81 lines
2.9 KiB
Go
81 lines
2.9 KiB
Go
package middleware
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import (
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"context"
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"net/http"
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)
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// Client metadata context keys.
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//
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// Populated by ClientMetadata middleware from X-Client-Platform / X-Client-Version /
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// X-Client-OS request headers. Sent by every first-party client (Web, Desktop, CLI,
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// Daemon) so the server can split logs / metrics / gating decisions by caller
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// without having to reverse-engineer User-Agent strings or upgrade payloads.
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//
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// All three values are best-effort: handlers must treat missing values as
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// "unknown" and never make security decisions based on them — these headers
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// are client-controlled and trivial to spoof.
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type clientMetadataKey int
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const (
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ctxKeyClientPlatform clientMetadataKey = iota
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ctxKeyClientVersion
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ctxKeyClientOS
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)
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// Header names — exported so other packages (request logger, realtime hub)
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// can stay in sync without re-declaring magic strings.
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const (
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HeaderClientPlatform = "X-Client-Platform"
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HeaderClientVersion = "X-Client-Version"
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HeaderClientOS = "X-Client-OS"
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)
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// ClientMetadata extracts X-Client-Platform / X-Client-Version / X-Client-OS
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// from the request and stashes them in the request context so downstream
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// handlers and the request logger can read them via ClientMetadataFromContext.
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//
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// Wired in router.go before route mounting so every authenticated and
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// unauthenticated handler benefits from the same observability dimensions.
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func ClientMetadata(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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ctx := r.Context()
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if v := r.Header.Get(HeaderClientPlatform); v != "" {
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ctx = context.WithValue(ctx, ctxKeyClientPlatform, v)
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}
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if v := r.Header.Get(HeaderClientVersion); v != "" {
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ctx = context.WithValue(ctx, ctxKeyClientVersion, v)
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}
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if v := r.Header.Get(HeaderClientOS); v != "" {
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ctx = context.WithValue(ctx, ctxKeyClientOS, v)
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}
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next.ServeHTTP(w, r.WithContext(ctx))
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})
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}
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// ClientMetadataFromContext returns the platform/version/os captured from
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// X-Client-* headers. Empty strings are returned for any value that wasn't
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// sent — callers must treat missing values as "unknown" rather than failing.
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func ClientMetadataFromContext(ctx context.Context) (platform, version, os string) {
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platform, _ = ctx.Value(ctxKeyClientPlatform).(string)
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version, _ = ctx.Value(ctxKeyClientVersion).(string)
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os, _ = ctx.Value(ctxKeyClientOS).(string)
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return platform, version, os
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}
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// SetClientMetadata explicitly attaches client metadata to a context. Used
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// by the realtime hub, where metadata arrives via WS query parameters
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// (`client_platform`, `client_version`, `client_os`) instead of headers.
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func SetClientMetadata(ctx context.Context, platform, version, os string) context.Context {
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if platform != "" {
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ctx = context.WithValue(ctx, ctxKeyClientPlatform, platform)
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}
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if version != "" {
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ctx = context.WithValue(ctx, ctxKeyClientVersion, version)
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}
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if os != "" {
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ctx = context.WithValue(ctx, ctxKeyClientOS, os)
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}
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return ctx
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}
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