feat: more elaborate XFF compute (#350)

* feat: more elaborate XFF compute

#328 followup

now featuring configuration and
defaults that shouldn't break most
setups.

fixes #344

* refactor: obvious condition eval order optimization

* feat: add StripLLU implementation

* chore: I'm sorry it's 7 AM

* test: add test environment for unix socket serving

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test(unix-socket-xff): comment out the shell script more

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(internal): fix logic bug in XFF computation, add tests

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(internal): prevent panic in local testing

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(internal): shuffle around return values to flow better

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>
Co-authored-by: Xe Iaso <me@xeiaso.net>

2 files changed, 199 insertions, 0 deletions

diff --git a/test/cmd/relayd/main.go b/test/cmd/relayd/main.go
new file mode 100644
index 0000000..26700d7
--- /dev/null
+++ b/test/cmd/relayd/main.go
@@ -0,0 +1,124 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"log/slog"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/TecharoHQ/anubis/internal"
+	"github.com/facebookgo/flagenv"
+	"github.com/google/uuid"
+)
+
+var (
+	bind      = flag.String("bind", ":3004", "port to listen on")
+	certDir   = flag.String("cert-dir", "/xe/pki", "where to read mounted certificates from")
+	certFname = flag.String("cert-fname", "cert.pem", "certificate filename")
+	keyFname  = flag.String("key-fname", "key.pem", "key filename")
+	proxyTo   = flag.String("proxy-to", "http://localhost:5000", "where to reverse proxy to")
+	slogLevel = flag.String("slog-level", "info", "logging level")
+)
+
+func main() {
+	flagenv.Parse()
+	flag.Parse()
+
+	internal.InitSlog(*slogLevel)
+
+	slog.Info("starting",
+		"bind", *bind,
+		"cert-dir", *certDir,
+		"cert-fname", *certFname,
+		"key-fname", *keyFname,
+		"proxy-to", *proxyTo,
+	)
+
+	cert := filepath.Join(*certDir, *certFname)
+	key := filepath.Join(*certDir, *keyFname)
+
+	st, err := os.Stat(cert)
+
+	if err != nil {
+		slog.Error("can't stat cert file", "certFname", cert)
+		os.Exit(1)
+	}
+
+	lastModified := st.ModTime()
+
+	go func(lm time.Time) {
+		t := time.NewTicker(time.Hour)
+		defer t.Stop()
+
+		for range t.C {
+			st, err := os.Stat(cert)
+			if err != nil {
+				slog.Error("can't stat file", "fname", cert, "err", err)
+				continue
+			}
+
+			if st.ModTime().After(lm) {
+				slog.Info("new cert detected", "oldTime", lm.Format(time.RFC3339), "newTime", st.ModTime().Format(time.RFC3339))
+				os.Exit(0)
+			}
+		}
+	}(lastModified)
+
+	u, err := url.Parse(*proxyTo)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	h := httputil.NewSingleHostReverseProxy(u)
+
+	if u.Scheme == "unix" {
+		slog.Info("using unix socket proxy")
+
+		h = &httputil.ReverseProxy{
+			Director: func(r *http.Request) {
+				r.URL.Scheme = "http"
+				r.URL.Host = r.Host
+
+				r.Header.Set("X-Forwarded-Proto", "https")
+				r.Header.Set("X-Forwarded-Scheme", "https")
+				r.Header.Set("X-Request-Id", uuid.NewString())
+				r.Header.Set("X-Scheme", "https")
+
+				remoteHost, remotePort, err := net.SplitHostPort(r.Host)
+				if err == nil {
+					r.Header.Set("X-Forwarded-Host", remoteHost)
+					r.Header.Set("X-Forwarded-Port", remotePort)
+				} else {
+					r.Header.Set("X-Forwarded-Host", r.Host)
+				}
+
+				host, _, err := net.SplitHostPort(r.RemoteAddr)
+				if err == nil {
+					r.Header.Set("X-Real-Ip", host)
+				}
+			},
+			Transport: &http.Transport{
+				DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+					return net.Dial("unix", strings.TrimPrefix(*proxyTo, "unix://"))
+				},
+			},
+		}
+	}
+
+	log.Fatal(
+		http.ListenAndServeTLS(
+			*bind,
+			cert,
+			key,
+			h,
+		),
+	)
+}
diff --git a/test/cmd/unixhttpd/main.go b/test/cmd/unixhttpd/main.go
new file mode 100644
index 0000000..a57c202
--- /dev/null
+++ b/test/cmd/unixhttpd/main.go
@@ -0,0 +1,75 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"log/slog"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/TecharoHQ/anubis/internal"
+	"github.com/facebookgo/flagenv"
+)
+
+var (
+	dir        = flag.String("dir", ".", "directory to serve")
+	slogLevel  = flag.String("slog-level", "info", "logging level")
+	socketPath = flag.String("socket-path", "./unixhttpd.sock", "unix socket path to use")
+)
+
+func init() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage of %s:\n", filepath.Base(os.Args[0]))
+		fmt.Fprintf(os.Stderr, "  %s [--dir=.] [--socket-path=./unixhttpd.sock]\n\n", filepath.Base(os.Args[0]))
+		flag.PrintDefaults()
+		os.Exit(2)
+	}
+}
+
+func main() {
+	flagenv.Parse()
+	flag.Parse()
+
+	internal.InitSlog(*slogLevel)
+
+	if *dir == "" && *socketPath == "" {
+		flag.Usage()
+	}
+
+	slog.Info("starting up", "dir", *dir, "socketPath", *socketPath)
+
+	os.Remove(*socketPath)
+
+	mux := http.NewServeMux()
+
+	mux.HandleFunc("/reqmeta", func(w http.ResponseWriter, r *http.Request) {
+		contains := strings.Contains(r.Header.Get("Accept"), "text/html")
+
+		if contains {
+			w.Header().Add("Content-Type", "text/html")
+			fmt.Fprint(w, "<pre id=\"main\"><code>")
+		}
+
+		r.Write(w)
+
+		if contains {
+			fmt.Fprintln(w, "</pre></code>")
+		}
+	})
+
+	mux.Handle("/", http.FileServer(http.Dir(*dir)))
+
+	server := http.Server{
+		Handler: mux,
+	}
+
+	unixListener, err := net.Listen("unix", *socketPath)
+	if err != nil {
+		panic(err)
+	}
+	log.Fatal(server.Serve(unixListener))
+}