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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/sctp/output.c | |
download | linux-fsl-qoriq-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'net/sctp/output.c')
-rw-r--r-- | net/sctp/output.c | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/net/sctp/output.c b/net/sctp/output.c new file mode 100644 index 0000000..9013f64 --- /dev/null +++ b/net/sctp/output.c @@ -0,0 +1,646 @@ +/* SCTP kernel reference Implementation + * (C) Copyright IBM Corp. 2001, 2004 + * Copyright (c) 1999-2000 Cisco, Inc. + * Copyright (c) 1999-2001 Motorola, Inc. + * + * This file is part of the SCTP kernel reference Implementation + * + * These functions handle output processing. + * + * The SCTP reference implementation 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, or (at your option) + * any later version. + * + * The SCTP reference implementation is distributed in the hope that it + * will be useful, but WITHOUT ANY WARRANTY; without even the implied + * ************************ + * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + * See the GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU CC; see the file COPYING. If not, write to + * the Free Software Foundation, 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + * + * Please send any bug reports or fixes you make to the + * email address(es): + * lksctp developers <lksctp-developers@lists.sourceforge.net> + * + * Or submit a bug report through the following website: + * http://www.sf.net/projects/lksctp + * + * Written or modified by: + * La Monte H.P. Yarroll <piggy@acm.org> + * Karl Knutson <karl@athena.chicago.il.us> + * Jon Grimm <jgrimm@austin.ibm.com> + * Sridhar Samudrala <sri@us.ibm.com> + * + * Any bugs reported given to us we will try to fix... any fixes shared will + * be incorporated into the next SCTP release. + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/wait.h> +#include <linux/time.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/init.h> +#include <net/inet_ecn.h> +#include <net/icmp.h> + +#ifndef TEST_FRAME +#include <net/tcp.h> +#endif /* TEST_FRAME (not defined) */ + +#include <linux/socket.h> /* for sa_family_t */ +#include <net/sock.h> + +#include <net/sctp/sctp.h> +#include <net/sctp/sm.h> + +/* Forward declarations for private helpers. */ +static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, + struct sctp_chunk *chunk); + +/* Config a packet. + * This appears to be a followup set of initializations. + */ +struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, + __u32 vtag, int ecn_capable) +{ + struct sctp_chunk *chunk = NULL; + + SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __FUNCTION__, + packet, vtag); + + packet->vtag = vtag; + packet->has_cookie_echo = 0; + packet->has_sack = 0; + packet->ipfragok = 0; + + if (ecn_capable && sctp_packet_empty(packet)) { + chunk = sctp_get_ecne_prepend(packet->transport->asoc); + + /* If there a is a prepend chunk stick it on the list before + * any other chunks get appended. + */ + if (chunk) + sctp_packet_append_chunk(packet, chunk); + } + + return packet; +} + +/* Initialize the packet structure. */ +struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, + struct sctp_transport *transport, + __u16 sport, __u16 dport) +{ + struct sctp_association *asoc = transport->asoc; + size_t overhead; + + SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __FUNCTION__, + packet, transport); + + packet->transport = transport; + packet->source_port = sport; + packet->destination_port = dport; + skb_queue_head_init(&packet->chunks); + if (asoc) { + struct sctp_sock *sp = sctp_sk(asoc->base.sk); + overhead = sp->pf->af->net_header_len; + } else { + overhead = sizeof(struct ipv6hdr); + } + overhead += sizeof(struct sctphdr); + packet->overhead = overhead; + packet->size = overhead; + packet->vtag = 0; + packet->has_cookie_echo = 0; + packet->has_sack = 0; + packet->ipfragok = 0; + packet->malloced = 0; + return packet; +} + +/* Free a packet. */ +void sctp_packet_free(struct sctp_packet *packet) +{ + struct sctp_chunk *chunk; + + SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet); + + while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) + sctp_chunk_free(chunk); + + if (packet->malloced) + kfree(packet); +} + +/* This routine tries to append the chunk to the offered packet. If adding + * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk + * is not present in the packet, it transmits the input packet. + * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long + * as it can fit in the packet, but any more data that does not fit in this + * packet can be sent only after receiving the COOKIE_ACK. + */ +sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk) +{ + sctp_xmit_t retval; + int error = 0; + + SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__, + packet, chunk); + + switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { + case SCTP_XMIT_PMTU_FULL: + if (!packet->has_cookie_echo) { + error = sctp_packet_transmit(packet); + if (error < 0) + chunk->skb->sk->sk_err = -error; + + /* If we have an empty packet, then we can NOT ever + * return PMTU_FULL. + */ + retval = sctp_packet_append_chunk(packet, chunk); + } + break; + + case SCTP_XMIT_RWND_FULL: + case SCTP_XMIT_OK: + case SCTP_XMIT_NAGLE_DELAY: + break; + }; + + return retval; +} + +/* Try to bundle a SACK with the packet. */ +static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, + struct sctp_chunk *chunk) +{ + sctp_xmit_t retval = SCTP_XMIT_OK; + + /* If sending DATA and haven't aleady bundled a SACK, try to + * bundle one in to the packet. + */ + if (sctp_chunk_is_data(chunk) && !pkt->has_sack && + !pkt->has_cookie_echo) { + struct sctp_association *asoc; + asoc = pkt->transport->asoc; + + if (asoc->a_rwnd > asoc->rwnd) { + struct sctp_chunk *sack; + asoc->a_rwnd = asoc->rwnd; + sack = sctp_make_sack(asoc); + if (sack) { + struct timer_list *timer; + retval = sctp_packet_append_chunk(pkt, sack); + asoc->peer.sack_needed = 0; + timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; + if (timer_pending(timer) && del_timer(timer)) + sctp_association_put(asoc); + } + } + } + return retval; +} + +/* Append a chunk to the offered packet reporting back any inability to do + * so. + */ +sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, + struct sctp_chunk *chunk) +{ + sctp_xmit_t retval = SCTP_XMIT_OK; + __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); + size_t psize; + size_t pmtu; + int too_big; + + SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__, packet, + chunk); + + retval = sctp_packet_bundle_sack(packet, chunk); + psize = packet->size; + + if (retval != SCTP_XMIT_OK) + goto finish; + + pmtu = ((packet->transport->asoc) ? + (packet->transport->asoc->pmtu) : + (packet->transport->pmtu)); + + too_big = (psize + chunk_len > pmtu); + + /* Decide if we need to fragment or resubmit later. */ + if (too_big) { + /* Both control chunks and data chunks with TSNs are + * non-fragmentable. + */ + if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk)) { + /* We no longer do re-fragmentation. + * Just fragment at the IP layer, if we + * actually hit this condition + */ + packet->ipfragok = 1; + goto append; + + } else { + retval = SCTP_XMIT_PMTU_FULL; + goto finish; + } + } + +append: + /* We believe that this chunk is OK to add to the packet (as + * long as we have the cwnd for it). + */ + + /* DATA is a special case since we must examine both rwnd and cwnd + * before we send DATA. + */ + if (sctp_chunk_is_data(chunk)) { + retval = sctp_packet_append_data(packet, chunk); + /* Disallow SACK bundling after DATA. */ + packet->has_sack = 1; + if (SCTP_XMIT_OK != retval) + goto finish; + } else if (SCTP_CID_COOKIE_ECHO == chunk->chunk_hdr->type) + packet->has_cookie_echo = 1; + else if (SCTP_CID_SACK == chunk->chunk_hdr->type) + packet->has_sack = 1; + + /* It is OK to send this chunk. */ + __skb_queue_tail(&packet->chunks, (struct sk_buff *)chunk); + packet->size += chunk_len; + chunk->transport = packet->transport; +finish: + return retval; +} + +/* All packets are sent to the network through this function from + * sctp_outq_tail(). + * + * The return value is a normal kernel error return value. + */ +int sctp_packet_transmit(struct sctp_packet *packet) +{ + struct sctp_transport *tp = packet->transport; + struct sctp_association *asoc = tp->asoc; + struct sctphdr *sh; + __u32 crc32; + struct sk_buff *nskb; + struct sctp_chunk *chunk; + struct sock *sk; + int err = 0; + int padding; /* How much padding do we need? */ + __u8 has_data = 0; + struct dst_entry *dst; + + SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet); + + /* Do NOT generate a chunkless packet. */ + chunk = (struct sctp_chunk *)skb_peek(&packet->chunks); + if (unlikely(!chunk)) + return err; + + /* Set up convenience variables... */ + sk = chunk->skb->sk; + + /* Allocate the new skb. */ + nskb = dev_alloc_skb(packet->size); + if (!nskb) + goto nomem; + + /* Make sure the outbound skb has enough header room reserved. */ + skb_reserve(nskb, packet->overhead); + + /* Set the owning socket so that we know where to get the + * destination IP address. + */ + skb_set_owner_w(nskb, sk); + + /* Build the SCTP header. */ + sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); + sh->source = htons(packet->source_port); + sh->dest = htons(packet->destination_port); + + /* From 6.8 Adler-32 Checksum Calculation: + * After the packet