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package http
import (
"context"
"encoding/json"
"net"
"net/http"
"strconv"
"time"
"github.com/mpolden/zdns/cache"
"github.com/mpolden/zdns/dns"
"github.com/mpolden/zdns/log"
)
// A Server defines paramaters for running an HTTP server. The HTTP server serves an API for inspecting cache contents
// and request log.
type Server struct {
cache *cache.Cache
logger *log.Logger
server *http.Server
}
type entry struct {
Time string `json:"time"`
TTL int64 `json:"ttl,omitempty"`
RemoteAddr net.IP `json:"remote_addr,omitempty"`
Qtype string `json:"type"`
Question string `json:"question"`
Answers []string `json:"answers,omitempty"`
Rcode string `json:"rcode,omitempty"`
}
type httpError struct {
err error
Status int `json:"status"`
Message string `json:"message"`
}
// NewServer creates a new HTTP server, serving logs from the given logger and listening on addr.
func NewServer(logger *log.Logger, cache *cache.Cache, addr string) *Server {
server := &http.Server{Addr: addr}
s := &Server{
cache: cache,
logger: logger,
server: server,
}
s.server.Handler = s.handler()
return s
}
func (s *Server) handler() http.Handler {
mux := http.NewServeMux()
mux.Handle("/cache/v1/", appHandler(s.cacheHandler))
mux.Handle("/log/v1/", appHandler(s.logHandler))
mux.Handle("/", appHandler(notFoundHandler))
return requestFilter(mux)
}
type appHandler func(http.ResponseWriter, *http.Request) (interface{}, *httpError)
func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
data, e := fn(w, r)
if e != nil { // e is *Error, not os.Error.
if e.Message == "" {
e.Message = e.err.Error()
}
out, err := json.Marshal(e)
if err != nil {
panic(err)
}
w.WriteHeader(e.Status)
w.Write(out)
} else if data != nil {
out, err := json.Marshal(data)
if err != nil {
panic(err)
}
w.Write(out)
}
}
func requestFilter(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
next.ServeHTTP(w, r)
})
}
func notFoundHandler(w http.ResponseWriter, r *http.Request) (interface{}, *httpError) {
return nil, &httpError{
Status: http.StatusNotFound,
Message: "Resource not found",
}
}
func listCountFrom(r *http.Request) int {
defaultCount := 100
param := r.URL.Query().Get("n")
n, err := strconv.Atoi(param)
if err != nil {
return defaultCount
}
return n
}
func (s *Server) cacheHandler(w http.ResponseWriter, r *http.Request) (interface{}, *httpError) {
cacheValues := s.cache.List(listCountFrom(r))
entries := make([]entry, 0, len(cacheValues))
for _, v := range cacheValues {
entries = append(entries, entry{
Time: v.CreatedAt.UTC().Format(time.RFC3339),
TTL: int64(v.TTL().Truncate(time.Second).Seconds()),
Qtype: dns.TypeToString[v.Qtype()],
Question: v.Question(),
Answers: v.Answers(),
Rcode: dns.RcodeToString[v.Rcode()],
})
}
return entries, nil
}
func (s *Server) logHandler(w http.ResponseWriter, r *http.Request) (interface{}, *httpError) {
logEntries, err := s.logger.Get(listCountFrom(r))
if err != nil {
return nil, &httpError{
err: err,
Status: http.StatusInternalServerError,
}
}
entries := make([]entry, 0, len(logEntries))
for _, le := range logEntries {
entries = append(entries, entry{
Time: le.Time.UTC().Format(time.RFC3339),
RemoteAddr: le.RemoteAddr,
Qtype: dns.TypeToString[le.Qtype],
Question: le.Question,
Answers: le.Answers,
})
}
return entries, nil
}
// Close shuts down the HTTP server.
func (s *Server) Close() error { return s.server.Shutdown(context.Background()) }
// ListenAndServe starts the HTTP server listening on the configured address.
func (s *Server) ListenAndServe() error {
s.logger.Printf("http server listening on http://%s", s.server.Addr)
err := s.server.ListenAndServe()
if err == http.ErrServerClosed {
return nil // Do not treat server closing as an error
}
return err
}
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