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article_scraper/src/full_text_parser/mod.rs
2022-12-13 08:54:57 +01:00

804 lines
27 KiB
Rust

pub mod config;
pub mod error;
mod fingerprints;
#[cfg(test)]
mod tests;
use self::config::{ConfigCollection, ConfigEntry};
use self::error::FullTextParserError;
use crate::article::Article;
use crate::util::Util;
use chrono::DateTime;
use encoding_rs::Encoding;
use fingerprints::Fingerprints;
use libxml::parser::Parser;
use libxml::tree::{Document, Node};
use libxml::xpath::Context;
use log::{debug, error, info, warn};
use reqwest::header::HeaderMap;
use reqwest::Client;
use std::path::Path;
use std::str::{from_utf8, FromStr};
pub struct FullTextParser {
config_files: ConfigCollection,
}
impl FullTextParser {
pub async fn new(config_path: Option<&Path>) -> Self {
let config_files = ConfigCollection::parse(config_path).await;
Self { config_files }
}
pub async fn parse(
&self,
url: &url::Url,
client: &Client,
) -> Result<Article, FullTextParserError> {
info!("Scraping article: '{}'", url.as_str());
// check if we have a config for the url
let config = self.get_grabber_config(url);
let global_config = self
.config_files
.get("global.txt")
.ok_or(FullTextParserError::Config)?;
let headers = Util::generate_headers(config, global_config)?;
let response = client
.head(url.clone())
.headers(headers)
.send()
.await
.map_err(|err| {
error!("Failed head request to: '{}' - '{}'", url.as_str(), err);
FullTextParserError::Http
})?;
// check if url redirects and we need to pick up the new url
let url = if let Some(new_url) = Util::check_redirect(&response, url) {
debug!("Url '{}' redirects to '{}'", url.as_str(), new_url.as_str());
new_url
} else {
url.clone()
};
// check if we are dealing with text/html
if !Util::check_content_type(&response)? {
return Err(FullTextParserError::ContentType);
}
let mut article = Article {
title: None,
author: None,
url: url.clone(),
date: None,
thumbnail_url: None,
document: None,
};
let mut document = Document::new().map_err(|()| FullTextParserError::Xml)?;
let mut root =
Node::new("article", None, &document).map_err(|()| FullTextParserError::Xml)?;
document.set_root_element(&root);
Self::generate_head(&mut root, &document)?;
let headers = Util::generate_headers(config, global_config)?;
let html = Self::download(&url, client, headers).await?;
// check for fingerprints
let config = if config.is_none() {
if let Some(url) = Fingerprints::detect(&html) {
self.get_grabber_config(&url)
} else {
config
}
} else {
config
};
self.parse_pages(
&mut article,
&url,
&html,
&mut root,
config,
global_config,
client,
)
.await?;
let context = Context::new(&document).map_err(|()| {
error!("Failed to create xpath context for extracted article");
FullTextParserError::Xml
})?;
if let Err(error) = Self::prevent_self_closing_tags(&context) {
error!("Preventing self closing tags failed - '{}'", error);
return Err(error);
}
article.document = Some(document);
Ok(article)
}
async fn parse_pages(
&self,
article: &mut Article,
url: &url::Url,
html: &str,
root: &mut Node,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
client: &Client,
) -> Result<(), FullTextParserError> {
let mut document = Self::parse_html(html, config, global_config)?;
let mut xpath_ctx = Self::get_xpath_ctx(&document)?;
// check for single page link
let rule = Util::select_rule(
config.and_then(|c| c.single_page_link.as_deref()),
global_config.single_page_link.as_deref(),
);
if let Some(xpath_single_page_link) = rule {
debug!(
"Single page link xpath specified in config '{}'",
xpath_single_page_link
);
if let Some(single_page_url) = Util::find_page_url(&xpath_ctx, xpath_single_page_link) {
// parse again with single page url
debug!("Single page link found '{}'", single_page_url);
return self
.parse_single_page(
article,
&single_page_url,
root,
config,
global_config,
client,
)
.await;
}
}
Self::extract_metadata(&xpath_ctx, config, global_config, article);
if article.thumbnail_url.is_none() {
Self::check_for_thumbnail(&xpath_ctx, article);
}
Self::strip_junk(&xpath_ctx, config, global_config, url);
Self::extract_body(&xpath_ctx, root, config, global_config)?;
while let Some(url) = self.check_for_next_page(&xpath_ctx, config, global_config) {
