+/*
+ utcp.h -- Userspace TCP
+ Copyright (C) 2014 Guus Sliepen <guus@tinc-vpn.org>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef UTCP_PRIV_H
+#define UTCP_PRIV_H
+
+#define UTCP_INTERNAL
+#include "utcp.h"
+
+#define PREP(l) char pkt[(l) + sizeof struct hdr]; struct hdr *hdr = &pkt;
+
+#define SYN 1
+#define ACK 2
+#define FIN 4
+#define RST 8
+#define MF 16
+
+#define AUX_INIT 1
+#define AUX_FRAME 2
+#define AUX_SAK 3
+#define AUX_TIMESTAMP 4
+
+#define NSACKS 4
+#define DEFAULT_SNDBUFSIZE 4096
+#define DEFAULT_MAXSNDBUFSIZE 131072
+#define DEFAULT_RCVBUFSIZE 0
+#define DEFAULT_MAXRCVBUFSIZE 131072
+
+#define MAX_UNRELIABLE_SIZE 65536
+#define DEFAULT_MTU 1000
+
+#define USEC_PER_SEC 1000000L
+#define NSEC_PER_SEC 1000000000L
+#define DEFAULT_USER_TIMEOUT 60
+#define START_RTO (1 * USEC_PER_SEC)
+#define MAX_RTO (3 * USEC_PER_SEC)
+
+struct hdr {
+ uint16_t src; // Source port
+ uint16_t dst; // Destination port
+ uint32_t seq; // Sequence number
+ uint32_t ack; // Acknowledgement number
+ uint32_t wnd; // Window size
+ uint16_t ctl; // Flags (SYN, ACK, FIN, RST)
+ uint16_t aux; // other stuff
+};
+
+enum state {
+ CLOSED,
+ LISTEN,
+ SYN_SENT,
+ SYN_RECEIVED,
+ ESTABLISHED,
+ FIN_WAIT_1,
+ FIN_WAIT_2,
+ CLOSE_WAIT,
+ CLOSING,
+ LAST_ACK,
+ TIME_WAIT
+};
+
+static const char *strstate[] __attribute__((unused)) = {
+ [CLOSED] = "CLOSED",
+ [LISTEN] = "LISTEN",
+ [SYN_SENT] = "SYN_SENT",
+ [SYN_RECEIVED] = "SYN_RECEIVED",
+ [ESTABLISHED] = "ESTABLISHED",
+ [FIN_WAIT_1] = "FIN_WAIT_1",
+ [FIN_WAIT_2] = "FIN_WAIT_2",
+ [CLOSE_WAIT] = "CLOSE_WAIT",
+ [CLOSING] = "CLOSING",
+ [LAST_ACK] = "LAST_ACK",
+ [TIME_WAIT] = "TIME_WAIT"
+};
+
+struct buffer {
+ char *data;
+ uint32_t offset;
+ uint32_t used;
+ uint32_t size;
+ uint32_t maxsize;
+};
+
+struct sack {
+ uint32_t offset;
+ uint32_t len;
+};
+
+struct utcp_connection {
+ void *priv;
+ struct utcp *utcp;
+ uint32_t flags;
+
+ bool reapable;
+ bool do_poll;
+
+ // Callbacks
+
+ utcp_recv_t recv;
+ utcp_poll_t poll;
+
+ // TCP State
+
+ uint16_t src;
+ uint16_t dst;
+ enum state state;
+
+ struct {
+ uint32_t una;
+ uint32_t nxt;
+ uint32_t wnd;
+ uint32_t iss;
+
+ uint32_t last;
+ uint32_t cwnd;
+ uint32_t ssthresh;
+ } snd;
+
+ struct {
+ uint32_t nxt;
+ uint32_t irs;
+ } rcv;
+
+ int dupack;
+
+ // Timers
+
+ struct timespec conn_timeout;
+ struct timespec rtrx_timeout;
+ struct timespec rtt_start;
+ uint32_t rtt_seq;
+
+ // RTT variables
+
+ uint32_t srtt; // usec
+ uint32_t rttvar; // usec
+ uint32_t rto; // usec
+
+ // Buffers
+
+ uint32_t prev_free;
+ struct buffer sndbuf;
+ struct buffer rcvbuf;
+ struct sack sacks[NSACKS];
+
+ // Per-socket options
+
+ bool nodelay;
+ bool keepalive;
+ bool shut_wr;
+
+ // Congestion avoidance state
+
+ struct timespec tlast;
+ uint64_t bandwidth;
+};
+
+struct utcp {
+ void *priv;
+
+ // Callbacks
+
+ utcp_accept_t accept;
+ utcp_pre_accept_t pre_accept;
+ utcp_retransmit_t retransmit;
+ utcp_send_t send;
+
+ // Packet buffer
+
+ void *pkt;
+
+ // Global socket options
+
+ uint16_t mtu; // The maximum size of a UTCP packet, including headers.
+ uint16_t mss; // The maximum size of the payload of a UTCP packet.
+ int timeout; // sec
+
+ // Connection management
+
+ struct utcp_connection **connections;
+ int nconnections;
+ int nallocated;
+};
+
+#endif