364 lines
12 KiB
C++
364 lines
12 KiB
C++
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#include "http.hpp"
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#include <boost/asio/connect.hpp>
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#include <boost/asio/io_context.hpp>
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#include <boost/asio/ip/tcp.hpp>
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#include <boost/asio/ssl.hpp>
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#include <boost/asio/steady_timer.hpp>
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#include <boost/beast/core/flat_buffer.hpp>
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#include <boost/beast/http.hpp>
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#include <boost/beast/ssl.hpp>
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#include <chrono>
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#include <functional>
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#include <ostream>
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#include <regex>
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namespace vanetza
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{
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namespace pki
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{
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namespace asio = boost::asio;
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namespace beast = boost::beast;
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namespace ssl = boost::asio::ssl;
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std::ostream& operator<<(std::ostream& os, const HttpException& e)
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{
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os << e.what();
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if (const auto& response = e.response()) {
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os << " (HTTP " << response->result_int();
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if (!response->body().empty()) {
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os << ": " << response->body();
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}
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os << ")";
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}
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return os;
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}
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HttpQuery HttpQuery::from_url(const std::string& url)
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{
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std::regex url_regex { "^(https?)://([^:/]+)(?::([[:digit:]]+))?(/?|/.*)$" };
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std::smatch match;
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if (std::regex_match(url, match, url_regex) && match.size() == 5) {
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HttpQuery query;
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query.secure = (match[1] == "https");
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query.host = match[2];
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query.path = match[4];
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if (match[3].matched) {
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query.service = match[3];
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} else {
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query.service = match[1];
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}
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return query;
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} else {
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throw HttpException("URL is not acceptable");
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}
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}
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std::string resolve_url(const std::string& base, const std::string& reference)
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{
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if (reference.empty()) {
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return base;
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}
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// A reference with its own scheme is already absolute (RFC 3986 §5.2.2).
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static const std::regex scheme_re { "^[a-zA-Z][a-zA-Z0-9+.-]*://" };
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if (std::regex_search(reference, scheme_re)) {
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return reference;
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}
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// Split the base into scheme, authority and path (RFC 3986 §3); drop any query/fragment.
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static const std::regex base_re { "^([a-zA-Z][a-zA-Z0-9+.-]*)://([^/?#]*)(/[^?#]*)?.*$" };
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std::smatch m;
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if (!std::regex_match(base, m, base_re)) {
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throw HttpException("base URL is not acceptable");
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}
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const std::string scheme = m[1];
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const std::string origin = scheme + "://" + std::string(m[2]); // scheme + authority
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const std::string base_path = m[3].matched ? std::string(m[3]) : "/";
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if (reference.compare(0, 2, "//") == 0) {
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// network-path reference: keep the base scheme, replace authority and path
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return scheme + ":" + reference;
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} else if (reference.front() == '/') {
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// absolute-path reference: replace the whole path
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return origin + reference;
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} else {
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// relative-path reference: merge onto the base's directory
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const std::string dir = base_path.substr(0, base_path.find_last_of('/') + 1);
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return origin + dir + reference;
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}
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}
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const std::string& HttpQuery::which_service() const
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{
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if (service.empty()) {
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static const std::string http_service = "http";
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static const std::string https_service = "https";
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return secure ? https_service : http_service;
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} else {
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return service;
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}
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}
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namespace
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{
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// resolve and connect lifecycle of one address family taking part in a Happy Eyeballs race
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class Family
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{
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public:
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explicit Family(asio::io_context& ctx) : m_socket(ctx) {}
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bool resolved() const { return static_cast<bool>(m_addresses); }
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bool connected() const { return m_error && !*m_error; }
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bool failed() const { return m_error && *m_error; }
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boost::system::error_code error() const { return m_error.value_or(boost::system::error_code {}); }
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void resolve(asio::ip::tcp::resolver& resolver, const asio::ip::tcp& protocol,
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const std::string& host, const std::string& service, const std::function<void()>& notify)
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{
