feat: add tracking of request body reads

curl.go

@@ -44,3 +44,10 @@ func scheme(r *http.Request) string {
 func requestURL(r *http.Request) string {
 	return fmt.Sprintf("%s://%s%s", scheme(r), r.Host, r.URL)
 }
+
+func bytesRead(r *countingReader) int64 {
+	if r == nil {
+		return 0
+	}
+	return r.bytesRead
+}

middleware.go

@@ -41,8 +41,16 @@ func RequestLogger(logger *slog.Logger, o *Options) func(http.Handler) http.Hand
 			logReqBody := o.LogRequestBody != nil && o.LogRequestBody(r)
 			logRespBody := o.LogResponseBody != nil && o.LogResponseBody(r)
 
+			hasReqBody := r.Body != nil && r.Body != http.NoBody
+			var bodyReader *countingReader
+			if hasReqBody {
+				bodyReader = &countingReader{reader: r.Body}
+				r.Body = bodyReader
+			}
+
+			consumeBody := hasReqBody && (logReqBody || o.LogExtraAttrs != nil)
 			var reqBody bytes.Buffer
-			if logReqBody || o.LogExtraAttrs != nil {
+			if consumeBody {
 				r.Body = io.NopCloser(io.TeeReader(r.Body, &reqBody))
 			}
 
@@ -130,6 +138,7 @@ func RequestLogger(logger *slog.Logger, o *Options) func(http.Handler) http.Hand
 					slog.String(s.RequestProto, r.Proto),
 					slog.Any(s.RequestHeaders, slog.GroupValue(getHeaderAttrs(r.Header, o.LogRequestHeaders)...)),
 					slog.Int64(s.RequestBytes, r.ContentLength),
+					slog.Int64(s.RequestBytesRead, bytesRead(bodyReader)),
 					slog.String(s.RequestUserAgent, r.UserAgent()),
 					slog.String(s.RequestReferer, r.Referer()),
 					slog.Any(s.ResponseHeaders, slog.GroupValue(getHeaderAttrs(ww.Header(), o.LogResponseHeaders)...)),
@@ -142,7 +151,7 @@ func RequestLogger(logger *slog.Logger, o *Options) func(http.Handler) http.Hand
 					logAttrs = appendAttrs(logAttrs, slog.Any(ErrorKey, ErrClientAborted), slog.String(s.ErrorType, "ClientAborted"))
 				}
 
-				if logReqBody || o.LogExtraAttrs != nil {
+				if consumeBody {
 					// Ensure the request body is fully read if the underlying HTTP handler didn't do so.
 					n, _ := io.Copy(io.Discard, r.Body)
 					if n > 0 {
@@ -231,3 +240,18 @@ func logBody(body *bytes.Buffer, header http.Header, o *Options) string {
 	}
 	return fmt.Sprintf("[body redacted for Content-Type: %s]", contentType)
 }
+
+type countingReader struct {
+	reader    io.ReadCloser
+	bytesRead int64
+}
+
+func (cr *countingReader) Read(p []byte) (int, error) {
+	n, err := cr.reader.Read(p)
+	cr.bytesRead += int64(n)
+	return n, err
+}
+
+func (cr *countingReader) Close() error {
+	return cr.reader.Close()
+}

schema.go

@@ -37,6 +37,7 @@ type Schema struct {
 	RequestHeaders     string // Selected request headers
 	RequestBody        string // Request body content, if logged.
 	RequestBytes       string // Size of request body in bytes
+	RequestBytesRead   string // Read bytes in request body
 	RequestBytesUnread string // Unread bytes in request body
 	RequestUserAgent   string // User-Agent header value
 	RequestReferer     string // Referer header value
@@ -78,6 +79,7 @@ var (
 		RequestHeaders:     "http.request.headers",
 		RequestBody:        "http.request.body.content",
 		RequestBytes:       "http.request.body.bytes",
+		RequestBytesRead:   "http.request.body.read.bytes",
 		RequestBytesUnread: "http.request.body.unread.bytes",
 		RequestUserAgent:   "user_agent.original",
 		RequestReferer:     "http.request.referrer",
@@ -112,6 +114,7 @@ var (
 		RequestHeaders:     "http.request.header",
 		RequestBody:        "http.request.body.content",
 		RequestBytes:       "http.request.body.size",
+		RequestBytesRead:   "http.request.body.read.size",
 		RequestBytesUnread: "http.request.body.unread.size",
 		RequestUserAgent:   "user_agent.original",
 		RequestReferer:     "http.request.header.referer",
@@ -148,6 +151,7 @@ var (
 		RequestHeaders:     "httpRequest:requestHeaders",
 		RequestBody:        "httpRequest:requestBody",
 		RequestBytes:       "httpRequest:requestSize",
+		RequestBytesRead:   "httpRequest:requestReadSize",
 		RequestBytesUnread: "httpRequest:requestUnreadSize",
 		RequestUserAgent:   "httpRequest:userAgent",
 		RequestReferer:     "httpRequest:referer",