From: Ralph Dolmans <ralph@nlnetlabs.nl>
Date: Wed, 15 Jul 2020 13:49:42 +0000 (+0200)
Subject: - Handle SSL_ERROR_WANT_WRITE on SSL_read for negotiation
X-Git-Tag: release-1.11.0~14^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db3ac2335cc5d2de1e6c8f73626cb65ef18b4d2d;p=thirdparty%2Funbound.git

- Handle SSL_ERROR_WANT_WRITE on SSL_read for negotiation
- Close connection when receiving overly large frame
---

diff --git a/dnstap/dtstream.c b/dnstap/dtstream.c
index 030b66eee..171fe1c12 100644
--- a/dnstap/dtstream.c
+++ b/dnstap/dtstream.c
@@ -94,6 +94,8 @@ static int dtio_control_start_send(struct dt_io_thread* dtio);
 #ifdef HAVE_SSL
 /** enable briefly waiting for a read event, for SSL negotiation */
 static int dtio_enable_brief_read(struct dt_io_thread* dtio);
+/** enable briefly waiting for a write event, for SSL negotiation */
+static int dtio_enable_brief_write(struct dt_io_thread* dtio);
 #endif
 
 struct dt_msg_queue*
@@ -945,7 +947,7 @@ static int ssl_read_bytes(struct dt_io_thread* dtio, void* buf, size_t len)
 			/* continue later */
 			return -1;
 		} else if(want == SSL_ERROR_WANT_WRITE) {
-			(void)dtio_add_output_event_write(dtio);
+			(void)dtio_enable_brief_write(dtio);
 			return -1;
 		} else if(want == SSL_ERROR_SYSCALL) {
 #ifdef ECONNRESET
@@ -1036,9 +1038,9 @@ static int dtio_read_accept_frame(struct dt_io_thread* dtio)
 		dtio->read_frame.frame_len = ntohl(dtio->read_frame.frame_len);
 		if(dtio->read_frame.frame_len > DTIO_RECV_FRAME_MAX_LEN) {
 			verbose(VERB_OPS, "dnstap: received frame exceeds max "
-				"length, capped to %d bytes",
+				"length of %d bytes, closing connection",
 				DTIO_RECV_FRAME_MAX_LEN);
-			dtio->read_frame.frame_len = DTIO_RECV_FRAME_MAX_LEN;
+			goto close_connection;
 		}
 		dtio->read_frame.buf = calloc(1, dtio->read_frame.frame_len);
 		dtio->read_frame.buf_cap = dtio->read_frame.frame_len;
@@ -1207,6 +1209,24 @@ static int dtio_disable_brief_read(struct dt_io_thread* dtio)
 }
 #endif /* HAVE_SSL */
 
+#ifdef HAVE_SSL
+/** enable the brief write condition */
+static int dtio_enable_brief_write(struct dt_io_thread* dtio)
+{
+	dtio->ssl_brief_write = 1;
+	return dtio_add_output_event_write(dtio);
+}
+#endif /* HAVE_SSL */
+
+#ifdef HAVE_SSL
+/** disable the brief write condition */
+static int dtio_disable_brief_write(struct dt_io_thread* dtio)
+{
+	dtio->ssl_brief_write = 0;
+	return dtio_add_output_event_read(dtio);
+}
+#endif /* HAVE_SSL */
+
 #ifdef HAVE_SSL
 /** check peer verification after ssl handshake connection, false if closed*/
 static int dtio_ssl_check_peer(struct dt_io_thread* dtio)
@@ -1380,7 +1400,9 @@ void dtio_output_cb(int ATTR_UNUSED(fd), short bits, void* arg)
 	}
 #endif
 
-	if((bits&UB_EV_READ)) {
+	if((bits&UB_EV_READ || dtio->ssl_brief_write)) {
+		if(dtio->ssl_brief_write)
+			(void)dtio_disable_brief_write(dtio);
 		if(dtio->ready_frame_sent && !dtio->accept_frame_received) {
 			if(dtio_read_accept_frame(dtio) <= 0)
 				return;
diff --git a/dnstap/dtstream.h b/dnstap/dtstream.h
index d93714baf..ede491f30 100644
--- a/dnstap/dtstream.h
+++ b/dnstap/dtstream.h
@@ -151,6 +151,9 @@ struct dt_io_thread {
 	 * This happens during negotiation, we then do not want to write,
 	 * but wait for a read event. */
 	int ssl_brief_read;
+	/** true if SSL_read is waiting for a write event. Set back to 0 after
+	 * single write event is handled. */
+	int ssl_brief_write;
 
 	/** the buffer that currently getting written, or NULL if no
 	 * (partial) message written now */