X-Git-Url: https://git.sesse.net/?p=cubemap;a=blobdiff_plain;f=server.cpp;h=852ecddf1f6212bfb1efb93d050d4fc37473a673;hp=8a8e867be1bf64f3cf47fc3a2c14e2dca37b9b4b;hb=50651c954803c1941e6ad1bb494712891c18f7d2;hpb=683141e8898415ba949161971b0c7f5508c92d14

diff --git a/server.cpp b/server.cpp
index 8a8e867..852ecdd 100644
--- a/server.cpp
+++ b/server.cpp
@@ -17,10 +17,12 @@
 #include <utility>
 #include <vector>
 
+#include "tlse.h"
+
+#include "acceptor.h"
 #include "accesslog.h"
 #include "log.h"
 #include "metacube2.h"
-#include "mutexlock.h"
 #include "parse.h"
 #include "server.h"
 #include "state.pb.h"
@@ -54,9 +56,6 @@ inline bool is_earlier(timespec a, timespec b)
 
 Server::Server()
 {
-	pthread_mutex_init(&mutex, NULL);
-	pthread_mutex_init(&queued_clients_mutex, NULL);
-
 	epoll_fd = epoll_create(1024);  // Size argument is ignored.
 	if (epoll_fd == -1) {
 		log_perror("epoll_fd");
@@ -66,10 +65,6 @@ Server::Server()
 
 Server::~Server()
 {
-	for (size_t i = 0; i < streams.size(); ++i) {	
-		delete streams[i];
-	}
-
 	safe_close(epoll_fd);
 }
 
@@ -77,11 +72,9 @@ vector<ClientStats> Server::get_client_stats() const
 {
 	vector<ClientStats> ret;
 
-	MutexLock lock(&mutex);
-	for (map<int, Client>::const_iterator client_it = clients.begin();
-	     client_it != clients.end();
-	     ++client_it) {
-		ret.push_back(client_it->second.get_stats());
+	lock_guard<mutex> lock(mu);
+	for (const auto &fd_and_client : clients) {
+		ret.push_back(fd_and_client.second.get_stats());
 	}
 	return ret;
 }
@@ -103,13 +96,13 @@ void Server::do_work()
 			exit(1);
 		}
 
-		MutexLock lock(&mutex);  // We release the mutex between iterations.
+		lock_guard<mutex> lock(mu);  // We release the mutex between iterations.
 	
 		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);
+			Client *client = reinterpret_cast<Client *>(events[i].data.ptr);
 
 			if (events[i].events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
 				close_client(client);
@@ -121,11 +114,11 @@ void Server::do_work()
 
 		// 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) {	
+		for (unique_ptr<Stream> &stream : streams) {
 			vector<Client *> to_process;
-			swap(streams[i]->to_process, to_process);
-			for (size_t i = 0; i < to_process.size(); ++i) {
-				process_client(to_process[i]);
+			swap(stream->to_process, to_process);
+			for (Client *client : to_process) {
+				process_client(client);
 			}
 		}
 
@@ -140,7 +133,7 @@ void Server::do_work()
 		}
 		timeout_time.tv_sec -= REQUEST_READ_TIMEOUT_SEC;
 		while (!clients_ordered_by_connect_time.empty()) {
-			pair<timespec, int> &connect_time_and_fd = clients_ordered_by_connect_time.front();
+			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)) {
@@ -149,7 +142,7 @@ void Server::do_work()
 
 			// If this client doesn't exist anymore, just ignore it
 			// (it was deleted earlier).
-			std::map<int, Client>::iterator client_it = clients.find(connect_time_and_fd.second);
+			auto client_it = clients.find(connect_time_and_fd.second);
 			if (client_it == clients.end()) {
 				clients_ordered_by_connect_time.pop();
 				continue;
@@ -186,36 +179,32 @@ CubemapStateProto Server::serialize()
 	//
 	// TODO: Do this when clients are added back from serialized state instead;
 	// it would probably be less wasteful.
-	for (map<int, Client>::iterator client_it = clients.begin();
-	     client_it != clients.end();
-	     ++client_it) {
-		skip_lost_data(&client_it->second);
+	for (auto &fd_and_client : clients) {
+		skip_lost_data(&fd_and_client.second);
 	}
 
