package httpapi

import (

"context"

"cdr.dev/slog/v3"

"github.com/coder/coder/v2/coderd/httpmw/loggermw"

)

// RequestBodyLimitTracker records that a request was rejected for exceeding a

// request body size limit.

//

// Middleware installs it on the way in and reads it on the way out, so a

// rejection written deep in a handler can be attributed without that handler

// knowing a metric exists. It is written and read on the request's own

// goroutine, so it needs no synchronization.

type RequestBodyLimitTracker struct {

exceeded bool

}

// Exceeded reports whether a body size limit rejected this request.

func (t *RequestBodyLimitTracker) Exceeded() bool {

return t.exceeded

}

type requestBodyLimitContextKey struct{}

// WithRequestBodyLimitTracker returns a context carrying tracker.

func WithRequestBodyLimitTracker(ctx context.Context, tracker *RequestBodyLimitTracker) context.Context {

return context.WithValue(ctx, requestBodyLimitContextKey{}, tracker)

}

// RecordRequestBodyLimit reports the body size limit that rejected this

// request. It names the limit on the request's existing log line and marks the

// request so middleware can tell a body size rejection from the other reasons

// coderd answers 413, such as agent log storage overflow.

//

// The limit goes on the existing log line rather than one of its own: a caller

// can produce 413s at will, so a dedicated line is attacker-controlled log

// volume.

//

// Every site that answers 413 because a request body exceeded a limit must call

// this, and a site answering 413 for any other reason must not. ctx must be the

// request's context, which is what carries both the logger and the tracker.

func RecordRequestBodyLimit(ctx context.Context, limit int64) {

if requestLogger := loggermw.RequestLoggerFromContext(ctx); requestLogger != nil {

requestLogger.WithFields(slog.F("max_request_body_bytes", limit))

}

if tracker, ok := ctx.Value(requestBodyLimitContextKey{}).(*RequestBodyLimitTracker); ok {

tracker.exceeded = true

}

}