let headers = Util::generate_headers(config, global_config)?;
let html = Self::download(&url, client, headers).await?;
document = Self::parse_html(&html, config, global_config)?;
xpath_ctx = Self::get_xpath_ctx(&document)?;
Self::strip_junk(&xpath_ctx, config, global_config, &url);
Self::extract_body(&xpath_ctx, root, config, global_config)?;
}
Ok(())
}
fn parse_html(
html: &str,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
) -> Result<Document, FullTextParserError> {
// replace matches in raw html
let mut html = html.to_owned();
if let Some(config) = config {
for replace in &config.replace {
html = html.replace(&replace.to_replace, &replace.replace_with);
}
}
for replace in &global_config.replace {
html = html.replace(&replace.to_replace, &replace.replace_with);
}
// parse html
let parser = Parser::default_html();
parser.parse_string(html.as_str()).map_err(|err| {
error!("Parsing HTML failed for downloaded HTML {:?}", err);
FullTextParserError::Xml
})
}
fn get_xpath_ctx(doc: &Document) -> Result<Context, FullTextParserError> {
Context::new(doc).map_err(|()| {
error!("Creating xpath context failed for downloaded HTML");
FullTextParserError::Xml
})
}
async fn parse_single_page(
&self,
article: &mut Article,
url: &url::Url,
root: &mut Node,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
client: &Client,
) -> Result<(), FullTextParserError> {
let headers = Util::generate_headers(config, global_config)?;
let html = Self::download(url, client, headers).await?;
let document = Self::parse_html(&html, config, global_config)?;
let xpath_ctx = Self::get_xpath_ctx(&document)?;
Self::extract_metadata(&xpath_ctx, config, global_config, article);
Self::check_for_thumbnail(&xpath_ctx, article);
Self::strip_junk(&xpath_ctx, config, global_config, url);
Self::extract_body(&xpath_ctx, root, config, global_config)?;
Ok(())
}
async fn download(
url: &url::Url,
client: &Client,
headers: HeaderMap,
) -> Result<String, FullTextParserError> {
let response = client
.get(url.as_str())
.headers(headers)
.send()
.await
.map_err(|err| {
error!(
"Downloading HTML failed: GET '{}' - '{}'",
url.as_str(),
err
);
FullTextParserError::Http
})?;
if response.status().is_success() {
let headers = response.headers().clone();
let bytes = response
.bytes()
.await
.map_err(|_| FullTextParserError::Http)?;
match from_utf8(&bytes) {
Ok(utf8_str) => {
debug!("Valid utf-8 string");
return Ok(utf8_str.into());
}
Err(error) => {
debug!("Invalid utf-8 string");
let lossy_string = std::string::String::from_utf8_lossy(&bytes);
if let Some(encoding) = Self::get_encoding_from_html(&lossy_string) {
debug!("Encoding extracted from HTML: '{}'", encoding);
if let Some(decoded_html) = Self::decode_html(&bytes, encoding) {
return Ok(decoded_html);
}
}
if let Some(encoding) = Self::get_encoding_from_http_header(&headers) {
debug!("Encoding extracted from headers: '{}'", encoding);
if let Some(decoded_html) = Self::decode_html(&bytes, encoding) {
return Ok(decoded_html);
}
}
return Err(FullTextParserError::Utf8(error));
}
}
}
Err(FullTextParserError::Http)
}
fn get_encoding_from_http_header(headers: &reqwest::header::HeaderMap) -> Option<&str> {
headers
.get(reqwest::header::CONTENT_TYPE)
.and_then(|header| header.to_str().ok())
.and_then(|content_type| {
regex::Regex::new(r#"charset=([^"']+)"#)
.expect("Failed to parse regex")
.captures(content_type)
})
.and_then(|captures| captures.get(1))
.map(|regex_match| regex_match.as_str())
}
fn get_encoding_from_html(html: &str) -> Option<&str> {
let regex =
regex::Regex::new(r#"<meta.*?charset="*(.*?)""#).expect("Failed to parse regex");
if let Some(captures) = regex.captures(html) {
if let Some(regex_match) = captures.get(1) {
return Some(regex_match.as_str());
}
}
None
}
fn decode_html(bytes: &[u8], encoding: &str) -> Option<String> {
if let Some(encoding) = Encoding::for_label(encoding.as_bytes()) {
let (decoded_html, _, invalid_chars) = encoding.decode(bytes);
if !invalid_chars {
return Some(decoded_html.into_owned());
}
}
warn!("Could not decode HTML. Encoding: '{}'", encoding);
None
}
fn get_host_name(url: &url::Url) -> Result<String, FullTextParserError> {
match url.host_str() {
Some(name) => {
let mut name = name;
if name.starts_with("www.") && name.len() > 4 {
name = &name[4..]
