1 |
1275 |
phoenix |
/* SCTP kernel reference Implementation
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2 |
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* (C) Copyright IBM Corp. 2001, 2004
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* Copyright (c) 1999-2000 Cisco, Inc.
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* Copyright (c) 1999-2001 Motorola, Inc.
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*
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* This file is part of the SCTP kernel reference Implementation
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*
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* These functions handle output processing.
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*
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* The SCTP reference implementation is free software;
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* you can redistribute it and/or modify it under the terms of
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* the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* The SCTP reference implementation is distributed in the hope that it
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* will be useful, but WITHOUT ANY WARRANTY; without even the implied
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* ************************
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU CC; see the file COPYING. If not, write to
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* the Free Software Foundation, 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* Please send any bug reports or fixes you make to the
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* email address(es):
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* lksctp developers <lksctp-developers@lists.sourceforge.net>
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*
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* Or submit a bug report through the following website:
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* http://www.sf.net/projects/lksctp
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*
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* Written or modified by:
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* La Monte H.P. Yarroll <piggy@acm.org>
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* Karl Knutson <karl@athena.chicago.il.us>
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* Jon Grimm <jgrimm@austin.ibm.com>
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* Sridhar Samudrala <sri@us.ibm.com>
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*
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* Any bugs reported given to us we will try to fix... any fixes shared will
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* be incorporated into the next SCTP release.
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*/
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#include <linux/types.h>
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45 |
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#include <linux/kernel.h>
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46 |
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#include <linux/wait.h>
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47 |
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#include <linux/time.h>
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48 |
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#include <linux/ip.h>
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49 |
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#include <linux/ipv6.h>
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50 |
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#include <linux/init.h>
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#include <net/inet_ecn.h>
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#include <net/icmp.h>
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53 |
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54 |
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#ifndef TEST_FRAME
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#include <net/tcp.h>
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#endif /* TEST_FRAME (not defined) */
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#include <linux/socket.h> /* for sa_family_t */
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59 |
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#include <net/sock.h>
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61 |
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#include <net/sctp/sctp.h>
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#include <net/sctp/sm.h>
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63 |
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64 |
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/* Forward declarations for private helpers. */
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65 |
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static void sctp_packet_reset(struct sctp_packet *packet);
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static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet,
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67 |
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struct sctp_chunk *chunk);
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68 |
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69 |
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/* Config a packet.
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70 |
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* This appears to be a followup set of initializations.)
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71 |
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*/
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72 |
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struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
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73 |
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__u32 vtag, int ecn_capable,
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74 |
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sctp_packet_phandler_t *prepend_handler)
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75 |
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{
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76 |
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int packet_empty = (packet->size == SCTP_IP_OVERHEAD);
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78 |
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packet->vtag = vtag;
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79 |
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packet->ecn_capable = ecn_capable;
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80 |
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packet->get_prepend_chunk = prepend_handler;
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81 |
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packet->has_cookie_echo = 0;
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packet->has_sack = 0;
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83 |
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packet->ipfragok = 0;
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84 |
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85 |
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/* We might need to call the prepend_handler right away. */
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86 |
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if (packet_empty)
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87 |
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sctp_packet_reset(packet);
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88 |
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return packet;
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89 |
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}
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90 |
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91 |
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/* Initialize the packet structure. */
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struct sctp_packet *sctp_packet_init(struct sctp_packet *packet,
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93 |
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struct sctp_transport *transport,
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94 |
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__u16 sport, __u16 dport)
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95 |
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{
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96 |
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packet->transport = transport;
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97 |
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packet->source_port = sport;
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98 |
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packet->destination_port = dport;
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99 |
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skb_queue_head_init(&packet->chunks);
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100 |
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packet->size = SCTP_IP_OVERHEAD;
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101 |
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packet->vtag = 0;
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102 |
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packet->ecn_capable = 0;
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103 |
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packet->get_prepend_chunk = NULL;
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104 |
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packet->has_cookie_echo = 0;
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105 |
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packet->has_sack = 0;
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106 |
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packet->ipfragok = 0;
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107 |
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packet->malloced = 0;
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108 |
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sctp_packet_reset(packet);
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109 |
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return packet;
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110 |
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}
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111 |
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112 |
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/* Free a packet. */
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113 |
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void sctp_packet_free(struct sctp_packet *packet)
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114 |
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{
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115 |
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struct sctp_chunk *chunk;
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116 |
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117 |
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while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)))
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sctp_chunk_free(chunk);
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119 |
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120 |
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if (packet->malloced)
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kfree(packet);
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122 |
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}
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123 |
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124 |
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/* This routine tries to append the chunk to the offered packet. If adding
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125 |
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* the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
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126 |
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* is not present in the packet, it transmits the input packet.
