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bitwarden/src/Icons/Services/IconFetchingService.cs
2018-06-28 10:15:54 -04:00

360 lines
13 KiB
C#

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using Bit.Icons.Models;
using AngleSharp.Parser.Html;
namespace Bit.Icons.Services
{
public class IconFetchingService : IIconFetchingService
{
private readonly HashSet<string> _iconRels =
new HashSet<string> { "icon", "apple-touch-icon", "shortcut icon" };
private readonly HashSet<string> _iconExtensions =
new HashSet<string> { ".ico", ".png", ".jpg", ".jpeg" };
private readonly string _pngMediaType = "image/png";
private readonly byte[] _pngHeader = new byte[] { 137, 80, 78, 71 };
private readonly string _icoMediaType = "image/x-icon";
private readonly string _icoAltMediaType = "image/vnd.microsoft.icon";
private readonly byte[] _icoHeader = new byte[] { 00, 00, 01, 00 };
private readonly string _jpegMediaType = "image/jpeg";
private readonly byte[] _jpegHeader = new byte[] { 255, 216, 255 };
private readonly HashSet<string> _allowedMediaTypes;
private readonly HttpClient _httpClient;
public IconFetchingService()
{
_allowedMediaTypes = new HashSet<string>
{
_pngMediaType,
_icoMediaType,
_icoAltMediaType,
_jpegMediaType
};
_httpClient = new HttpClient(new HttpClientHandler
{
AllowAutoRedirect = false,
AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate,
});
_httpClient.Timeout = TimeSpan.FromSeconds(20);
}
public async Task<IconResult> GetIconAsync(string domain)
{
if(!Uri.TryCreate($"https://{domain}", UriKind.Absolute, out var parsedUri))
{
return null;
}
var uri = parsedUri;
var response = await GetAndFollowAsync(uri, 2);
if(response == null || !response.IsSuccessStatusCode)
{
Cleanup(response);
uri = new Uri($"http://{domain}");
response = await GetAndFollowAsync(uri, 2);
if(response == null || !response.IsSuccessStatusCode)
{
Cleanup(response);
uri = new Uri($"https://www.{domain}");
response = await GetAndFollowAsync(uri, 2);
}
}
if(response?.Content == null || !response.IsSuccessStatusCode)
{
Cleanup(response);
return null;
}
var parser = new HtmlParser();
using(response)
using(var htmlStream = await response.Content.ReadAsStreamAsync())
using(var document = await parser.ParseAsync(htmlStream))
{
uri = response.RequestMessage.RequestUri;
if(document.DocumentElement == null)
{
return null;
}
var baseUrl = "/";
var baseUrlNode = document.QuerySelector("head base[href]");
if(baseUrlNode != null)
{
var hrefAttr = baseUrlNode.Attributes["href"];
if(!string.IsNullOrWhiteSpace(hrefAttr?.Value))
{
baseUrl = hrefAttr.Value;
}
baseUrlNode = null;
hrefAttr = null;
}
var icons = new List<IconResult>();
var links = document.QuerySelectorAll("head link[href]");
if(links != null)
{
foreach(var link in links.Take(200))
{
var hrefAttr = link.Attributes["href"];
if(string.IsNullOrWhiteSpace(hrefAttr?.Value))
{
continue;
}
var relAttr = link.Attributes["rel"];
var sizesAttr = link.Attributes["sizes"];
if(relAttr != null && _iconRels.Contains(relAttr.Value.ToLower()))
{
icons.Add(new IconResult(hrefAttr.Value, sizesAttr?.Value));
}
else
{
try
{
var extension = Path.GetExtension(hrefAttr.Value);
if(_iconExtensions.Contains(extension.ToLower()))
{
icons.Add(new IconResult(hrefAttr.Value, sizesAttr?.Value));
}
}
catch(ArgumentException) { }
}
sizesAttr = null;
relAttr = null;
hrefAttr = null;
}
links = null;
}
var iconResultTasks = new List<Task>();
foreach(var icon in icons.OrderBy(i => i.Priority).Take(10))
{
Uri iconUri = null;
if(icon.Path.StartsWith("//") && Uri.TryCreate($"{GetScheme(uri)}://{icon.Path.Substring(2)}",
UriKind.Absolute, out var slashUri))
{
iconUri = slashUri;
}
else if(Uri.TryCreate(icon.Path, UriKind.Relative, out var relUri))
{
iconUri = ResolveUri($"{GetScheme(uri)}://{uri.Host}", baseUrl, relUri.OriginalString);
}
else if(Uri.TryCreate(icon.Path, UriKind.Absolute, out var absUri))
{
iconUri = absUri;
}
if(iconUri != null)
{
var task = GetIconAsync(iconUri).ContinueWith(async (r) =>
{
var result = await r;
if(result != null)
{
icon.Path = iconUri.ToString();
icon.Icon = result.Icon;
