From 5e9d508e91b2029c108b7865ff053281005379e7 Mon Sep 17 00:00:00 2001
From: TJ Saunders <tj@castaglia.org>
Date: Sat, 17 Aug 2024 10:30:18 -0700
Subject: [PATCH] Attempt to more gracefully handle the case where the
 `session.notes` table is unexpectedly full.

---
 mod_proxy.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/mod_proxy.c b/mod_proxy.c
index e4f0f80..fe9b1c2 100644
--- a/mod_proxy.c
+++ b/mod_proxy.c
@@ -5569,8 +5569,38 @@ static int proxy_sess_init(void) {
    * needed.
    */
   proxy_sess = (struct proxy_session *) proxy_session_alloc(proxy_pool);
-  if (pr_table_add(session.notes, "mod_proxy.proxy-session", proxy_sess,
-      sizeof(struct proxy_session)) < 0) {
+  res = pr_table_add(session.notes, "mod_proxy.proxy-session", proxy_sess,
+    sizeof(struct proxy_session));
+
+  if (res < 0 &&
+      errno == ENOSPC) {
+    int nents, nmaxents;
+
+    nents = pr_table_count(session.notes);
+    nmaxents = nents * 2;
+
+    /* Attempt to handle the unusual case where the table is full, since
+     * we really need this note.
+     */
+    pr_trace_msg(trace_channel, 1,
+      "session notes table is full (%u), increasing entry limit to %u",
+      nents, nmaxents);
+
+    if (pr_table_ctl(session.notes, PR_TABLE_CTL_SET_MAX_ENTS,
+        &nmaxents) == 0) {
+      res = pr_table_add(session.notes, "mod_proxy.proxy-session", proxy_sess,
+        sizeof(struct proxy_session));
+
+    } else {
+      (void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
+        "error increasing session notes max entries: %s", strerror(errno));
+
+      res = -1;
+      errno = ENOSPC;
+    }
+  }
+
+  if (res < 0) {
     (void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
       "error stashing proxy session note: %s", strerror(errno));