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passt/tcp_conn.h
David Gibson ee8f8e9564 tcp: Unify spliced and non-spliced connection tables 
Currently spliced and non-spliced connections are stored in completely
separate tables, so there are completely independent limits on the number
of spliced and non-spliced connections.  This is a bit counter-intuitive.

More importantly, the fact that the tables are separate prevents us from
unifying some other logic between the two cases.  So, merge these two
tables into one, using the 'c.spliced' common field to distinguish between
them when necessary.

For now we keep a common limit of 128k connections, whether they're spliced
or non-spliced, which means we save memory overall.  If necessary we could
increase this to a 256k or higher total, which would cost memory but give
some more flexibility.

For now, the code paths which need to step through all extant connections
are still separate for the two cases, just skipping over entries which
aren't for them.  We'll improve that in later patches.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-11-25 01:34:51 +01:00

205 lines
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/* SPDX-License-Identifier: AGPL-3.0-or-later
* Copyright Red Hat
* Author: Stefano Brivio <sbrivio@redhat.com>
* Author: David Gibson <david@gibson.dropbear.id.au>
*
* TCP connection tracking data structures, used by tcp.c and
* tcp_splice.c. Shouldn't be included in non-TCP code.
*/
#ifndef TCP_CONN_H
#define TCP_CONN_H
#define TCP_HASH_BUCKET_BITS (TCP_CONN_INDEX_BITS + 1)
/**
* struct tcp_conn_common - Common fields for spliced and non-spliced
* @spliced: Is this a spliced connection?
*/
struct tcp_conn_common {
bool spliced :1;
};
extern const char *tcp_common_flag_str[];
/**
* struct tcp_tap_conn - Descriptor for a TCP connection (not spliced)
* @c: Fields common with tcp_splice_conn
* @next_index: Connection index of next item in hash chain, -1 for none
* @tap_mss: MSS advertised by tap/guest, rounded to 2 ^ TCP_MSS_BITS
* @sock: Socket descriptor number
* @events: Connection events, implying connection states
* @timer: timerfd descriptor for timeout events
* @flags: Connection flags representing internal attributes
* @hash_bucket: Bucket index in connection lookup hash table
* @retrans: Number of retransmissions occurred due to ACK_TIMEOUT
* @ws_from_tap: Window scaling factor advertised from tap/guest
* @ws_to_tap: Window scaling factor advertised to tap/guest
* @sndbuf: Sending buffer in kernel, rounded to 2 ^ SNDBUF_BITS
* @seq_dup_ack_approx: Last duplicate ACK number sent to tap
* @a.a6: IPv6 remote address, can be IPv4-mapped
* @a.a4.zero: Zero prefix for IPv4-mapped, see RFC 6890, Table 20
* @a.a4.one: Ones prefix for IPv4-mapped
* @a.a4.a: IPv4 address
* @tap_port: Guest-facing tap port
* @sock_port: Remote, socket-facing port
* @wnd_from_tap: Last window size from tap, unscaled (as received)
* @wnd_to_tap: Sending window advertised to tap, unscaled (as sent)
* @seq_to_tap: Next sequence for packets to tap
* @seq_ack_from_tap: Last ACK number received from tap
* @seq_from_tap: Next sequence for packets from tap (not actually sent)
* @seq_ack_to_tap: Last ACK number sent to tap
* @seq_init_from_tap: Initial sequence number from tap
*/
struct tcp_tap_conn {
/* Must be first element to match tcp_splice_conn */
struct tcp_conn_common c;
int next_index :TCP_CONN_INDEX_BITS + 2;
#define TCP_RETRANS_BITS 3
unsigned int retrans :TCP_RETRANS_BITS;
#define TCP_MAX_RETRANS ((1U << TCP_RETRANS_BITS) - 1)
#define TCP_WS_BITS 4 /* RFC 7323 */
#define TCP_WS_MAX 14
