init

internal/server/server.go

@@ -0,0 +1,146 @@
+package server
+
+import (
+	"encoding/json"
+	"errors"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"github.com/wzray/dns/internal/resolv"
+)
+
+type Server struct {
+	mgr    *resolv.Manager
+	log    *slog.Logger
+	mux    *http.ServeMux
+}
+
+func New(mgr *resolv.Manager, log *slog.Logger) *Server {
+	s := &Server{mgr: mgr, log: log, mux: http.NewServeMux()}
+	s.routes()
+	return s
+}
+
+func (s *Server) Handler() http.Handler {
+	return s.withLogging(s.mux)
+}
+
+func (s *Server) routes() {
+	s.mux.HandleFunc("GET /health", s.handleHealth)
+	s.mux.HandleFunc("GET /dns", s.handleList)
+	s.mux.HandleFunc("POST /dns", s.handleAdd)
+	s.mux.HandleFunc("DELETE /dns/{address}", s.handleRemove)
+}
+
+type listResponse struct {
+	Servers []string `json:"servers"`
+}
+
+type addRequest struct {
+	Address string `json:"address"`
+}
+
+type errorResponse struct {
+	Error string `json:"error"`
+}
+
+func (s *Server) handleHealth(w http.ResponseWriter, _ *http.Request) {
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+}
+
+func (s *Server) handleList(w http.ResponseWriter, r *http.Request) {
+	servers, err := s.mgr.List()
+	if err != nil {
+		s.log.Error("list nameservers", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to read nameservers")
+		return
+	}
+	if servers == nil {
+		servers = []string{}
+	}
+	writeJSON(w, http.StatusOK, listResponse{Servers: servers})
+}
+
+func (s *Server) handleAdd(w http.ResponseWriter, r *http.Request) {
+	var req addRequest
+	dec := json.NewDecoder(r.Body)
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON body")
+		return
+	}
+	if req.Address == "" {
+		writeError(w, http.StatusBadRequest, "address is required")
+		return
+	}
+
+	err := s.mgr.Add(req.Address)
+	switch {
+	case err == nil:
+		writeJSON(w, http.StatusCreated, map[string]string{"address": req.Address})
+	case errors.Is(err, resolv.ErrInvalidAddress):
+		writeError(w, http.StatusBadRequest, err.Error())
+	case errors.Is(err, resolv.ErrAlreadyExists):
+		writeError(w, http.StatusConflict, err.Error())
+	default:
+		s.log.Error("add nameserver", "addr", req.Address, "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to add nameserver")
+	}
+}
+
+func (s *Server) handleRemove(w http.ResponseWriter, r *http.Request) {
+	addr := r.PathValue("address")
+	if addr == "" {
+		writeError(w, http.StatusBadRequest, "address is required")
+		return
+	}
+
+	err := s.mgr.Remove(addr)
+	switch {
+	case err == nil:
+		w.WriteHeader(http.StatusNoContent)
+	case errors.Is(err, resolv.ErrInvalidAddress):
+		writeError(w, http.StatusBadRequest, err.Error())
+	case errors.Is(err, resolv.ErrNotFound):
+		writeError(w, http.StatusNotFound, err.Error())
+	default:
+		s.log.Error("remove nameserver", "addr", addr, "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to remove nameserver")
+	}
+}
+
+func writeJSON(w http.ResponseWriter, status int, body any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(body)
+}
+
+func writeError(w http.ResponseWriter, status int, msg string) {
+	writeJSON(w, status, errorResponse{Error: msg})
+}
+
+type statusRecorder struct {
+	http.ResponseWriter
+	status int
+}
+
+func (r *statusRecorder) WriteHeader(code int) {
+	r.status = code
+	r.ResponseWriter.WriteHeader(code)
+}
+
+func (s *Server) withLogging(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		rec := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
+		next.ServeHTTP(rec, r)
+		s.log.Info("http request",
+			"method", r.Method,
+			"path", r.URL.Path,
+			"status", rec.status,
+			"duration_ms", time.Since(start).Milliseconds(),
+			"remote", r.RemoteAddr,
+		)
+	})
+}