]> git.sesse.net Git - cubemap/blobdiff - server.cpp
Stop leaking TLS contexts.
[cubemap] / server.cpp
index b381e7947d6d53d670042758cde01c7126b26738..7f07483390a8b2846013e594668831b48d5b884b 100644 (file)
 #include <utility>
 #include <vector>
 
+#include "tlse.h"
+
+#include "acceptor.h"
 #include "accesslog.h"
 #include "log.h"
-#include "markpool.h"
 #include "metacube2.h"
 #include "mutexlock.h"
 #include "parse.h"
@@ -36,6 +38,23 @@ using namespace std;
 
 extern AccessLogThread *access_log;
 
+namespace {
+
+inline bool is_equal(timespec a, timespec b)
+{
+       return a.tv_sec == b.tv_sec &&
+              a.tv_nsec == b.tv_nsec;
+}
+
+inline bool is_earlier(timespec a, timespec b)
+{
+       if (a.tv_sec != b.tv_sec)
+               return a.tv_sec < b.tv_sec;
+       return a.tv_nsec < b.tv_nsec;
+}
+
+}  // namespace
+
 Server::Server()
 {
        pthread_mutex_init(&mutex, NULL);
@@ -91,6 +110,7 @@ void Server::do_work()
        
                process_queued_data();
 
+               // Process each client where we have socket activity.
                for (int i = 0; i < nfds; ++i) {
                        Client *client = reinterpret_cast<Client *>(events[i].data.u64);
 
@@ -102,6 +122,8 @@ void Server::do_work()
                        process_client(client);
                }
 
+               // Process each client where its stream has new data,
+               // even if there was no socket activity.
                for (size_t i = 0; i < streams.size(); ++i) {   
                        vector<Client *> to_process;
                        swap(streams[i]->to_process, to_process);
@@ -109,6 +131,49 @@ void Server::do_work()
                                process_client(to_process[i]);
                        }
                }
+
+               // Finally, go through each client to see if it's timed out
+               // in the READING_REQUEST state. (Seemingly there are clients
+               // that can hold sockets up for days at a time without sending
+               // anything at all.)
+               timespec timeout_time;
+               if (clock_gettime(CLOCK_MONOTONIC_COARSE, &timeout_time) == -1) {
+                       log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
+                       continue;
+               }
+               timeout_time.tv_sec -= REQUEST_READ_TIMEOUT_SEC;
+               while (!clients_ordered_by_connect_time.empty()) {
+                       const pair<timespec, int> &connect_time_and_fd = clients_ordered_by_connect_time.front();
+
+                       // See if we have reached the end of clients to process.
+                       if (is_earlier(timeout_time, connect_time_and_fd.first)) {
+                               break;
+                       }
+
+                       // If this client doesn't exist anymore, just ignore it
+                       // (it was deleted earlier).
+                       map<int, Client>::iterator client_it = clients.find(connect_time_and_fd.second);
+                       if (client_it == clients.end()) {
+                               clients_ordered_by_connect_time.pop();
+                               continue;
+                       }
+                       Client *client = &client_it->second;
+                       if (!is_equal(client->connect_time, connect_time_and_fd.first)) {
+                               // Another client has taken this fd in the meantime.
+                               clients_ordered_by_connect_time.pop();
+                               continue;
+                       }
+
+                       if (client->state != Client::READING_REQUEST) {
+                               // Only READING_REQUEST can time out.
+                               clients_ordered_by_connect_time.pop();
+                               continue;
+                       }
+
+                       // OK, it timed out.
+                       close_client(client);
+                       clients_ordered_by_connect_time.pop();
+               }
        }
 }
 
@@ -142,28 +207,59 @@ CubemapStateProto Server::serialize()
        return serialized;
 }
 
-void Server::add_client_deferred(int sock)
+void Server::add_client_deferred(int sock, Acceptor *acceptor)
 {
        MutexLock lock(&queued_clients_mutex);
-       queued_add_clients.push_back(sock);
+       queued_add_clients.push_back(std::make_pair(sock, acceptor));
 }
 
