kopher/js/hi01379.js

// Platform-agnostic Gopher response handler and Gophermap parser
// Depends on the platform-specific gopherRequest(resource, input, success, error) function
// (defined in the transport.js file here)

Hi01379 = (function(psGopherRequest) {

  var tagsToReplace = {'&': '&amp;', '<': '&lt;', '>': '&gt;'}

  function esc(str) { // escape HTML entities
    return str.replace(/[&<>]/g, function(tag) {return tagsToReplace[tag] || tag})
  }

  function gophermapToHTML(gmap, chost, cport) {
    if(!cport) cport = 70
    if(!chost) chost = 'localhost'
    var lines = gmap.split(/\r?\n/), line, l = lines.length, i, lbr = '<br>',
        type, rest, desc, sel, host, port,
        output = '', pretag = 'pre', preflag = false
    for(i=0;i<l;i++) {
      line = lines[i]
      if(line === '.')
        break // immediately stop parsing on the . line
      if(line.indexOf('\t') == -1 && !line.startsWith('i')) // this also handles empty lines
        line = 'i' + line
      type = line[0] // type
      rest = line.substr(1).split('\t')
      desc = esc(rest[0]) // escaping description (obviously must not contain tabs)
      sel = rest.length > 1 ? rest[1] : ''      // selector
      host = rest.length > 2 ? rest[2] : ''     // hostname
      port = rest.length > 3 ? (0|rest[3]) : '' // port
      // selector defaults to the description only if there are no other fields
      if(!sel && rest.length < 2) sel = desc
      if(!host) host = chost  // host defaults to the current host
      if(!port) port = cport  // port defaults to the current port
      if(type == 'i') {  // information message - wrap them in pretag
        if(!preflag) {
          preflag = true
          output += '<' + pretag + '>'
        }
        output += desc + '\n'
      }
      else { //information messages ended, stop preformatting
        if(preflag) {
          preflag = false
          output += '</' + pretag + '>'
        }
        if(desc = desc.trim()) { // ignore empty descriptions
          if(type == '3') // error message
            output += '<span class=error>' + desc + '</span>' + lbr
          else { // shape the link (internal hi:type|sel|host|port format unless it's an external URL)
            var deflink = 'hi:'+[type,sel,host,port].join('|'), link = deflink
            if(type == 'h' && sel.startsWith('URL:')) {
              link = sel.split(':').slice(1).join(':').trim()
              if(link.startsWith('javascript:')) // XSS protection
                link = deflink
            }
            output += '<a href="' + encodeURI(link) + '">' + desc + '</a>' + lbr
          }
        }
      }
    }
    return output
  }

  // resource format: [type, selector, host, port]
  function loadHole(resource, input, successCb, errorCb) {
    var fname = resource[1].split('/').pop(), // as the most intelligent guess
        ext = fname.split('.').pop().toLowerCase(), // presumed extension
        extMappings = { // not including AVIF here because they aren't supported by Gecko 48 anyway
          'gif': 'image/gif', // including GIF though because nothing prevents using I instead of g
          'png': 'image/png',
          'svg': 'image/svg+xml',
          'webp': 'image/webp',
          'apng': 'image/apng',
          'jpg': 'image/jpeg',
          'jpeg': 'image/jpeg',
          'jfif': 'image/jpeg',
          'pjpeg': 'image/jpeg',
          'pjp': 'image/jpeg'
        }
    psGopherRequest(resource, input, function(rawdata, type) {
      if(type == '5' || type == 's' || type == ';' || type == 'd')
        type = '9' // remap unknown binary types to 9
      if(type == '9' || type == 'g' || type == 'I') { // binary file
        var ctype = 'application/octet-stream' // the default one if everything else fails
        // update content type
        if(type == 'g') // GIF-only resource type
          ctype = 'image/gif'
        else if(type == 'I') // attempt to guess the image MIME type by the extension
          ctype = extMappings[ext]
        var datablob = new Blob([rawdata], {type: ctype})
        successCb({
          content: datablob,
          contentType: ctype,
          contentName: fname,
          serviceMsg: type + ' ' + resource[1],
          updateAddr: false
        })
      }
      else { // assuming text content otherwise
        var output = (new TextDecoder).decode(rawdata), ctype = 'text/plain' // defaulting to type 0
        if(type == '1' || type == '7') { // gophermap
          output = gophermapToHTML(output, resource[2], resource[3])
          ctype = 'text/html'
        }
        successCb({
          content: output,
          contentType: ctype,
          serviceMsg: type + ' ' + resource[1]
        })
      }
    }, errorCb)
  }

  return {load: loadHole, render: gophermapToHTML}
})(gopherRequest)