From 54b17b0700dc7f8e756d06e0123e03cad08d252a Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Thu, 24 Apr 2025 23:37:48 -0400
Subject: [PATCH] improve robustness of timestamp parsing (#2250)

* Clamp CHATHISTORY timestamp selectors to be in [0, MaxInt64]
* Convert everything to UTC up front (probably a no-op)
---
 irc/handlers.go | 9 +++++++++
 irc/server.go   | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/irc/handlers.go b/irc/handlers.go
index 2256af79..d0d619c0 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -755,6 +755,14 @@ func chathistoryHandler(server *Server, client *Client, msg ircmsg.Message, rb *
 			return
 		} else if identifier == "timestamp" {
 			timestamp, err = time.Parse(IRCv3TimestampFormat, value)
+			if err == nil {
+				timestamp = timestamp.UTC()
+				if timestamp.Before(unixEpoch) {
+					timestamp = unixEpoch
+				} else if timestamp.After(year2262Problem) {
+					timestamp = year2262Problem
+				}
+			}
 			return
 		}
 		return
@@ -3052,6 +3060,7 @@ func markReadHandler(server *Server, client *Client, msg ircmsg.Message, rb *Res
 		rb.Add(nil, server.name, "FAIL", "MARKREAD", "INVALID_PARAMS", utils.SafeErrorParam(readTimestamp), client.t("Invalid timestamp"))
 		return
 	}
+	readTime = readTime.UTC()
 	result := client.SetReadMarker(cftarget, readTime)
 	readTimestamp = fmt.Sprintf("timestamp=%s", result.Format(IRCv3TimestampFormat))
 	// inform the originating session whether it was a success or a no-op:
diff --git a/irc/server.go b/irc/server.go
index aefeb00d..88203e50 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -65,6 +65,9 @@ var (
 	throttleMessage = "You have attempted to connect too many times within a short duration. Wait a while, and you will be able to connect."
 
 	httpVerbs = utils.SetLiteral("CONNECT", "DELETE", "GET", "HEAD", "OPTIONS", "PATCH", "POST", "PUT", "TRACE")
+
+	unixEpoch       = time.Unix(0, 0).UTC()
+	year2262Problem = time.Unix(0, 1<<63-1).UTC() // this is the maximum time for which (*time.Time).UnixNano() is well-defined
 )
 
 // Server is the main Oragono server.