-void Server::add_client(int sock)
+void Server::add_client(int sock, Acceptor *acceptor)
 {
+       const bool is_tls = acceptor->is_tls();
        pair<map<int, Client>::iterator, bool> ret =
                clients.insert(make_pair(sock, Client(sock)));
        assert(ret.second == true);  // Should not already exist.
        Client *client_ptr = &ret.first->second;
 
+       // Connection timestamps must be nondecreasing. I can't find any guarantee
+       // that even the monotonic clock can't go backwards by a small amount
+       // (think switching between CPUs with non-synchronized TSCs), so if
+       // this actually should happen, we hack around it by fudging
+       // connect_time.
+       if (!clients_ordered_by_connect_time.empty() &&
+           is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first)) {
+               client_ptr->connect_time = clients_ordered_by_connect_time.back().first;
+       }
+       clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, sock));
+
        // Start listening on data from this socket.
        epoll_event ev;
-       ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+       if (is_tls) {
+               // Even in the initial state (READING_REQUEST), TLS needs to
+               // send data for the handshake, and thus might end up needing
+               // to know about EPOLLOUT.
+               ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
+       } else {
+               // EPOLLOUT will be added once we go out of READING_REQUEST.
+               ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+       }
        ev.data.u64 = reinterpret_cast<uint64_t>(client_ptr);
        if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) == -1) {
                log_perror("epoll_ctl(EPOLL_CTL_ADD)");
                exit(1);
        }
 
+       if (is_tls) {
+               assert(tls_server_contexts.count(acceptor));
+               client_ptr->tls_context = tls_accept(tls_server_contexts[acceptor]);
+               if (client_ptr->tls_context == NULL) {
+                       log(ERROR, "tls_accept() failed");
+                       close_client(client_ptr);
+                       return;
+               }
+               tls_make_exportable(client_ptr->tls_context, 1);
+       }
+
        process_client(client_ptr);
 }
 
@@ -183,10 +279,20 @@ void Server::add_client_from_serialized(const ClientProto &client)
        assert(ret.second == true);  // Should not already exist.
        Client *client_ptr = &ret.first->second;
 
+       // Connection timestamps must be nondecreasing.
+       assert(clients_ordered_by_connect_time.empty() ||
+              !is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first));
+       clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, client.sock()));
+
        // Start listening on data from this socket.
        epoll_event ev;
        if (client.state() == Client::READING_REQUEST) {
-               ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+               // See the corresponding comment in Server::add_client().
+               if (client.has_tls_context()) {
+                       ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
+               } else {
+                       ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+               }
        } else {
                // If we don't have more data for this client, we'll be putting it into
                // the sleeping array again soon.
@@ -199,6 +305,7 @@ void Server::add_client_from_serialized(const ClientProto &client)
        }
 
        if (client_ptr->state == Client::WAITING_FOR_KEYFRAME ||
+           client_ptr->state == Client::PREBUFFERING ||
            (client_ptr->state == Client::SENDING_DATA &&
             client_ptr->stream_pos == client_ptr->stream->bytes_received)) {
                client_ptr->stream->put_client_to_sleep(client_ptr);
@@ -207,27 +314,27 @@ void Server::add_client_from_serialized(const ClientProto &client)
        }
 }
 
-int Server::lookup_stream_by_url(const std::string &url) const
+int Server::lookup_stream_by_url(const string &url) const
 {
-       map<string, int>::const_iterator url_it = url_map.find(url);
-       if (url_it == url_map.end()) {
+       map<string, int>::const_iterator stream_url_it = stream_url_map.find(url);
+       if (stream_url_it == stream_url_map.end()) {
                return -1;
        }
-       return url_it->second;
+       return stream_url_it->second;
 }
 
