From b6e5548a3ecc562db4c8d5356bdfd9a3fa5e59f8 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@nbd.name>
Date: Fri, 29 Mar 2024 13:32:35 +0100
Subject: [PATCH] uclient: defer read notifications to uloop timer

This gets rid of potentially harmful recursion when polling from within the
read callback

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 uclient-backend.h |  4 ++++
 uclient-http.c    |  4 +---
 uclient.c         | 11 +++++++++++
 uclient.h         |  1 +
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/uclient-backend.h b/uclient-backend.h
index c2b9fd5..b013cde 100644
--- a/uclient-backend.h
+++ b/uclient-backend.h
@@ -41,5 +41,9 @@ void uclient_backend_set_eof(struct uclient *cl);
 void uclient_backend_reset_state(struct uclient *cl);
 struct uclient_url *uclient_get_url(const char *url_str, const char *auth_str);
 struct uclient_url *uclient_get_url_location(struct uclient_url *url, const char *location);
+static inline void uclient_backend_read_notify(struct uclient *cl)
+{
+	uloop_timeout_set(&cl->read_notify, 1);
+}
 
 #endif
diff --git a/uclient-http.c b/uclient-http.c
index 935d50f..83c268f 100644
--- a/uclient-http.c
+++ b/uclient-http.c
@@ -780,9 +780,7 @@ static void __uclient_notify_read(struct uclient_http *uh)
 	if (uh->state == HTTP_STATE_RECV_DATA) {
 		/* Now it's uclient user turn to read some data */
 		uloop_timeout_cancel(&uc->connection_timeout);
-
-		if (uc->cb->data_read)
-			uc->cb->data_read(uc);
+		uclient_backend_read_notify(uc);
 	}
 }
 
diff --git a/uclient.c b/uclient.c
index 4214c62..a309de8 100644
--- a/uclient.c
+++ b/uclient.c
@@ -239,6 +239,14 @@ static void uclient_connection_timeout(struct uloop_timeout *timeout)
 	uclient_backend_set_error(cl, UCLIENT_ERROR_TIMEDOUT);
 }
 
+static void __uclient_read_notify(struct uloop_timeout *timeout)
+{
+	struct uclient *cl = container_of(timeout, struct uclient, read_notify);
+
+	if (cl->cb->data_read)
+		cl->cb->data_read(cl);
+}
+
 struct uclient *uclient_new(const char *url_str, const char *auth_str, const struct uclient_cb *cb)
 {
 	struct uclient *cl;
@@ -257,6 +265,7 @@ struct uclient *uclient_new(const char *url_str, const char *auth_str, const str
 	cl->url = url;
 	cl->timeout_msecs = UCLIENT_DEFAULT_TIMEOUT_MS;
 	cl->connection_timeout.cb = uclient_connection_timeout;
+	cl->read_notify.cb = __uclient_read_notify;
 
 	return cl;
 }
@@ -401,6 +410,7 @@ void uclient_disconnect(struct uclient *cl)
 {
 	uloop_timeout_cancel(&cl->connection_timeout);
 	uloop_timeout_cancel(&cl->timeout);
+	uloop_timeout_cancel(&cl->read_notify);
 
 	if (!cl->backend->disconnect)
 		return;
@@ -450,6 +460,7 @@ void __hidden uclient_backend_reset_state(struct uclient *cl)
 	cl->eof = false;
 	cl->error_code = 0;
 	uloop_timeout_cancel(&cl->timeout);
+	uloop_timeout_cancel(&cl->read_notify);
 }
 
 const char * uclient_strerror(unsigned err)
diff --git a/uclient.h b/uclient.h
index ffe159a..29563b3 100644
--- a/uclient.h
+++ b/uclient.h
@@ -75,6 +75,7 @@ struct uclient {
 	struct blob_attr *meta;
 
 	struct uloop_timeout connection_timeout;
+	struct uloop_timeout read_notify;
 	struct uloop_timeout timeout;
 };
 
-- 
2.30.2