Building Go Programs For DD-WRT Routers

Having a difficult time finding an obvious solution I read through relevant Go development forums and pieced together a working solution that allows one to build Go binaries that work on DD-WRT routers. I used an ASUS RT-AC66U, so this method is confirmed working with Broadcom (BCM) routers running the DD-WRT software. Frustrated with the annoying responses to people asking for help, typically being told to just use different software, specifically Open-WRT, a solution that does not work work out of the box for the router I'm currently working with. So I put together this package to help explain how a development environment for developing Go programs can be setup, and how to quickly use this project as a scaffold to compile your own programs.

Starting from scratch

One will need to start by installing Go, because Go is needed to build modern versions of Go, so once you installed Golang 1.8 from apt-get using the command:

    apt-get install golang

Once you have Go installed, you can start the process of building a DD-WRT Go development environment by building a patched version of Go 1.8 with mips32 with FPU support.

    # Create the project folder
    mkdir project && cd project

    git clone https://go.googlesource.com/go go-mips32
    cd go-mips32
    git reset --hard 26e726c3092264584053a4f81714dcc8c91d2153
    git pull https://go.googlesource.com/go refs/changes/58/37958/1
    cd src
    GOROOT_BOOTSTRAP=/usr/local/go ./make.bash

    # Return to the project folder
    cd ../..

If there are no errors, you are very close to being able to build Go software that works on a BCM DD-WRT router, next is building the binary, which we will simplify with a Makefile.

Before we create the Makefile, we will start by enabling SSH on the router, building a very simple "hello world" application and pushing it to the router to test if this will work before making the effort to create the Makefile.

    # Confirm everything is working before creating a Makefile
    GOOS=linux GOARCH=mipsle GOMIPS=mips32r2,soft-float go-mips32/bin/go build -a -ldflags '-s -w' main.go
    scp main.go root@router:~/
    ssh root@router
    ./main

If everything is working, you should see the "hello world" message appear in your terminal. Now you can build a Makefile utilizing the new patched Go binary, so all one will have to do to compile is type make.

    # Golang DD-WRT Makefile
    # Compiling for mips32le with FPU support  
    # Confirmed working with DD-WRT + Broadcom (BCM)
    BINARY=hello
    
    # Go binary
    GOBINARY="go-mips32/bin/go"
    
    # Go build flags
    GOOS=linux
    GOARCH=mipsle
    GOMIPS=soft-float,mips32r2
    
    # LDFLAGS
    LDFLAGS=-s -w
    
    # GOOS=linux GOARCH=mipsle GOMIPS=soft-float,mips32r2 go-mips32/bin/go build -a -ldflags='-s -w' -o hello -a main.go
    all:
    	GOOS=${GOOS} GOARCH=${GOARCH} GOMIPS=${GOMIPS} ${GOBINARY} build -a -ldflags='${LDFLAGS}' -o ${BINARY} main.go

Using this project as foundation

Once you have a handle on how this project was created, one may wish to avoid any extra work and simply use it as foundation for creating their own Go based DD-WRT binaries.

    git clone (this project)
    # Modify the makefile to match your binary name
    make
    # Then work on the main.go file

Credits

Thanks to the Go developers for creating the patches and the curious users who provided an explanation which saved me a lot of time. I hope others frustrated with some of the answers on forums find this project and help them get directly to the creative bits.