Allow (and forward) zero-byte UDP packets.

[cubemap] / client.h

#ifndef _CLIENT_H
#define _CLIENT_H 1

// A Client represents a single connection from a client (watching a single stream).

#include <stddef.h>
#include <time.h>

#include <memory>
#include <string>
#include <unordered_map>
#include <vector>

#include "tlse.h"

class ClientProto;
struct Stream;

// Digested statistics for writing to logs etc.
// Note that "referer" and "user_agent" here are already escaped for scary characters.
struct ClientStats {
        std::string url;
        int sock;
        std::string remote_addr;
        std::string referer;
        std::string user_agent;
        timespec connect_time;
        size_t bytes_sent;
        size_t bytes_lost;
        size_t num_loss_events;
        std::string hls_zombie_key;
};

struct Client {
        Client(int sock);

        // Serialization/deserialization.
        Client(const ClientProto &serialized, const std::vector<std::shared_ptr<const std::string>> &short_responses, Stream *stream);
        ClientProto serialize(std::unordered_map<const std::string *, size_t> *short_response_pool) const;

        ClientStats get_stats() const;

        std::string get_hls_zombie_key() const {
                if (x_playback_session_id.empty()) {
                        return remote_addr;
                } else {
                        return x_playback_session_id;
                }
        }

        // The file descriptor associated with this socket.
        int sock;

        // When the client connected (or went into keepalive), in terms of CLOCK_MONOTONIC_COARSE.
        timespec connect_time;

        // Some information only used for logging.
        std::string remote_addr;
        std::string referer;
        std::string user_agent;
        std::string x_playback_session_id;

        enum State { READING_REQUEST, SENDING_HEADER, SENDING_DATA, SENDING_SHORT_RESPONSE, WAITING_FOR_KEYFRAME, PREBUFFERING };
        State state = READING_REQUEST;

        // The HTTP request, as sent by the client. If we are in READING_REQUEST,
        // this might not be finished.
        std::string request;

        // What stream we're connecting to; parsed from <request>.
        // Not relevant for READING_REQUEST.
        std::string url;
        Stream *stream = nullptr;

        // If true, we don't actually serve the stream, but its HLS playlist.
        // TODO: Maybe this shouldn't be part of Client, since it's only
        // really used in communicating once from parse_request() to
        // process_client(); it's not permanent state (and is not serialized).
        bool serving_hls_playlist = false;

        // Whether we should close the connection after sending the response.
        // Not relevant for READING_REQUEST. Must be true if http_11 is false.
        bool close_after_response;

        // Whether the request came in over HTTP/1.1 or higher.
        bool http_11;

        // The header we want to send, or the response with headers if we know
        // it in its entirety after reading the request (typically an error).
        // This is nominally a copy of Stream::header, but since that might
        // change on reconnects etc., we keep a local copy here. Only relevant
        // for SENDING_HEADER or SENDING_SHORT_RESPONSE; blank otherwise.
        //
        // Must start with the string "HTTP/1.0 ", which will be changed to 1.1
        // if relevant.
        const std::string *header_or_short_response = nullptr;

        // <header_or_short_response> can come from two distinct places; it can be
        // local to the Client object, or it can be shared between many Clients
        // (typically HLS playlists, that can be so large that they are expensive
        // to hold in many copies). <header_or_short_response> will point to exactly
        // one of these, which should be cleared out/dereferenced when it is
        // no longer needed.
        //
        // The use of shared_ptr is somewhat overkill since we don't need
        // to access the HLS playlists from multiple threads, but it's not a
        // big deal for us.
        std::string header_or_short_response_holder;
        std::shared_ptr<const std::string> header_or_short_response_ref;

        // Number of bytes we've sent of the header. Only relevant for SENDING_HEADER
        // or SENDING_SHORT_RESPONSE.
        size_t header_or_short_response_bytes_sent = 0;

        // Number of bytes we are into the stream (ie., the end of last send).
        // -1 means we want to send from the end of the backlog (the normal case),
        // although only at a keyframe.
        // -2 means we want to send from the _beginning_ of the backlog.
        // -3 means we sent the header only.
        static const uint64_t STREAM_POS_AT_END = -1;
        static const uint64_t STREAM_POS_AT_START = -2;
        static const uint64_t STREAM_POS_HEADER_ONLY = -3;

        // Once we go into WAITING_FOR_KEYFRAME, PREBUFFERING or SENDING_DATA,
        // these negative values will be translated to real numbers.
        uint64_t stream_pos = 0;

        // Position at which to end the stream (one-past-the-end, used for fragments).
        // -1 means never to end; this is the common case.
        static const uint64_t STREAM_POS_NO_END = -1;
        uint64_t stream_pos_end = 0;

        // Number of bytes we've sent of data. Only relevant for SENDING_DATA.
        uint64_t bytes_sent = 0;

        // Number of times we've skipped forward due to the backlog being too big,
        // and how many bytes we've skipped over in all. Only relevant for SENDING_DATA.
        uint64_t bytes_lost = 0, num_loss_events = 0;

        TLSContext *tls_context = nullptr;
        const unsigned char *tls_data_to_send = nullptr;
        unsigned tls_data_left_to_send = 0;
        bool in_ktls_mode = false;
};

#endif  // !defined(_CLIENT_H)