1 files changed, 128 insertions, 0 deletions
diff --git a/server.go b/server.go
new file mode 100644
index 0000000..ad00d26
--- /dev/null
+++ b/server.go
@@ -0,0 +1,128 @@
+package main
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+)
+
+type multipleReverseProxyServer struct {
+	rules []rewriteRule
+}
+
+type rewriteRule struct {
+	fromHost string
+	toUrl    *url.URL
+	proxy    *httputil.ReverseProxy
+}
+
+func newMultipleReverseProxyServer(ps []ProxyConfig) *multipleReverseProxyServer {
+	var rules []rewriteRule
+	for _, p := range ps {
+		targetUrl, err := url.Parse(fmt.Sprintf("http://%s:%d", p.To.Host, p.To.Port))
+		if err != nil {
+			// This setting should be validated when loading config.
+			panic(err)
+		}
+		rules = append(rules, rewriteRule{
+			fromHost: p.From.Host,
+			toUrl:    targetUrl,
+			proxy: &httputil.ReverseProxy{
+				Rewrite: func(r *httputil.ProxyRequest) {
+					r.SetURL(targetUrl)
+					r.SetXForwarded()
+				},
+			},
+		})
+	}
+	return &multipleReverseProxyServer{
+		rules: rules,
+	}
+}
+
+func (s *multipleReverseProxyServer) tryServeHTTP(w http.ResponseWriter, r *http.Request) bool {
+	for _, rule := range s.rules {
+		if r.Host == rule.fromHost {
+			rule.proxy.ServeHTTP(w, r)
+			return true
+		}
+	}
+	return false
+}
+
+type Server struct {
+	s          http.Server
+	tlsEnabled bool
+}
+
+func NewServer(cfg *ServerConfig) *Server {
+	h := http.NewServeMux()
+
+	if cfg.ACMEChallenge != nil {
+		h.Handle(
+			"/.well-known/acme-challenge/",
+			http.FileServer(http.Dir(cfg.ACMEChallenge.Root)),
+		)
+	}
+
+	if cfg.RedirectToHTTPS {
+		h.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			target := r.URL
+			target.Scheme = "https"
+			target.Host = r.Host
+			http.Redirect(w, r, target.String(), http.StatusMovedPermanently)
+		})
+	} else {
+		reverseProxyServer := newMultipleReverseProxyServer(cfg.Proxies)
+		h.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			found := reverseProxyServer.tryServeHTTP(w, r)
+			if !found {
+				http.NotFound(w, r)
+			}
+		})
+	}
+
+	var tlsConfig *tls.Config
+	if cfg.TLSCertFile != "" && cfg.TLSKeyFile != "" {
+		cert, err := tls.LoadX509KeyPair(cfg.TLSCertFile, cfg.TLSKeyFile)
+		if err != nil {
+			panic(err)
+		}
+		tlsConfig = &tls.Config{
+			Certificates: []tls.Certificate{cert},
+		}
+	}
+
+	return &Server{
+		tlsEnabled: cfg.Protocol == "https",
+		s: http.Server{
+			Addr:      fmt.Sprintf("%s:%d", cfg.Host, cfg.Port),
+			Handler:   h,
+			TLSConfig: tlsConfig,
+		},
+	}
+}
+
+func (s *Server) Label() string {
+	return s.s.Addr
+}
+
+func (s *Server) Serve(listener net.Listener) error {
+	if s.tlsEnabled {
+		return s.s.ServeTLS(listener, "", "")
+	} else {
+		return s.s.Serve(listener)
+	}
+}
+
+func (s *Server) Shutdown(ctx context.Context) {
+	s.s.Shutdown(ctx)
+}
+
+func NewListener(cfg *ServerConfig) (net.Listener, error) {
+	return net.Listen("tcp", fmt.Sprintf("%s:%d", cfg.Host, cfg.Port))
+}