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'use strict'
const {Transform} = require('stream')
const {MESSAGES} = require('./statuses')
// https://gemini.circumlunar.space/docs/spec-spec.txt, 1.3.1
// > Gemini response headers look like this:
// > <STATUS><whitespace><META><CR><LF>
// > <STATUS> is a two-digit numeric status code [...].
// > <whitespace> is any non-zero number of consecutive spaces or tabs.
// > <META> is a UTF-8 encoded string of maximum length 1024, whose meaning is
// > <STATUS> dependent.
const CRLF = '\r\n'
const MAX_HEADER_SIZE = 2048 // cutoff
const createParser = () => {
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 statusCodeAndSpace = peek.slice(0, 3).toString('utf8')
if (!/\d{2} /.test(statusCodeAndSpace)) return invalid()
const iCRLF = peek.indexOf(CRLF)
if (iCRLF < 0) return invalid()
let statusCode = parseInt(statusCodeAndSpace)
let statusMsg = MESSAGES[statusCode]
if (!statusMsg) {
statusCode = Math.floor(statusCode / 10) * 10
statusMsg = MESSAGES[statusCode]
if (!statusMsg) return invalid()
}
const meta = peek.slice(3, iCRLF).toString('utf8').trim()
headerParsed = true
out.emit('header', {
type: (
statusCode >= 10 && statusCode < 20
? 'request' : 'response'
),
statusCode, statusMsg,
meta,
})
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 = createParser()
// 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('12 gemini://examp'))
// p.write(b('le.org/foo?bar#baz\r\nhel'))
// p.end(b('lo server!'))
module.exports = {
MESSAGES,
createParser,
}
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