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127 |
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* Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
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128 |
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* as it can fit in the packet, but any more data that does not fit in this
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129 |
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* packet can be sent only after receiving the COOKIE_ACK.
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130 |
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*/
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131 |
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sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet,
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132 |
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struct sctp_chunk *chunk)
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133 |
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{
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134 |
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sctp_xmit_t retval;
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135 |
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int error = 0;
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136 |
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137 |
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switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
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138 |
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case SCTP_XMIT_PMTU_FULL:
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139 |
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if (!packet->has_cookie_echo) {
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140 |
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error = sctp_packet_transmit(packet);
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if (error < 0)
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142 |
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chunk->skb->sk->sk_err = -error;
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143 |
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144 |
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/* If we have an empty packet, then we can NOT ever
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* return PMTU_FULL.
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146 |
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*/
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147 |
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retval = sctp_packet_append_chunk(packet, chunk);
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}
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break;
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150 |
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case SCTP_XMIT_MUST_FRAG:
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case SCTP_XMIT_RWND_FULL:
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case SCTP_XMIT_OK:
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case SCTP_XMIT_NAGLE_DELAY:
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break;
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};
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return retval;
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}
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/* Try to bundle a SACK with the packet. */
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static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt,
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struct sctp_chunk *chunk)
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{
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sctp_xmit_t retval = SCTP_XMIT_OK;
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/* If sending DATA and haven't aleady bundled a SACK, try to
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* bundle one in to the packet.
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*/
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170 |
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if (sctp_chunk_is_data(chunk) && !pkt->has_sack &&
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!pkt->has_cookie_echo) {
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struct sctp_association *asoc;
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asoc = pkt->transport->asoc;
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if (asoc->a_rwnd > asoc->rwnd) {
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struct sctp_chunk *sack;
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asoc->a_rwnd = asoc->rwnd;
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sack = sctp_make_sack(asoc);
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179 |
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if (sack) {
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180 |
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struct timer_list *timer;
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retval = sctp_packet_append_chunk(pkt, sack);
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182 |
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asoc->peer.sack_needed = 0;
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timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
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184 |
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if (timer_pending(timer) && del_timer(timer))
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185 |
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sctp_association_put(asoc);
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186 |
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}
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187 |
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}
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188 |
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}
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189 |
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return retval;
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190 |
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}
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191 |
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192 |
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/* Append a chunk to the offered packet reporting back any inability to do
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193 |
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* so.
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194 |
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*/
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195 |
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sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
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196 |
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struct sctp_chunk *chunk)
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197 |
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{
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198 |
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sctp_xmit_t retval = SCTP_XMIT_OK;
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199 |
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__u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length));
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200 |
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size_t psize;
|
201 |
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size_t pmtu;
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202 |
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int too_big;
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203 |
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|
204 |
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retval = sctp_packet_bundle_sack(packet, chunk);
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205 |
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psize = packet->size;
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206 |
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|
207 |
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if (retval != SCTP_XMIT_OK)
|
208 |
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goto finish;
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209 |
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|
210 |
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pmtu = ((packet->transport->asoc) ?