-int Server::add_stream(const string &url, size_t backlog_size, Stream::Encoding encoding)
+int Server::add_stream(const string &url, size_t backlog_size, size_t prebuffering_bytes, Stream::Encoding encoding, Stream::Encoding src_encoding)
 {
        MutexLock lock(&mutex);
-       url_map.insert(make_pair(url, streams.size()));
-       streams.push_back(new Stream(url, backlog_size, encoding));
+       stream_url_map.insert(make_pair(url, streams.size()));
+       streams.push_back(new Stream(url, backlog_size, prebuffering_bytes, encoding, src_encoding));
        return streams.size() - 1;
 }
 
 int Server::add_stream_from_serialized(const StreamProto &stream, int data_fd)
 {
        MutexLock lock(&mutex);
-       url_map.insert(make_pair(stream.url(), streams.size()));
+       stream_url_map.insert(make_pair(stream.url(), streams.size()));
        streams.push_back(new Stream(stream, data_fd));
        return streams.size() - 1;
 }
@@ -238,6 +345,13 @@ void Server::set_backlog_size(int stream_index, size_t new_size)
        assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
        streams[stream_index]->set_backlog_size(new_size);
 }
+
+void Server::set_prebuffering_bytes(int stream_index, size_t new_amount)
+{
+       MutexLock lock(&mutex);
+       assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
+       streams[stream_index]->prebuffering_bytes = new_amount;
+}
        
 void Server::set_encoding(int stream_index, Stream::Encoding encoding)
 {
@@ -245,35 +359,70 @@ void Server::set_encoding(int stream_index, Stream::Encoding encoding)
        assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
        streams[stream_index]->encoding = encoding;
 }
+
+void Server::set_src_encoding(int stream_index, Stream::Encoding encoding)
+{
+       MutexLock lock(&mutex);
+       assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
+       streams[stream_index]->src_encoding = encoding;
+}
        
 void Server::set_header(int stream_index, const string &http_header, const string &stream_header)
 {
        MutexLock lock(&mutex);
        assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
        streams[stream_index]->http_header = http_header;
+
+       if (stream_header != streams[stream_index]->stream_header) {
+               // We cannot start at any of the older starting points anymore,
+               // since they'd get the wrong header for the stream (not to mention
+               // that a changed header probably means the stream restarted,
+               // which means any client starting on the old one would probably
+               // stop playing properly at the change point). Next block
+               // should be a suitable starting point (if not, something is
+               // pretty strange), so it will fill up again soon enough.
+               streams[stream_index]->suitable_starting_points.clear();
+       }
        streams[stream_index]->stream_header = stream_header;
 }
        
-void Server::set_mark_pool(int stream_index, MarkPool *mark_pool)
+void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
 {
        MutexLock lock(&mutex);
        assert(clients.empty());
        assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
-       streams[stream_index]->mark_pool = mark_pool;
+       streams[stream_index]->pacing_rate = pacing_rate;
 }
 
-void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
+void Server::add_gen204(const std::string &url, const std::string &allow_origin)
 {
        MutexLock lock(&mutex);
        assert(clients.empty());
-       assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
-       streams[stream_index]->pacing_rate = pacing_rate;
+       ping_url_map[url] = allow_origin;
+}
+
+void Server::create_tls_context_for_acceptor(const Acceptor *acceptor)
+{
+       assert(acceptor->is_tls());
+
+       bool is_server = true;
+       TLSContext *server_context = tls_create_context(is_server, TLS_V12);
+
+       const string &cert = acceptor->get_certificate_chain();
+       int num_cert = tls_load_certificates(server_context, reinterpret_cast<const unsigned char *>(cert.data()), cert.size());
+       assert(num_cert > 0);  // Should have been checked by config earlier.
+
+       const string &key = acceptor->get_private_key();
+       int num_key = tls_load_private_key(server_context, reinterpret_cast<const unsigned char *>(key.data()), key.size());
+       assert(num_key > 0);  // Should have been checked by config earlier.
+
+       tls_server_contexts.insert(make_pair(acceptor, server_context));
 }
 
