250 lines
8.5 KiB
C++
250 lines
8.5 KiB
C++
#include <memory>
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#include <exception>
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#include <stdexcept>
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#include <FastHash.h>
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#include <curl/curl.h>
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#include "config.h"
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#include "servehelper.h"
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#include "lxb_wrapper.h"
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#include "routes/routes.h"
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static inline void preprocess_html(const httplib::Request& req, const std::string& domain_name, lxb_dom_element_t* element);
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static inline void preprocess_link(const httplib::Request& req, const std::string& domain_name, lxb_dom_element_t* element);
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static inline bool should_fix_link(lxb_dom_element_t* element);
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class CurlUrlException : public std::exception {
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public:
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CurlUrlException(CURLUcode code_) : code(code_) {}
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const char* what() const noexcept {
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return curl_url_strerror(this->code);
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}
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CURLUcode code;
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};
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void serve(const httplib::Request& req, httplib::Response& res, std::string title, Element element, Nodes extra_head) {
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using namespace std::string_literals;
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std::string css_url = get_origin(req) + "/style.css";
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res.set_header("Content-Security-Policy", "default-src 'none'; img-src https:; media-src: https:; style-src "s + css_url);
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Element head("head", {
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Element("meta", {{"charset", "utf-8"}}, {}),
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Element("title", {std::move(title)}),
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Element("link", {{"rel", "stylesheet"}, {"href", std::move(css_url) + "?v=" + std::to_string(css_hash)}}, {}),
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Element("meta", {{"name", "viewport"}, {"content", "width=device-width,initial-scale=1"}}, {})
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});
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head.nodes.reserve(head.nodes.size() + extra_head.size());
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head.nodes.insert(head.nodes.end(), extra_head.begin(), extra_head.end());
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std::string html = "<!DOCTYPE html>"s + Element("html", {
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std::move(head),
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std::move(element)
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}).serialize();
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uint64_t hash = FastHash(html.data(), html.size(), 0);
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res.set_header("ETag", std::string(1, '"') + std::to_string(hash) + '"');
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if (should_send_304(req, hash)) {
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res.status = 304;
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res.set_header("Content-Length", std::to_string(html.size()));
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res.set_header("Content-Type", "text/html");
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} else {
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res.set_content(std::move(html), "text/html");
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}
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}
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void serve_error(const httplib::Request& req, httplib::Response& res,
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std::string title, std::optional<std::string> subtitle, std::optional<std::string> info) {
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Element error_div("div", {{"class", "error"}}, {
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Element("h2", {title})
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});
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if (subtitle) {
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error_div.nodes.push_back(Element("p", {
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std::move(*subtitle)
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}));
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}
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if (info) {
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error_div.nodes.push_back(Element("pre", {
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Element("code", {std::move(*info)})
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}));
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}
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Element body("body", {std::move(error_div)});
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serve(req, res, std::move(title), std::move(body));
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}
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void serve_redirect(const httplib::Request& req, httplib::Response& res, std::string url, bool permanent) {
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using namespace std::string_literals;
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Element body("body", {
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"Redirecting to ",
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Element("a", {{"href", url}}, {url}),
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"…"
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});
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res.set_redirect(url, permanent ? 301 : 302);
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serve(req, res, "Redirecting to "s + std::move(url) + "…", std::move(body));
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}
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std::string get_origin(const httplib::Request& req) {
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if (req.has_header("X-Canonical-Origin")) {
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return req.get_header_value("X-Canonical-Origin");
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}
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if (config.canonical_origin) {
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return *config.canonical_origin;
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}
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std::string origin = "http://";
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if (req.has_header("Host")) {
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origin += req.get_header_value("Host");
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} else {
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origin += config.bind_host;
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if (config.bind_port != 80) {
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origin += ':' + std::to_string(config.bind_port);
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}
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}
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return origin;
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}
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std::string proxy_mastodon_url(const httplib::Request& req, const std::string& url_str) {
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using CurlStr = std::unique_ptr<char, decltype(&curl_free)>;
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std::unique_ptr<CURLU, decltype(&curl_url_cleanup)> url(curl_url(), curl_url_cleanup);
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if (!url) {
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throw std::bad_alloc();
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}
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CURLUcode code = curl_url_set(url.get(), CURLUPART_URL, url_str.c_str(), 0);
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if (code) {
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throw CurlUrlException(code);
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}
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auto get_part = [&](CURLUPart part, CURLUcode ignore = CURLUE_OK) {
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char* content = nullptr;