}
Ok(name.into())
}
None => {
error!("Getting config failed due to bad Url");
Err(FullTextParserError::Config)
}
}
}
fn get_grabber_config(&self, url: &url::Url) -> Option<&ConfigEntry> {
let conf = Self::get_host_name(url)
.ok()
.map(|url| url + ".txt")
.and_then(|name| self.config_files.get(&name));
if conf.is_none() {
log::warn!("No config found for url '{}'", url);
}
conf
}
fn check_for_thumbnail(context: &Context, article: &mut Article) {
if let Ok(thumb) = Self::get_attribute(
context,
"//meta[contains(@name, 'twitter:image')]",
"content",
) {
article.thumbnail_url = Some(thumb);
return;
}
if let Ok(thumb) =
Self::get_attribute(context, "//meta[contains(@name, 'og:image')]", "content")
{
article.thumbnail_url = Some(thumb);
return;
}
if let Ok(thumb) =
Self::get_attribute(context, "//link[contains(@rel, 'image_src')]", "href")
{
article.thumbnail_url = Some(thumb);
}
}
fn fix_lazy_images(
context: &Context,
class: &str,
property_url: &str,
) -> Result<(), FullTextParserError> {
let xpath = &format!("//img[contains(@class, '{}')]", class);
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if node
.get_property(property_url)
.and_then(|correct_url| node.set_property("src", &correct_url).ok())
.is_none()
{
warn!("Failed to fix lazy loading image");
}
}
Ok(())
}
fn fix_iframe_size(context: &Context, site_name: &str) -> Result<(), FullTextParserError> {
let xpath = &format!("//iframe[contains(@src, '{}')]", site_name);
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
let video_wrapper = node
.get_parent()
.and_then(|mut parent| parent.new_child(None, "div").ok());
if let Some(mut video_wrapper) = video_wrapper {
let success = video_wrapper
.set_property("class", "videoWrapper")
.ok()
.and_then(|()| node.set_property("width", "100%").ok())
.and_then(|()| node.set_property("height", "100%").ok())
.ok_or_else(|| {
node.unlink();
video_wrapper.add_child(&mut node)
})
.is_err();
if !success {
warn!("Failed to add iframe as child of video wrapper <div>");
}
} else {
warn!("Failed to get parent of iframe");
}
}
Ok(())
}
fn remove_attribute(
context: &Context,
tag: Option<&str>,
attribute: &str,
) -> Result<(), FullTextParserError> {
let xpath_tag = tag.unwrap_or("*");
let xpath = &format!("//{}[@{}]", xpath_tag, attribute);
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if let Err(err) = node.remove_property(attribute) {
log::warn!(
"Failed to remove attribute '{}' from node: {}",
attribute,
err
);
}
}
Ok(())
}
fn add_attribute(
context: &Context,
tag: Option<&str>,
attribute: &str,
value: &str,
) -> Result<(), FullTextParserError> {
let xpath_tag = tag.unwrap_or("*");
let xpath = &format!("//{}", xpath_tag);
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if let Err(err) = node.set_attribute(attribute, value) {
log::warn!("Failed to set attribute '{}' on node: {}", attribute, err);
}
}
Ok(())
}
fn get_attribute(
context: &Context,
xpath: &str,
attribute: &str,
) -> Result<String, FullTextParserError> {
Util::evaluate_xpath(context, xpath, false)?
