public async Task <CrawledContent> Parse(Uri uri, HttpResponseMessage response, CrawlSettings settings)
{
var crawledContent = new CrawledContent
{
ContentType = response.Content.Headers.ContentType.MediaType,
CharacterSet = response.Content.Headers.ContentType.CharSet,
ContentEncoding = string.Join(",", response.Content.Headers.ContentEncoding)
};
var contentStream = new MemoryStream();
await(await response.Content.ReadAsStreamAsync()).CopyToAsync(contentStream);
crawledContent.RawContent = new StreamReader(contentStream).ReadToEnd();
contentStream.Seek(0, SeekOrigin.Begin);
using (contentStream)
{
var parsedContent = Parse(uri, contentStream);
crawledContent.CanonicalUri = parsedContent.CanonicalUri;
if (response.Headers.Contains("X-Robots-Tag"))
{
var robotsHeaderValues = response.Headers.GetValues("X-Robots-Tag");
parsedContent.NoIndex = robotsHeaderValues.Any(r =>
r.IndexOf("noindex", StringComparison.InvariantCultureIgnoreCase) != -1
);
parsedContent.NoFollow = robotsHeaderValues.Any(r =>
r.IndexOf("nofollow", StringComparison.InvariantCultureIgnoreCase) != -1
);
}
if (parsedContent.NoIndex)
{
crawledContent.RawContent = null;
}
if (!parsedContent.NoFollow)
{
crawledContent.Links = parsedContent.Links;
}
return(crawledContent);
}
}
public CrawledContent Parse(Uri requestUri, CrawlHeaders headers, Stream contentStream)
{
var crawledContent = new CrawledContent
{
ContentType = headers.ContentHeaders.ContentType?.MediaType,
CharacterSet = headers.ContentHeaders.ContentType?.CharSet,
ContentEncoding = headers.ContentHeaders.ContentEncoding != null?string.Join(",", headers.ContentHeaders.ContentEncoding) : null
};
var document = new HtmlDocument();
document.Load(contentStream);
var pageRobotRules = new List <string>();
if (headers.ResponseHeaders.Contains("X-Robots-Tag"))
{
var robotsHeaderValues = headers.ResponseHeaders.GetValues("X-Robots-Tag");
pageRobotRules.AddRange(robotsHeaderValues);
}
var metaNodes = document.DocumentNode.SelectNodes("html/head/meta");
if (metaNodes != null)
{
var robotsMetaValue = metaNodes
.Where(n => n.Attributes.Any(a => a.Name == "name" && a.Value.Equals("robots", StringComparison.InvariantCultureIgnoreCase)))
.SelectMany(n => n.Attributes.Where(a => a.Name == "content").Select(a => a.Value))
.FirstOrDefault();
if (robotsMetaValue != null)
{
pageRobotRules.Add(robotsMetaValue);
}
}
crawledContent.PageRobotRules = pageRobotRules.ToArray();
crawledContent.CanonicalUri = GetCanonicalUri(document, requestUri);
crawledContent.Links = GetLinks(document, requestUri).ToArray();
return(crawledContent);
}
public void AddResult(Uri requestUri, CrawledContent content)
{
if (UriCrawlStates.TryGetValue(requestUri, out var crawlState))
{
var robotsPageDefinition = RobotsPageParser.FromRules(content.PageRobotRules);
if (!robotsPageDefinition.CanIndex(Settings.UserAgent))
{
Logger?.LogDebug($"Result content for {requestUri} has been blocked by an in-page Robots rule.");
AddResult(new CrawledUri
{
Location = crawlState.Location,
Status = CrawlStatus.RobotsBlocked,
Requests = crawlState.Requests,
RedirectChain = crawlState.Redirects
});
}
else
{
Logger?.LogDebug($"Result for {requestUri} has completed successfully with content.");
AddResult(new CrawledUri
{
Location = crawlState.Location,
Status = CrawlStatus.Crawled,
RedirectChain = crawlState.Redirects,
Requests = crawlState.Requests,
Content = content
});
if (robotsPageDefinition.CanFollowLinks(Settings.UserAgent))
{
foreach (var crawlLink in content.Links)
{
AddLink(crawlLink);
}
}
}
}
}
public void AddResult(Uri requestUri, CrawledContent content)
{
if (UriCrawlStates.TryGetValue(requestUri, out var crawlState))
{
if (content != null)
{
var robotsPageDefinition = RobotsPageParser.FromRules(content.PageRobotRules);
if (!robotsPageDefinition.CanIndex(Settings.UserAgent))
{
AddResult(new CrawledUri
{
Location = crawlState.Location,
Status = CrawlStatus.RobotsBlocked,
Requests = crawlState.Requests,
RedirectChain = crawlState.Redirects
});
return;
}
if (robotsPageDefinition.CanFollowLinks(Settings.UserAgent))
{
foreach (var crawlLink in content.Links)
{
AddLink(crawlLink);
}
}
}
AddResult(new CrawledUri
{
Location = crawlState.Location,
Status = CrawlStatus.Crawled,
RedirectChain = crawlState.Redirects,
Requests = crawlState.Requests,
Content = content
});
}
}