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tcp_internal.h
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/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright (c) 2021 Red Hat GmbH
* Author: Stefano Brivio <[email protected]>
*/
#ifndef TCP_INTERNAL_H
#define TCP_INTERNAL_H
#define MAX_WS 8
#define MAX_WINDOW (1 << (16 + (MAX_WS)))
#define MSS4 ROUND_DOWN(IP_MAX_MTU - \
sizeof(struct tcphdr) - \
sizeof(struct iphdr), \
sizeof(uint32_t))
#define MSS6 ROUND_DOWN(IP_MAX_MTU - \
sizeof(struct tcphdr) - \
sizeof(struct ipv6hdr), \
sizeof(uint32_t))
#define SEQ_LE(a, b) ((b) - (a) < MAX_WINDOW)
#define SEQ_LT(a, b) ((b) - (a) - 1 < MAX_WINDOW)
#define SEQ_GE(a, b) ((a) - (b) < MAX_WINDOW)
#define SEQ_GT(a, b) ((a) - (b) - 1 < MAX_WINDOW)
#define FIN (1 << 0)
#define SYN (1 << 1)
#define RST (1 << 2)
#define ACK (1 << 4)
/* Flags for internal usage */
#define DUP_ACK (1 << 5)
#define OPT_EOL 0
#define OPT_NOP 1
#define OPT_MSS 2
#define OPT_WS 3
#define OPT_SACKP 4
#define OPT_SACK 5
#define OPT_TS 8
#define TAPSIDE(conn_) ((conn_)->f.pif[1] == PIF_TAP)
#define TAPFLOW(conn_) (&((conn_)->f.side[TAPSIDE(conn_)]))
#define TAP_SIDX(conn_) (FLOW_SIDX((conn_), TAPSIDE(conn_)))
#define CONN_V4(conn) (!!inany_v4(&TAPFLOW(conn)->oaddr))
#define CONN_V6(conn) (!CONN_V4(conn))
/*
* enum tcp_iov_parts - I/O vector parts for one TCP frame
* @TCP_IOV_TAP tap backend specific header
* @TCP_IOV_ETH Ethernet header
* @TCP_IOV_IP IP (v4/v6) header
* @TCP_IOV_PAYLOAD IP payload (TCP header + data)
* @TCP_NUM_IOVS the number of entries in the iovec array
*/
enum tcp_iov_parts {
TCP_IOV_TAP = 0,
TCP_IOV_ETH = 1,
TCP_IOV_IP = 2,
TCP_IOV_PAYLOAD = 3,
TCP_NUM_IOVS
};
/**
* struct tcp_payload_t - TCP header and data to send segments with payload
* @th: TCP header
* @data: TCP data
*/
struct tcp_payload_t {
struct tcphdr th;
uint8_t data[IP_MAX_MTU - sizeof(struct tcphdr)];
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32))); /* For AVX2 checksum routines */
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))));
#endif
/** struct tcp_opt_nop - TCP NOP option
* @kind: Option kind (OPT_NOP = 1)
*/
struct tcp_opt_nop {
uint8_t kind;
} __attribute__ ((packed));
#define TCP_OPT_NOP ((struct tcp_opt_nop){ .kind = OPT_NOP, })
/** struct tcp_opt_mss - TCP MSS option
* @kind: Option kind (OPT_MSS == 2)
* @len: Option length (4)
* @mss: Maximum Segment Size
*/
struct tcp_opt_mss {
uint8_t kind;
uint8_t len;
uint16_t mss;
} __attribute__ ((packed));
#define TCP_OPT_MSS(mss_) \
((struct tcp_opt_mss) { \
.kind = OPT_MSS, \
.len = sizeof(struct tcp_opt_mss), \
.mss = htons(mss_), \
})
/** struct tcp_opt_ws - TCP Window Scaling option
* @kind: Option kind (OPT_WS == 3)
* @len: Option length (3)
* @shift: Window scaling shift
*/
struct tcp_opt_ws {
uint8_t kind;
uint8_t len;
uint8_t shift;
} __attribute__ ((packed));
#define TCP_OPT_WS(shift_) \
((struct tcp_opt_ws) { \
.kind = OPT_WS, \
.len = sizeof(struct tcp_opt_ws), \
.shift = (shift_), \
})
/** struct tcp_syn_opts - TCP options we apply to SYN packets
* @mss: Maximum Segment Size (MSS) option
* @nop: NOP opt (for alignment)
* @ws: Window Scaling (WS) option
*/
struct tcp_syn_opts {
struct tcp_opt_mss mss;
struct tcp_opt_nop nop;
struct tcp_opt_ws ws;
} __attribute__ ((packed));
#define TCP_SYN_OPTS(mss_, ws_) \
((struct tcp_syn_opts){ \
.mss = TCP_OPT_MSS(mss_), \
.nop = TCP_OPT_NOP, \
.ws = TCP_OPT_WS(ws_), \
})
extern char tcp_buf_discard [MAX_WINDOW];
void conn_flag_do(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned long flag);
#define conn_flag(c, conn, flag) \
do { \
flow_trace(conn, "flag at %s:%i", __func__, __LINE__); \
conn_flag_do(c, conn, flag); \
} while (0)
void conn_event_do(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned long event);
#define conn_event(c, conn, event) \
do { \
flow_trace(conn, "event at %s:%i", __func__, __LINE__); \
conn_event_do(c, conn, event); \
} while (0)
void tcp_rst_do(const struct ctx *c, struct tcp_tap_conn *conn);
#define tcp_rst(c, conn) \
do { \
flow_dbg((conn), "TCP reset at %s:%i", __func__, __LINE__); \
tcp_rst_do(c, conn); \
} while (0)
struct tcp_info_linux;
void tcp_update_csum(uint32_t psum, struct tcphdr *th,
struct iov_tail *payload);
void tcp_fill_headers(const struct tcp_tap_conn *conn,
struct tap_hdr *taph,
struct iphdr *ip4h, struct ipv6hdr *ip6h,
struct tcphdr *th, struct iov_tail *payload,
const uint16_t *ip4_check, uint32_t seq, bool no_tcp_csum);
int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn,
bool force_seq, struct tcp_info_linux *tinfo);
int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn,
int flags, struct tcphdr *th, struct tcp_syn_opts *opts,
size_t *optlen);
#endif /* TCP_INTERNAL_H */