.iter()
.find_map(|node| node.get_attribute(attribute))
.ok_or(FullTextParserError::Xml)
}
fn repair_urls(
context: &Context,
xpath: &str,
attribute: &str,
article_url: &url::Url,
) -> Result<(), FullTextParserError> {
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if let Some(url) = node.get_attribute(attribute) {
let is_relative_url = url::Url::parse(&url)
.err()
.map(|err| err == url::ParseError::RelativeUrlWithoutBase)
.unwrap_or(false);
if is_relative_url {
let completed_url = Self::complete_url(article_url, &url)?;
node.set_attribute(attribute, completed_url.as_str())
.map_err(|_| FullTextParserError::Scrape)?;
}
}
}
Ok(())
}
fn complete_url(
article_url: &url::Url,
incomplete_url: &str,
) -> Result<url::Url, FullTextParserError> {
let mut completed_url = article_url.scheme().to_owned();
completed_url.push(':');
if !incomplete_url.starts_with("//") {
match article_url.host() {
Some(url::Host::Domain(host)) => {
completed_url.push_str("//");
completed_url.push_str(host);
}
_ => return Err(FullTextParserError::Scrape),
};
}
if !completed_url.ends_with('/') && !incomplete_url.starts_with('/') {
completed_url.push('/');
}
completed_url.push_str(incomplete_url);
let url = url::Url::parse(&completed_url)?;
Ok(url)
}
fn strip_junk(
context: &Context,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
url: &url::Url,
) {
// strip specified xpath
if let Some(config) = config {
for xpath_strip in &config.xpath_strip {
let _ = Util::strip_node(context, xpath_strip);
}
}
for xpath_strip in &global_config.xpath_strip {
let _ = Util::strip_node(context, xpath_strip);
}
// strip everything with specified 'id' or 'class'
if let Some(config) = config {
for xpaht_strip_class in &config.strip_id_or_class {
let _ = Util::strip_id_or_class(context, xpaht_strip_class);
}
}
for xpaht_strip_class in &global_config.strip_id_or_class {
let _ = Util::strip_id_or_class(context, xpaht_strip_class);
}
// strip any <img> element where @src attribute contains this substring
if let Some(config) = config {
for xpath_strip_img_src in &config.strip_image_src {
let _ = Util::strip_node(
context,
&format!("//img[contains(@src,'{}')]", xpath_strip_img_src),
);
}
}
for xpath_strip_img_src in &global_config.strip_image_src {
let _ = Util::strip_node(
context,
&format!("//img[contains(@src,'{}')]", xpath_strip_img_src),
);
}
let _ = Self::fix_lazy_images(context, "lazyload", "data-src");
let _ = Self::fix_iframe_size(context, "youtube.com");
let _ = Self::remove_attribute(context, None, "style");
let _ = Self::remove_attribute(context, Some("a"), "onclick");
let _ = Self::remove_attribute(context, Some("img"), "srcset");
let _ = Self::remove_attribute(context, Some("img"), "sizes");
let _ = Self::add_attribute(context, Some("a"), "target", "_blank");
let _ = Self::repair_urls(context, "//img", "src", url);
let _ = Self::repair_urls(context, "//a", "src", url);
let _ = Self::repair_urls(context, "//a", "href", url);
let _ = Self::repair_urls(context, "//object", "data", url);
let _ = Self::repair_urls(context, "//iframe", "src", url);
// strip elements using Readability.com and Instapaper.com ignore class names
// .entry-unrelated and .instapaper_ignore
// See http://blog.instapaper.com/post/730281947
let _ = Util::strip_node(
context,
"//*[contains(@class,' entry-unrelated ') or contains(@class,' instapaper_ignore ')]",
);
// strip elements that contain style="display: none;"
let _ = Util::strip_node(context, "//*[contains(@style,'display:none')]");
// strip all comments
let _ = Util::strip_node(context, "//comment()");
// strip all empty url-tags <a/>
let _ = Util::strip_node(context, "//a[not(node())]");
// strip all external css and fonts
let _ = Util::strip_node(context, "//*[@type='text/css']");
}
fn extract_metadata(
context: &Context,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
article: &mut Article,
) {
// try to get title
if let Some(config) = config {
for xpath_title in &config.xpath_title {
if let Ok(title) = Util::extract_value_merge(context, xpath_title) {
debug!("Article title: '{}'", title);
article.title = Some(title);
