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OpenCloudOS-Kernel/net/dccp/output.c

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/*
* net/dccp/output.c
*
* An implementation of the DCCP protocol
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <linux/dccp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include "ccid.h"
#include "dccp.h"
static inline void dccp_event_ack_sent(struct sock *sk)
{
inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
}
/*
* All SKB's seen here are completely headerless. It is our
* job to build the DCCP header, and pass the packet down to
* IP so it can do the same plus pass the packet off to the
* device.
*/
int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
{
if (likely(skb != NULL)) {
const struct inet_sock *inet = inet_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
struct dccp_hdr *dh;
/* XXX For now we're using only 48 bits sequence numbers */
const int dccp_header_size = sizeof(*dh) +
sizeof(struct dccp_hdr_ext) +
dccp_packet_hdr_len(dcb->dccpd_type);
int err, set_ack = 1;
u64 ackno = dp->dccps_gsr;
dccp_inc_seqno(&dp->dccps_gss);
switch (dcb->dccpd_type) {
case DCCP_PKT_DATA:
set_ack = 0;
break;
case DCCP_PKT_SYNC:
case DCCP_PKT_SYNCACK:
ackno = dcb->dccpd_seq;
break;
}
dcb->dccpd_seq = dp->dccps_gss;
dccp_insert_options(sk, skb);
skb->h.raw = skb_push(skb, dccp_header_size);
dh = dccp_hdr(skb);
/*
* Data packets are not cloned as they are never retransmitted
*/
if (skb_cloned(skb))
skb_set_owner_w(skb, sk);
/* Build DCCP header and checksum it. */
memset(dh, 0, dccp_header_size);
dh->dccph_type = dcb->dccpd_type;
dh->dccph_sport = inet->sport;
dh->dccph_dport = inet->dport;
dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
dh->dccph_ccval = dcb->dccpd_ccval;
/* XXX For now we're using only 48 bits sequence numbers */
dh->dccph_x = 1;
dp->dccps_awh = dp->dccps_gss;
dccp_hdr_set_seq(dh, dp->dccps_gss);
if (set_ack)
dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
switch (dcb->dccpd_type) {
case DCCP_PKT_REQUEST:
dccp_hdr_request(skb)->dccph_req_service =
dcb->dccpd_service;
break;
case DCCP_PKT_RESET:
dccp_hdr_reset(skb)->dccph_reset_code =
dcb->dccpd_reset_code;
break;
}
dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
inet->daddr);
if (dcb->dccpd_type == DCCP_PKT_ACK ||
dcb->dccpd_type == DCCP_PKT_DATAACK)
dccp_event_ack_sent(sk);
DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
err = ip_queue_xmit(skb, 0);
if (err <= 0)
return err;
/* NET_XMIT_CN is special. It does not guarantee,
* that this packet is lost. It tells that device
* is about to start to drop packets or already
* drops some packets of the same priority and
* invokes us to send less aggressively.
*/
return err == NET_XMIT_CN ? 0 : err;
}
return -ENOBUFS;
}
unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
{
struct dccp_sock *dp = dccp_sk(sk);
int mss_now;
/*
* FIXME: we really should be using the af_specific thing to support
* IPv6.
* mss_now = pmtu - tp->af_specific->net_header_len -
* sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
*/
mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
sizeof(struct dccp_hdr_ext);
/* Now subtract optional transport overhead */
mss_now -= dp->dccps_ext_header_len;
/*
* FIXME: this should come from the CCID infrastructure, where, say,
* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
* make it a multiple of 4
*/
mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
/* And store cached results */
dp->dccps_pmtu_cookie = pmtu;
dp->dccps_mss_cache = mss_now;
return mss_now;
}
int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, const int len)
{
const struct dccp_sock *dp = dccp_sk(sk);
int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, len);
if (err == 0) {
const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
if (sk->sk_state == DCCP_PARTOPEN) {
/* See 8.1.5. Handshake Completion */
inet_csk_schedule_ack(sk);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
inet_csk(sk)->icsk_rto,
DCCP_RTO_MAX);
dcb->dccpd_type = DCCP_PKT_DATAACK;
/*
* FIXME: we really should have a
* dccps_ack_pending or use icsk.
*/
} else if (inet_csk_ack_scheduled(sk) ||
(dp->dccps_options.dccpo_send_ack_vector &&
ap->dccpap_buf_ackno != DCCP_MAX_SEQNO + 1 &&
ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1))
dcb->dccpd_type = DCCP_PKT_DATAACK;
else
dcb->dccpd_type = DCCP_PKT_DATA;
err = dccp_transmit_skb(sk, skb);
ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
}
return err;
}
int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
{
if (inet_sk_rebuild_header(sk) != 0)
return -EHOSTUNREACH; /* Routing failure or similar. */
return dccp_transmit_skb(sk, (skb_cloned(skb) ?