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211 |
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(packet->transport->asoc->pmtu) :
|
212 |
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(packet->transport->pmtu));
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213 |
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|
214 |
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too_big = (psize + chunk_len > pmtu);
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215 |
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|
216 |
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/* Decide if we need to fragment or resubmit later. */
|
217 |
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if (too_big) {
|
218 |
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int packet_empty = (packet->size == SCTP_IP_OVERHEAD);
|
219 |
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|
220 |
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/* Both control chunks and data chunks with TSNs are
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221 |
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* non-fragmentable.
|
222 |
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*/
|
223 |
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if (packet_empty || !sctp_chunk_is_data(chunk)) {
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224 |
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/* We no longer do re-fragmentation.
|
225 |
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* Just fragment at the IP layer, if we
|
226 |
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* actually hit this condition
|
227 |
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*/
|
228 |
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|
229 |
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packet->ipfragok = 1;
|
230 |
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goto append;
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231 |
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232 |
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} else {
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233 |
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retval = SCTP_XMIT_PMTU_FULL;
|
234 |
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goto finish;
|
235 |
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}
|
236 |
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} else {
|
237 |
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/* The chunk fits in the packet. */
|
238 |
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goto append;
|
239 |
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}
|
240 |
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|
241 |
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append:
|
242 |
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/* We believe that this chunk is OK to add to the packet (as
|
243 |
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* long as we have the cwnd for it).
|
244 |
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*/
|
245 |
|
|
|
246 |
|
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/* DATA is a special case since we must examine both rwnd and cwnd
|
247 |
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* before we send DATA.
|
248 |
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*/
|
249 |
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if (sctp_chunk_is_data(chunk)) {
|
250 |
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retval = sctp_packet_append_data(packet, chunk);
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251 |
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/* Disallow SACK bundling after DATA. */
|
252 |
|
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packet->has_sack = 1;
|
253 |
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if (SCTP_XMIT_OK != retval)
|
254 |
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goto finish;
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255 |
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} else if (SCTP_CID_COOKIE_ECHO == chunk->chunk_hdr->type)
|
256 |
|
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packet->has_cookie_echo = 1;
|
257 |
|
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else if (SCTP_CID_SACK == chunk->chunk_hdr->type)
|
258 |
|
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packet->has_sack = 1;
|
259 |
|
|
|
260 |
|
|
/* It is OK to send this chunk. */
|
261 |
|
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__skb_queue_tail(&packet->chunks, (struct sk_buff *)chunk);
|
262 |
|
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packet->size += chunk_len;
|
263 |
|
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finish:
|
264 |
|
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return retval;
|
265 |
|
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}
|
266 |
|
|
|
267 |
|
|
/* All packets are sent to the network through this function from
|
268 |
|
|
* sctp_outq_tail().
|
269 |
|
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*
|
270 |
|
|
* The return value is a normal kernel error return value.
|
271 |
|
|
*/
|
272 |
|
|
int sctp_packet_transmit(struct sctp_packet *packet)
|
273 |
|
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{
|
274 |
|
|
struct sctp_transport *tp = packet->transport;
|
275 |
|
|
struct sctp_association *asoc = tp->asoc;
|
276 |
|
|
struct sctphdr *sh;
|
277 |
|
|
__u32 crc32;
|
278 |
|
|
struct sk_buff *nskb;
|
279 |
|
|
struct sctp_chunk *chunk;
|
280 |
|
|
struct sock *sk;
|
281 |
|
|
int err = 0;
|
282 |
|
|
int padding; /* How much padding do we need? */
|
283 |
|
|
__u8 has_data = 0;
|
284 |
|
|
struct dst_entry *dst;
|
285 |
|
|
|
286 |
|
|
/* Do NOT generate a chunkless packet. */
|
287 |
|
|
chunk = (struct sctp_chunk *)skb_peek(&packet->chunks);
|
288 |
|
|
if (unlikely(!chunk))
|
289 |
|
|
return err;
|
290 |
|
|
|
291 |
|
|
/* Set up convenience variables... */
|
292 |
|
|
sk = chunk->skb->sk;
|
293 |
|
|
|
294 |
|
|
/* Allocate the new skb. */
|
295 |
|
|
nskb = dev_alloc_skb(packet->size);
|
296 |
|
|
if (!nskb)
|
297 |
|
|
goto nomem;
|
298 |
|
|
|
299 |
|
|
/* Make sure the outbound skb has enough header room reserved. */
|
300 |
|
|
skb_reserve(nskb, SCTP_IP_OVERHEAD);
|
301 |
|
|
|
302 |
|
|
/* Set the owning socket so that we know where to get the
|
303 |
|
|
* destination IP address.
