#additional files that your plugin is dependent on
idabook_plugin.o: idabook_plugin.cpp

The preceding makefile uses the uname command to determine the platform on which it is running and configures some build flags accordingly. Additional source files can be added to the plug-in project by appending the names of the associated object files to the $OBJS variable and to the end of the makefile. If your plug-in requires additional libraries, you should specify the library names in $EXTRALIBS. The $IDA_SDK variable is used to specify the location of the <SDKDIR>, and $IDA_SDK may be specified as an absolute or a relative path. In this example, $IDA_SDK is specified as a relative path, indicating that <SDKDIR> lies two directories above the plug-in’s directory. This is in keeping with locating plug-in projects within <SDKDIR>/plugins (<SDKDIR>/plugins/idabook_plugin in this case). If you choose to locate your plug-in’s project directory in some other location relative to <SDKDIR>, you must ensure that $IDA_SDK properly refers to <SDKDIR>. Finally, the preceding example is configured to store successfully compiled plug-ins in <SDKDIR>/bin/plugins. It is important to understand that successfully compiling a plug-in does not necessarily install the plug-in. We cover plug-in installation in the next section.

The use of Microsoft’s Visual C++ Express to build IDA modules is discussed in install_visual.txt. To create a project from scratch using Visual Studio 2008, perform the following steps:

The settings that require modification are spread throughout the Configuration Properties section at the left side of the dialog. Figure 17-3 is representative of the manner in which properties are set throughout a project. For each property category selected in the left-hand portion of the dialog, a list of configurable properties is displayed in the right-hand portion of the dialog. Note that property categories are organized in a hierarchical fashion. Properties are edited using file-selection controls, single-line edit controls, multiline edit controls, or drop-down-list-selection controls. Table 17-1 details the properties that must be edited to create a plug-in project.

Note that Visual Studio allows you to specify separate configuration options for Debug and Release versions of the project (see top left of Figure 17-3). If you intend to build separate Debug and Release versions of your plug-in, make certain that you have modified the properties in both configurations. Alternatively, you may save some time by selecting All Configurations from the Configurations drop-down list (at the top left of the Properties dialog), in which case your property changes will be applied to all build configurations.