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client.js
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client.js
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// User-Agent header and software name
const userAgent = 'Reginaldo Web Downloader';
// Expected content type
const acceptContent = 'text/plain;q=0.9,text/html,application/xhtml+xml,application/xml;q=0.8,*/*;q=0.7';
// Expected languages
const acceptLanguage = 'pt-BR,pt;q=0.8,en-US;q=0.5,en;q=0.3';
// Maximum of redirections accepted to avoid infinite loop
const maxRedirects = 3;
// Sets the parameters expected
const opt = require('./getopt').create([
['o', '=', 'arquivo para salvar (padrão: saída padrão)'],
['h', '', 'mostra esta ajuda'],
['x', '', 'mostrar cabeçalhos recebidos']
]).parseSystem();
// If help parameter were requested, show it and quit
if (opt.options.h) {
opt.showHelp();
process.exit(0)
}
const net = require('net');
const tls = require('tls');
const fs = require('fs');
const lib = require('./lib');
var request = process.argv[2], urlparts = request ? parseurl(request) : false, countredirects = 0, output;
// Requires a URL as a parameter from console
if (!urlparts) {
console.error('Você deve especificar a URL.');
process.exit(1)
}
// If a host is not set in the URL, quit
if (!urlparts.host) {
console.error('Você deve especificar um host para estabelecer conexão.');
process.exit(1)
}
// If a file is set to output stream, try to create the file.
// If there is no file set, use standard output.
try {
output = opt.options.o ? fs.createWriteStream(/^\s*\//.test(opt.options.o) ? opt.options.o : './' + opt.options.o) : process.stdout
} catch (x) {
console.error('O arquivo não pode ser criado ou modificado.');
process.exit(5)
}
// Defines the class for HTTP standard request
function Request() {
var
set = {Host: '', 'User-Agent': userAgent, Accept: acceptContent, 'Accept-Language': acceptLanguage, Connection: 'close'},
method = 'GET',
uri = '/',
data = '';
this.setHeader = function(name, value){
set[name] = value;
return this
};
this.setMethod = function(m){
method = m.toUpperCase()
};
this.setData = function(vdata){
data = vdata;
return this
};
this.setURI = function(u){
uri = u;
return this
};
// Sets the HTTP request
this.toString = function(){
var r = method + ' ' + uri + ' HTTP/1.1', i;
for (i in set)
r += "\r\n" + i + ': ' + set[i];
if (!'Content-Length' in set)
r += "\r\nContent-Length: " + data.length;
r += "\r\n\r\n";
if (data instanceof Buffer) {
var buffer = new Buffer(r);
return Buffer.concat([buffer, data], buffer.length + data.length);
}
return r + data
}
}
// Segments URL string into separated components. Returns false when bad.
function parseurl(url) {
var matches = url.match(/^((.*?):\/\/)?(.*?)(:(\d+))?(\/.*?)?(\?(.*?))?(#(.*))?$/);
return matches ? {
protocol: (matches[2] || 'http').toLowerCase(),
host: matches[3] ? matches[3].toLowerCase() : undefined,
port: matches[5],
uri: matches[6] || '/',
query: matches[8],
hash: matches[10]
} : false
}
function fetch(urlparts) {
// Opens a SSL/TLS stream when "https" is used. Otherwise, use clear text stream.
(urlparts.protocol == 'https' ? tls.connect : net.createConnection)(urlparts.port || (urlparts.protocol == 'https' ? 443 : 80), urlparts.host, function(){
var socket = this, buffer = new Buffer(''), pos = 4, headers, matches, location, size = 0;
// Forward data received into the output set
function writedata(){
size += buffer.length - pos;
output.write(pos ? buffer.slice(pos) : buffer)
}
socket.on('data', (data) => {
// If all headers were already read, all buffer is remaining data only.
