From 91b1278224692433c4ec42ee04e06cf64373dde3 Mon Sep 17 00:00:00 2001
From: Ed Kellett <e@kellett.im>
Date: Mon, 27 Apr 2020 00:14:56 +0100
Subject: [PATCH 1/3] Implement hook priorities

---
 include/hook.h    | 11 +++++++++++
 include/modules.h |  2 +-
 ircd/hook.c       | 48 ++++++++++++++++++++++++++++++++++++++++++-----
 ircd/modules.c    |  5 +++++
 4 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/include/hook.h b/include/hook.h
index 099eeec7..e185d46b 100644
--- a/include/hook.h
+++ b/include/hook.h
@@ -11,6 +11,16 @@ typedef struct
 	rb_dlink_list hooks;
 } hook;
 
+enum hook_priority
+{
+	HOOK_LOWEST = 10,
+	HOOK_LOW = 20,
+	HOOK_NORMAL = 30,
+	HOOK_HIGH = 40,
+	HOOK_HIGHEST = 50,
+	HOOK_MONITOR = 100
+};
+
 typedef void (*hookfn) (void *data);
 
 extern int h_iosend_id;
@@ -39,6 +49,7 @@ extern int h_rehash;
 void init_hook(void);
 int register_hook(const char *name);
 void add_hook(const char *name, hookfn fn);
+void add_hook_prio(const char *name, hookfn fn, enum hook_priority priority);
 void remove_hook(const char *name, hookfn fn);
 void call_hook(int id, void *arg);
 
diff --git a/include/modules.h b/include/modules.h
index 49539865..9a362c11 100644
--- a/include/modules.h
+++ b/include/modules.h
@@ -70,9 +70,9 @@ typedef struct
 {
 	const char *hapi_name;
 	hookfn fn;
+	enum hook_priority priority;
 } mapi_hfn_list_av1;
 
-
 #define MAPI_CAP_CLIENT		1
 #define MAPI_CAP_SERVER		2
 
diff --git a/ircd/hook.c b/ircd/hook.c
index 70defd1c..bda9fc0c 100644
--- a/ircd/hook.c
+++ b/ircd/hook.c
@@ -42,6 +42,13 @@ hook *hooks;
 
 #define HOOK_INCREMENT 1000
 
+struct hook_entry
+{
+	rb_dlink_node node;
+	hookfn fn;
+	enum hook_priority priority;
+};
+
 int num_hooks = 0;
 int last_hook = 0;
 int max_hooks = HOOK_INCREMENT;
@@ -174,11 +181,34 @@ register_hook(const char *name)
 void
 add_hook(const char *name, hookfn fn)
 {
+	add_hook_prio(name, fn, HOOK_NORMAL);
+}
+
+/* add_hook_prio()
+ *   Adds a hook with the specified priority
+ */
+void
+add_hook_prio(const char *name, hookfn fn, enum hook_priority priority)
+{
+	rb_dlink_node *ptr;
+	struct hook_entry *entry = rb_malloc(sizeof *entry);
 	int i;
 
 	i = register_hook(name);
+	entry->fn = fn;
+	entry->priority = priority;
 
-	rb_dlinkAddAlloc(fn, &hooks[i].hooks);
+	RB_DLINK_FOREACH(ptr, &hooks[i].hooks.head)
+	{
+		struct hook_entry *o = ptr->data;
+		if (entry->priority < o->priority)
+		{
+			rb_dlinkAddBefore(ptr, entry, &entry->node, &hooks[i].hooks);
+			return;
+		}
+	}
+
+	rb_dlinkAddTail(entry, &entry->node, &hooks[i].hooks);
 }
 
 /* remove_hook()
@@ -187,12 +217,21 @@ add_hook(const char *name, hookfn fn)
 void
 remove_hook(const char *name, hookfn fn)
 {
+	rb_dlink_node *ptr, *scratch;
 	int i;
 
 	if((i = find_hook(name)) < 0)
 		return;
 
-	rb_dlinkFindDestroy(fn, &hooks[i].hooks);
+	RB_DLINK_FOREACH_SAFE(ptr, scratch, &hooks[i].hooks.head)
+	{
+		struct hook_entry *entry = ptr->data;
+		if (entry->fn == fn)
+		{
+			rb_dlinkDelete(ptr, &hooks[i].hooks);
+			return;
+		}
+	}
 }
 
 /* call_hook()
@@ -201,7 +240,6 @@ remove_hook(const char *name, hookfn fn)
 void
 call_hook(int id, void *arg)
 {
-	hookfn fn;
 	rb_dlink_node *ptr;
 
 	/* The ID we were passed is the position in the hook table of this
@@ -209,8 +247,8 @@ call_hook(int id, void *arg)
 	 */
 	RB_DLINK_FOREACH(ptr, hooks[id].hooks.head)
 	{
-		fn = ptr->data;
-		fn(arg);
+		struct hook_entry *entry = ptr->data;
+		entry->fn(arg);
 	}
 }
 
diff --git a/ircd/modules.c b/ircd/modules.c
index 7a246cbe..6602a21d 100644
--- a/ircd/modules.c
+++ b/ircd/modules.c
@@ -586,7 +586,12 @@ load_a_module(const char *path, bool warn, int origin, bool core)
 			{
 				mapi_hfn_list_av1 *m;
 				for (m = mheader->mapi_hfn_list; m->hapi_name; ++m)
+				{
+					int priority = m->priority;
+					if (priority == 0)
+						priority = HOOK_NORMAL;
 					add_hook(m->hapi_name, m->fn);
+				}
 			}
 