pskb_copy(skb, GFP_ATOMIC):
skb_clone(skb, GFP_ATOMIC)));
}
struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
struct request_sock *req)
{
struct dccp_hdr *dh;
const int dccp_header_size = sizeof(struct dccp_hdr) +
sizeof(struct dccp_hdr_ext) +
sizeof(struct dccp_hdr_response);
struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
dccp_header_size, 1,
GFP_ATOMIC);
if (skb == NULL)
return NULL;
/* Reserve space for headers. */
skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
skb->dst = dst_clone(dst);
skb->csum = 0;
DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
DCCP_SKB_CB(skb)->dccpd_seq = dccp_rsk(req)->dreq_iss;
dccp_insert_options(sk, skb);
skb->h.raw = skb_push(skb, dccp_header_size);
dh = dccp_hdr(skb);
memset(dh, 0, dccp_header_size);
dh->dccph_sport = inet_sk(sk)->sport;
dh->dccph_dport = inet_rsk(req)->rmt_port;
dh->dccph_doff = (dccp_header_size +
DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
dh->dccph_type = DCCP_PKT_RESPONSE;
dh->dccph_x = 1;
dccp_hdr_set_seq(dh, dccp_rsk(req)->dreq_iss);
dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr);
dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
inet_rsk(req)->rmt_addr);
DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
return skb;
}
struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
const enum dccp_reset_codes code)
{
struct dccp_hdr *dh;
struct dccp_sock *dp = dccp_sk(sk);
const int dccp_header_size = sizeof(struct dccp_hdr) +
sizeof(struct dccp_hdr_ext) +
sizeof(struct dccp_hdr_reset);
struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
dccp_header_size, 1,
GFP_ATOMIC);
if (skb == NULL)
return NULL;
/* Reserve space for headers. */
skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
skb->dst = dst_clone(dst);
skb->csum = 0;
dccp_inc_seqno(&dp->dccps_gss);
DCCP_SKB_CB(skb)->dccpd_reset_code = code;
DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
dccp_insert_options(sk, skb);
skb->h.raw = skb_push(skb, dccp_header_size);
dh = dccp_hdr(skb);
memset(dh, 0, dccp_header_size);
dh->dccph_sport = inet_sk(sk)->sport;
dh->dccph_dport = inet_sk(sk)->dport;
dh->dccph_doff = (dccp_header_size +
DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
dh->dccph_type = DCCP_PKT_RESET;
dh->dccph_x = 1;
dccp_hdr_set_seq(dh, dp->dccps_gss);
dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
dccp_hdr_reset(skb)->dccph_reset_code = code;
dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
inet_sk(sk)->daddr);
DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
return skb;
}
/*
* Do all connect socket setups that can be done AF independent.
*/
static inline void dccp_connect_init(struct sock *sk)
{
struct dst_entry *dst = __sk_dst_get(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
sk->sk_err = 0;
sock_reset_flag(sk, SOCK_DONE);
dccp_sync_mss(sk, dst_mtu(dst));
/*
* FIXME: set dp->{dccps_swh,dccps_swl}, with
* something like dccp_inc_seq
*/
icsk->icsk_retransmits = 0;
}
int dccp_connect(struct sock *sk)
{
struct sk_buff *skb;
struct inet_connection_sock *icsk = inet_csk(sk);
dccp_connect_init(sk);
skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
if (unlikely(skb == NULL))
return -ENOBUFS;
/* Reserve space for headers. */
skb_reserve(skb, MAX_DCCP_HEADER);
DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
/* FIXME: set service to something meaningful, coming
* from userspace*/
DCCP_SKB_CB(skb)->dccpd_service = 0;
skb->csum = 0;
skb_set_owner_w(skb, sk);
BUG_TRAP(sk->sk_send_head == NULL);
sk->sk_send_head = skb;
dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
/* Timer for repeating the REQUEST until an answer. */
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
icsk->icsk_rto, DCCP_RTO_MAX);
return 0;
}
void dccp_send_ack(struct sock *sk)
{
/* If we have been reset, we may not send again. */
if (sk->sk_state != DCCP_CLOSED) {
struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
if (skb == NULL) {
inet_csk_schedule_ack(sk);
inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
TCP_DELACK_MAX,
DCCP_RTO_MAX);
return;
}
/* Reserve space for headers */
skb_reserve(skb, MAX_DCCP_HEADER);
skb->csum = 0;
DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
skb_set_owner_w(skb, sk);
dccp_transmit_skb(sk, skb);
}
}
EXPORT_SYMBOL_GPL(dccp_send_ack);
void dccp_send_delayed_ack(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
/*
* FIXME: tune this timer. elapsed time fixes the skew, so no problem
* with using 2s, and active senders also piggyback the ACK into a
* DATAACK packet, so this is really for quiescent senders.
*/
unsigned long timeout = jiffies + 2 * HZ;
/* Use new timeout only if there wasn't a older one earlier. */
if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
/* If delack timer was blocked or is about to expire,
* send ACK now.
*
* FIXME: check the "about to expire" part
*/
if (icsk->icsk_ack.blocked) {
dccp_send_ack(sk);
return;
}
if (!time_before(timeout, icsk->icsk_ack.timeout))
timeout = icsk->icsk_ack.timeout;
}
icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
icsk->icsk_ack.timeout = timeout;
sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
}
void dccp_send_sync(struct sock *sk, const u64 seq,
const enum dccp_pkt_type pkt_type)
{
/*
* We are not putting this on the write queue, so
* dccp_transmit_skb() will set the ownership to this
* sock.
*/
struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
if (skb == NULL)
/* FIXME: how to make sure the sync is sent? */
return;
/* Reserve space for headers and prepare control bits. */
skb_reserve(skb, MAX_DCCP_HEADER);
skb->csum = 0;
DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
DCCP_SKB_CB(skb)->dccpd_seq = seq;
skb_set_owner_w(skb, sk);
dccp_transmit_skb(sk, skb);
}
/*
* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
* cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
* any circumstances.
*/
void dccp_send_close(struct sock *sk)
{
struct dccp_sock *dp = dccp_sk(sk);
struct sk_buff *skb;
/* Socket is locked, keep trying until memory is available. */
for (;;) {
skb = alloc_skb(sk->sk_prot->max_header, GFP_KERNEL);
if (skb != NULL)
break;
yield();
}
/* Reserve space for headers and prepare control bits. */
skb_reserve(skb, sk->sk_prot->max_header);
skb->csum = 0;
DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
skb_set_owner_w(skb, sk);
dccp_transmit_skb(sk, skb);
ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
}
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