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Fix silent failure receiving files: read large frames in bounded chunks #225

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Fix silent failure receiving files: read large frames in bounded chunks #225

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8369d9b
fix: read large frames in bounded chunks instead of one oversized rec…
aryzae Sep 1, 2026
a2e89f7
refactor: accumulate frame chunks in NSMutableData to avoid repeated …
aryzae Sep 1, 2026
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20 changes: 16 additions & 4 deletions NearbyShare/NearbyConnection.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ import BigInt

class NearbyConnection{
internal static let SANE_FRAME_LENGTH=5*1024*1024
private static let MAX_RECEIVE_LENGTH=16*1024
private static let dispatchQueue=DispatchQueue(label: "me.grishka.NearDrop.queue", qos: .utility) // FIFO (non-concurrent) queue to avoid those exciting concurrency bugs

internal let connection:NWConnection
Expand Down Expand Up @@ -125,20 +126,31 @@ class NearbyConnection{
}

private func receiveFrameAsync(length:UInt32){
connection.receive(minimumIncompleteLength: Int(length), maximumLength: Int(length)) { content, contentContext, isComplete, error in
receiveFrameChunkAsync(remaining: Int(length), accumulated: NSMutableData(capacity: Int(length)) ?? NSMutableData())
}

// File payloads arrive in 512 KB frames, and asking for one of those in a single receive
// hands back damaged bytes, so reassemble the frame from bounded reads instead.
private func receiveFrameChunkAsync(remaining:Int, accumulated:NSMutableData){
if remaining<=0{
processReceivedFrame(frameData: accumulated as Data)
receiveFrameAsync()
return
}
connection.receive(minimumIncompleteLength: 1, maximumLength: min(remaining, NearbyConnection.MAX_RECEIVE_LENGTH)) { content, contentContext, isComplete, error in
if self.connectionClosed{
return
}
if isComplete{
self.handleConnectionClosure()
return
}
guard let content=content else {
guard let content=content, !content.isEmpty else {
self.protocolError()
return
}
self.processReceivedFrame(frameData: content)
self.receiveFrameAsync()
accumulated.append(content)
self.receiveFrameChunkAsync(remaining: remaining-content.count, accumulated: accumulated)
}
}

Expand Down