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- #ifndef _GPXE_TCP_H
- #define _GPXE_TCP_H
-
- /** @file
- *
- * TCP protocol
- *
- * This file defines the gPXE TCP API.
- *
- */
-
- #include "latch.h"
- #include <gpxe/tcpip.h>
-
- /**
- * A TCP header
- */
- struct tcp_header {
- uint16_t src; /* Source port */
- uint16_t dest; /* Destination port */
- uint32_t seq; /* Sequence number */
- uint32_t ack; /* Acknowledgement number */
- uint8_t hlen; /* Header length (4), Reserved (4) */
- uint8_t flags; /* Reserved (2), Flags (6) */
- uint16_t win; /* Advertised window */
- uint16_t csum; /* Checksum */
- uint16_t urg; /* Urgent pointer */
- };
-
- /** @defgroup tcpopts TCP options
- * @{
- */
-
- /** End of TCP options list */
- #define TCP_OPTION_END 0
-
- /** TCP option pad */
- #define TCP_OPTION_NOP 1
-
- /** Generic TCP option */
- struct tcp_option {
- uint8_t kind;
- uint8_t length;
- } __attribute__ (( packed ));
-
- /** TCP MSS option */
- struct tcp_mss_option {
- uint8_t kind;
- uint8_t length;
- uint16_t mss;
- } __attribute__ (( packed ));
-
- /** Code for the TCP MSS option */
- #define TCP_OPTION_MSS 2
-
- /** TCP timestamp option */
- struct tcp_timestamp_option {
- uint8_t kind;
- uint8_t length;
- uint32_t tsval;
- uint32_t tsecr;
- } __attribute__ (( packed ));
-
- /** Padded TCP timestamp option (used for sending) */
- struct tcp_timestamp_padded_option {
- uint8_t nop[2];
- struct tcp_timestamp_option tsopt;
- } __attribute__ (( packed ));
-
- /** Code for the TCP timestamp option */
- #define TCP_OPTION_TS 8
-
- /** Parsed TCP options */
- struct tcp_options {
- /** MSS option, if present */
- const struct tcp_mss_option *mssopt;
- /** Timestampe option, if present */
- const struct tcp_timestamp_option *tsopt;
- };
-
- /** @} */
-
- /*
- * TCP flags
- */
- #define TCP_CWR 0x80
- #define TCP_ECE 0x40
- #define TCP_URG 0x20
- #define TCP_ACK 0x10
- #define TCP_PSH 0x08
- #define TCP_RST 0x04
- #define TCP_SYN 0x02
- #define TCP_FIN 0x01
-
- /**
- * @defgroup tcpstates TCP states
- *
- * The TCP state is defined by a combination of the flags that have
- * been sent to the peer, the flags that have been acknowledged by the
- * peer, and the flags that have been received from the peer.
- *
- * @{
- */
-
- /** TCP flags that have been sent in outgoing packets */
- #define TCP_STATE_SENT(flags) ( (flags) << 0 )
- #define TCP_FLAGS_SENT(state) ( ( (state) >> 0 ) & 0xff )
-
- /** TCP flags that have been acknowledged by the peer
- *
- * Note that this applies only to SYN and FIN.
- */
- #define TCP_STATE_ACKED(flags) ( (flags) << 8 )
- #define TCP_FLAGS_ACKED(state) ( ( (state) >> 8 ) & 0xff )
-
- /** TCP flags that have been received from the peer
- *
- * Note that this applies only to SYN and FIN, and that once SYN has
- * been received, we should always be sending ACK.
- */
- #define TCP_STATE_RCVD(flags) ( (flags) << 16 )
- #define TCP_FLAGS_RCVD(state) ( ( (state) >> 16 ) & 0xff )
-
- /** TCP flags that are currently being sent in outgoing packets */
- #define TCP_FLAGS_SENDING(state) \
- ( TCP_FLAGS_SENT ( state ) & ~TCP_FLAGS_ACKED ( state ) )
-
- /** CLOSED
- *
- * The connection has not yet been used for anything.
- */
- #define TCP_CLOSED TCP_RST
-
- /** LISTEN
- *
- * Not currently used as a state; we have no support for listening
- * connections. Given a unique value to avoid compiler warnings.
- */
- #define TCP_LISTEN 0
-
- /** SYN_SENT
- *
- * SYN has been sent, nothing has yet been received or acknowledged.
- */
- #define TCP_SYN_SENT ( TCP_STATE_SENT ( TCP_SYN ) )
-
- /** SYN_RCVD
- *
- * SYN has been sent but not acknowledged, SYN has been received.
- */
- #define TCP_SYN_RCVD ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK ) | \
- TCP_STATE_RCVD ( TCP_SYN ) )
-
- /** ESTABLISHED
- *
- * SYN has been sent and acknowledged, SYN has been received.
- */
- #define TCP_ESTABLISHED ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK ) | \
- TCP_STATE_ACKED ( TCP_SYN ) | \
- TCP_STATE_RCVD ( TCP_SYN ) )
-
- /** FIN_WAIT_1
- *
- * SYN has been sent and acknowledged, SYN has been received, FIN has
- * been sent but not acknowledged, FIN has not been received.
- *
- * RFC 793 shows that we can enter FIN_WAIT_1 without have had SYN
- * acknowledged, i.e. if the application closes the connection after
- * sending and receiving SYN, but before having had SYN acknowledged.
- * However, we have to *pretend* that SYN has been acknowledged
- * anyway, otherwise we end up sending SYN and FIN in the same
- * sequence number slot. Therefore, when we transition from SYN_RCVD
- * to FIN_WAIT_1, we have to remember to set TCP_STATE_ACKED(TCP_SYN)
- * and increment our sequence number.