is constructed (containing the SCTP common + * header and one or more control or DATA chunks), the + * transmitter shall: + * + * 1) Fill in the proper Verification Tag in the SCTP common + * header and initialize the checksum field to 0's. + */ + sh->vtag = htonl(packet->vtag); + sh->checksum = 0; + + /* 2) Calculate the Adler-32 checksum of the whole packet, + * including the SCTP common header and all the + * chunks. + * + * Note: Adler-32 is no longer applicable, as has been replaced + * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. + */ + crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr)); + + /** + * 6.10 Bundling + * + * An endpoint bundles chunks by simply including multiple + * chunks in one outbound SCTP packet. ... + */ + + /** + * 3.2 Chunk Field Descriptions + * + * The total length of a chunk (including Type, Length and + * Value fields) MUST be a multiple of 4 bytes. If the length + * of the chunk is not a multiple of 4 bytes, the sender MUST + * pad the chunk with all zero bytes and this padding is not + * included in the chunk length field. The sender should + * never pad with more than 3 bytes. + * + * [This whole comment explains WORD_ROUND() below.] + */ + SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); + while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) { + if (sctp_chunk_is_data(chunk)) { + + if (!chunk->has_tsn) { + sctp_chunk_assign_ssn(chunk); + sctp_chunk_assign_tsn(chunk); + + /* 6.3.1 C4) When data is in flight and when allowed + * by rule C5, a new RTT measurement MUST be made each + * round trip. Furthermore, new RTT measurements + * SHOULD be made no more than once per round-trip + * for a given destination transport address. + */ + + if (!tp->rto_pending) { + chunk->rtt_in_progress = 1; + tp->rto_pending = 1; + } + } else + chunk->resent = 1; + + chunk->sent_at = jiffies; + has_data = 1; + } + + padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; + if (padding) + memset(skb_put(chunk->skb, padding), 0, padding); + + crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len), + chunk->skb->data, + chunk->skb->len, crc32); + + SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", + "*** Chunk", chunk, + sctp_cname(SCTP_ST_CHUNK( + chunk->chunk_hdr->type)), + chunk->has_tsn ? "TSN" : "No TSN", + chunk->has_tsn ? + ntohl(chunk->subh.data_hdr->tsn) : 0, + "length", ntohs(chunk->chunk_hdr->length), + "chunk->skb->len", chunk->skb->len, + "rtt_in_progress", chunk->rtt_in_progress); + + /* + * If this is a control chunk, this is our last + * reference. Free data chunks after they've been + * acknowledged or have failed. + */ + if (!sctp_chunk_is_data(chunk)) + sctp_chunk_free(chunk); + } + + /* Perform final transformation on checksum. */ + crc32 = sctp_end_cksum(crc32); + + /* 3) Put the resultant value into the checksum field in the + * common header, and leave the rest of the bits unchanged. + */ + sh->checksum = htonl(crc32); + + /* IP layer ECN support + * From RFC 2481 + * "The ECN-Capable Transport (ECT) bit would be set by the + * data sender to indicate that the end-points of the + * transport protocol are ECN-capable." + * + * Now setting the ECT bit all the time, as it should not cause + * any problems protocol-wise even if our peer ignores it. + * + * Note: The works for IPv6 layer checks this bit too later + * in transmission. See IP6_ECN_flow_xmit(). + */ + INET_ECN_xmit(nskb->sk); + + /* Set up the IP options. */ + /* BUG: not implemented + * For v4 this all lives somewhere in sk->sk_opt... + */ + + /* Dump that on IP! */ + if (asoc && asoc->peer.last_sent_to != tp) { + /* Considering the multiple CPU scenario, this is a + * "correcter" place for last_sent_to. --xguo + */ + asoc->peer.last_sent_to = tp; + } + + if (has_data) { + struct timer_list *timer; + unsigned long timeout; + + tp->last_time_used = jiffies; + + /* Restart the AUTOCLOSE timer when sending data. */ + if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { + timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; + timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; + + if (!mod_timer(timer, jiffies + timeout)) + sctp_association_hold(asoc); + } + } + + dst = tp->dst; + /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ + if (!dst || (dst->obsolete > 1)) { + dst_release(dst); + sctp_transport_route(tp, NULL, sctp_sk(sk)); + sctp_assoc_sync_pmtu(asoc); + } + + nskb->dst = dst_clone(tp->dst); + if (!nskb->dst) + goto no_route; + + SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", + nskb->len); + + (*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok); + +out: + packet->size = packet->overhead; + return err; +no_route: + kfree_skb(nskb); + IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES); + + /* FIXME: Returning the 'err' will effect all the associations + * associated with a socket, although only one of the paths of the + * association is unreachable. + * The real failure of a transport or association can be passed on + * to the user via notifications. So setting this error may not be + * required. + */ + /* err = -EHOSTUNREACH; */ +err: + /* Control chunks are unreliable so just drop them. DATA chunks + * will get resent or dropped later. + */ + + while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) { + if (!sctp_chunk_is_data(chunk)) + sctp_chunk_free(chunk); + } + goto out; +nomem: + err = -ENOMEM; + goto err; +} + +/******************************************************************** + * 2nd Level Abstractions + ********************************************************************/ + +/* This private function handles the specifics of appending DATA chunks. */ +static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, + struct sctp_chunk *chunk) +{ + sctp_xmit_t retval = SCTP_XMIT_OK; + size_t datasize, rwnd, inflight; + struct sctp_transport *transport = packet->transport; + __u32 max_burst_bytes; + struct sctp_association *asoc = transport->asoc; + struct sctp_sock *sp = sctp_sk(asoc->base.sk); + struct sctp_outq *q = &asoc->outqueue; + + /* RFC 2960 6.1 Transmission of DATA Chunks + * + * A) At any given time, the data sender MUST NOT transmit new data to + * any destination transport address if its peer's rwnd indicates + * that the peer has no buffer space (i.e. rwnd is 0, see Section + * 6.2.1). However, regardless of the value of rwnd (including if it + * is 0), the data sender can always have one DATA chunk in flight to + * the receiver if allowed by cwnd (see rule B below). This rule + * allows the sender to probe for a change in rwnd that the sender + * missed due to the SACK having been lost in transit from the data + * receiver to the data sender. + */ + + rwnd = asoc->peer.rwnd; + inflight = asoc->outqueue.outstanding_bytes; + + datasize = sctp_data_size(chunk); + + if (datasize > rwnd) { + if (inflight > 0) { + /* We have (at least) one data chunk in flight, + * so we can't fall back to rule 6.1 B). + */ + retval = SCTP_XMIT_RWND_FULL; + goto finish; + } + } + + /* sctpimpguide-05 2.14.2 + * D) When the time comes for the sender to + * transmit new DATA chunks, the protocol parameter Max.Burst MUST + * first be applied to limit how many new DATA chunks may be sent. + * The limit is applied by adjusting cwnd as follows: + * if ((flightsize + Max.Burst * MTU) < cwnd) + * cwnd = flightsize + Max.Burst * MTU + */ + max_burst_bytes = asoc->max_burst * asoc->pmtu; + if ((transport->flight_size + max_burst_bytes) < transport->cwnd) { + transport->cwnd = transport->flight_size + max_burst_bytes; + SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: " + "transport: %p, cwnd: %d, " + "ssthresh: %d, flight_size: %d, " + "pba: %d\n", + __FUNCTION__, transport, + transport->cwnd, + transport->ssthresh, + transport->flight_size, + transport->partial_bytes_acked); + } + + /* RFC 2960 6.1 Transmission of DATA Chunks + * + * B) At any given time, the sender MUST NOT transmit new data + * to a given transport address if it has cwnd or more bytes + * of data outstanding to that transport address. + */ + /* RFC 7.2.4 & the Implementers Guide 2.8. + * + * 3) ... + * When a Fast Retransmit is being performed the sender SHOULD + * ignore the value of cwnd and SHOULD NOT delay retransmission. + */ + if (!chunk->fast_retransmit) + if (transport->flight_size >= transport->cwnd) { + retval = SCTP_XMIT_RWND_FULL; + goto finish; + } + + /* Nagle's algorithm to solve small-packet problem: + * Inhibit the sending of new chunks when new outgoing data arrives + * if any previously transmitted data on the connection remains + * unacknowledged. + */ + if (!sp->nodelay && sctp_packet_empty(packet) && + q->outstanding_bytes && sctp_state(asoc, ESTABLISHED)) { + unsigned len = datasize + q->out_qlen; + + /* Check whether this chunk and all the rest of pending + * data will fit or delay in hopes of bundling a full + * sized packet. + */ + if (len < asoc->pmtu - packet->overhead) { + retval = SCTP_XMIT_NAGLE_DELAY; + goto finish; + } + } + + /* Keep track of how many bytes are in flight over this transport. */ + transport->flight_size += datasize; + + /* Keep track of how many bytes are in flight to the receiver. */ + asoc->outqueue.outstanding_bytes += datasize; + + /* Update our view of the receiver's rwnd. */ + if (datasize < rwnd) + rwnd -= datasize; + else + rwnd = 0; + + asoc->peer.rwnd = rwnd; + /* Has been accepted for transmission. */ + if (!asoc->peer.prsctp_capable) + chunk->msg->can_abandon = 0; + +finish: + return retval; +} |