/
middleware.go
310 lines (279 loc) · 11.4 KB
/
middleware.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
package main
import (
"errors"
"expvar"
"fmt"
"github.com/felixge/httpsnoop"
"github.com/muchlist/greenlight/internal/data"
"github.com/muchlist/greenlight/internal/validator"
"golang.org/x/time/rate"
"net"
"net/http"
"strconv"
"strings"
"sync"
"time"
)
func (app *application) recoverPanic(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Create a deferred function (which will always be run in the event of a panic
// as Go unwinds the stack).
defer func() {
// Use the builtin recover function to check if there has been a panic or
// not.
if err := recover(); err != nil {
// If there was a panic, set a "Connection: close" header on the
// response. This acts as a trigger to make Go's HTTP server
// automatically close the current connection after a response has been
// sent.
w.Header().Set("Connection", "close")
// The value returned by recover() has the type interface{}, so we use
// fmt.Errorf() to normalize it into an error and call our
// serverErrorResponse() helper. In turn, this will log the error using
// our custom Logger type at the ERROR level and send the client a 500
// Internal Server Error response.
app.serverErrorResponse(w, r, fmt.Errorf("%s", err))
}
}()
next.ServeHTTP(w, r)
})
}
func (app *application) rateLimit(next http.Handler) http.Handler {
type client struct {
limiter *rate.Limiter
lastSeen time.Time
}
// Declare a mutex and a map to hold the clients' IP addresses and rate limiters.
var (
mu sync.Mutex
clients = make(map[string]*client)
)
// Launch a background goroutine which removes old entries from the clients map once
// every minute.
go func() {
for {
time.Sleep(time.Minute)
// Lock the mutex to prevent any rate limiter checks from happening while
// the cleanup is taking place.
mu.Lock()
// Loop through all clients. If they haven't been seen within the last three
// minutes, delete the corresponding entry from the map.
for ip, client := range clients {
if time.Since(client.lastSeen) > 3*time.Minute {
if time.Since(client.lastSeen) > 3*time.Minute {
delete(clients, ip)
}
}
// Importantly, unlock the mutex when the cleanup is complete.
mu.Unlock()
}
}
}()
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if app.config.limiter.enabled {
// Extract the client's IP address from the request.
ip, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
app.serverErrorResponse(w, r, err)
return
}
// Lock the mutex to prevent this code from being executed concurrently.
mu.Lock()
if _, found := clients[ip]; !found {
// Create and add a new client struct to the map if it doesn't already exist.
clients[ip] = &client{limiter: rate.NewLimiter(2, 4)}
}
// Update the last seen time for the client.
clients[ip].lastSeen = time.Now()
// Call the Allow() method on the rate limiter for the current IP address. If
// the request isn't allowed, unlock the mutex and send a 429 Too Many Requests
// response, just like before.
if !clients[ip].limiter.Allow() {
mu.Unlock()
app.rateLimitExceededResponse(w, r)
return
}
// Very importantly, unlock the mutex before calling the next handler in the
// chain. Notice that we DON'T use defer to unlock the mutex, as that would mean
// that the mutex isn't unlocked until all the handlers downstream of this
// middleware have also returned.
mu.Unlock()
}
next.ServeHTTP(w, r)
})
}
func (app *application) authenticate(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Add the "Vary: Authorization" header to the response. 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")
// Retrieve the value of the Authorization header from the request. This will
// return the empty string "" if there is no such header found.
authorizationHeader := r.Header.Get("Authorization")
// If there is no Authorization header found, use the contextSetUser() helper
// that we just made to add the AnonymousUser to the request context. Then we
// call the next handler in the chain and return without executing any of the
// code below.
if authorizationHeader == "" {
r = app.contextSetUser(r, data.AnonymousUser)
next.ServeHTTP(w, r)
return
}
// Otherwise, we expect the value of the Authorization header to be in the format
// "Bearer <token>". We try to split this into its constituent parts, and if the
// header isn't in the expected format we return a 401 Unauthorized response
// using the invalidAuthenticationTokenResponse() helper (which we will create
// in a moment).
headerParts := strings.Split(authorizationHeader, " ")
if len(headerParts) != 2 || headerParts[0] != "Bearer" {
app.invalidAuthenticationTokenResponse(w, r)
return
}
// Extract the actual authentication token from the header parts.
token := headerParts[1]
// Validate the token to make sure it is in a sensible format.
v := validator.New()
// If the token isn't valid, use the invalidAuthenticationTokenResponse()
// helper to send a response, rather than the failedValidationResponse() helper
// that we'd normally use.
if data.ValidateTokenPlaintext(v, token); !v.Valid() {
app.invalidAuthenticationTokenResponse(w, r)
return
}
// Retrieve the details of the user associated with the authentication token,
// again calling the invalidAuthenticationTokenResponse() helper if no
// matching record was found. IMPORTANT: Notice that we are using
// ScopeAuthentication as the first parameter here.
