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sctp: add the constants/variables and states and some APIs for transport

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These are 4 constants described in rfc8899#section-5.1.2:

  MAX_PROBES, MIN_PLPMTU, MAX_PLPMTU, BASE_PLPMTU;

And 2 variables described in rfc8899#section-5.1.3:

  PROBED_SIZE, PROBE_COUNT;

And 5 states described in rfc8899#section-5.2:

  DISABLED, BASE, SEARCH, SEARCH_COMPLETE, ERROR;

And these 4 APIs are used to reset/update PLPMTUD, check if PLPMTUD is
enabled, and calculate the additional headers length for a transport.

Note the member 'probe_high' in transport will be set to the probe
size when a probe fails with this probe size in the next patches.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2021-06-22 14:04:50 -04:00 committed by David S. Miller
parent 3190b649b4
commit d9e2e410ae
3 changed files with 70 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/net/sctp/constants.h
View File

@ -200,6 +200,23 @@ enum sctp_sock_state {
SCTP_SS_CLOSING = TCP_CLOSE_WAIT,
};
enum sctp_plpmtud_state {
SCTP_PL_DISABLED,
SCTP_PL_BASE,
SCTP_PL_SEARCH,
SCTP_PL_COMPLETE,
SCTP_PL_ERROR,
};
#define SCTP_BASE_PLPMTU 1200
#define SCTP_MAX_PLPMTU 9000
#define SCTP_MIN_PLPMTU 512
#define SCTP_MAX_PROBES 3
#define SCTP_PL_BIG_STEP 32
#define SCTP_PL_MIN_STEP 4
/* These functions map various type to printable names. */
const char *sctp_cname(const union sctp_subtype id); /* chunk types */
const char *sctp_oname(const union sctp_subtype id); /* other events */

48
include/net/sctp/sctp.h
View File

@ -573,14 +573,15 @@ static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *
/* Calculate max payload size given a MTU, or the total overhead if
* given MTU is zero
*/
static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
__u32 mtu, __u32 extra)
static inline __u32 __sctp_mtu_payload(const struct sctp_sock *sp,
const struct sctp_transport *t,
__u32 mtu, __u32 extra)
{
__u32 overhead = sizeof(struct sctphdr) + extra;
if (sp) {
overhead += sp->pf->af->net_header_len;
if (sp->udp_port)
if (sp->udp_port && (!t || t->encap_port))
overhead += sizeof(struct udphdr);
} else {
overhead += sizeof(struct ipv6hdr);
@ -592,6 +593,12 @@ static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
return mtu ? mtu - overhead : overhead;
}
static inline __u32 sctp_mtu_payload(const struct sctp_sock *sp,
__u32 mtu, __u32 extra)
{
return __sctp_mtu_payload(sp, NULL, mtu, extra);
}
static inline __u32 sctp_dst_mtu(const struct dst_entry *dst)
{
return SCTP_TRUNC4(max_t(__u32, dst_mtu(dst),
@ -615,6 +622,41 @@ static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize)
return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize);
}
static inline int sctp_transport_pl_hlen(struct sctp_transport *t)
{
return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0);
}
static inline void sctp_transport_pl_reset(struct sctp_transport *t)
{
if (t->probe_interval && (t->param_flags & SPP_PMTUD_ENABLE) &&
(t->state == SCTP_ACTIVE || t->state == SCTP_UNKNOWN)) {
if (t->pl.state == SCTP_PL_DISABLED) {
t->pl.state = SCTP_PL_BASE;
t->pl.pmtu = SCTP_BASE_PLPMTU;
t->pl.probe_size = SCTP_BASE_PLPMTU;
}
} else {
if (t->pl.state != SCTP_PL_DISABLED)
t->pl.state = SCTP_PL_DISABLED;
}
}
static inline void sctp_transport_pl_update(struct sctp_transport *t)
{
if (t->pl.state == SCTP_PL_DISABLED)
return;
t->pl.state = SCTP_PL_BASE;
t->pl.pmtu = SCTP_BASE_PLPMTU;
t->pl.probe_size = SCTP_BASE_PLPMTU;
}
static inline bool sctp_transport_pl_enabled(struct sctp_transport *t)
{
return t->pl.state != SCTP_PL_DISABLED;
}
static inline bool sctp_newsk_ready(const struct sock *sk)
{
return sock_flag(sk, SOCK_DEAD) || sk->sk_socket;

8
include/net/sctp/structs.h
View File

@ -978,6 +978,14 @@ struct sctp_transport {
char cacc_saw_newack;
} cacc;
struct {
__u16 pmtu;
__u16 probe_size;
__u16 probe_high;
__u8 probe_count;
__u8 state;
} pl; /* plpmtud related */
/* 64-bit random number sent with heartbeat. */
__u64 hb_nonce;