|
304 |
|
|
*/
|
305 |
|
|
skb_set_owner_w(nskb, sk);
|
306 |
|
|
|
307 |
|
|
/* Build the SCTP header. */
|
308 |
|
|
sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
|
309 |
|
|
sh->source = htons(packet->source_port);
|
310 |
|
|
sh->dest = htons(packet->destination_port);
|
311 |
|
|
|
312 |
|
|
/* From 6.8 Adler-32 Checksum Calculation:
|
313 |
|
|
* After the packet is constructed (containing the SCTP common
|
314 |
|
|
* header and one or more control or DATA chunks), the
|
315 |
|
|
* transmitter shall:
|
316 |
|
|
*
|
317 |
|
|
* 1) Fill in the proper Verification Tag in the SCTP common
|
318 |
|
|
* header and initialize the checksum field to 0's.
|
319 |
|
|
*/
|
320 |
|
|
sh->vtag = htonl(packet->vtag);
|
321 |
|
|
sh->checksum = 0;
|
322 |
|
|
|
323 |
|
|
/* 2) Calculate the Adler-32 checksum of the whole packet,
|
324 |
|
|
* including the SCTP common header and all the
|
325 |
|
|
* chunks.
|
326 |
|
|
*
|
327 |
|
|
* Note: Adler-32 is no longer applicable, as has been replaced
|
328 |
|
|
* by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
|
329 |
|
|
*/
|
330 |
|
|
crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr));
|
331 |
|
|
|
332 |
|
|
/**
|
333 |
|
|
* 6.10 Bundling
|
334 |
|
|
*
|
335 |
|
|
* An endpoint bundles chunks by simply including multiple
|
336 |
|
|
* chunks in one outbound SCTP packet. ...
|
337 |
|
|
*/
|
338 |
|
|
|
339 |
|
|
/**
|
340 |
|
|
* 3.2 Chunk Field Descriptions
|
341 |
|
|
*
|
342 |
|
|
* The total length of a chunk (including Type, Length and
|
343 |
|
|
* Value fields) MUST be a multiple of 4 bytes. If the length
|
344 |
|
|
* of the chunk is not a multiple of 4 bytes, the sender MUST
|
345 |
|
|
* pad the chunk with all zero bytes and this padding is not
|
346 |
|
|
* included in the chunk length field. The sender should
|
347 |
|
|
* never pad with more than 3 bytes.
|
348 |
|
|
*
|
349 |
|
|
* [This whole comment explains WORD_ROUND() below.]
|
350 |
|
|
*/
|
351 |
|
|
SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
|
352 |
|
|
while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks))) {
|
353 |
|
|
if (sctp_chunk_is_data(chunk)) {
|
354 |
|
|
|
355 |
|
|
if (!chunk->has_tsn) {
|
356 |
|
|
sctp_chunk_assign_ssn(chunk);
|
357 |
|
|
sctp_chunk_assign_tsn(chunk);
|
358 |
|
|
|
359 |
|
|
/* 6.3.1 C4) When data is in flight and when allowed
|
360 |
|
|
* by rule C5, a new RTT measurement MUST be made each
|
361 |
|
|
* round trip. Furthermore, new RTT measurements
|
362 |
|
|
* SHOULD be made no more than once per round-trip
|
363 |
|
|
* for a given destination transport address.
|
364 |
|
|
*/
|
365 |
|
|
|
366 |
|
|
if (!tp->rto_pending) {
|
367 |
|
|
chunk->rtt_in_progress = 1;
|
368 |
|
|
tp->rto_pending = 1;
|
369 |
|
|
}
|
370 |
|
|
} else
|
371 |
|
|
chunk->resent = 1;
|
372 |
|
|
|
373 |
|
|
chunk->sent_at = jiffies;
|
374 |
|
|
has_data = 1;
|
375 |
|
|
}
|
376 |
|
|
|
377 |
|
|
padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
|
378 |
|
|
if (padding)
|
379 |
|
|
memset(skb_put(chunk->skb, padding), 0, padding);
|
380 |
|
|
|
381 |
|
|
crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len),
|
382 |
|
|
chunk->skb->data,
|
383 |
|
|
chunk->skb->len, crc32);
|
384 |
|
|
|
385 |
|
|
SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
|
386 |
|
|
"*** Chunk", chunk,
|
387 |
|
|
sctp_cname(SCTP_ST_CHUNK(
|
388 |
|
|
chunk->chunk_hdr->type)),
|
389 |
|
|
chunk->has_tsn ? "TSN" : "No TSN",
|
390 |
|
|
chunk->has_tsn ?
