skip: bind address flag, serve skip.pac via http (#185)

Add --bind address for local address. Uses kingpin to parse flags simply
because this library is already in use in this repo.

The skip.pac file is now interpreted as a template so that the local
address can be filled in and served on http (instead of previously just
installing it with a file://-URL).
For this, we use the new "go:embed" feature to embed the template file
into the binary (hence the update to go-1.16).

Configuring the skip.pac file with an http://-URL appears to make this
work in chrome 🎉.

Also:
- update to go-1.16 (for go:embed, see above)
  - fix go 1.16 invalid non-alphanumeric build constraint (test-bat-httplib -> testbathttplib)
  - bump scion dependency to latest scionlab version which builds on go-1.15
  - ci: bump machine for integration tests, now runs go-1.15. Some cheat to avoid building scion-skip in integration tests.
  - ci: fix cache paths for integration tests, separate cache key
- update golangci-lint version in Makefile
- Makefile: do not run linter on make test/integration, messes up CI
- go mod tidy

Author: matzf

.circleci/config.yml

@@ -2,7 +2,7 @@ version: 2
 jobs:
   build:
     docker:
-      - image: circleci/golang:1.14
+      - image: circleci/golang:1.16
 
     steps:
       - run:
@@ -14,14 +14,14 @@ jobs:
           keys:
             - v1-pkg-cache-{{ checksum "go.sum" }}
             - v1-pkg-cache
+      - run:
+          name: Build
+          command: make build
       - run:
           name: Run Linters
           command: |
             make setup_lint
             make lint
-      - run:
-          name: Build
-          command: make all
       - run:
           name: Run unit tests
           command: make test
@@ -32,7 +32,7 @@ jobs:
 
   integration:
     machine:
-      image: ubuntu-1604:202007-01
+      image: ubuntu-2004:202101-01
 
     steps:
       - checkout
@@ -51,9 +51,9 @@ jobs:
             git checkout --quiet ${scion_commit}
       - restore_cache:
           keys:
-            - v1-pkg-cache-{{ checksum "~/scion/go.sum" }}-{{ checksum "go.sum" }}
-            - v1-pkg-cache-{{ checksum "~/scion/go.sum" }}-
-            - v1-pkg-cache-
+            - v2-integration-pkg-cache-{{ checksum "~/scion/go.sum" }}-{{ checksum "go.sum" }}
+            - v2-integration-pkg-cache-{{ checksum "~/scion/go.sum" }}-
+            - v2-integration-pkg-cache-
       - run:
           name: Build SCION services and install python3 dependencies
           command: |
@@ -86,21 +86,23 @@ jobs:
             supervisor/supervisor.sh reload
             supervisor/supervisor.sh start all
       - run:
-          name: Prepare integration test
-          command: |
-            # Handle the two special ones
-            make setup_lint 
+          name: Install libpam0g-dev
+          command:
             sudo apt-get update && sudo apt-get install -y libpam0g-dev
       - run:
           name: Integration tests
           command: |
+            # XXX: hack, don't build skip here, needs go-1.16, currently this runs on go-1.15.
+            # As there are currently no integration tests for scion-skip, we don't need it here.
+            sed -i '/^\s*scion-skip\s*\\$/d' Makefile
             make integration
       - store_artifacts:
           path: /tmp/scion-apps-integration/
       - save_cache:
-          key: v1-pkg-cache-{{ checksum "~/scion/go.sum" }}-{{ checksum "go.sum" }}
+          key: v2-integration-pkg-cache-{{ checksum "~/scion/go.sum" }}-{{ checksum "go.sum" }}
           paths:
-            - "/go/pkg"
+            - "~/.go_workspace/"
+            - "~/.cache/go-build/"
 
 workflows:
   version: 2

Makefile

@@ -30,12 +30,12 @@ clean:
 	go clean ./...
 	rm -f bin/*
 
-test: lint
+test:
 	go test -v -tags=$(TAGS) ./...
 
 setup_lint:
 	@# Install golangci-lint (as dumb as this looks, this is the recommended way to install)
-	curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b ${DESTDIR} v1.31.0
+	curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b ${DESTDIR} v1.37.1
 
 lint:
 	@type golangci-lint > /dev/null || ( echo "golangci-lint not found. Install it manually or by running 'make setup_lint'."; exit 1 )
@@ -46,7 +46,7 @@ install: all
 	mkdir -p $(DESTDIR)
 	cp -t $(DESTDIR) $(BIN)/scion-*
 
-integration: all
+integration: build
 	go test -v -tags=integration,$(TAGS) ./... ./_examples/helloworld/
 
 .PHONY: scion-bat

README.md

@@ -17,7 +17,7 @@ sudo apt install scion-apps-*
 
 ### Build:
 
-1. Install go 1.14
+1. Install go 1.16
 
     See e.g. https://github.com/golang/go/wiki/Ubuntu
 

bat/httplib/httplib_test.go

@@ -17,7 +17,7 @@
 // different value than expected.
 // There is not much value in running these tests for our fork anyway, so skip
 // them.
-// +build test-bat-httplib
+// +build testbathttplib
 
 package httplib
 

go.mod

@@ -1,9 +1,8 @@
 module github.com/netsec-ethz/scion-apps
 
-go 1.14
+go 1.16
 
 require (
-	github.com/BurntSushi/toml v0.3.1
 	github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d // indirect
 	github.com/bclicn/color v0.0.0-20180711051946-108f2023dc84
 	github.com/gorilla/handlers v1.5.1
@@ -22,4 +21,4 @@ require (
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 )
 