-void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
+void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, uint16_t metacube_flags)
 {
        assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
-       streams[stream_index]->add_data_deferred(data, bytes, suitable_for_stream_start);
+       streams[stream_index]->add_data_deferred(data, bytes, metacube_flags);
 }
 
 // See the .h file for postconditions after this function.     
@@ -281,28 +430,29 @@ void Server::process_client(Client *client)
 {
        switch (client->state) {
        case Client::READING_REQUEST: {
+               if (client->tls_context != NULL) {
+                       if (send_pending_tls_data(client)) {
+                               // send_pending_tls_data() hit postconditions #1 or #4.
+                               return;
+                       }
+               }
+
 read_request_again:
                // Try to read more of the request.
                char buf[1024];
                int ret;
-               do {
-                       ret = read(client->sock, buf, sizeof(buf));
-               } while (ret == -1 && errno == EINTR);
-
-               if (ret == -1 && errno == EAGAIN) {
-                       // No more data right now. Nothing to do.
-                       // This is postcondition #2.
-                       return;
-               }
-               if (ret == -1) {
-                       log_perror("read");
-                       close_client(client);
-                       return;
-               }
-               if (ret == 0) {
-                       // OK, the socket is closed.
-                       close_client(client);
-                       return;
+               if (client->tls_context == NULL) {
+                       ret = read_nontls_data(client, buf, sizeof(buf));
+                       if (ret == -1) {
+                               // read_nontls_data() hit postconditions #1 or #2.
+                               return;
+                       }
+               } else {
+                       ret = read_tls_data(client, buf, sizeof(buf));
+                       if (ret == -1) {
+                               // read_tls_data() hit postconditions #1, #2 or #4.
+                               return;
+                       }
                }
 
                RequestParseStatus status = wait_for_double_newline(&client->request, buf, ret);
@@ -326,25 +476,43 @@ read_request_again:
 
                assert(status == RP_FINISHED);
 
+               if (client->tls_context && !client->in_ktls_mode && tls_established(client->tls_context)) {
+                       // We're ready to enter kTLS mode, unless we still have some
+                       // handshake data to send (which then must be sent as non-kTLS).
+                       if (send_pending_tls_data(client)) {
+                               // send_pending_tls_data() hit postconditions #1 or #4.
+                               return;
+                       }
+                       ret = tls_make_ktls(client->tls_context, client->sock);
+                       if (ret < 0) {
+                               log_tls_error("tls_make_ktls", ret);
+                               close_client(client);
+                               return;
+                       }
+                       client->in_ktls_mode = true;
+               }
+
                int error_code = parse_request(client);
                if (error_code == 200) {
                        construct_header(client);
+               } else if (error_code == 204) {
+                       construct_204(client);
                } else {
                        construct_error(client, error_code);
                }
 
                // We've changed states, so fall through.
-               assert(client->state == Client::SENDING_ERROR ||
+               assert(client->state == Client::SENDING_SHORT_RESPONSE ||
                       client->state == Client::SENDING_HEADER);
        }
-       case Client::SENDING_ERROR:
+       case Client::SENDING_SHORT_RESPONSE:
        case Client::SENDING_HEADER: {
-sending_header_or_error_again:
+sending_header_or_short_response_again:
                int ret;
                do {
                        ret = write(client->sock,
-                                   client->header_or_error.data() + client->header_or_error_bytes_sent,
-                                   client->header_or_error.size() - client->header_or_error_bytes_sent);
+                                   client->header_or_short_response.data() + client->header_or_short_response_bytes_sent,
+                                   client->header_or_short_response.size() - client->header_or_short_response_bytes_sent);
                } while (ret == -1 && errno == EINTR);
 
                if (ret == -1 && errno == EAGAIN) {
@@ -362,56 +530,94 @@ sending_header_or_error_again:
                        return;
                }
                
