From c05e15124728823ec03190402dd2af85d37a328a Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 21 Aug 2025 16:32:44 +1000
Subject: [PATCH] compare webseed OK responses to correct expected
 Content-Length

Should compare to the entire file length, not the end of the current part (good guess tho).
Also fix bad URL conversion to struct in logger, and don't skip logging interesting case before returning error.
---
 webseed/client.go | 40 +++++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/webseed/client.go b/webseed/client.go
index 28b49b58..9c97e4da 100644
--- a/webseed/client.go
+++ b/webseed/client.go
@@ -38,10 +38,11 @@ func init() {
 type RequestSpec = segments.Extent
 
 type requestPart struct {
-	req       *http.Request
-	e         segments.Extent
-	do        func() (*http.Response, error)
-	fileIndex int
+	req        *http.Request
+	fileRange  segments.Extent
+	fileLength int64
+	do         func() (*http.Response, error)
+	fileIndex  int
 }
 
 type Request struct {
@@ -117,9 +118,10 @@ func (ws *Client) StartNewRequest(ctx context.Context, r RequestSpec, debugLogge
 		)
 		panicif.Err(err)
 		part := requestPart{
-			req:       req,
-			e:         e,
-			fileIndex: i,
+			req:        req,
+			fileRange:  e,
+			fileLength: ws.fileIndex.Index(i).Length,
+			fileIndex:  i,
 		}
 		part.do = func() (resp *http.Response, err error) {
 			resp, err = ws.HttpClient.Do(req)
@@ -183,7 +185,7 @@ func (me *Client) checkContentLength(resp *http.Response, part requestPart, expe
 		me.Logger.Warn("unexpected identity response Content-Length value",
 			"actual", resp.ContentLength,
 			"expected", expectedLen,
-			"url", part.req.URL)
+			"url", part.req.URL.String())
 	}
 }
 
@@ -206,24 +208,21 @@ func (me *Client) recvPartResult(ctx context.Context, w io.Writer, part requestP
 	switch resp.StatusCode {
 	case http.StatusPartialContent:
 		// The response should be just as long as we requested.
-		me.checkContentLength(resp, part, part.e.Length)
+		me.checkContentLength(resp, part, part.fileRange.Length)
 		buf := bufPool.Get().(*[]byte)
 		defer bufPool.Put(buf)
 		copied, err := io.CopyBuffer(w, body, *buf)
 		if err != nil {
 			return err
 		}
-		if copied != part.e.Length {
-			return fmt.Errorf("got %v bytes, expected %v", copied, part.e.Length)
+		if copied != part.fileRange.Length {
+			return fmt.Errorf("got %v bytes, expected %v", copied, part.fileRange.Length)
 		}
 		return nil
 	case http.StatusOK:
-		// The response is from the beginning.
-		me.checkContentLength(resp, part, part.e.End())
-		discard := part.e.Start
-		if discard > MaxDiscardBytes {
-			return ErrBadResponse{"resp status ok but requested range", resp}
-		}
+		// The response is from the beginning of the file.
+		me.checkContentLength(resp, part, part.fileRange.End())
+		discard := part.fileRange.Start
 		if discard != 0 {
 			if PrintDebug {
 				fmt.Printf("resp status ok but requested range [url=%q, range=%q]",
@@ -231,9 +230,12 @@ func (me *Client) recvPartResult(ctx context.Context, w io.Writer, part requestP
 					part.req.Header.Get("Range"))
 			}
 			me.Logger.Debug("resp status ok but requested range",
-				"url", part.req.URL,
+				"url", part.req.URL.String(),
 				"range", part.req.Header.Get("Range"))
 		}
+		if discard > MaxDiscardBytes {
+			return ErrBadResponse{"resp status ok but requested range", resp}
+		}
 		// Instead of discarding, we could try receiving all the chunks present in the response
 		// body. I don't know how one would handle multiple chunk requests resulting in an OK
 		// response for the same file. The request algorithm might be need to be smarter for that.
@@ -244,7 +246,7 @@ func (me *Client) recvPartResult(ctx context.Context, w io.Writer, part requestP
 		panicif.NotEq(discarded, discard)
 		// Because the reply is not a partial aware response, we limit the body reader
 		// intentionally.
-		_, err = io.CopyN(w, body, part.e.Length)
+		_, err = io.CopyN(w, body, part.fileRange.Length)
 		return err
 	case http.StatusServiceUnavailable:
 		// TODO: Include all of Erigon's cases here?
-- 
2.51.0