 	CubemapStateProto serialized;
-	for (map<int, Client>::const_iterator client_it = clients.begin();
-	     client_it != clients.end();
-	     ++client_it) {
-		serialized.add_clients()->MergeFrom(client_it->second.serialize());
+	for (const auto &fd_and_client : clients) {
+		serialized.add_clients()->MergeFrom(fd_and_client.second.serialize());
 	}
-	for (size_t i = 0; i < streams.size(); ++i) {	
-		serialized.add_streams()->MergeFrom(streams[i]->serialize());
+	for (unique_ptr<Stream> &stream : streams) {
+		serialized.add_streams()->MergeFrom(stream->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);
+	lock_guard<mutex> lock(queued_clients_mutex);
+	queued_add_clients.push_back(std::make_pair(sock, acceptor));
 }
 
-void Server::add_client(int sock)
+void Server::add_client(int sock, Acceptor *acceptor)
 {
-	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;
+	const bool is_tls = acceptor->is_tls();
+	auto inserted = clients.insert(make_pair(sock, Client(sock)));
+	assert(inserted.second == true);  // Should not already exist.
+	Client *client_ptr = &inserted.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
@@ -230,31 +219,49 @@ void Server::add_client(int sock)
 
 	// Start listening on data from this socket.
 	epoll_event ev;
-	ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
-	ev.data.u64 = reinterpret_cast<uint64_t>(client_ptr);
+	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.ptr = 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 == nullptr) {
+			log(ERROR, "tls_accept() failed");
+			close_client(client_ptr);
+			return;
+		}
+		tls_make_exportable(client_ptr->tls_context, 1);
+	}
+
 	process_client(client_ptr);
 }
 
 void Server::add_client_from_serialized(const ClientProto &client)
 {
-	MutexLock lock(&mutex);
+	lock_guard<mutex> lock(mu);
 	Stream *stream;
 	int stream_index = lookup_stream_by_url(client.url());
 	if (stream_index == -1) {
 		assert(client.state() != Client::SENDING_DATA);
-		stream = NULL;
+		stream = nullptr;
 	} else {
-		stream = streams[stream_index];
+		stream = streams[stream_index].get();
 	}
-	pair<map<int, Client>::iterator, bool> ret =
-		clients.insert(make_pair(client.sock(), Client(client, stream)));
-	assert(ret.second == true);  // Should not already exist.
-	Client *client_ptr = &ret.first->second;
+	auto inserted = clients.insert(make_pair(client.sock(), Client(client, stream)));
+	assert(inserted.second == true);  // Should not already exist.
+	Client *client_ptr = &inserted.first->second;
 
 	// Connection timestamps must be nondecreasing.
 	assert(clients_ordered_by_connect_time.empty() ||
@@ -264,13 +271,18 @@ void Server::add_client_from_serialized(const ClientProto &client)
 	// 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.
 		ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 	}
-	ev.data.u64 = reinterpret_cast<uint64_t>(client_ptr);
+	ev.data.ptr = client_ptr;
 	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client.sock(), &ev) == -1) {
 		log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 		exit(1);
@@ -286,55 +298,62 @@ 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, size_t prebuffering_bytes, 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, prebuffering_bytes, encoding));
+	lock_guard<mutex> lock(mu);
+	stream_url_map.insert(make_pair(url, streams.size()));
+	streams.emplace_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()));
-	streams.push_back(new Stream(stream, data_fd));
+	lock_guard<mutex> lock(mu);
+	stream_url_map.insert(make_pair(stream.url(), streams.size()));
+	streams.emplace_back(new Stream(stream, data_fd));
 	return streams.size() - 1;
 }
 	
 void Server::set_backlog_size(int stream_index, size_t new_size)
 {
-	MutexLock lock(&mutex);
+	lock_guard<mutex> lock(mu);
 	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);
+	lock_guard<mutex> lock(mu);
 	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)
 {
-	MutexLock lock(&mutex);
+	lock_guard<mutex> lock(mu);
 	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)
+{
+	lock_guard<mutex> lock(mu);
+	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);
+	lock_guard<mutex> lock(mu);
 	assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 	streams[stream_index]->http_header = http_header;
 
@@ -353,16 +372,41 @@ void Server::set_header(int stream_index, const string &http_header, const strin
 	
 void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
 {
-	MutexLock lock(&mutex);
+	lock_guard<mutex> lock(mu);
 	assert(clients.empty());
 	assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 	streams[stream_index]->pacing_rate = pacing_rate;
 }
 