-               client->header_or_error_bytes_sent += ret;
-               assert(client->header_or_error_bytes_sent <= client->header_or_error.size());
+               client->header_or_short_response_bytes_sent += ret;
+               assert(client->header_or_short_response_bytes_sent <= client->header_or_short_response.size());
 
-               if (client->header_or_error_bytes_sent < client->header_or_error.size()) {
+               if (client->header_or_short_response_bytes_sent < client->header_or_short_response.size()) {
                        // We haven't sent all yet. Fine; go another round.
-                       goto sending_header_or_error_again;
+                       goto sending_header_or_short_response_again;
                }
 
                // We're done sending the header or error! Clear it to release some memory.
-               client->header_or_error.clear();
+               client->header_or_short_response.clear();
 
-               if (client->state == Client::SENDING_ERROR) {
+               if (client->state == Client::SENDING_SHORT_RESPONSE) {
                        // We're done sending the error, so now close.  
                        // This is postcondition #1.
                        close_client(client);
                        return;
                }
 
-               // Start sending from the first keyframe we get. In other
-               // words, we won't send any of the backlog, but we'll start
-               // sending immediately as we get the next keyframe block.
-               // This is postcondition #3.
+               Stream *stream = client->stream;
                if (client->stream_pos == size_t(-2)) {
-                       client->stream_pos = std::min<size_t>(
-                           client->stream->bytes_received - client->stream->backlog_size,
+                       // Start sending from the beginning of the backlog.
+                       client->stream_pos = min<size_t>(
+                           stream->bytes_received - stream->backlog_size,
                            0);
                        client->state = Client::SENDING_DATA;
-               } else {
-                       // client->stream_pos should be -1, but it might not be,
-                       // if we have clients from an older version.
-                       client->stream_pos = client->stream->bytes_received;
+                       goto sending_data;
+               } else if (stream->prebuffering_bytes == 0) {
+                       // Start sending from the first keyframe we get. In other
+                       // words, we won't send any of the backlog, but we'll start
+                       // sending immediately as we get the next keyframe block.
+                       // Note that this is functionally identical to the next if branch,
+                       // except that we save a binary search.
+                       client->stream_pos = stream->bytes_received;
                        client->state = Client::WAITING_FOR_KEYFRAME;
+               } else {
+                       // We're not going to send anything to the client before we have
+                       // N bytes. However, this wait might be boring; we can just as well
+                       // use it to send older data if we have it. We use lower_bound()
+                       // so that we are conservative and never add extra latency over just
+                       // waiting (assuming CBR or nearly so); otherwise, we could want e.g.
+                       // 100 kB prebuffer but end up sending a 10 MB GOP.
+                       deque<size_t>::const_iterator starting_point_it =
+                               lower_bound(stream->suitable_starting_points.begin(),
+                                           stream->suitable_starting_points.end(),
+                                           stream->bytes_received - stream->prebuffering_bytes);
+                       if (starting_point_it == stream->suitable_starting_points.end()) {
+                               // None found. Just put us at the end, and then wait for the
+                               // first keyframe to appear.
+                               client->stream_pos = stream->bytes_received;
+                               client->state = Client::WAITING_FOR_KEYFRAME;
+                       } else {
+                               client->stream_pos = *starting_point_it;
+                               client->state = Client::PREBUFFERING;
+                               goto prebuffering;
+                       }
                }
-               client->stream->put_client_to_sleep(client);
-               return;
+               // Fall through.
        }
        case Client::WAITING_FOR_KEYFRAME: {
                Stream *stream = client->stream;
-               if (ssize_t(client->stream_pos) > stream->last_suitable_starting_point) {
+               if (stream->suitable_starting_points.empty() ||
+                   client->stream_pos > stream->suitable_starting_points.back()) {
                        // We haven't received a keyframe since this stream started waiting,
                        // so keep on waiting for one.
                        // This is postcondition #3.
                        stream->put_client_to_sleep(client);
                        return;
                }
-               client->stream_pos = stream->last_suitable_starting_point;
+               client->stream_pos = stream->suitable_starting_points.back();
+               client->state = Client::PREBUFFERING;
+               // Fall through.
+       }
+       case Client::PREBUFFERING: {
+prebuffering:
+               Stream *stream = client->stream;
+               size_t bytes_to_send = stream->bytes_received - client->stream_pos;
+               assert(bytes_to_send <= stream->backlog_size);
+               if (bytes_to_send < stream->prebuffering_bytes) {
+                       // We don't have enough bytes buffered to start this client yet.
+                       // This is postcondition #3.
+                       stream->put_client_to_sleep(client);
+                       return;
+               }
                client->state = Client::SENDING_DATA;
                // Fall through.
        }
        case Client::SENDING_DATA: {
+sending_data:
                skip_lost_data(client);
                Stream *stream = client->stream;
 
