From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 31 Jul 2025 01:54:39 +0000 (+1000)
Subject: Truncate webseed requests to response body cache boundaries
X-Git-Tag: v1.59.0~2^2~79
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=50c5d486d4940c49467d232a14b5b634bce4ca41;p=btrtrc.git

Truncate webseed requests to response body cache boundaries
---

diff --git a/webseed-requesting.go b/webseed-requesting.go
index ee1f9396..2376e685 100644
--- a/webseed-requesting.go
+++ b/webseed-requesting.go
@@ -205,6 +205,7 @@ func (cl *Client) updateWebseedRequests() {
 			panicif.LessThan(last, begin)
 			// Hello C++ my old friend.
 			end := last + 1
+			truncateEndToCacheBoundary(begin, &end, t.chunkSize)
 			if webseed.PrintDebug && end != fileEnd {
 				debugLogger.Debug(
 					"shortened webseed request",
@@ -218,6 +219,16 @@ func (cl *Client) updateWebseedRequests() {
 	}
 }
 
+// Limit a webseed request end request index so that the required response body size fits within
+// cache limits for a WebSeed provider.
+func truncateEndToCacheBoundary(start RequestIndex, end *RequestIndex, chunkSize pp.Integer) {
+	// Cloudflare caches up to 512 MB responses by default.
+	const cacheResponseBodyLimit = 256 << 20
+	chunksPerAlignedResponse := RequestIndex(cacheResponseBodyLimit / chunkSize)
+	startIndex := start / chunksPerAlignedResponse
+	*end = min(*end, (startIndex+1)*chunksPerAlignedResponse)
+}
+
 func (cl *Client) dumpCurrentWebseedRequests() {
 	if webseed.PrintDebug {
 		fmt.Println("current webseed requests:")
diff --git a/webseed/request.go b/webseed/request.go
index ce8e0cd5..ff679ace 100644
--- a/webseed/request.go
+++ b/webseed/request.go
@@ -75,7 +75,7 @@ func newRequest(
 		return nil, err
 	}
 	// We avoid Range requests if we can. We check the Content-Length elsewhere so that early
-	// detection is not lost.
+	// detection is not lost. TODO: Try disabling this for CloudFlare?
 	if offset != 0 || length != fileInfo.Length {
 		req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
 	}