 			/* New in MAPI v2 - version replacement */

From c500b0bdb56a311859461b7b6ac68bdaaf6330e3 Mon Sep 17 00:00:00 2001
From: Ed Kellett <e@kellett.im>
Date: Mon, 27 Apr 2020 00:42:53 +0100
Subject: [PATCH 2/3] Add priorities to some hooks

---
 extensions/invite_notify.c          | 2 +-
 extensions/m_webirc.c               | 3 ++-
 extensions/override.c               | 8 ++++----
 extensions/override_kick_immunity.c | 2 +-
 ircd/hook.c                         | 4 ++--
 5 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/extensions/invite_notify.c b/extensions/invite_notify.c
index bc7c84f7..19708f90 100644
--- a/extensions/invite_notify.c
+++ b/extensions/invite_notify.c
@@ -13,7 +13,7 @@ static void m_invited(struct MsgBuf *, struct Client *, struct Client *, int, co
 static unsigned int CAP_INVITE_NOTIFY;
 
 mapi_hfn_list_av1 inv_notify_hfnlist[] = {
-	{ "invite", hook_invite },
+	{ "invite", hook_invite, HOOK_MONITOR },
 	{ NULL, NULL }
 };
 
diff --git a/extensions/m_webirc.c b/extensions/m_webirc.c
index 04f59c96..2937189e 100644
--- a/extensions/m_webirc.c
+++ b/extensions/m_webirc.c
@@ -66,7 +66,8 @@ mapi_clist_av1 webirc_clist[] = { &webirc_msgtab, NULL };
 
 static void new_local_user(void *data);
 mapi_hfn_list_av1 webirc_hfnlist[] = {
-	{ "new_local_user", (hookfn) new_local_user },
+	/* unintuitive but correct--we want to be called first */
+	{ "new_local_user", (hookfn) new_local_user, HOOK_LOWEST },
 	{ NULL, NULL }
 };
 
diff --git a/extensions/override.c b/extensions/override.c
index 20110a65..91b3d6eb 100644
--- a/extensions/override.c
+++ b/extensions/override.c
@@ -34,10 +34,10 @@ static void handle_client_exit(void *data);
 
 mapi_hfn_list_av1 override_hfnlist[] = {
 	{ "umode_changed", (hookfn) check_umode_change },
-	{ "get_channel_access", (hookfn) hack_channel_access },
-	{ "can_join", (hookfn) hack_can_join },
-	{ "can_kick", (hookfn) hack_can_kick },
-	{ "can_send", (hookfn) hack_can_send },
+	{ "get_channel_access", (hookfn) hack_channel_access, HOOK_HIGHEST },
+	{ "can_join", (hookfn) hack_can_join, HOOK_HIGHEST },
+	{ "can_kick", (hookfn) hack_can_kick, HOOK_HIGHEST },
+	{ "can_send", (hookfn) hack_can_send, HOOK_HIGHEST },
 	{ "client_exit", (hookfn) handle_client_exit },
 	{ NULL, NULL }
 };
diff --git a/extensions/override_kick_immunity.c b/extensions/override_kick_immunity.c
index b6f7e518..df10ae8b 100644
--- a/extensions/override_kick_immunity.c
+++ b/extensions/override_kick_immunity.c
@@ -14,7 +14,7 @@ static const char override_kick_immunity_desc[] =
 static void can_kick(void *data);
 
 mapi_hfn_list_av1 override_kick_immunity_hfnlist[] = {
-	{ "can_kick", (hookfn) can_kick },
+	{ "can_kick", (hookfn) can_kick, HOOK_HIGHEST },
 	{ NULL, NULL }
 };
 
diff --git a/ircd/hook.c b/ircd/hook.c
index bda9fc0c..bd6f39eb 100644
--- a/ircd/hook.c
+++ b/ircd/hook.c
@@ -198,7 +198,7 @@ add_hook_prio(const char *name, hookfn fn, enum hook_priority priority)
 	entry->fn = fn;
 	entry->priority = priority;
 
-	RB_DLINK_FOREACH(ptr, &hooks[i].hooks.head)
+	RB_DLINK_FOREACH(ptr, hooks[i].hooks.head)
 	{
 		struct hook_entry *o = ptr->data;
 		if (entry->priority < o->priority)
@@ -223,7 +223,7 @@ remove_hook(const char *name, hookfn fn)
 	if((i = find_hook(name)) < 0)
 		return;
 
-	RB_DLINK_FOREACH_SAFE(ptr, scratch, &hooks[i].hooks.head)
+	RB_DLINK_FOREACH_SAFE(ptr, scratch, hooks[i].hooks.head)
 	{
 		struct hook_entry *entry = ptr->data;
 		if (entry->fn == fn)

From c6b2dacad4614246fe0860b361c3e9b8c7414a2a Mon Sep 17 00:00:00 2001
From: Ed Kellett <e@kellett.im>
Date: Mon, 27 Apr 2020 16:36:40 +0100
Subject: [PATCH 3/3] hook: Use old insertion order for equal priority

---
 ircd/hook.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ircd/hook.c b/ircd/hook.c
index bd6f39eb..2721a35c 100644
--- a/ircd/hook.c
+++ b/ircd/hook.c
@@ -201,7 +201,7 @@ add_hook_prio(const char *name, hookfn fn, enum hook_priority priority)
 	RB_DLINK_FOREACH(ptr, hooks[i].hooks.head)
 	{
 		struct hook_entry *o = ptr->data;
-		if (entry->priority < o->priority)
+		if (entry->priority <= o->priority)
 		{
 			rb_dlinkAddBefore(ptr, entry, &entry->node, &hooks[i].hooks);
 			return;