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middleware.go
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middleware.go
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package http
import (
"encoding/json"
"fmt"
"net"
"net/http"
"strings"
"sync"
"time"
"github.com/denpeshkov/greenlight/internal/greenlight"
"golang.org/x/time/rate"
)
// hijackResponseWriter records status of the HTTP response.
type hijackResponseWriter struct {
http.ResponseWriter
status int
}
func (w *hijackResponseWriter) WriteHeader(statusCode int) {
w.status = statusCode
w.ResponseWriter.WriteHeader(statusCode)
}
type notFoundResponseWriter struct {
hijackResponseWriter
}
func (w *notFoundResponseWriter) Write(data []byte) (n int, err error) {
if w.hijackResponseWriter.status == http.StatusNotFound {
data, err = json.Marshal(ErrorResponse{Msg: greenlight.ErrNotFound.Msg})
}
if err != nil {
return 0, err
}
return w.hijackResponseWriter.Write(data)
}
// notFound returns a request handler that handles [http.StatusNotFound] status code.
func (s *Server) notFound(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
hw := hijackResponseWriter{ResponseWriter: w, status: http.StatusOK}
nfw := ¬FoundResponseWriter{hijackResponseWriter: hw}
h.ServeHTTP(nfw, r)
})
}
type methodNotAllowedResponseWriter struct {
hijackResponseWriter
}
func (w *methodNotAllowedResponseWriter) Write(data []byte) (n int, err error) {
if w.hijackResponseWriter.status == http.StatusMethodNotAllowed {
data, err = json.Marshal(ErrorResponse{Msg: http.StatusText(http.StatusMethodNotAllowed)})
}
if err != nil {
return 0, err
}
return w.hijackResponseWriter.Write(data)
}
// methodNotAllowed returns a request handler that handles [http.StatusMethodNotAllowed] status code.
func (s *Server) methodNotAllowed(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
hw := hijackResponseWriter{ResponseWriter: w, status: http.StatusOK}
mrw := &methodNotAllowedResponseWriter{hijackResponseWriter: hw}
h.ServeHTTP(mrw, r)
})
}
func (s *Server) recoverPanic(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
defer func() {
if err := recover(); err != nil {
// Acts as a trigger to make HTTP server automatically close the current connection after a response has been sent.
w.Header().Set("Connection", "close")
s.Error(w, r, fmt.Errorf("%v", err))
}
}()
h.ServeHTTP(w, r)
})
}
func (s *Server) rateLimit(h http.Handler) http.Handler {
op := "http.Server.rateLimit"
type clientLim struct {
lim *rate.Limiter
lastSeen time.Time
}
lims := sync.Map{}
// cleanup unused limiters
go func() {
for {
time.Sleep(time.Minute)
lims.Range(func(ip, v any) bool {
clim := v.(clientLim)
if time.Since(clim.lastSeen) > 3*time.Minute {
lims.Delete(ip)
}
return true
})
}
}()
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ip, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
s.Error(w, r, fmt.Errorf("%s: %w", op, err))
return
}
v, _ := lims.LoadOrStore(ip, clientLim{lim: rate.NewLimiter(rate.Limit(s.opts.limiterRps), s.opts.limiterBurst)})
clim := v.(clientLim)
clim.lastSeen = time.Now()
if !clim.lim.Allow() {
s.Error(w, r, greenlight.NewRateLimitError("Rate limit exceeded."))
return
}
h.ServeHTTP(w, r)
})
}
func (s *Server) authenticate(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
op := "http.Server.authenticate"
// This indicates to any caches that the response may vary based on the value of the Authorization header in the request.
w.Header().Add("Vary", "Authorization")
authzHeader := r.Header.Get("Authorization")
if authzHeader == "" {
s.Error(w, r, fmt.Errorf("%s: %w", op, greenlight.NewUnauthorizedError("You must be authenticated to access this resource.")))
return
}
headerParts := strings.Split(authzHeader, " ")
if len(headerParts) != 2 || headerParts[0] != "Bearer" {
s.Error(w, r, fmt.Errorf("%s: %w", op, greenlight.NewUnauthorizedError("Invalid or missing authentication token.")))
return
}
userId, err := s.authService.ParseToken(headerParts[1])
if err != nil {
s.Error(w, r, fmt.Errorf("%s: %w", op, err))
return
}
r = r.WithContext(greenlight.NewContextWithUserID(r.Context(), userId))
h.ServeHTTP(w, r)
})
}