|
391 |
|
|
ntohl(chunk->subh.data_hdr->tsn) : 0,
|
392 |
|
|
"length", ntohs(chunk->chunk_hdr->length),
|
393 |
|
|
"chunk->skb->len", chunk->skb->len,
|
394 |
|
|
"rtt_in_progress", chunk->rtt_in_progress);
|
395 |
|
|
|
396 |
|
|
/*
|
397 |
|
|
* If this is a control chunk, this is our last
|
398 |
|
|
* reference. Free data chunks after they've been
|
399 |
|
|
* acknowledged or have failed.
|
400 |
|
|
*/
|
401 |
|
|
if (!sctp_chunk_is_data(chunk))
|
402 |
|
|
sctp_chunk_free(chunk);
|
403 |
|
|
}
|
404 |
|
|
|
405 |
|
|
/* Perform final transformation on checksum. */
|
406 |
|
|
crc32 = sctp_end_cksum(crc32);
|
407 |
|
|
|
408 |
|
|
/* 3) Put the resultant value into the checksum field in the
|
409 |
|
|
* common header, and leave the rest of the bits unchanged.
|
410 |
|
|
*/
|
411 |
|
|
sh->checksum = htonl(crc32);
|
412 |
|
|
|
413 |
|
|
/* IP layer ECN support
|
414 |
|
|
* From RFC 2481
|
415 |
|
|
* "The ECN-Capable Transport (ECT) bit would be set by the
|
416 |
|
|
* data sender to indicate that the end-points of the
|
417 |
|
|
* transport protocol are ECN-capable."
|
418 |
|
|
*
|
419 |
|
|
* Now setting the ECT bit all the time, as it should not cause
|
420 |
|
|
* any problems protocol-wise even if our peer ignores it.
|
421 |
|
|
*
|
422 |
|
|
* Note: The works for IPv6 layer checks this bit too later
|
423 |
|
|
* in transmission. See IP6_ECN_flow_xmit().
|
424 |
|
|
*/
|
425 |
|
|
INET_ECN_xmit(nskb->sk);
|
426 |
|
|
|
427 |
|
|
/* Set up the IP options. */
|
428 |
|
|
/* BUG: not implemented
|
429 |
|
|
* For v4 this all lives somewhere in sk->sk_opt...
|
430 |
|
|
*/
|
431 |
|
|
|
432 |
|
|
/* Dump that on IP! */
|
433 |
|
|
if (asoc && asoc->peer.last_sent_to != tp) {
|
434 |
|
|
/* Considering the multiple CPU scenario, this is a
|
435 |
|
|
* "correcter" place for last_sent_to. --xguo
|
436 |
|
|
*/
|
437 |
|
|
asoc->peer.last_sent_to = tp;
|
438 |
|
|
}
|
439 |
|
|
|
440 |
|
|
if (has_data) {
|
441 |
|
|
struct timer_list *timer;
|
442 |
|
|
unsigned long timeout;
|
443 |
|
|
|
444 |
|
|
tp->last_time_used = jiffies;
|
445 |
|
|
|
446 |
|
|
/* Restart the AUTOCLOSE timer when sending data. */
|
447 |
|
|
if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) {
|
448 |
|
|
timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
|
449 |
|
|
timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
|
450 |
|
|
|
451 |
|
|
if (!mod_timer(timer, jiffies + timeout))
|
452 |
|
|
sctp_association_hold(asoc);
|
453 |
|
|
}
|
454 |
|
|
}
|
455 |
|
|
|
456 |
|
|
dst = tp->dst;
|
457 |
|
|
/* The 'obsolete' field of dst is set to 2 when a dst is freed. */
|
458 |
|
|
if (!dst || (dst->obsolete > 1)) {
|
459 |
|
|
dst_release(dst);
|
460 |
|
|
sctp_transport_route(tp, NULL, sctp_sk(sk));
|
461 |
|
|
sctp_assoc_sync_pmtu(asoc);
|
462 |
|
|
}
|
463 |
|
|
|
464 |
|
|
nskb->dst = dst_clone(tp->dst);
|
465 |
|
|
if (!nskb->dst)
|
466 |
|
|
goto no_route;
|
467 |
|
|
|
468 |
|
|
SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
|
469 |
|
|
nskb->len);
|
470 |
|
|
|
471 |
|
|
(*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok);
|
472 |
|
|
|
473 |
|
|
out:
|
474 |
|
|
packet->size = SCTP_IP_OVERHEAD;
|
475 |
|
|
return err;
|
476 |
|
|
no_route:
|
477 |
|
|
kfree_skb(nskb);
|
478 |
|
|
IP_INC_STATS_BH(IpOutNoRoutes);
|
479 |
|
|
|
480 |
|
|
/* FIXME: Returning the 'err' will effect all the associations
|
481 |
|
|
* associated with a socket, although only one of the paths of the
|
482 |
|
|
* association is unreachable.
