mirror of
https://github.com/go-gitea/gitea
synced 2024-11-02 00:04:25 +00:00
97 lines
2.9 KiB
Go
97 lines
2.9 KiB
Go
|
package middleware
|
||
|
|
|
||
|
|
// Ported from Goji's middleware, source:
|
||
|
|
// https://github.com/zenazn/goji/tree/master/web/middleware
|
||
|
|
|
||
|
|
import (
|
||
|
|
"context"
|
||
|
|
"crypto/rand"
|
||
|
|
"encoding/base64"
|
||
|
|
"fmt"
|
||
|
|
"net/http"
|
||
|
|
"os"
|
||
|
|
"strings"
|
||
|
|
"sync/atomic"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Key to use when setting the request ID.
|
||
|
|
type ctxKeyRequestID int
|
||
|
|
|
||
|
|
// RequestIDKey is the key that holds the unique request ID in a request context.
|
||
|
|
const RequestIDKey ctxKeyRequestID = 0
|
||
|
|
|
||
|
|
// RequestIDHeader is the name of the HTTP Header which contains the request id.
|
||
|
|
// Exported so that it can be changed by developers
|
||
|
|
var RequestIDHeader = "X-Request-Id"
|
||
|
|
|
||
|
|
var prefix string
|
||
|
|
var reqid uint64
|
||
|
|
|
||
|
|
// A quick note on the statistics here: we're trying to calculate the chance that
|
||
|
|
// two randomly generated base62 prefixes will collide. We use the formula from
|
||
|
|
// http://en.wikipedia.org/wiki/Birthday_problem
|
||
|
|
//
|
||
|
|
// P[m, n] \approx 1 - e^{-m^2/2n}
|
||
|
|
//
|
||
|
|
// We ballpark an upper bound for $m$ by imagining (for whatever reason) a server
|
||
|
|
// that restarts every second over 10 years, for $m = 86400 * 365 * 10 = 315360000$
|
||
|
|
//
|
||
|
|
// For a $k$ character base-62 identifier, we have $n(k) = 62^k$
|
||
|
|
//
|
||
|
|
// Plugging this in, we find $P[m, n(10)] \approx 5.75%$, which is good enough for
|
||
|
|
// our purposes, and is surely more than anyone would ever need in practice -- a
|
||
|
|
// process that is rebooted a handful of times a day for a hundred years has less
|
||
|
|
// than a millionth of a percent chance of generating two colliding IDs.
|
||
|
|
|
||
|
|
func init() {
|
||
|
|
hostname, err := os.Hostname()
|
||
|
|
if hostname == "" || err != nil {
|
||
|
|
hostname = "localhost"
|
||
|
|
}
|
||
|
|
var buf [12]byte
|
||
|
|
var b64 string
|
||
|
|
for len(b64) < 10 {
|
||
|
|
rand.Read(buf[:])
|
||
|
|
b64 = base64.StdEncoding.EncodeToString(buf[:])
|
||
|
|
b64 = strings.NewReplacer("+", "", "/", "").Replace(b64)
|
||
|
|
}
|
||
|
|
|
||
|
|
prefix = fmt.Sprintf("%s/%s", hostname, b64[0:10])
|
||
|
|
}
|
||
|
|
|
||
|
|
// RequestID is a middleware that injects a request ID into the context of each
|
||
|
|
// request. A request ID is a string of the form "host.example.com/random-0001",
|
||
|
|
// where "random" is a base62 random string that uniquely identifies this go
|
||
|
|
// process, and where the last number is an atomically incremented request
|
||
|
|
// counter.
|
||
|
|
func RequestID(next http.Handler) http.Handler {
|
||
|
|
fn := func(w http.ResponseWriter, r *http.Request) {
|
||
|
|
ctx := r.Context()
|
||
|
|
requestID := r.Header.Get(RequestIDHeader)
|
||
|
|
if requestID == "" {
|
||
|
|
myid := atomic.AddUint64(&reqid, 1)
|
||
|
|
requestID = fmt.Sprintf("%s-%06d", prefix, myid)
|
||
|
|
}
|
||
|
|
ctx = context.WithValue(ctx, RequestIDKey, requestID)
|
||
|
|
next.ServeHTTP(w, r.WithContext(ctx))
|
||
|
|
}
|
||
|
|
return http.HandlerFunc(fn)
|
||
|
|
}
|
||
|
|
|
||
|
|
// GetReqID returns a request ID from the given context if one is present.
|
||
|
|
// Returns the empty string if a request ID cannot be found.
|
||
|
|
func GetReqID(ctx context.Context) string {
|
||
|
|
if ctx == nil {
|
||
|
|
return ""
|
||
|
|
}
|
||
|
|
if reqID, ok := ctx.Value(RequestIDKey).(string); ok {
|
||
|
|
return reqID
|
||
|
|
}
|
||
|
|
return ""
|
||
|
|
}
|
||
|
|
|
||
|
|
// NextRequestID generates the next request ID in the sequence.
|
||
|
|
func NextRequestID() uint64 {
|
||
|
|
return atomic.AddUint64(&reqid, 1)
|
||
|
|
}
|