- */
- #define TCP_FIN_WAIT_1 ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK | TCP_FIN ) | \
- TCP_STATE_ACKED ( TCP_SYN ) | \
- TCP_STATE_RCVD ( TCP_SYN ) )
-
- /** FIN_WAIT_2
- *
- * SYN has been sent and acknowledged, SYN has been received, FIN has
- * been sent and acknowledged, FIN ha not been received.
- */
- #define TCP_FIN_WAIT_2 ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK | TCP_FIN ) | \
- TCP_STATE_ACKED ( TCP_SYN | TCP_FIN ) | \
- TCP_STATE_RCVD ( TCP_SYN ) )
-
- /** CLOSING / LAST_ACK
- *
- * SYN has been sent and acknowledged, SYN has been received, FIN has
- * been sent but not acknowledged, FIN has been received.
- *
- * This state actually encompasses both CLOSING and LAST_ACK; they are
- * identical with the definition of state that we use. I don't
- * *believe* that they need to be distinguished.
- */
- #define TCP_CLOSING_OR_LAST_ACK \
- ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK | TCP_FIN ) | \
- TCP_STATE_ACKED ( TCP_SYN ) | \
- TCP_STATE_RCVD ( TCP_SYN | TCP_FIN ) )
-
- /** TIME_WAIT
- *
- * SYN has been sent and acknowledged, SYN has been received, FIN has
- * been sent and acknowledged, FIN has been received.
- */
- #define TCP_TIME_WAIT ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK | TCP_FIN ) | \
- TCP_STATE_ACKED ( TCP_SYN | TCP_FIN ) | \
- TCP_STATE_RCVD ( TCP_SYN | TCP_FIN ) )
-
- /** CLOSE_WAIT
- *
- * SYN has been sent and acknowledged, SYN has been received, FIN has
- * been received.
- */
- #define TCP_CLOSE_WAIT ( TCP_STATE_SENT ( TCP_SYN | TCP_ACK ) | \
- TCP_STATE_ACKED ( TCP_SYN ) | \
- TCP_STATE_RCVD ( TCP_SYN | TCP_FIN ) )
-
- /** Can send data in current state
- *
- * We can send data if and only if we have had our SYN acked and we
- * have not yet sent our FIN.
- */
- #define TCP_CAN_SEND_DATA(state) \
- ( ( (state) & ( TCP_STATE_ACKED ( TCP_SYN ) | \
- TCP_STATE_SENT ( TCP_FIN ) ) ) \
- == TCP_STATE_ACKED ( TCP_SYN ) )
-
- /** Have closed gracefully
- *
- * We have closed gracefully if we have both received a FIN and had
- * our own FIN acked.
- */
- #define TCP_CLOSED_GRACEFULLY(state) \
- ( ( (state) & ( TCP_STATE_ACKED ( TCP_FIN ) | \
- TCP_STATE_RCVD ( TCP_FIN ) ) ) \
- == ( TCP_STATE_ACKED ( TCP_FIN ) | TCP_STATE_RCVD ( TCP_FIN ) ) )
-
- /** @} */
-
- /** Mask for TCP header length field */
- #define TCP_MASK_HLEN 0xf0
-
- /** Smallest port number on which a TCP connection can listen */
- #define TCP_MIN_PORT 1
-
- /* Some IOB constants */
- #define MAX_HDR_LEN 100
- #define MAX_IOB_LEN 1500
- #define MIN_IOB_LEN MAX_HDR_LEN + 100 /* To account for padding by LL */
-
- /**
- * Maxmimum advertised TCP window size
- *
- * We estimate the TCP window size as the amount of free memory we
- * have. This is not strictly accurate (since it ignores any space
- * already allocated as RX buffers), but it will do for now.
- *
- * Since we don't store out-of-order received packets, the
- * retransmission penalty is that the whole window contents must be
- * resent. This suggests keeping the window size small, but bear in
- * mind that the maximum bandwidth on any link is limited to
- *
- * max_bandwidth = ( tcp_window / round_trip_time )
- *
- * With a 48kB window, which probably accurately reflects our amount
- * of free memory, and a WAN RTT of say 200ms, this gives a maximum
- * bandwidth of 240kB/s. This is sufficiently close to realistic that
- * we will need to be careful that our advertised window doesn't end
- * up limiting WAN download speeds.
- *
- * Finally, since the window goes into a 16-bit field and we cannot
- * actually use 65536, we use a window size of (65536-4) to ensure
- * that payloads remain dword-aligned.
- */
- //#define TCP_MAX_WINDOW_SIZE ( 65536 - 4 )
- #define TCP_MAX_WINDOW_SIZE 4096
-
- /**
- * Path MTU
- *
- * We really ought to implement Path MTU discovery. Until we do,
- * anything with a path MTU greater than this may fail.
- */
- #define TCP_PATH_MTU 1460
-
- /**
- * Advertised TCP MSS
- *
- * We currently hardcode this to a reasonable value and hope that the
- * sender uses path MTU discovery. The alternative is breaking the
- * abstraction layer so that we can find out the MTU from the IP layer
- * (which would have to find out from the net device layer).
- */
- #define TCP_MSS 1460
-
- /** TCP maximum segment lifetime
- *
- * Currently set to 2 minutes, as per RFC 793.
- */
- #define TCP_MSL ( 2 * 60 * TICKS_PER_SEC )
-
- extern struct tcpip_protocol tcp_protocol;
-
- #endif /* _GPXE_TCP_H */
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