}
});
iconResultTasks.Add(task);
}
}
await Task.WhenAll(iconResultTasks);
if(!icons.Any(i => i.Icon != null))
{
var faviconUri = ResolveUri($"{GetScheme(uri)}://{uri.Host}", "favicon.ico");
var result = await GetIconAsync(faviconUri);
if(result != null)
{
icons.Add(result);
}
else
{
return null;
}
}
return icons.Where(i => i.Icon != null).OrderBy(i => i.Priority).First();
}
}
private async Task<IconResult> GetIconAsync(Uri uri)
{
using(var response = await GetAndFollowAsync(uri, 2))
{
if(response?.Content?.Headers == null || !response.IsSuccessStatusCode)
{
response?.Content?.Dispose();
return null;
}
var format = response.Content.Headers?.ContentType?.MediaType;
var bytes = await response.Content.ReadAsByteArrayAsync();
response.Content.Dispose();
if(format == null || !_allowedMediaTypes.Contains(format))
{
if(HeaderMatch(bytes, _icoHeader))
{
format = _icoMediaType;
}
else if(HeaderMatch(bytes, _pngHeader))
{
format = _pngMediaType;
}
else if(HeaderMatch(bytes, _jpegHeader))
{
format = _jpegMediaType;
}
else
{
return null;
}
}
return new IconResult(uri, bytes, format);
}
}
private async Task<HttpResponseMessage> GetAndFollowAsync(Uri uri, int maxRedirectCount)
{
var response = await GetAsync(uri);
if(response == null)
{
return null;
}
return await FollowRedirectsAsync(response, maxRedirectCount);
}
private async Task<HttpResponseMessage> GetAsync(Uri uri)
{
using(var message = new HttpRequestMessage())
{
message.RequestUri = uri;
message.Method = HttpMethod.Get;
// Let's add some headers to look like we're coming from a web browser request. Some websites
// will block our request without these.
message.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " +
"(KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36 Edge/16.16299");
message.Headers.Add("Accept-Language", "en-US,en;q=0.8");
message.Headers.Add("Cache-Control", "no-cache");
message.Headers.Add("Pragma", "no-cache");
message.Headers.Add("Accept", "text/html,application/xhtml+xml,application/xml;" +
"q=0.9,image/webp,image/apng,*/*;q=0.8");
try
{
return await _httpClient.SendAsync(message);
}
catch
{
return null;
}
}
}
private async Task<HttpResponseMessage> FollowRedirectsAsync(HttpResponseMessage response,
int maxFollowCount, int followCount = 0)
{
if(response == null || response.IsSuccessStatusCode || followCount > maxFollowCount)
{
return response;
}
if(!(response.StatusCode == HttpStatusCode.Redirect ||
response.StatusCode == HttpStatusCode.MovedPermanently ||
response.StatusCode == HttpStatusCode.RedirectKeepVerb ||
response.StatusCode == HttpStatusCode.SeeOther) ||
response.Headers.Location == null)
{
Cleanup(response);
return null;
}
Uri location = null;
if(response.Headers.Location.IsAbsoluteUri)
{
if(response.Headers.Location.Scheme != "http" && response.Headers.Location.Scheme != "https")
{
if(Uri.TryCreate($"https://{response.Headers.Location.OriginalString}",
UriKind.Absolute, out var newUri))
{
location = newUri;
}
}
else
{
location = response.Headers.Location;
}
}
else
{
var requestUri = response.RequestMessage.RequestUri;
location = ResolveUri($"{GetScheme(requestUri)}://{requestUri.Host}",
response.Headers.Location.OriginalString);
}
Cleanup(response);
var newResponse = await GetAsync(location);
if(newResponse != null)
{
followCount++;
var redirectedResponse = await FollowRedirectsAsync(newResponse, maxFollowCount, followCount);
if(redirectedResponse != null)
{
if(redirectedResponse != newResponse)
{
Cleanup(newResponse);
}
return redirectedResponse;
}
}
return null;
}
private bool HeaderMatch(byte[] imageBytes, byte[] header)
{
return imageBytes.Length >= header.Length && header.SequenceEqual(imageBytes.Take(header.Length));
}
private Uri ResolveUri(string baseUrl, params string[] paths)
{
var url = baseUrl;
foreach(var path in paths)
{
if(Uri.TryCreate(new Uri(url), path, out var r))
{
url = r.ToString();
}
}
return new Uri(url);
}
private void Cleanup(IDisposable obj)
{
obj?.Dispose();
obj = null;
}
private string GetScheme(Uri uri)
{
return uri != null && uri.Scheme == "http" ? "http" : "https";
}
}
}