vweb: add multipart/form-data parser and file upload (#8160)

examples/vweb/file_upload/index.html

@@ -0,0 +1,6 @@
+<h2>File Upload</h2>
+
+<form method="POST" enctype="multipart/form-data" action="/upload">
+	<input type="file" name="upfile" multiple>
+    <input type="submit" value="Press">
+</form>

examples/vweb/file_upload/upload.html

@@ -0,0 +1,14 @@
+<meta charset="utf-8">
+
+File amount: @fdata.len
+
+@for i, data in fdata
+
+<h2>Filename: @data.filename</h2>
+<h2>Type: @data.content_type</h2>
+
+<p>@{files[i]}</p>
+
+@end
+
+<a href="/">Back</a>

examples/vweb/file_upload/vweb_example.v

@@ -0,0 +1,33 @@
+module main
+
+import vweb
+
+const (
+	port = 8082
+)
+
+struct App {
+	vweb.Context
+}
+
+fn main() {
+	vweb.run<App>(port)
+}
+
+pub fn (mut app App) index() vweb.Result {
+	return $vweb.html()
+}
+
+[post]
+['/upload']
+pub fn (mut app App) upload() vweb.Result {
+	fdata := app.files['upfile']
+
+	mut files := []vweb.RawHtml{}
+
+	for d in fdata {
+		files << d.data.replace_each(['\n', '<br>', '\n\r', '<br>' '\t', '	', ' ', '&nbsp;'])
+	}
+
+	return $vweb.html()
+}

vlib/vweb/vweb.v

@@ -52,6 +52,7 @@ pub mut:
 	static_mime_types map[string]string
 	form              map[string]string
 	query             map[string]string
+	files             map[string][]FileData
 	headers           string // response headers
 	done              bool
 	page_gen_start    i64
@@ -60,6 +61,13 @@ pub mut:
 	max_chunk_len     int = 20
 }
 
+struct FileData {
+pub:
+	filename     string
+	content_type string
+	data         string
+}
+
 // declaring init_once in your App struct is optional
 pub fn (ctx Context) init_once() {}
 
@@ -316,6 +324,9 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T) {
 	mut body := ''
 	mut in_headers := true
 	mut len := 0
+	// File receive stuff
+	mut ct := 'text/plain'
+	mut boundary := ''
 	// for line in lines[1..] {
 	for lindex in 0 .. 100 {
 		// println(j)
@@ -324,6 +335,14 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T) {
 			break
 		}
 		sline := strip(line)
+		// Parse content type
+		if sline.len >= 14 && sline[..14] == 'Content-Type: ' {
+			args := sline[14..].split('; ')
+			ct = args[0]
+			if args.len > 1 {
+				boundary = args[1][9..]
+			}
+		}
 		if sline == '' {
 			// if in_headers {
 			// End of headers, no body => exit
@@ -340,8 +359,13 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T) {
 			body += read_body.bytestr()
 			break
 		}
+		if ct == 'multipart/form-data' && sline == boundary {
+			body += boundary
+			read_body := io.read_all(reader: reader) or { []byte{} }
+			body += read_body.bytestr()
+			break
+		}
 		if in_headers {
-			// println(sline)
 			headers << sline
 			if sline.starts_with('Content-Length') {
 				len = sline.all_after(': ').int()
@@ -374,7 +398,11 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T) {
 	}
 	// }
 	if req.method in methods_with_form {
-		app.parse_form(req.data)
+		if ct == 'multipart/form-data' {
+			app.parse_multipart_form(body, boundary)
+		} else {
+			app.parse_form(req.data)
+		}
 	}
 	if vals.len < 2 {
 		$if debug {
@@ -603,6 +631,63 @@ pub fn (mut ctx Context) parse_form(s string) {
 	// ...
 }
 
+[manualfree]
+pub fn (mut ctx Context) parse_multipart_form(s string, b string) {
+	if ctx.req.method !in methods_with_form {
+		return
+	}
+	a := s.split('$b')[1..]
+	fields := a[..a.len - 1]
+	for field in fields {
+		lines := field.split_into_lines()[1..]
+		mut l := 0
+		// Parse name
+		disposition_data := lines[l].split('; ')[1..]
+		l++
+		name := disposition_data[0][6..disposition_data[0].len - 1]
+		// Parse files
+		if disposition_data.len > 1 {
+			filename := disposition_data[1][10..disposition_data[1].len - 1]
+			ct := lines[l].split(': ')[1]
+			l++
+			if name !in ctx.files {
+				ctx.files[name] = []FileData{}
+			}
+			mut sb := strings.new_builder(field.len)
+			for i in l + 1 .. lines.len - 1 {
+				sb.writeln(lines[i])
+			}
+			ctx.files[name] << FileData{
+				filename: filename
+				content_type: ct
+				data: sb.str()
+			}
+			unsafe {
+				filename.free()
+				ct.free()
+				sb.free()
+			}
+			continue
+		}
+		mut sb := strings.new_builder(field.len)
+		for i in l + 1 .. lines.len - 1 {
+			sb.writeln(lines[i])
+		}
+		ctx.form[name] = sb.str()
+		unsafe {
+			disposition_data.free()
+			name.free()
+			sb.free()
+		}
+	}
+	unsafe {
+		fields.free()
+		s.free()
+		b.free()
+		a.free()
+	}
+}
+
 fn (mut ctx Context) scan_static_directory(directory_path string, mount_path string) {
 	files := os.ls(directory_path) or { panic(err) }
 	if files.len > 0 {