@@ -464,6 +670,133 @@ sending_data_again:
        }
 }
 
+bool Server::send_pending_tls_data(Client *client)
+{
+       // See if there's data from the TLS library to write.
+       if (client->tls_data_to_send == NULL) {
+               client->tls_data_to_send = tls_get_write_buffer(client->tls_context, &client->tls_data_left_to_send);
+               if (client->tls_data_to_send == NULL) {
+                       // Really no data to send.
+                       return false;
+               }
+       }
+
+send_data_again:
+       int ret;
+       do {
+               ret = write(client->sock, client->tls_data_to_send, client->tls_data_left_to_send);
+       } while (ret == -1 && errno == EINTR);
+       assert(ret < 0 || size_t(ret) <= client->tls_data_left_to_send);
+
+       if (ret == -1 && errno == EAGAIN) {
+               // We're out of socket space, so now we're at the “low edge” of epoll's
+               // edge triggering. epoll will tell us when there is more room, so for now,
+               // just return.
+               // This is postcondition #4.
+               return true;
+       }
+       if (ret == -1) {
+               // Error! Postcondition #1.
+               log_perror("write");
+               close_client(client);
+               return true;
+       }
+       if (ret > 0 && size_t(ret) == client->tls_data_left_to_send) {
+               // All data has been sent, so we don't need to go to sleep.
+               tls_buffer_clear(client->tls_context);
+               client->tls_data_to_send = NULL;
+               return false;
+       }
+
+       // More data to send, so try again.
+       client->tls_data_to_send += ret;
+       client->tls_data_left_to_send -= ret;
+       goto send_data_again;
+}
+
+int Server::read_nontls_data(Client *client, char *buf, size_t max_size)
+{
+       int ret;
+       do {
+               ret = read(client->sock, buf, max_size);
+       } while (ret == -1 && errno == EINTR);
+
+       if (ret == -1 && errno == EAGAIN) {
+               // No more data right now. Nothing to do.
+               // This is postcondition #2.
+               return -1;
+       }
+       if (ret == -1) {
+               log_perror("read");
+               close_client(client);
+               return -1;
+       }
+       if (ret == 0) {
+               // OK, the socket is closed.
+               close_client(client);
+               return -1;
+       }
+
+       return ret;
+}
+
+int Server::read_tls_data(Client *client, char *buf, size_t max_size)
+{
+read_again:
+       int ret;
+       do {
+               ret = read(client->sock, buf, max_size);
+       } while (ret == -1 && errno == EINTR);
+
+       if (ret == -1 && errno == EAGAIN) {
+               // No more data right now. Nothing to do.
+               // This is postcondition #2.
+               return -1;
+       }
+       if (ret == -1) {
+               log_perror("read");
+               close_client(client);
+               return -1;
+       }
+       if (ret == 0) {
+               // OK, the socket is closed.
+               close_client(client);
+               return -1;
+       }
+
+       // Give it to the TLS library.
+       int err = tls_consume_stream(client->tls_context, reinterpret_cast<const unsigned char *>(buf), ret, nullptr);
+       if (err < 0) {
+               log_tls_error("tls_consume_stream", err);
+               close_client(client);
+               return -1;
+       }
+       if (err == 0) {
+               // Not consumed any data. See if we can read more.
+               goto read_again;
+       }
+
+       // Read any decrypted data available for us. (We can reuse buf, since it's free now.)
+       ret = tls_read(client->tls_context, reinterpret_cast<unsigned char *>(buf), max_size);
+       if (ret == 0) {
+               // No decrypted data for us yet, but there might be some more handshaking
+               // to send. Do that if needed, then look for more data.
+               if (send_pending_tls_data(client)) {
+                       // send_pending_tls_data() hit postconditions #1 or #4.
+                       return -1;
+               }
+               goto read_again;
+       }
+       if (ret < 0) {
+               log_tls_error("tls_read", ret);
+               close_client(client);
+               return -1;
+       }
+
+       assert(ret > 0);
+       return ret;
+}
+
 // See if there's some data we've lost. Ideally, we should drop to a block boundary,
 // but resync will be the mux's problem.
 void Server::skip_lost_data(Client *client)
@@ -488,6 +821,18 @@ int Server::parse_request(Client *client)
                return 400;  // Bad request (empty).
        }
 
