From 105e24c9e001d98a901eb4869c5dd9b7e19e548f Mon Sep 17 00:00:00 2001
From: Hanspeter Portner <dev@open-music-kontrollers.ch>
Date: Sun, 3 Dec 2023 10:01:19 +0100
Subject: [PATCH] Properly estimate slip encoded size

---
 osc.lv2/stream.h |  3 +++
 src/stream.c     | 27 ++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/osc.lv2/stream.h b/osc.lv2/stream.h
index 4dcbcd8..10b7d0d 100644
--- a/osc.lv2/stream.h
+++ b/osc.lv2/stream.h
@@ -86,6 +86,9 @@ int
 lv2_osc_stream_init(LV2_OSC_Stream *stream, const char *url,
 	const LV2_OSC_Driver *driv, void *data);
 
+size_t
+lv2_osc_slip_encode_size(const uint8_t *dst, size_t len);
+
 size_t
 lv2_osc_slip_encode_inline(uint8_t *dst, size_t len);
 
diff --git a/src/stream.c b/src/stream.c
index 0bcbf53..9d4e452 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -592,7 +592,7 @@ lv2_osc_stream_init(LV2_OSC_Stream *stream, const char *url,
 
 // SLIP encoding
 size_t
-lv2_osc_slip_encode_inline(uint8_t *dst, size_t len)
+lv2_osc_slip_encode_size(const uint8_t *dst, size_t len)
 {
 	if(len == 0)
 	{
@@ -611,6 +611,21 @@ lv2_osc_slip_encode_inline(uint8_t *dst, size_t len)
 		}
 	}
 
+	return size;
+}
+
+size_t
+lv2_osc_slip_encode_inline(uint8_t *dst, size_t len)
+{
+	// estimate new size
+	const size_t size = lv2_osc_slip_encode_size(dst, len);
+
+	// ignore empty message
+	if(len == 0)
+	{
+		return 0;
+	}
+
 	// fast track if no escaping needed
 	if(size == len + 2)
 	{
@@ -621,6 +636,8 @@ lv2_osc_slip_encode_inline(uint8_t *dst, size_t len)
 		return size;
 	}
 
+	const uint8_t *end = dst + len;
+
 	// slow track if some escaping needed
 	uint8_t *to = dst + size - 1;
 	*to-- = SLIP_END;
@@ -876,7 +893,9 @@ _lv2_osc_stream_run_tcp(LV2_OSC_Stream *stream)
 			{
 				if(stream->slip) // SLIP framed
 				{
-					if(tosend <= sizeof(stream->tx_buf)) // check if there is enough memory
+					const size_t nsize = lv2_osc_slip_encode_size(buf, tosend);
+
+					if(nsize <= sizeof(stream->tx_buf)) // check if there is enough memory
 					{
 						memcpy(stream->tx_buf, buf, tosend);
 						tosend = lv2_osc_slip_encode_inline(stream->tx_buf, tosend);
@@ -1087,7 +1106,9 @@ _lv2_osc_stream_run_ser(LV2_OSC_Stream *stream)
 			{
 				if(stream->slip) // SLIP framed
 				{
-					if(tosend <= sizeof(stream->tx_buf)) // check if there is enough memory
+					const size_t nsize = lv2_osc_slip_encode_size(buf, tosend);
+
+					if(nsize <= sizeof(stream->tx_buf)) // check if there is enough memory
 					{
 						memcpy(stream->tx_buf, buf, tosend);
 						tosend = lv2_osc_slip_encode_inline(stream->tx_buf, tosend);
-- 
2.38.5