Reject overlong input with ERR_INPUTTOOLONG

process-message! now rejects lines whose payload exceeds 510 bytes
or whose tags exceed 4094 bytes with 417 ERR_INPUTTOOLONG instead of
silently truncating, matching IRCv3 message-tags expectations.

1 files changed, 30 insertions, 3 deletions

diff --git a/src/papod.clj b/src/papod.clj
index 4055e8a..8b7d4d5 100644
--- a/src/papod.clj
+++ b/src/papod.clj
@@ -3862,11 +3862,38 @@
            [(str "BATCH -" batch-id)]))
          w)))))
 
+(defn- byte-length
+  [^String s]
+  (alength (.getBytes s "UTF-8")))
+
+(defn- input-too-long?
+  [^String raw]
+  (let [tagged? (.startsWith raw "@")
+        sp      (when tagged? (.indexOf raw " "))
+        tags    (when (and tagged? (pos? sp))
+                  (subs raw 1 sp))
+        body    (cond
+                  (not tagged?) raw
+                  (pos? sp)     (subs raw (inc sp))
+                  :else         "")
+        tag-len (if tags (byte-length tags) 0)
+        body-len (byte-length body)]
+    (or (and tagged? (> tag-len 4094))
+        (> body-len 510))))
+
 (defn- process-message!
   [raw-message w client components]
-  (let [[message err] (parse-message raw-message)]
-    (when-not err
-      (handle-message! message w client components))))
+  (cond
+    (input-too-long? raw-message)
+    (let [nick (or (:nick @client) "*")
+          line (str ":" +server-name+ " 417 " nick
+                    " :Input line was too long")]
+      (deliver-to-client! w line))
+
+    :else
+    (let [[message err] (parse-message raw-message)]
+      (when-not err
+        (handle-message! message w client components)))))
 
 (defn- process-input!
   [input w client components]