+       // Parse the headers, for logging purposes.
+       // TODO: Case-insensitivity.
+       multimap<string, string> headers = extract_headers(lines, client->remote_addr);
+       multimap<string, string>::const_iterator referer_it = headers.find("Referer");
+       if (referer_it != headers.end()) {
+               client->referer = referer_it->second;
+       }
+       multimap<string, string>::const_iterator user_agent_it = headers.find("User-Agent");
+       if (user_agent_it != headers.end()) {
+               client->user_agent = user_agent_it->second;
+       }
+
        vector<string> request_tokens = split_tokens(lines[0]);
        if (request_tokens.size() < 2) {
                return 400;  // Bad request (empty).
@@ -497,35 +842,30 @@ int Server::parse_request(Client *client)
        }
 
        string url = request_tokens[1];
-       if (url.find("?backlog") == url.size() - 8) {
+       client->url = url;
+       if (url.size() > 8 && url.find("?backlog") == url.size() - 8) {
                client->stream_pos = -2;
                url = url.substr(0, url.size() - 8);
        } else {
                client->stream_pos = -1;
        }
 
-       map<string, int>::const_iterator url_map_it = url_map.find(url);
-       if (url_map_it == url_map.end()) {
-               return 404;  // Not found.
+       map<string, int>::const_iterator stream_url_map_it = stream_url_map.find(url);
+       if (stream_url_map_it == stream_url_map.end()) {
+               map<string, string>::const_iterator ping_url_map_it = ping_url_map.find(url);
+               if (ping_url_map_it == ping_url_map.end()) {
+                       return 404;  // Not found.
+               } else {
+                       return 204;  // No error.
+               }
        }
 
-       Stream *stream = streams[url_map_it->second];
+       Stream *stream = streams[stream_url_map_it->second];
        if (stream->http_header.empty()) {
                return 503;  // Service unavailable.
        }
 