unsigned int ws_from_tap :TCP_WS_BITS;
unsigned int ws_to_tap :TCP_WS_BITS;
int sock :SOCKET_REF_BITS;
uint8_t events;
#define CLOSED 0
#define SOCK_ACCEPTED BIT(0) /* implies SYN sent to tap */
#define TAP_SYN_RCVD BIT(1) /* implies socket connecting */
#define TAP_SYN_ACK_SENT BIT( 3) /* implies socket connected */
#define ESTABLISHED BIT(2)
#define SOCK_FIN_RCVD BIT( 3)
#define SOCK_FIN_SENT BIT( 4)
#define TAP_FIN_RCVD BIT( 5)
#define TAP_FIN_SENT BIT( 6)
#define TAP_FIN_ACKED BIT( 7)
#define CONN_STATE_BITS /* Setting these clears other flags */ \
(SOCK_ACCEPTED | TAP_SYN_RCVD | ESTABLISHED)
int timer :SOCKET_REF_BITS;
uint8_t flags;
#define STALLED BIT(0)
#define LOCAL BIT(1)
#define WND_CLAMPED BIT(2)
#define IN_EPOLL BIT(3)
#define ACTIVE_CLOSE BIT(4)
#define ACK_TO_TAP_DUE BIT(5)
#define ACK_FROM_TAP_DUE BIT(6)
unsigned int hash_bucket :TCP_HASH_BUCKET_BITS;
#define TCP_MSS_BITS 14
unsigned int tap_mss :TCP_MSS_BITS;
#define MSS_SET(conn, mss) (conn->tap_mss = (mss >> (16 - TCP_MSS_BITS)))
#define MSS_GET(conn) (conn->tap_mss << (16 - TCP_MSS_BITS))
#define SNDBUF_BITS 24
unsigned int sndbuf :SNDBUF_BITS;
#define SNDBUF_SET(conn, bytes) (conn->sndbuf = ((bytes) >> (32 - SNDBUF_BITS)))
#define SNDBUF_GET(conn) (conn->sndbuf << (32 - SNDBUF_BITS))
uint8_t seq_dup_ack_approx;
union {
struct in6_addr a6;
struct {
uint8_t zero[10];
uint8_t one[2];
struct in_addr a;
} a4;
} a;
in_port_t tap_port;
in_port_t sock_port;
uint16_t wnd_from_tap;
uint16_t wnd_to_tap;
uint32_t seq_to_tap;
uint32_t seq_ack_from_tap;
uint32_t seq_from_tap;
uint32_t seq_ack_to_tap;
uint32_t seq_init_from_tap;
};
/**
* struct tcp_splice_conn - Descriptor for a spliced TCP connection
* @c: Fields common with tcp_tap_conn
* @a: File descriptor number of socket for accepted connection
* @pipe_a_b: Pipe ends for splice() from @a to @b
* @b: File descriptor number of peer connected socket
* @pipe_b_a: Pipe ends for splice() from @b to @a
* @events: Events observed/actions performed on connection
* @flags: Connection flags (attributes, not events)
* @a_read: Bytes read from @a (not fully written to @b in one shot)
* @a_written: Bytes written to @a (not fully written from one @b read)
* @b_read: Bytes read from @b (not fully written to @a in one shot)
* @b_written: Bytes written to @b (not fully written from one @a read)
*/
struct tcp_splice_conn {
/* Must be first element to match tcp_tap_conn */
struct tcp_conn_common c;
int a;
int pipe_a_b[2];
int b;
int pipe_b_a[2];
uint8_t events;
#define SPLICE_CLOSED 0
#define SPLICE_CONNECT BIT(0)
#define SPLICE_ESTABLISHED BIT(1)
#define A_OUT_WAIT BIT(2)
#define B_OUT_WAIT BIT(3)
#define A_FIN_RCVD BIT(4)
#define B_FIN_RCVD BIT(5)
#define A_FIN_SENT BIT(6)
#define B_FIN_SENT BIT(7)
uint8_t flags;
#define SPLICE_V6 BIT(0)
#define SPLICE_IN_EPOLL BIT(1)
#define RCVLOWAT_SET_A BIT(2)
#define RCVLOWAT_SET_B BIT(3)
#define RCVLOWAT_ACT_A BIT(4)
#define RCVLOWAT_ACT_B BIT(5)
#define CLOSING BIT(6)
uint32_t a_read;
uint32_t a_written;
uint32_t b_read;
uint32_t b_written;
};
/**
* union tcp_conn - Descriptor for a TCP connection (spliced or non-spliced)
* @c: Fields common between all variants
* @tap: Fields specific to non-spliced connections
* @splice: Fields specific to spliced connections
*/
union tcp_conn {
struct tcp_conn_common c;
struct tcp_tap_conn tap;
struct tcp_splice_conn splice;
};
/* TCP connections */
extern union tcp_conn tc[];
void tcp_splice_conn_update(struct ctx *c, struct tcp_splice_conn *new);
void tcp_table_compact(struct ctx *c, union tcp_conn *hole);
#endif /* TCP_CONN_H */
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