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resolver.async_resolve(protocol, host, service,
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[this, notify](boost::system::error_code ec, asio::ip::tcp::resolver::results_type results) {
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if (ec) {
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m_error = ec;
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} else {
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m_addresses = results;
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}
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notify();
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});
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}
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void connect(const std::function<void()>& notify)
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{
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if (resolved() && !m_connecting && !m_error) {
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m_connecting = true;
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asio::async_connect(m_socket, *m_addresses,
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[this, notify](boost::system::error_code ec, const asio::ip::tcp::endpoint&) {
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m_connecting = false;
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m_error = ec;
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notify();
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});
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}
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}
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// hand the connected socket over to another io_context
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asio::ip::tcp::socket release(asio::io_context& io)
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{
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return asio::ip::tcp::socket { io, m_socket.local_endpoint().protocol(), m_socket.release() };
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}
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private:
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asio::ip::tcp::socket m_socket;
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boost::optional<asio::ip::tcp::resolver::results_type> m_addresses;
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boost::optional<boost::system::error_code> m_error;
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bool m_connecting = false; // a connect attempt is in flight
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};
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// Happy Eyeballs (RFC 8305): race AAAA/A lookups and per-family connect attempts, preferring IPv6
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class HappyEyeballsRace
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{
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public:
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// winning socket is adopted by the caller's io_context
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static asio::ip::tcp::socket connect(asio::io_context& io, const std::string& host,
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const std::string& service, std::chrono::milliseconds deadline)
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{
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HappyEyeballsRace race;
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return race.run(host, service, deadline).release(io);
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}
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private:
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// run the race and return the winning family, throw when nobody wins
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Family& run(const std::string& host, const std::string& service, std::chrono::milliseconds deadline)
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{
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timeout.expires_after(deadline);
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timeout.async_wait([this](boost::system::error_code ec) {
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if (!ec) {
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race.stop();
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}
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});
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v6.resolve(resolver, asio::ip::tcp::v6(), host, service, [this]() { on_v6_resolve_done(); });
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v4.resolve(resolver, asio::ip::tcp::v4(), host, service, [this]() { on_v4_resolve_done(); });
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race.run();
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if (v6.connected() || v4.connected()) {
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return v6.connected() ? v6 : v4;
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} else if (!v6.failed() || !v4.failed()) {
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throw HttpException("connect timed out");
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} else if (v6.resolved() || v4.resolved()) {
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throw HttpException("connect failed: " + (v6.resolved() ? v6.error() : v4.error()).message());
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} else {
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throw HttpException("resolve failed: " + (v6.error() ? v6.error() : v4.error()).message());
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}
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}
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void on_v6_resolve_done()
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{
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if (v6.resolved()) {
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v6.connect([this]() { on_v6_connect_done(); });
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open_v4_gate(stagger_delay); // IPv4 may compete once the attempt delay elapsed
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} else {
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open_v4_gate(std::chrono::milliseconds::zero()); // no AAAA answer, IPv4 goes at once
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}
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settle();
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}
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void on_v4_resolve_done()
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{
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if (is_v4_gate_open()) {
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v4.connect([this]() { settle(); });
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} else if (v4.resolved() && !v6.resolved()) {
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open_v4_gate(resolution_delay); // pending AAAA answer gets a short head start
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}
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settle();
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}
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void on_v6_connect_done()
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{
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if (v6.failed()) {
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open_v4_gate(std::chrono::milliseconds::zero()); // IPv6 lost, IPv4 takes over
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}
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settle();
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}
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void open_v4_gate(std::chrono::milliseconds delay)
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{
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v4_gate.expires_after(delay);
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v4_gate.async_wait([this](boost::system::error_code ec) {
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if (!ec) {
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v4.connect([this]() { settle(); });
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}
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});
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}
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bool is_v4_gate_open() const
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{
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return v4_gate.expiry() <= asio::steady_timer::clock_type::now();
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}
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void settle()
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{
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// stop the race once a connection is established or both families have failed