|
483 |
|
|
* The real failure of a transport or association can be passed on
|
484 |
|
|
* to the user via notifications. So setting this error may not be
|
485 |
|
|
* required.
|
486 |
|
|
*/
|
487 |
|
|
/* err = -EHOSTUNREACH; */
|
488 |
|
|
err:
|
489 |
|
|
/* Control chunks are unreliable so just drop them. DATA chunks
|
490 |
|
|
* will get resent or dropped later.
|
491 |
|
|
*/
|
492 |
|
|
|
493 |
|
|
while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks))) {
|
494 |
|
|
if (!sctp_chunk_is_data(chunk))
|
495 |
|
|
sctp_chunk_free(chunk);
|
496 |
|
|
}
|
497 |
|
|
goto out;
|
498 |
|
|
nomem:
|
499 |
|
|
err = -ENOMEM;
|
500 |
|
|
printk("%s alloc_skb failed.\n", __FUNCTION__);
|
501 |
|
|
goto err;
|
502 |
|
|
}
|
503 |
|
|
|
504 |
|
|
/********************************************************************
|
505 |
|
|
* 2nd Level Abstractions
|
506 |
|
|
********************************************************************/
|
507 |
|
|
|
508 |
|
|
/*
|
509 |
|
|
* This private function resets the packet to a fresh state.
|
510 |
|
|
*/
|
511 |
|
|
static void sctp_packet_reset(struct sctp_packet *packet)
|
512 |
|
|
{
|
513 |
|
|
struct sctp_chunk *chunk = NULL;
|
514 |
|
|
|
515 |
|
|
packet->size = SCTP_IP_OVERHEAD;
|
516 |
|
|
|
517 |
|
|
if (packet->get_prepend_chunk)
|
518 |
|
|
chunk = packet->get_prepend_chunk(packet->transport->asoc);
|
519 |
|
|
|
520 |
|
|
/* If there a is a prepend chunk stick it on the list before
|
521 |
|
|
* any other chunks get appended.
|
522 |
|
|
*/
|
523 |
|
|
if (chunk)
|
524 |
|
|
sctp_packet_append_chunk(packet, chunk);
|
525 |
|
|
}
|
526 |
|
|
|
527 |
|
|
/* This private function handles the specifics of appending DATA chunks. */
|
528 |
|
|
static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet,
|
529 |
|
|
struct sctp_chunk *chunk)
|
530 |
|
|
{
|
531 |
|
|
sctp_xmit_t retval = SCTP_XMIT_OK;
|
532 |
|
|
size_t datasize, rwnd, inflight;
|
533 |
|
|
struct sctp_transport *transport = packet->transport;
|
534 |
|
|
__u32 max_burst_bytes;
|
535 |
|
|
struct sctp_association *asoc = transport->asoc;
|
536 |
|
|
struct sctp_opt *sp = sctp_sk(asoc->base.sk);
|
537 |
|
|
struct sctp_outq *q = &asoc->outqueue;
|
538 |
|
|
|
539 |
|
|
/* RFC 2960 6.1 Transmission of DATA Chunks
|
540 |
|
|
*
|
541 |
|
|
* A) At any given time, the data sender MUST NOT transmit new data to
|
542 |
|
|
* any destination transport address if its peer's rwnd indicates
|
543 |
|
|
* that the peer has no buffer space (i.e. rwnd is 0, see Section
|
544 |
|
|
* 6.2.1). However, regardless of the value of rwnd (including if it
|
545 |
|
|
* is 0), the data sender can always have one DATA chunk in flight to
|
546 |
|
|
* the receiver if allowed by cwnd (see rule B below). This rule
|
547 |
|
|
* allows the sender to probe for a change in rwnd that the sender
|
548 |
|
|
* missed due to the SACK having been lost in transit from the data
|
549 |
|
|
* receiver to the data sender.
