fix crash in case of specially-crafted HTTP requests (#2166) (#2169)

internal/httpserv/handler_exit_on_panic.go

@@ -0,0 +1,27 @@
+package httpserv
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"runtime"
+)
+
+// exit when there's a panic inside the HTTP handler.
+// https://github.com/golang/go/issues/16542
+type handlerExitOnPanic struct {
+	http.Handler
+}
+
+func (h *handlerExitOnPanic) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	defer func() {
+		err := recover()
+		if err != nil {
+			buf := make([]byte, 1<<20)
+			n := runtime.Stack(buf, true)
+			fmt.Fprintf(os.Stderr, "panic: %v\n\n%s", err, buf[:n])
+			os.Exit(1)
+		}
+	}()
+	h.Handler.ServeHTTP(w, r)
+}