add image-measurement tool (#106)

Signed-off-by: Benedict Schlueter <bs@edgeless.systems>
Co-authored-by: Daniel Weiße <dw@edgeless.systems>

hack/image-measurement/server/server.go

@@ -0,0 +1,81 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"net"
+	"net/http"
+
+	"github.com/edgelesssys/constellation/internal/logger"
+	"go.uber.org/zap"
+)
+
+type Server struct {
+	log    *logger.Logger
+	server http.Server
+	done   chan<- struct{}
+}
+
+func New(log *logger.Logger, done chan<- struct{}) *Server {
+	return &Server{
+		log:  log,
+		done: done,
+	}
+}
+
+func (s *Server) ListenAndServe(port string) error {
+	mux := http.NewServeMux()
+	mux.Handle("/pcrs", http.HandlerFunc(s.logPCRs))
+
+	s.server = http.Server{
+		Handler: mux,
+	}
+
+	lis, err := net.Listen("tcp", net.JoinHostPort("", port))
+	if err != nil {
+		return err
+	}
+	s.log.Infof("Starting QEMU metadata API on %s", lis.Addr())
+	return s.server.Serve(lis)
+}
+
+func (s *Server) Shutdown() error {
+	return s.server.Shutdown(context.Background())
+}
+
+// logPCRs allows QEMU instances to export their TPM state during boot.
+func (s *Server) logPCRs(w http.ResponseWriter, r *http.Request) {
+	log := s.log.With(zap.String("peer", r.RemoteAddr))
+	if r.Method != http.MethodPost {
+		log.With(zap.String("method", r.Method)).Errorf("Invalid method for /log")
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	log.Infof("Serving POST request for /pcrs")
+
+	if r.Body == nil {
+		log.Errorf("Request body is empty")
+		http.Error(w, "Request body is empty", http.StatusBadRequest)
+		return
+	}
+
+	// unmarshal the request body into a map of PCRs
+	var pcrs map[uint32][]byte
+	if err := json.NewDecoder(r.Body).Decode(&pcrs); err != nil {
+		log.With(zap.Error(err)).Errorf("Failed to read request body")
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	log.Infof("PCR 4 %x", pcrs[4])
+	log.Infof("PCR 8 %x", pcrs[8])
+	log.Infof("PCR 9 %x", pcrs[9])
+	s.done <- struct{}{}
+}