// Then, forward socket data into output efficiently.
if (headers) {
pos = 0;
buffer = data;
writedata()
} else {
// Otherwise, read till headers are over
// by concatenating next received data into buffer.
buffer = Buffer.concat([buffer, data]);
// Loops till finding out empty line that separates
// headers from requested content.
while (pos < buffer.length) {
if (/(\r\n|\n\r|\n){2}$/.test(buffer.slice(pos - 3, pos + 1) + '')) {
// Get headers and format them in order to easy handling
(matches = (buffer.slice(0, pos) + '').split(/[\r\n]+/)).splice(-1, 1);
headers = {};
matches.forEach((header) => {
if (header.length) {
var parts = header.split(':');
headers[parts[0].replace(/\s+$/, '').toUpperCase()] = parts.slice(1).join(':').replace(/^\s+/, '')
}
});
// Check if first line matches HTTP standard
if (matches = matches[0].match(/^HTTP\/1\.[01]\s+(\d+)\s+(.+)/)) {
// If the header "Location" is set, format the received
// URL for redirection.
if (location = headers['LOCATION'] ? parseurl(headers['LOCATION']) : false) {
location.protocol = location.protocol || urlparts.protocol;
location.host = location.host || urlparts.host;
location.port = location.port || urlparts.port
}
// Check HTTP status
switch (parseInt(matches[1])) {
case 200:
console.error('Recurso obtido com sucesso.');
break;
case 301:
case 302:
case 303:
break;
case 403:
console.error('Acesso proibido.');
process.exit(3);
case 404:
console.error('Recurso não encontrado.');
process.exit(3);
default:
console.error('O servidor retornou o estado ' + matches[1] + ' com a informação "' + matches[2] + '" para o recurso solicitado.');
process.exit(3)
}
// If the "Location" header were set,
// prepare for redirection.
if (location) {
socket.destroy();
// If the maximum redirections count were
// reached, quit. Otherwise, redirect.
if (countredirects++ < maxRedirects) {
console.error('Redirecionamento ' + (matches[1] == 301 ? 'permanente' : 'temporário') + ' para "' + (location.protocol != urlparts.protocol || location.host != urlparts.host || location.port != urlparts.port ? location.protocol + '://' + location.host + (location.port && location.port != 80 ? ':' + location.port : '') : '') + location.uri + (location.query ? '?' + location.query : '') + '"...');
return fetch(location)
} else {
console.error('Tentativa de redirecionamento ' + (matches[1] == 301 ? 'permanente' : 'temporário') + ' para "' + (location.protocol != urlparts.protocol || location.host != urlparts.host || location.port != urlparts.port ? location.protocol + '://' + location.host + (location.port && location.port != 80 ? ':' + location.port : '') : '') + location.uri + (location.query ? '?' + location.query : '') + '" bloqueado, porque excedeu o número de ' + maxRedirects + ' tentativa(s).');
process.exit(4)
}
}
++pos;
// Print the received headers, if the
// parameter "x" were set.
if (opt.options.x)
console.error("\nCabeçalho da resposta:\n" + (buffer.slice(0, pos) + '').replace(/(\r|[\r\n]+$)/g, '') + "\n");
// Forward stream from socket into output
writedata()
} else {
console.error('A resposta não corresponde ao protocolo HTTP.');
process.exit(2)
}
break
}
++pos
}
}
}).on('end', function(){
// At the end of transmission, print statistics out.
console.error('Recebido ' + lib.formatNumber(size) + ' bytes' + (size >= 1000 ? ' (≈ ' + lib.humanSizeFormat(size) + ')' : '') + '.')
});
// Send HTTP request into the socket to the Web Server
socket.write(new Request().setURI(urlparts.uri + (!(urlparts.query || '') ? '' : '?' + urlparts.query)).setHeader('Host', urlparts.host).toString())
}).on('error', function(){
console.error('Falha ao conexão em "' + urlparts.host + ':' + (urlparts.port || (urlparts.protocol == 'https' ? 443 : 80)) + '".')
})
}
fetch(urlparts)