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middleware.go
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middleware.go
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package relay
import (
"context"
"encoding/base64"
"encoding/json"
"errors"
"net/http"
"github.com/gorilla/mux"
ld "gopkg.in/launchdarkly/go-server-sdk.v4"
"gopkg.in/launchdarkly/ld-relay.v5/internal/metrics"
"gopkg.in/launchdarkly/ld-relay.v5/internal/version"
)
type corsContext interface {
AllowedOrigins() []string
}
func chainMiddleware(middlewares ...mux.MiddlewareFunc) mux.MiddlewareFunc {
return func(next http.Handler) http.Handler {
handler := next
for i := len(middlewares) - 1; i >= 0; i-- {
handler = middlewares[i](handler)
}
return handler
}
}
type clientMux struct {
clientContextByKey map[string]*clientContextImpl
}
func (m clientMux) getStatus(w http.ResponseWriter, req *http.Request) {
w.Header().Set("Content-Type", "application/json")
envs := make(map[string]environmentStatus)
healthy := true
for _, clientCtx := range m.clientContextByKey {
var status environmentStatus
if clientCtx.envId != nil {
status.EnvId = *clientCtx.envId
}
if clientCtx.mobileKey != nil {
status.MobileKey = obscureKey(*clientCtx.mobileKey)
}
status.SdkKey = obscureKey(clientCtx.sdkKey)
client := clientCtx.getClient()
if client == nil || !client.Initialized() {
status.Status = "disconnected"
healthy = false
} else {
status.Status = "connected"
}
envs[clientCtx.name] = status
}
resp := struct {
Environments map[string]environmentStatus `json:"environments"`
Status string `json:"status"`
Version string `json:"version"`
ClientVersion string `json:"clientVersion"`
}{
Environments: envs,
Version: version.Version,
ClientVersion: ld.Version,
}
if healthy {
resp.Status = "healthy"
} else {
resp.Status = "degraded"
}
data, _ := json.Marshal(resp)
w.Write(data)
}
func (m clientMux) selectClientByAuthorizationKey(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
authKey, err := fetchAuthToken(req)
if err != nil {
w.WriteHeader(http.StatusUnauthorized)
return
}
clientCtx := m.clientContextByKey[authKey]
if clientCtx == nil {
w.WriteHeader(http.StatusUnauthorized)
w.Write([]byte("ld-relay is not configured for the provided key"))
return
}
if clientCtx.getClient() == nil {
w.WriteHeader(http.StatusServiceUnavailable)
w.Write([]byte("client was not initialized"))
return
}
req = req.WithContext(context.WithValue(req.Context(), contextKey, clientCtx))
next.ServeHTTP(w, req)
})
}
func getClientContext(req *http.Request) clientContext {
return req.Context().Value(contextKey).(clientContext)
}
func withCount(handler http.Handler, measure metrics.Measure) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
ctx := getClientContext(req)
userAgent := getUserAgent(req)
metrics.WithCount(ctx.getMetricsCtx(), userAgent, func() {
handler.ServeHTTP(w, req)
}, measure)
})
}
func countMobileConns(handler http.Handler) http.Handler {
return withCount(withGauge(handler, metrics.MobileConns), metrics.NewMobileConns)
}
func countBrowserConns(handler http.Handler) http.Handler {
return withCount(withGauge(handler, metrics.BrowserConns), metrics.NewBrowserConns)
}
func countServerConns(handler http.Handler) http.Handler {
return withCount(withGauge(handler, metrics.ServerConns), metrics.NewServerConns)
}
func requestCountMiddleware(measure metrics.Measure) mux.MiddlewareFunc {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
ctx := getClientContext(req)
userAgent := getUserAgent(req)
// Ignoring internal routing error that would have been ignored anyway
route, _ := mux.CurrentRoute(req).GetPathTemplate()
metrics.WithRouteCount(ctx.getMetricsCtx(), userAgent, route, req.Method, func() {
next.ServeHTTP(w, req)
}, measure)
})
}
}
func withGauge(handler http.Handler, measure metrics.Measure) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
ctx := getClientContext(req)
userAgent := getUserAgent(req)
metrics.WithGauge(ctx.getMetricsCtx(), userAgent, func() {
handler.ServeHTTP(w, req)
}, measure)
})
}
func corsMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var domains []string
if context, ok := r.Context().Value(contextKey).(corsContext); ok {
domains = context.AllowedOrigins()
}
if len(domains) > 0 {
for _, d := range domains {
if r.Header.Get("Origin") == d {
setCorsHeaders(w, d)
return
}
}
// Not a valid origin, set allowed origin to any allowed origin
setCorsHeaders(w, domains[0])
} else {
origin := defaultAllowedOrigin
if r.Header.Get("Origin") != "" {
origin = r.Header.Get("Origin")
}
setCorsHeaders(w, origin)
}
next.ServeHTTP(w, r)
})
}
func streamingMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
// If Nginx is being used as a proxy/load balancer, adding this header tells it not to buffer this response because
// it is a streaming response. If Nginx is not being used, this header has no effect.
w.Header().Add("X-Accel-Buffering", "no")
next.ServeHTTP(w, req)
})
}
// UserV2FromBase64 decodes a base64-encoded go-server-sdk v2 user.
// If any decoding/unmarshaling errors occur or
// the user is missing the 'key' attribute an error is returned.
func UserV2FromBase64(base64User string) (*ld.User, error) {
var user ld.User
idStr, decodeErr := base64urlDecode(base64User)
if decodeErr != nil {
return nil, errors.New("User part of url path did not decode as valid base64")
}
jsonErr := json.Unmarshal(idStr, &user)
if jsonErr != nil {
return nil, errors.New("User part of url path did not decode to valid user as json")
}
if user.Key == nil { //nolint:staticcheck // direct access to user.Key is deprecated
return nil, errors.New("User must have a 'key' attribute")
}
return &user, nil
}
func base64urlDecode(base64String string) ([]byte, error) {
idStr, decodeErr := base64.URLEncoding.DecodeString(base64String)
if decodeErr != nil {
// base64String could be unpadded
// see https://github.com/golang/go/issues/4237#issuecomment-267792481
idStrRaw, decodeErrRaw := base64.RawURLEncoding.DecodeString(base64String)
if decodeErrRaw != nil {
return nil, errors.New("String did not decode as valid base64")
}
return idStrRaw, nil
}
return idStr, nil
}
func fetchAuthToken(req *http.Request) (string, error) {
authHdr := req.Header.Get("Authorization")
match := uuidHeaderPattern.FindStringSubmatch(authHdr)
// successfully matched UUID from header
if len(match) == 2 {
return match[1], nil
}
return "", errors.New("No valid token found")
}