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We maintain pools of ready-to-connect sockets in both the original and (for pasta) guest namespace to reduce latency when starting new TCP connections. If we exhaust those pools we have to take a higher latency path to get a new socket. Currently we open-code that fallback in the places we need it. To improve clarity encapsulate that into helper functions. While we're at it, give those helpers clearer error reporting. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
167 lines
5.1 KiB
C
167 lines
5.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright Red Hat
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* Author: Stefano Brivio <sbrivio@redhat.com>
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* Author: David Gibson <david@gibson.dropbear.id.au>
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*
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* TCP connection tracking data structures, used by tcp.c and
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* tcp_splice.c. Shouldn't be included in non-TCP code.
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*/
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#ifndef TCP_CONN_H
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#define TCP_CONN_H
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/**
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* struct tcp_tap_conn - Descriptor for a TCP connection (not spliced)
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* @f: Generic flow information
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* @in_epoll: Is the connection in the epoll set?
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* @tap_mss: MSS advertised by tap/guest, rounded to 2 ^ TCP_MSS_BITS
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* @sock: Socket descriptor number
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* @events: Connection events, implying connection states
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* @timer: timerfd descriptor for timeout events
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* @flags: Connection flags representing internal attributes
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* @retrans: Number of retransmissions occurred due to ACK_TIMEOUT
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* @ws_from_tap: Window scaling factor advertised from tap/guest
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* @ws_to_tap: Window scaling factor advertised to tap/guest
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* @sndbuf: Sending buffer in kernel, rounded to 2 ^ SNDBUF_BITS
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* @seq_dup_ack_approx: Last duplicate ACK number sent to tap
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* @faddr: Guest side forwarding address (guest's remote address)
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* @eport: Guest side endpoint port (guest's local port)
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* @fport: Guest side forwarding port (guest's remote port)
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* @wnd_from_tap: Last window size from tap, unscaled (as received)
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* @wnd_to_tap: Sending window advertised to tap, unscaled (as sent)
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* @seq_to_tap: Next sequence for packets to tap
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* @seq_ack_from_tap: Last ACK number received from tap
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* @seq_from_tap: Next sequence for packets from tap (not actually sent)
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* @seq_ack_to_tap: Last ACK number sent to tap
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* @seq_init_from_tap: Initial sequence number from tap
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*/
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struct tcp_tap_conn {
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/* Must be first element */
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struct flow_common f;
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bool in_epoll :1;
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#define TCP_RETRANS_BITS 3
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unsigned int retrans :TCP_RETRANS_BITS;
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#define TCP_MAX_RETRANS MAX_FROM_BITS(TCP_RETRANS_BITS)
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#define TCP_WS_BITS 4 /* RFC 7323 */
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#define TCP_WS_MAX 14
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unsigned int ws_from_tap :TCP_WS_BITS;
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unsigned int ws_to_tap :TCP_WS_BITS;
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int sock :FD_REF_BITS;
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uint8_t events;
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#define CLOSED 0
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#define SOCK_ACCEPTED BIT(0) /* implies SYN sent to tap */
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#define TAP_SYN_RCVD BIT(1) /* implies socket connecting */
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#define TAP_SYN_ACK_SENT BIT( 3) /* implies socket connected */
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#define ESTABLISHED BIT(2)
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#define SOCK_FIN_RCVD BIT( 3)
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#define SOCK_FIN_SENT BIT( 4)
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#define TAP_FIN_RCVD BIT( 5)
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#define TAP_FIN_SENT BIT( 6)
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#define TAP_FIN_ACKED BIT( 7)
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#define CONN_STATE_BITS /* Setting these clears other flags */ \
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(SOCK_ACCEPTED | TAP_SYN_RCVD | ESTABLISHED)
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int timer :FD_REF_BITS;
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uint8_t flags;
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#define STALLED BIT(0)
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#define LOCAL BIT(1)
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#define ACTIVE_CLOSE BIT(2)
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#define ACK_TO_TAP_DUE BIT(3)
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#define ACK_FROM_TAP_DUE BIT(4)
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#define TCP_MSS_BITS 14
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unsigned int tap_mss :TCP_MSS_BITS;
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#define MSS_SET(conn, mss) (conn->tap_mss = (mss >> (16 - TCP_MSS_BITS)))
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#define MSS_GET(conn) (conn->tap_mss << (16 - TCP_MSS_BITS))
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#define SNDBUF_BITS 24
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unsigned int sndbuf :SNDBUF_BITS;
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#define SNDBUF_SET(conn, bytes) (conn->sndbuf = ((bytes) >> (32 - SNDBUF_BITS)))
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#define SNDBUF_GET(conn) (conn->sndbuf << (32 - SNDBUF_BITS))
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uint8_t seq_dup_ack_approx;
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union inany_addr faddr;
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in_port_t eport;
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in_port_t fport;
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uint16_t wnd_from_tap;
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uint16_t wnd_to_tap;
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uint32_t seq_to_tap;
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uint32_t seq_ack_from_tap;
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uint32_t seq_from_tap;
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uint32_t seq_ack_to_tap;
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uint32_t seq_init_from_tap;
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};
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#define SIDES 2
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/**
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* struct tcp_splice_conn - Descriptor for a spliced TCP connection
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* @f: Generic flow information
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* @in_epoll: Is the connection in the epoll set?
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* @s: File descriptor for sockets
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* @pipe: File descriptors for pipes
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* @events: Events observed/actions performed on connection
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* @flags: Connection flags (attributes, not events)
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* @read: Bytes read (not fully written to other side in one shot)
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* @written: Bytes written (not fully written from one other side read)
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*/
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struct tcp_splice_conn {
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/* Must be first element */
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struct flow_common f;
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bool in_epoll :1;
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int s[SIDES];
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int pipe[SIDES][2];
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uint8_t events;
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#define SPLICE_CLOSED 0
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#define SPLICE_CONNECT BIT(0)
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#define SPLICE_ESTABLISHED BIT(1)
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#define OUT_WAIT_0 BIT(2)
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#define OUT_WAIT_1 BIT(3)
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#define FIN_RCVD_0 BIT(4)
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#define FIN_RCVD_1 BIT(5)
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#define FIN_SENT_0 BIT(6)
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#define FIN_SENT_1 BIT(7)
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uint8_t flags;
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#define SPLICE_V6 BIT(0)
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#define RCVLOWAT_SET_0 BIT(1)
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#define RCVLOWAT_SET_1 BIT(2)
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#define RCVLOWAT_ACT_0 BIT(3)
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#define RCVLOWAT_ACT_1 BIT(4)
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#define CLOSING BIT(5)
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uint32_t read[SIDES];
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uint32_t written[SIDES];
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};
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/* Socket pools */
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#define TCP_SOCK_POOL_SIZE 32
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extern int init_sock_pool4 [TCP_SOCK_POOL_SIZE];
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extern int init_sock_pool6 [TCP_SOCK_POOL_SIZE];
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bool tcp_flow_defer(union flow *flow);
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bool tcp_splice_flow_defer(union flow *flow);
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void tcp_splice_timer(const struct ctx *c, union flow *flow);
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int tcp_conn_pool_sock(int pool[]);
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int tcp_conn_sock(const struct ctx *c, sa_family_t af);
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int tcp_sock_refill_pool(const struct ctx *c, int pool[], sa_family_t af);
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void tcp_splice_refill(const struct ctx *c);
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#endif /* TCP_CONN_H */
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