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if (v6.connected() || v4.connected() || (v6.failed() && v4.failed())) {
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race.stop();
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}
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}
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static constexpr std::chrono::milliseconds resolution_delay { 50 }; // RFC 8305 head start for the AAAA answer
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static constexpr std::chrono::milliseconds stagger_delay { 200 }; // connection attempt delay
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asio::io_context race;
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asio::ip::tcp::resolver resolver { race };
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Family v6 { race };
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Family v4 { race };
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asio::steady_timer v4_gate { race, asio::steady_timer::time_point::max() }; // gate starts closed
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asio::steady_timer timeout { race };
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};
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} // namespace
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static bool should_follow(int status)
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{
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switch (status) {
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case 301:
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case 302:
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case 303:
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case 307:
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case 308:
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return true;
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default:
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return false;
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}
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}
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template<typename T>
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HttpResponse query_http(const HttpQuery& query, const beast::http::request<T>& request, asio::io_context& io,
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ssl::context& ssl)
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{
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constexpr std::chrono::seconds connect_deadline { 10 };
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HttpResponse response;
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beast::flat_buffer buffer;
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asio::ip::tcp::socket socket = HappyEyeballsRace::connect(io, query.host, query.which_service(), connect_deadline);
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if (query.secure) {
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ssl::stream<asio::ip::tcp::socket> stream(std::move(socket), ssl);
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SSL_set_tlsext_host_name(stream.native_handle(), query.host.c_str());
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stream.lowest_layer().set_option(asio::ip::tcp::no_delay(true));
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stream.handshake(ssl::stream_base::client);
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beast::http::write(stream, request);
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beast::http::read(stream, buffer, response);
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beast::error_code ec;
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if (stream.shutdown(ec)) {
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// could log error in verbose mode
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}
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} else {
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beast::http::write(socket, request);
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beast::http::read(socket, buffer, response);
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}
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return response;
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}
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template<typename T>
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HttpResponse query_http_redirections(HttpQuery query, const beast::http::request<T>& request, asio::io_context& io,
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ssl::context& ssl)
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{
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constexpr unsigned max_hops = 5;
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for (unsigned hop = 0; hop < max_hops; ++hop) {
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auto resp = query_http(query, request, io, ssl);
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if (should_follow(resp.result_int())) {
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std::string location { resp[beast::http::field::location] };
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query = HttpQuery::from_url(location);
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} else {
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return resp;
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}
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}
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throw HttpException("too many redirects");
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}
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template<typename T> HttpResponse query_http(const HttpQuery& query, const beast::http::request<T>& request)
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{
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asio::io_context io;
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ssl::context ssl(ssl::context::tlsv13_client);
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ssl.set_default_verify_paths();
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ssl.set_verify_mode(ssl::context::verify_peer);
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ssl.set_verify_callback(ssl::host_name_verification(query.host));
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auto resp = query_http(query, request, io, ssl);
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if (should_follow(resp.result_int())) {
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std::string location { resp[beast::http::field::location] };
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auto redirection = HttpQuery::from_url(location);
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return query_http_redirections(std::move(redirection), request, io, ssl);
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} else {
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return resp;
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}
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}
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HttpResponse http_get(const HttpQuery& query)
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{
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beast::http::request<beast::http::empty_body> request;
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request.method(beast::http::verb::get);
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request.target(query.path);
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request.set(beast::http::field::host, query.host);
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return query_http(query, request);
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}
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HttpResponse http_post(const HttpQuery& query, const std::string& content_type, const ByteBuffer& data)
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{
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beast::http::request<beast::http::string_body> request;
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request.method(beast::http::verb::post);
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request.target(query.path);
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request.set(beast::http::field::host, query.host);
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request.set(beast::http::field::content_type, content_type);
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request.body().assign(data.begin(), data.end());
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request.prepare_payload();
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return query_http(query, request);
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}
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} // namespace pki
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} // namespace vanetza
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