-void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
+void Server::add_gen204(const std::string &url, const std::string &allow_origin)
+{
+	lock_guard<mutex> lock(mu);
+	assert(clients.empty());
+	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, 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.	
@@ -370,28 +414,29 @@ void Server::process_client(Client *client)
 {
 	switch (client->state) {
 	case Client::READING_REQUEST: {
+		if (client->tls_context != nullptr) {
+			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 == nullptr) {
+			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);
@@ -415,25 +460,43 @@ 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) {
@@ -451,41 +514,63 @@ 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;
@@ -502,6 +587,7 @@ sending_header_or_error_again:
 		// 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);
@@ -515,6 +601,7 @@ sending_header_or_error_again:
 		// Fall through.
 	}
 	case Client::SENDING_DATA: {
+sending_data:
 		skip_lost_data(client);
 		Stream *stream = client->stream;
 
@@ -567,12 +654,139 @@ 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 == nullptr) {
+		client->tls_data_to_send = tls_get_write_buffer(client->tls_context, &client->tls_data_left_to_send);
+		if (client->tls_data_to_send == nullptr) {
+			// 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 = nullptr;
+		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)
 {
 	Stream *stream = client->stream;
-	if (stream == NULL) {
+	if (stream == nullptr) {
 		return;
 	}
 	size_t bytes_to_send = stream->bytes_received - client->stream_pos;
@@ -612,25 +826,29 @@ 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].get();
 	if (stream->http_header.empty()) {
 		return 503;  // Service unavailable.
 	}
 
-	client->url = request_tokens[1];
-
 	client->stream = stream;
 	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) {
@@ -646,11 +864,11 @@ 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()) {
@@ -659,25 +877,17 @@ 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);
 	}
 
 	// Switch states.
 	client->state = Client::SENDING_HEADER;
-
-	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);
-	}
+	change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
 }
 	
 void Server::construct_error(Client *client, int error_code)
@@ -685,19 +895,35 @@ 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;
+	change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
+}
 
-	epoll_event ev;
-	ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
-	ev.data.u64 = reinterpret_cast<uint64_t>(client);
+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 (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
-		log_perror("epoll_ctl(EPOLL_CTL_MOD)");
-		exit(1);
+	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;
+	change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
 }
 
 template<class T>
@@ -709,17 +935,21 @@ void delete_from(vector<T> *v, T elem)
 	
 void Server::close_client(Client *client)
 {
-	if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client->sock, NULL) == -1) {
+	if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client->sock, nullptr) == -1) {
 		log_perror("epoll_ctl(EPOLL_CTL_DEL)");
 		exit(1);
 	}
 
 	// This client could be sleeping, so we'll need to fix that. (Argh, O(n).)
-	if (client->stream != NULL) {
+	if (client->stream != nullptr) {
 		delete_from(&client->stream->sleeping_clients, client);
 		delete_from(&client->stream->to_process, client);
 	}
 
+	if (client->tls_context) {
+		tls_destroy_context(client->tls_context);
+	}
+
 	// Log to access_log.
 	access_log->write(client->get_stats());
 
@@ -728,19 +958,31 @@ void Server::close_client(Client *client)
 
 	clients.erase(client->sock);
 }
-	
+
+void Server::change_epoll_events(Client *client, uint32_t events)
+{
+	epoll_event ev;
+	ev.events = events;
+	ev.data.ptr = client;
+
+	if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
+		log_perror("epoll_ctl(EPOLL_CTL_MOD)");
+		exit(1);
+	}
+}
+
 void Server::process_queued_data()
 {
 	{
-		MutexLock lock(&queued_clients_mutex);
+		lock_guard<mutex> lock(queued_clients_mutex);
 
-		for (size_t i = 0; i < queued_add_clients.size(); ++i) {
-			add_client(queued_add_clients[i]);
+		for (const pair<int, Acceptor *> &id_and_acceptor : queued_add_clients) {
+			add_client(id_and_acceptor.first, id_and_acceptor.second);
 		}
 		queued_add_clients.clear();
 	}
 
-	for (size_t i = 0; i < streams.size(); ++i) {	
-		streams[i]->process_queued_data();
+	for (unique_ptr<Stream> &stream : streams) {
+		stream->process_queued_data();
 	}
 }