From d58f56347a16947757a0112715b13561f49fb539 Mon Sep 17 00:00:00 2001
From: Thomas Sader <thommey@gmail.com>
Date: Wed, 5 Jun 2024 19:30:11 +0200
Subject: [PATCH] Reintroduce user lookup cache

Found by: mortmann
Patch by: thommey
Fixes: #1599
---
 src/chan.h             |  3 ++-
 src/chanprog.c         | 16 +++++++++++-----
 src/mod/irc.mod/chan.c |  6 +++++-
 src/userrec.c          | 16 +++++++++++++---
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/src/chan.h b/src/chan.h
index d5f11257d..31b639834 100644
--- a/src/chan.h
+++ b/src/chan.h
@@ -50,7 +50,8 @@ typedef struct memstruct {
   time_t split; /* in case they were just netsplit */
   time_t last;  /* for measuring idle time         */
   time_t delay; /* for delayed autoop              */
-  int tried_getuser; // TODO: use it to invalidate user cache
+  struct userrec *user; /* cached user lookup */
+  int tried_getuser; /* negative user lookup cache */
   struct memstruct *next;
 } memberlist;
 
diff --git a/src/chanprog.c b/src/chanprog.c
index 37e03d61a..f589593fb 100644
--- a/src/chanprog.c
+++ b/src/chanprog.c
@@ -118,8 +118,11 @@ struct chanset_t *findchan_by_dname(const char *name)
 
 /* Clear the user pointers in the chanlists.
  *
- * Necessary when a hostmask is added/removed, a user is added or a new
- * userfile is loaded.
+ * Necessary when:
+ * - a hostmask is added/removed
+ * - an account is added/removed
+ * - a user is added
+ * - new userfile is loaded
  */
 void clear_chanlist(void)
 {
@@ -128,14 +131,16 @@ void clear_chanlist(void)
 
   for (chan = chanset; chan; chan = chan->next)
     for (m = chan->channel.member; m && m->nick[0]; m = m->next) {
+      m->user = NULL;
       m->tried_getuser = 0;
     }
 }
 
 /* Clear the user pointer of a specific nick in the chanlists.
- 
- * Necessary when a hostmask is added/removed, a nick changes, etc.
- * Does not completely invalidate the channel cache like clear_chanlist().
+ *
+ * Necessary when:
+ * - their hostmask changed (chghost)
+ * - their account changed
  */
 void clear_chanlist_member(const char *nick)
 {
@@ -145,6 +150,7 @@ void clear_chanlist_member(const char *nick)
   for (chan = chanset; chan; chan = chan->next)
     for (m = chan->channel.member; m && m->nick[0]; m = m->next)
       if (!rfc_casecmp(m->nick, nick)) {
+        m->user = NULL;
         m->tried_getuser = 0;
         break;
       }
diff --git a/src/mod/irc.mod/chan.c b/src/mod/irc.mod/chan.c
index 1d0082547..f0cb827d7 100644
--- a/src/mod/irc.mod/chan.c
+++ b/src/mod/irc.mod/chan.c
@@ -116,6 +116,8 @@ static void setaccount(char *nick, char *account)
       }
     }
   }
+  /* Username for nick could be different after account change, invalidate cache */
+  clear_chanlist_member(nick);
 }
 
 /* Returns the current channel mode.
@@ -1220,7 +1222,7 @@ static int got354(char *from, char *msg)
  * :geo!awesome@eggdrop.com CHGHOST tehgeo foo.io
  * changes user hostmask to tehgeo@foo.io
  */
-static int gotchghost(char *from, char *msg){
+static int gotchghost(char *from, char *msg) {
   struct flag_record fr = { FR_GLOBAL | FR_CHAN, 0, 0, 0, 0, 0 };
   struct userrec *u;
   struct chanset_t *chan;
@@ -1247,6 +1249,8 @@ static int gotchghost(char *from, char *msg){
       check_this_member(chan, m->nick, &fr);
     }
   }
+  /* Username for nick could be different after host change, invalidate cache */
+  clear_chanlist_member(nick);
   return 0;
 }
 
diff --git a/src/userrec.c b/src/userrec.c
index 61af179d5..084dbcd64 100644
--- a/src/userrec.c
+++ b/src/userrec.c
@@ -224,24 +224,34 @@ struct userrec *get_user_by_handle(struct userrec *bu, char *handle)
 
 struct userrec *get_user_from_member(memberlist *m)
 {
-  struct userrec *ret;
+  struct userrec *ret = NULL;
+
+  /* Check positive/negative cache first */
+  if (m->user || m->tried_getuser) {
+    return m->user;
+  }
 
   /* Check if there is a user with a matching account if one is provided */
   if (m->account[0] != '*') {
     ret = get_user_by_account(m->account);
     if (ret) {
-      return ret;
+      goto getuser_done;
     }
   }
+
   /* Check if there is a user with a matching hostmask if one is provided */
   if ((m->userhost[0] != '\0') && (m->nick[0] != '\0')) {
     char s[NICKMAX+UHOSTLEN+1];
     sprintf(s, "%s!%s", m->nick, m->userhost);
     ret = get_user_by_host(s);
     if (ret) {
-      return ret;
+      goto getuser_done;
     }
   }
+
+getuser_done:
+  m->user = ret;
+  m->tried_getuser = 1;
   return NULL;
 }