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/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright Red Hat
* Author: David Gibson <david@gibson.dropbear.id.au>
*
* Tracking for logical "flows" of packets.
*/
#ifndef FLOW_H
#define FLOW_H
#define FLOW_TIMER_INTERVAL 1000 /* ms */
/**
* enum flow_state - States of a flow table entry
*
* An individual flow table entry moves through these states, usually in this
* order.
* General rules:
* - Code outside flow.c should never write common fields of union flow.
* - The state field may always be read.
*
* FREE - Part of the general pool of free flow table entries
* Operations:
* - flow_alloc() finds an entry and moves it to NEW
*
* NEW - Freshly allocated, uninitialised entry
* Operations:
* - flow_alloc_cancel() returns the entry to FREE
* - FLOW_SET_TYPE() sets the entry's type and moves to TYPED
* Caveats:
* - No fields other than state may be accessed
* - At most one entry may be NEW or TYPED at a time, so it's unsafe
* to use flow_alloc() again until this entry moves to ACTIVE or
* FREE
* - You may not return to the main epoll loop while any flow is NEW
*
* TYPED - Generic info initialised, type specific initialisation underway
* Operations:
* - All common fields may be read
* - Type specific fields may be read and written
* - flow_alloc_cancel() returns the entry to FREE
* - FLOW_ACTIVATE() moves the entry to ACTIVE
* Caveats:
* - At most one entry may be NEW or TYPED at a time, so it's unsafe
* to use flow_alloc() again until this entry moves to ACTIVE or
* FREE
* - You may not return to the main epoll loop while any flow is
* TYPED
*
* ACTIVE - An active, fully-initialised flow entry
* Operations:
* - All common fields may be read
* - Type specific fields may be read and written
* - Flow returns to FREE when it expires, signalled by returning
* 'true' from flow type specific deferred or timer handler
* Caveats:
* - flow_alloc_cancel() may not be called on it
*/
enum flow_state {
FLOW_STATE_FREE,
FLOW_STATE_NEW,
FLOW_STATE_TYPED,
FLOW_STATE_ACTIVE,
FLOW_NUM_STATES,
};
#define FLOW_STATE_BITS 8
static_assert(FLOW_NUM_STATES <= (1 << FLOW_STATE_BITS),
"Too many flow states for FLOW_STATE_BITS");
extern const char *flow_state_str[];
#define FLOW_STATE(f) \
((f)->state < FLOW_NUM_STATES ? flow_state_str[(f)->state] : "?")
/**
* enum flow_type - Different types of packet flows we track
*/
enum flow_type {
/* Represents an invalid or unused flow */
FLOW_TYPE_NONE = 0,
/* A TCP connection between a socket and tap interface */
FLOW_TCP,
/* A TCP connection between a host socket and ns socket */
FLOW_TCP_SPLICE,
/* ICMP echo requests from guest to host and matching replies back */
FLOW_PING4,
/* ICMPv6 echo requests from guest to host and matching replies back */
FLOW_PING6,
FLOW_NUM_TYPES,
};
#define FLOW_TYPE_BITS 8
static_assert(FLOW_NUM_TYPES <= (1 << FLOW_TYPE_BITS),
"Too many flow types for FLOW_TYPE_BITS");
extern const char *flow_type_str[];
#define FLOW_TYPE(f) \
((f)->type < FLOW_NUM_TYPES ? flow_type_str[(f)->type] : "?")
extern const uint8_t flow_proto[];
#define FLOW_PROTO(f) \
((f)->type < FLOW_NUM_TYPES ? flow_proto[(f)->type] : 0)
#define SIDES 2
#define INISIDE 0 /* Initiating side */
#define TGTSIDE 1 /* Target side */
/**
* struct flow_common - Common fields for packet flows
* @state: State of the flow table entry
* @type: Type of packet flow
*/
struct flow_common {
#ifdef __GNUC__
enum flow_state state:FLOW_STATE_BITS;
enum flow_type type:FLOW_TYPE_BITS;
#else
uint8_t state;
static_assert(sizeof(uint8_t) * 8 >= FLOW_STATE_BITS,
"Not enough bits for state field");
uint8_t type;
static_assert(sizeof(uint8_t) * 8 >= FLOW_TYPE_BITS,
"Not enough bits for type field");
#endif
};
#define FLOW_INDEX_BITS 17 /* 128k - 1 */
#define FLOW_MAX MAX_FROM_BITS(FLOW_INDEX_BITS)
#define FLOW_TABLE_PRESSURE 30 /* % of FLOW_MAX */
#define FLOW_FILE_PRESSURE 30 /* % of c->nofile */
/**
* struct flow_sidx - ID for one side of a specific flow
* @side: Side referenced (0 or 1)
* @flow: Index of flow referenced
*/
typedef struct flow_sidx {
unsigned side :1;
unsigned flow :FLOW_INDEX_BITS;
} flow_sidx_t;
static_assert(sizeof(flow_sidx_t) <= sizeof(uint32_t),
"flow_sidx_t must fit within 32 bits");
#define FLOW_SIDX_NONE ((flow_sidx_t){ .flow = FLOW_MAX })
/**
* flow_sidx_eq() - Test if two sidx values are equal
* @a, @b: sidx values
*
* Return: true iff @a and @b refer to the same side of the same flow
*/
static inline bool flow_sidx_eq(flow_sidx_t a, flow_sidx_t b)
{
return (a.flow == b.flow) && (a.side == b.side);
}
union flow;
void flow_init(void);
void flow_defer_handler(const struct ctx *c, const struct timespec *now);
void flow_log_(const struct flow_common *f, int pri, const char *fmt, ...)
__attribute__((format(printf, 3, 4)));
#define flow_log(f_, pri, ...) flow_log_(&(f_)->f, (pri), __VA_ARGS__)
#define flow_dbg(f, ...) flow_log((f), LOG_DEBUG, __VA_ARGS__)
#define flow_err(f, ...) flow_log((f), LOG_ERR, __VA_ARGS__)
#define flow_trace(f, ...) \
do { \
if (log_trace) \
flow_dbg((f), __VA_ARGS__); \
} while (0)
#endif /* FLOW_H */
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