1 files changed, 75 insertions, 0 deletions
diff --git a/lib/request-parser.js b/lib/request-parser.js
new file mode 100644
index 0000000..04c5cd6
--- /dev/null
+++ b/lib/request-parser.js
@@ -0,0 +1,75 @@
+'use strict'
+
+const {Transform} = require('stream')
+const {MESSAGES} = require('./statuses')
+
+// https://gemini.circumlunar.space/docs/spec-spec.txt, 1.2
+// > Gemini requests are a single CRLF-terminated line with the
+// > following structure: <URL><CR><LF>
+// > <URL> is a UTF-8 encoded absolute URL, of maximum length
+// > 1024 bytes. [...]
+
+const CRLF = '\r\n'
+const MAX_HEADER_SIZE = 1024 + CRLF.length
+
+const createRequestParser = () => {
+	let headerParsed = false
+	let peek = Buffer.alloc(0)
+
+	const invalid = () => {
+		peek = null
+		out.destroy(new Error('invalid Gemini request'))
+	}
+
+	const onData = (data) => {
+		if (headerParsed) {
+			out.push(data)
+			return;
+		}
+
+		peek = Buffer.concat([peek, data], peek.length + data.length)
+		if (
+			data.indexOf(CRLF) < 0 &&
+			peek.length < MAX_HEADER_SIZE
+		) return; // keep peeking
+
+		const iCRLF = peek.indexOf(CRLF)
+		if (iCRLF < 0) return invalid()
+
+		const url = peek.slice(0, iCRLF).toString('utf8')
+		headerParsed = true
+		out.emit('header', {url})
+
+		const iBody = iCRLF + 2
+		if (peek.length > (iBody + 1)) {
+			// `data` contains the beginning of the body
+			out.push(peek.slice(iBody))
+		}
+		peek = null // allow garbage collection
+	}
+
+	const out = new Transform({
+		write: (chunk, _, cb) => {
+			onData(chunk)
+			cb()
+		},
+		writev: (chunks, cb) => {
+			for (let i = 0; i < chunks.length; i++) {
+				onData(chunks[i].chunk)
+			}
+			cb()
+		},
+	})
+	return out
+}
+
+// const p = createRequestParser()
+// p.on('error', console.error)
+// p.on('header', h => console.log('header', h))
+// p.on('data', d => console.log('data', d.toString('utf8')))
+// const b = str => Buffer.from(str, 'utf8')
+// p.write(b('gemini://examp'))
+// p.write(b('le.org/foo?bar#baz\r\nhel'))
+// p.end(b('lo server!'))
+
+module.exports = createRequestParser