user, err := app.models.Users.GetForToken(data.ScopeAuthentication, token)
if err != nil {
switch {
case errors.Is(err, data.ErrRecordNotFound):
app.invalidAuthenticationTokenResponse(w, r)
default:
app.serverErrorResponse(w, r, err)
}
return
}
// Call the contextSetUser() helper to add the user information to the request
// context.
r = app.contextSetUser(r, user)
// Call the next handler in the chain.
next.ServeHTTP(w, r)
})
}
func (app *application) requireAuthenticatedUser(next http.HandlerFunc) http.HandlerFunc {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
user := app.contextGetUser(r)
if user.IsAnonymous() {
app.authenticationRequiredResponse(w, r)
return
}
next.ServeHTTP(w, r)
})
}
func (app *application) requireActivatedUser(next http.HandlerFunc) http.HandlerFunc {
// Rather than returning this http.HandlerFunc we assign it to the variable fn.
fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
user := app.contextGetUser(r)
// Check that a user is activated.
if !user.Activated {
app.inactiveAccountResponse(w, r)
return
}
next.ServeHTTP(w, r)
})
// Wrap fn with the requireAuthenticatedUser() middleware before returning it.
return app.requireAuthenticatedUser(fn)
}
// Note that the first parameter for the middleware function is the permission code that
// we require the user to have.
func (app *application) requirePermission(code string, next http.HandlerFunc) http.HandlerFunc {
fn := func(w http.ResponseWriter, r *http.Request) {
// Retrieve the user from the request context.
user := app.contextGetUser(r)
// Get the slice of permissions for the user.
permissions, err := app.models.Permissions.GetAllForUser(user.ID)
if err != nil {
app.serverErrorResponse(w, r, err)
return
}
// Check if the slice includes the required permission. If it doesn't, then
// return a 403 Forbidden response.
if !permissions.Include(code) {
app.notPermittedResponse(w, r)
return
}
// Otherwise they have the required permission so we call the next handler in
// the chain.
next.ServeHTTP(w, r)
}
// Wrap this with the requireActivatedUser() middleware before returning it.
return app.requireActivatedUser(fn)
}
func (app *application) enableCORS(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Vary", "Origin")
// Add the "Vary: Access-Control-Request-Method" header.
w.Header().Add("Vary", "Access-Control-Request-Method")
origin := r.Header.Get("Origin")
if origin != "" && len(app.config.cors.trustedOrigins) != 0 {
for i := range app.config.cors.trustedOrigins {
if origin == app.config.cors.trustedOrigins[i] {
w.Header().Set("Access-Control-Allow-Origin", origin)
// Check if the request has the HTTP method OPTIONS and contains the
// "Access-Control-Request-Method" header. If it does, then we treat
// it as a preflight request.
if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
// Set the necessary preflight response headers, as discussed
// previously.
w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, PUT, PATCH, DELETE")
w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
//w.Header().Set("Access-Control-Max-Age", "60")
// Write the headers along with a 200 OK status and return from
// the middleware with no further action.
w.WriteHeader(http.StatusOK)
return
}
}
}
}
next.ServeHTTP(w, r)
})
}
func (app *application) metrics(next http.Handler) http.Handler {
// Initialize the new expvar variables when the middleware chain is first built.
totalRequestsReceived := expvar.NewInt("total_requests_received")
totalResponsesSent := expvar.NewInt("total_responses_sent")
totalProcessingTimeMicroseconds := expvar.NewInt("total_processing_time_μs")
// Declare a new expvar map to hold the count of responses for each HTTP status
// code.
totalResponsesSentByStatus := expvar.NewMap("total_responses_sent_by_status")
// The following code will be run for every request...
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Record the time that we started to process the request.
//start := time.Now() === old
// Use the Add() method to increment the number of requests received by 1.
totalRequestsReceived.Add(1)
// Call the next handler in the chain. === old
//next.ServeHTTP(w, r) === old
// Call the httpsnoop.CaptureMetrics() function, passing in the next handler in
// the chain along with the existing http.ResponseWriter and http.Request. This
// returns the metrics struct that we saw above.
metrics := httpsnoop.CaptureMetrics(next, w, r)
// On the way back up the middleware chain, increment the number of responses
// sent by 1.
totalResponsesSent.Add(1)
// Get the request processing time in microseconds from httpsnoop and increment
// the cumulative processing time.
totalProcessingTimeMicroseconds.Add(metrics.Duration.Microseconds())
// Calculate the number of microseconds since we began to process the request,
// then increment the total processing time by this amount.
//duration := time.Now().Sub(start).Microseconds() === old
//totalProcessingTimeMicroseconds.Add(duration) === old
// Use the Add() method to increment the count for the given status code by 1.
// Note that the expvar map is string-keyed, so we need to use the strconv.Itoa()
// function to convert the status code (which is an integer) to a string.
totalResponsesSentByStatus.Add(strconv.Itoa(metrics.Code), 1)
})
}