break;
}
}
}
if article.title.is_none() {
for xpath_title in &global_config.xpath_title {
if let Ok(title) = Util::extract_value_merge(context, xpath_title) {
debug!("Article title: '{}'", title);
article.title = Some(title);
break;
}
}
}
// try to get the author
if let Some(config) = config {
for xpath_author in &config.xpath_author {
if let Ok(author) = Util::extract_value(context, xpath_author) {
debug!("Article author: '{}'", author);
article.author = Some(author);
break;
}
}
}
if article.author.is_none() {
for xpath_author in &global_config.xpath_author {
if let Ok(author) = Util::extract_value(context, xpath_author) {
debug!("Article author: '{}'", author);
article.author = Some(author);
break;
}
}
}
// try to get the date
if let Some(config) = config {
for xpath_date in &config.xpath_date {
if let Ok(date_string) = Util::extract_value(context, xpath_date) {
debug!("Article date: '{}'", date_string);
if let Ok(date) = DateTime::from_str(&date_string) {
article.date = Some(date);
break;
} else {
warn!("Parsing the date string '{}' failed", date_string);
}
}
}
}
if article.date.is_none() {
for xpath_date in &global_config.xpath_date {
if let Ok(date_string) = Util::extract_value(context, xpath_date) {
debug!("Article date: '{}'", date_string);
if let Ok(date) = DateTime::from_str(&date_string) {
article.date = Some(date);
break;
} else {
warn!("Parsing the date string '{}' failed", date_string);
}
}
}
}
}
fn extract_body(
context: &Context,
root: &mut Node,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
) -> Result<(), FullTextParserError> {
let mut found_something = false;
if let Some(config) = config {
for xpath_body in &config.xpath_body {
found_something = Self::extract_body_single(context, root, xpath_body)?;
}
}
if !found_something {
for xpath_body in &global_config.xpath_body {
found_something = Self::extract_body_single(context, root, xpath_body)?;
}
}
if !found_something {
log::error!("no body found");
return Err(FullTextParserError::Scrape);
}
Ok(())
}
fn extract_body_single(
context: &Context,
root: &mut Node,
xpath: &str,
) -> Result<bool, FullTextParserError> {
let mut found_something = false;
{
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if node.get_property("style").is_some() && node.remove_property("style").is_err() {
return Err(FullTextParserError::Xml);
}
node.unlink();
if root.add_child(&mut node).is_ok() {
found_something = true;
} else {
error!("Failed to add body to prepared document");
return Err(FullTextParserError::Xml);
}
}
}
Ok(found_something)
}
fn check_for_next_page(
&self,
context: &Context,
config: Option<&ConfigEntry>,
global_config: &ConfigEntry,
) -> Option<url::Url> {
if let Some(config) = config {
if let Some(next_page_xpath) = config.next_page_link.as_deref() {
if let Ok(next_page_string) = Self::get_attribute(context, next_page_xpath, "href")
{
if let Ok(next_page_url) = url::Url::parse(&next_page_string) {
return Some(next_page_url);
}
}
}
} else if let Some(next_page_xpath) = global_config.next_page_link.as_deref() {
if let Ok(next_page_string) = Self::get_attribute(context, next_page_xpath, "href") {
if let Ok(next_page_url) = url::Url::parse(&next_page_string) {
return Some(next_page_url);
}
}
}
// last page reached
None
}
fn generate_head(root: &mut Node, document: &Document) -> Result<(), FullTextParserError> {
if let Ok(mut head_node) = Node::new("head", None, document) {
if let Ok(()) = root.add_prev_sibling(&mut head_node) {
if let Ok(mut meta) = head_node.new_child(None, "meta") {
if meta.set_property("charset", "utf-8").is_ok() {
return Ok(());
}
}
}
}
Err(FullTextParserError::Xml)
}
fn prevent_self_closing_tags(context: &Context) -> Result<(), FullTextParserError> {
// search document for empty tags and add a empty text node as child
// this prevents libxml from self closing non void elements such as iframe
let xpath = "//*[not(node())]";
let node_vec = Util::evaluate_xpath(context, xpath, false)?;
for mut node in node_vec {
if node.get_name() == "meta" {
continue;
}
let _ = node.add_text_child(None, "empty", "");
}
Ok(())
}
}