-replace github.com/scionproto/scion => github.com/netsec-ethz/scion v0.0.0-20201217162907-707a5e6caaff
+replace github.com/scionproto/scion => github.com/netsec-ethz/scion v0.0.0-20210209094654-fbc7c985966b

go.sum

@@ -24,8 +24,8 @@ as either:
 
   In Firefox (currently v84.0), navigate to
   **Preferences** / **General** / **Network Settings**, enable "Automatic proxy
-  configuration URL" and enter `file://` and the path to the `skip.pac` file
-  (e.g. `file:///home/skipper/scion-apps/skip/skip.pac`).
+  configuration URL" and enter `http://localhost:8888/skip.pac`.
+  Adapt the address if you're running skip on a non-default address with `--bind`.
 
 ## Usage
 
@@ -41,7 +41,6 @@ Enter SCION addresses in the URL bar of your browser, mangled as described above
 
 ## Limitations
 
-* Chrome does not appear to honor the PAC (WPAD) configuration, even when it reads it. Not sure why.
 * Does not support HTTPS
 * Does not support WebSockets (HTTP CONNECT) method
 * Does not allow specifiying the protocol (e.g. as

skip/README.md

@@ -12,21 +12,28 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build go1.16
+
 package main
 
 import (
+	"bytes"
 	"crypto/tls"
+	_ "embed"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"os"
 	"regexp"
 	"strings"
+	"text/template"
 
 	"github.com/gorilla/handlers"
 	"github.com/netsec-ethz/scion-apps/pkg/shttp"
+	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 var (
@@ -39,20 +46,48 @@ const (
 	mungedScionAddrHostIndex = 3
 )
 
+//go:embed skip.pac
+var skipPAC string
+var skipPACtemplate = template.Must(template.New("skip.pac").Parse(skipPAC))
+
+type skipPACTemplateParams struct {
+	ProxyAddress string
+}
+
 func main() {
+	var bindAddress *net.TCPAddr
+	kingpin.Flag("bind", "Address to bind on").Default("localhost:8888").TCPVar(&bindAddress)
+	kingpin.Parse()
+
 	transport := shttp.NewRoundTripper(&tls.Config{InsecureSkipVerify: true}, nil)
 	defer transport.Close()
 	proxy := &proxyHandler{
 		transport: transport,
 	}
-
+	mux := http.NewServeMux()
+	mux.Handle("localhost/skip.pac", http.HandlerFunc(handleWPAD))
+	if bindAddress.IP != nil {
+		mux.Handle(bindAddress.IP.String()+"/skip.pac", http.HandlerFunc(handleWPAD))
+	}
+	mux.Handle("/", proxy) // everything else
 	server := &http.Server{
-		Addr:    "localhost:8888",
-		Handler: handlers.LoggingHandler(os.Stdout, proxy),
+		Addr:    bindAddress.String(),
+		Handler: handlers.LoggingHandler(os.Stdout, mux),
 	}
 	log.Fatal(server.ListenAndServe())
 }
 
+func handleWPAD(w http.ResponseWriter, req *http.Request) {
+	buf := &bytes.Buffer{}
+	err := skipPACtemplate.Execute(buf, skipPACTemplateParams{ProxyAddress: req.Host})
+	if err != nil {
+		http.Error(w, "error executing template", 500)
+		return
+	}
+	w.Header().Set("content-type", "application/x-ns-proxy-autoconfig")
+	_, _ = w.Write(buf.Bytes())
+}
+
 type proxyHandler struct {
 	transport http.RoundTripper
 }

skip/main.go

@@ -2,7 +2,7 @@ function FindProxyForURL(url, host)
 {
   let mungedScionAddr = /^\d+-[-_.\dA-Fa-f]+$/
   if (host.match(mungedScionAddr) != null || shExpMatch(host, "*.scion")) {
-	  return "PROXY localhost:8888";
+	  return "PROXY {{.ProxyAddress}}";
   }
   return "DIRECT";
 }

skip/skip.pac

@@ -71,22 +71,7 @@ Add alternate test forwarding port line in `Vagrantfile`:
   config.vm.network "forwarded_port", guest: 8080, host: 8080, protocol: "tcp"
 ```
 
-Update Go Paths:
-```shell
-echo 'export GOPATH="$HOME/go"' >> ~/.profile
-echo 'export GOBIN="$GOPATH/bin"' >> ~/.profile
-echo 'export PATH="$HOME/.local/bin:$GOPATH/bin:/usr/local/go/bin:$PATH"' >> ~/.profile
-source ~/.profile
-mkdir -p "$GOPATH"
-```
-
-Install Go 1.14:
-```shell
-cd ~
-sudo rm -rf /usr/local/go
-curl -LO https://golang.org/dl/go1.14.12.linux-amd64.tar.gz
-sudo tar -C /usr/local -xzf go1.14.12.linux-amd64.tar.gz
-```
+Install Go 1.16 (see e.g. https://github.com/golang/go/wiki/Ubuntu).
 
 Build and install `scion-apps`:
 ```shell