From 36d45c6d1418f50a87168e16a516e15a6c99d7dd Mon Sep 17 00:00:00 2001
From: l-m <l-m@l-m.dev>
Date: Fri, 21 Jul 2023 13:37:55 +0000
Subject: [PATCH] net.http.chunked: return `!string` on decode (#18928)

---
 vlib/net/http/chunked/dechunk.v      | 10 +++++++---
 vlib/net/http/chunked/dechunk_test.v | 16 ++++++++++++++++
 vlib/net/http/response.v             |  2 +-
 3 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 vlib/net/http/chunked/dechunk_test.v

diff --git a/vlib/net/http/chunked/dechunk.v b/vlib/net/http/chunked/dechunk.v
index 44f251231b..a4c30f368e 100644
--- a/vlib/net/http/chunked/dechunk.v
+++ b/vlib/net/http/chunked/dechunk.v
@@ -46,13 +46,16 @@ fn (mut s ChunkScanner) skip_crlf() {
 	s.pos += 2
 }
 
-fn (mut s ChunkScanner) read_chunk(chunksize u32) string {
+fn (mut s ChunkScanner) read_chunk(chunksize u32) !string {
 	startpos := s.pos
 	s.pos += int(chunksize)
+	if s.pos > s.text.len {
+		return error('invalid chunksize')
+	}
 	return s.text[startpos..s.pos]
 }
 
-pub fn decode(text string) string {
+pub fn decode(text string) !string {
 	mut sb := strings.new_builder(100)
 	mut cscanner := ChunkScanner{
 		pos: 0
@@ -64,7 +67,8 @@ pub fn decode(text string) string {
 			break
 		}
 		cscanner.skip_crlf()
-		sb.write_string(cscanner.read_chunk(csize))
+		ch := cscanner.read_chunk(csize)!
+		sb.write_string(ch)
 		cscanner.skip_crlf()
 	}
 	cscanner.skip_crlf()
diff --git a/vlib/net/http/chunked/dechunk_test.v b/vlib/net/http/chunked/dechunk_test.v
new file mode 100644
index 0000000000..0d9822453b
--- /dev/null
+++ b/vlib/net/http/chunked/dechunk_test.v
@@ -0,0 +1,16 @@
+module chunked
+
+fn test_invalid_chunk() {
+	mut is_failure := false
+
+	decode('eee') or { is_failure = true }
+
+	assert is_failure
+}
+
+fn test_valid_chunk() {
+	chunks := '4\r\nWiki\r\n7\r\npedia i\r\nB\r\nn \r\nchunks.\r\n0\r\n\r\n'
+	str := decode(chunks) or { panic('uh oh') }
+
+	assert str == 'Wikipedia in \r\nchunks.'
+}
diff --git a/vlib/net/http/response.v b/vlib/net/http/response.v
index d9819a78aa..10720efd1a 100644
--- a/vlib/net/http/response.v
+++ b/vlib/net/http/response.v
@@ -42,7 +42,7 @@ pub fn parse_response(resp string) !Response {
 	header := parse_headers(resp.substr(start_idx, end_idx))!
 	mut body := resp.substr(end_idx, resp.len)
 	if header.get(.transfer_encoding) or { '' } == 'chunked' {
-		body = chunked.decode(body)
+		body = chunked.decode(body)!
 	}
 	return Response{
 		http_version: version