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CURLUcode code = curl_url_get(url.get(), part, &content, 0);
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if (code && code != ignore) {
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throw CurlUrlException(code);
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}
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return CurlStr(content, curl_free);
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};
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CurlStr host = get_part(CURLUPART_HOST);
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CurlStr path = get_part(CURLUPART_PATH);
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CurlStr query = get_part(CURLUPART_QUERY, CURLUE_NO_QUERY);
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CurlStr fragment = get_part(CURLUPART_FRAGMENT, CURLUE_NO_FRAGMENT);
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std::string new_url = get_origin(req) + '/' + host.get() + path.get();
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if (query) {
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new_url += '?';
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new_url += query.get();
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}
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if (fragment) {
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new_url += '#';
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new_url += fragment.get();
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}
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return new_url;
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}
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bool should_send_304(const httplib::Request& req, uint64_t hash) {
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std::string header = req.get_header_value("If-None-Match");
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if (header == "*") {
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return true;
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}
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size_t pos = header.find(std::string(1, '"') + std::to_string(hash) + '"');
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return pos != std::string::npos && (pos == 0 || header[pos - 1] != '/');
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}
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blankie::html::HTMLString preprocess_html(const httplib::Request& req, const std::string& domain_name, const blankie::html::HTMLString& str) {
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LXB::HTML::Document document(str.str);
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preprocess_html(req, domain_name, document.body_element());
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return blankie::html::HTMLString(document.serialize());
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}
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static inline void preprocess_html(const httplib::Request& req, const std::string& domain_name, lxb_dom_element_t* element) {
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const char* tag_name = reinterpret_cast<const char*>(lxb_dom_element_tag_name(element, nullptr));
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if (strncmp(tag_name, "A", 2) == 0) {
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// Proprocess links
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preprocess_link(req, domain_name, element);
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}
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// Walk through the element's children
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lxb_dom_node_t* child = lxb_dom_node_first_child(lxb_dom_interface_node(element));
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while (child) {
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if (child->type == LXB_DOM_NODE_TYPE_ELEMENT) {
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preprocess_html(req, domain_name, lxb_dom_interface_element(child));
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}
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child = lxb_dom_node_next(child);
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}
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}
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static inline void preprocess_link(const httplib::Request& req, const std::string& domain_name, lxb_dom_element_t* element) {
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using namespace std::string_literals;
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size_t href_c_len;
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const lxb_char_t* href_c = lxb_dom_element_get_attribute(element, reinterpret_cast<const lxb_char_t*>("href"), 4, &href_c_len);
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if (!href_c) {
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return;
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}
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std::string href(reinterpret_cast<const char*>(href_c), href_c_len);
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std::string instance_url_base = "https://"s + domain_name;
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if (href.starts_with(instance_url_base + '/') || href == instance_url_base) {
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// Proxy this instance's URLs to Coyote
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href = proxy_mastodon_url(req, std::move(href));
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lxb_dom_element_set_attribute(element, reinterpret_cast<const lxb_char_t*>("href"), 4, reinterpret_cast<const lxb_char_t*>(href.data()), href.size());
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}
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if (should_fix_link(element)) {
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// Set the content of each <a> to its href
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lxb_status_t status = lxb_dom_node_text_content_set(lxb_dom_interface_node(element), reinterpret_cast<const lxb_char_t*>(href.data()), href.size());
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if (status != LXB_STATUS_OK) {
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throw LXB::Exception(status);
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}
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}
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}
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static inline bool should_fix_link(lxb_dom_element_t* element) {
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auto expected_element = [](lxb_dom_node_t* node, const char* expected_cls) {
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if (node->type != LXB_DOM_NODE_TYPE_ELEMENT) {
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return false;
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}
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lxb_dom_element_t* span = lxb_dom_interface_element(node);
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const char* tag_name = reinterpret_cast<const char*>(lxb_dom_element_tag_name(span, nullptr));
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if (strncmp(tag_name, "SPAN", 5) != 0) {
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return false;
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}
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const lxb_char_t* cls = lxb_dom_element_get_attribute(span, reinterpret_cast<const lxb_char_t*>("class"), 5, nullptr);
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return cls && strcmp(reinterpret_cast<const char*>(cls), expected_cls) == 0;
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};
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lxb_dom_node_t* child = lxb_dom_node_first_child(lxb_dom_interface_node(element));
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if (!expected_element(child, "invisible")) {
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return false;
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}
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child = lxb_dom_node_next(child);
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if (!expected_element(child, "ellipsis") && !expected_element(child, "")) {
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return false;
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}
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child = lxb_dom_node_next(child);
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if (!expected_element(child, "invisible")) {
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return false;
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}
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child = lxb_dom_node_next(child);
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return child == nullptr;
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}
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