-       client->url = request_tokens[1];
        client->stream = stream;
-       if (client->stream->mark_pool != NULL) {
-               client->fwmark = client->stream->mark_pool->get_mark();
-       } else {
-               client->fwmark = 0;  // No mark.
-       }
-       if (setsockopt(client->sock, SOL_SOCKET, SO_MARK, &client->fwmark, sizeof(client->fwmark)) == -1) {                          
-               if (client->fwmark != 0) {
-                       log_perror("setsockopt(SO_MARK)");
-               }
-       }
        if (setsockopt(client->sock, SOL_SOCKET, SO_MAX_PACING_RATE, &client->stream->pacing_rate, sizeof(client->stream->pacing_rate)) == -1) {
                if (client->stream->pacing_rate != ~0U) {
                        log_perror("setsockopt(SO_MAX_PACING_RATE)");
@@ -540,11 +880,11 @@ void Server::construct_header(Client *client)
 {
        Stream *stream = client->stream;
        if (stream->encoding == Stream::STREAM_ENCODING_RAW) {
-               client->header_or_error = stream->http_header +
+               client->header_or_short_response = stream->http_header +
                        "\r\n" +
                        stream->stream_header;
        } else if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
-               client->header_or_error = stream->http_header +
+               client->header_or_short_response = stream->http_header +
                        "Content-encoding: metacube\r\n" +
                        "\r\n";
                if (!stream->stream_header.empty()) {
@@ -553,10 +893,10 @@ void Server::construct_header(Client *client)
                        hdr.size = htonl(stream->stream_header.size());
                        hdr.flags = htons(METACUBE_FLAGS_HEADER);
                        hdr.csum = htons(metacube2_compute_crc(&hdr));
-                       client->header_or_error.append(
+                       client->header_or_short_response.append(
                                string(reinterpret_cast<char *>(&hdr), sizeof(hdr)));
                }
-               client->header_or_error.append(stream->stream_header);
+               client->header_or_short_response.append(stream->stream_header);
        } else {
                assert(false);
        }
@@ -579,10 +919,42 @@ void Server::construct_error(Client *client, int error_code)
        char error[256];
        snprintf(error, 256, "HTTP/1.0 %d Error\r\nContent-type: text/plain\r\n\r\nSomething went wrong. Sorry.\r\n",
                error_code);
-       client->header_or_error = error;
+       client->header_or_short_response = error;
 
        // Switch states.
-       client->state = Client::SENDING_ERROR;
+       client->state = Client::SENDING_SHORT_RESPONSE;
+
+       epoll_event ev;
+       ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
+       ev.data.u64 = reinterpret_cast<uint64_t>(client);
+
+       if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
+               log_perror("epoll_ctl(EPOLL_CTL_MOD)");
+               exit(1);
+       }
+}
+
+void Server::construct_204(Client *client)
+{
+       map<string, string>::const_iterator ping_url_map_it = ping_url_map.find(client->url);
+       assert(ping_url_map_it != ping_url_map.end());
+
+       if (ping_url_map_it->second.empty()) {
+               client->header_or_short_response =
+                       "HTTP/1.0 204 No Content\r\n"
+                       "\r\n";
+       } else {
+               char response[256];
+               snprintf(response, 256,
+                        "HTTP/1.0 204 No Content\r\n"
+                        "Access-Control-Allow-Origin: %s\r\n"
+                        "\r\n",
+                        ping_url_map_it->second.c_str());
+               client->header_or_short_response = response;
+       }
+
+       // Switch states.
+       client->state = Client::SENDING_SHORT_RESPONSE;
 
        epoll_event ev;
        ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
@@ -612,10 +984,10 @@ void Server::close_client(Client *client)
        if (client->stream != NULL) {
                delete_from(&client->stream->sleeping_clients, client);
                delete_from(&client->stream->to_process, client);
-               if (client->stream->mark_pool != NULL) {
-                       int fwmark = client->fwmark;
-                       client->stream->mark_pool->release_mark(fwmark);
-               }
+       }
+
+       if (client->tls_context) {
+               tls_destroy_context(client->tls_context);
        }
 
        // Log to access_log.
@@ -633,7 +1005,7 @@ void Server::process_queued_data()
                MutexLock lock(&queued_clients_mutex);
 
                for (size_t i = 0; i < queued_add_clients.size(); ++i) {
-                       add_client(queued_add_clients[i]);
+                       add_client(queued_add_clients[i].first, queued_add_clients[i].second);
                }
                queued_add_clients.clear();
        }