From bba679eaef99e04f151f7b57663f2eec9b3b281f Mon Sep 17 00:00:00 2001
From: Matthew Chen <matthew@signal.org>
Date: Fri, 25 Jan 2019 15:57:48 -0500
Subject: [PATCH] Add user-agent for media downloads.

---
 SignalServiceKit/src/Network/ProxiedContentDownloader.swift | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/SignalServiceKit/src/Network/ProxiedContentDownloader.swift b/SignalServiceKit/src/Network/ProxiedContentDownloader.swift
index 1dbc3a79c..b90276150 100644
--- a/SignalServiceKit/src/Network/ProxiedContentDownloader.swift
+++ b/SignalServiceKit/src/Network/ProxiedContentDownloader.swift
@@ -643,6 +643,8 @@ open class ProxiedContentDownloader: NSObject, URLSessionTaskDelegate, URLSessio
             var request = URLRequest(url: assetRequest.assetDescription.url as URL)
             request.httpMethod = "HEAD"
             request.httpShouldUsePipelining = true
+            // Some services like Reddit will severely rate-limit requests without a user agent.
+            request.addValue("Signal", forHTTPHeaderField: "User-Agent")
 
             let task = downloadSession.dataTask(with: request, completionHandler: { data, response, error -> Void in
                 if let data = data, data.count > 0 {