|
550 |
|
|
*/
|
551 |
|
|
|
552 |
|
|
rwnd = asoc->peer.rwnd;
|
553 |
|
|
inflight = asoc->outqueue.outstanding_bytes;
|
554 |
|
|
|
555 |
|
|
datasize = sctp_data_size(chunk);
|
556 |
|
|
|
557 |
|
|
if (datasize > rwnd) {
|
558 |
|
|
if (inflight > 0) {
|
559 |
|
|
/* We have (at least) one data chunk in flight,
|
560 |
|
|
* so we can't fall back to rule 6.1 B).
|
561 |
|
|
*/
|
562 |
|
|
retval = SCTP_XMIT_RWND_FULL;
|
563 |
|
|
goto finish;
|
564 |
|
|
}
|
565 |
|
|
}
|
566 |
|
|
|
567 |
|
|
/* sctpimpguide-05 2.14.2
|
568 |
|
|
* D) When the time comes for the sender to
|
569 |
|
|
* transmit new DATA chunks, the protocol parameter Max.Burst MUST
|
570 |
|
|
* first be applied to limit how many new DATA chunks may be sent.
|
571 |
|
|
* The limit is applied by adjusting cwnd as follows:
|
572 |
|
|
* if ((flightsize + Max.Burst * MTU) < cwnd)
|
573 |
|
|
* cwnd = flightsize + Max.Burst * MTU
|
574 |
|
|
*/
|
575 |
|
|
max_burst_bytes = asoc->max_burst * asoc->pmtu;
|
576 |
|
|
if ((transport->flight_size + max_burst_bytes) < transport->cwnd) {
|
577 |
|
|
transport->cwnd = transport->flight_size + max_burst_bytes;
|
578 |
|
|
SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: "
|
579 |
|
|
"transport: %p, cwnd: %d, "
|
580 |
|
|
"ssthresh: %d, flight_size: %d, "
|
581 |
|
|
"pba: %d\n",
|
582 |
|
|
__FUNCTION__, transport,
|
583 |
|
|
transport->cwnd,
|
584 |
|
|
transport->ssthresh,
|
585 |
|
|
transport->flight_size,
|
586 |
|
|
transport->partial_bytes_acked);
|
587 |
|
|
}
|
588 |
|
|
|
589 |
|
|
/* RFC 2960 6.1 Transmission of DATA Chunks
|
590 |
|
|
*
|
591 |
|
|
* B) At any given time, the sender MUST NOT transmit new data
|
592 |
|
|
* to a given transport address if it has cwnd or more bytes
|
593 |
|
|
* of data outstanding to that transport address.
|
594 |
|
|
*/
|
595 |
|
|
/* RFC 7.2.4 & the Implementers Guide 2.8.
|
596 |
|
|
*
|
597 |
|
|
* 3) ...
|
598 |
|
|
* When a Fast Retransmit is being performed the sender SHOULD
|
599 |
|
|
* ignore the value of cwnd and SHOULD NOT delay retransmission.
|
600 |
|
|
*/
|
601 |
|
|
if (!chunk->fast_retransmit)
|
602 |
|
|
if (transport->flight_size >= transport->cwnd) {
|
603 |
|
|
retval = SCTP_XMIT_RWND_FULL;
|
604 |
|
|
goto finish;
|
605 |
|
|
}
|
606 |
|
|
|
607 |
|
|
/* Nagle's algorithm to solve small-packet problem:
|
608 |
|
|
* Inhibit the sending of new chunks when new outgoing data arrives
|
609 |
|
|
* if any previously transmitted data on the connection remains
|
610 |
|
|
* unacknowledged.
|
611 |
|
|
*/
|
612 |
|
|
if (!sp->nodelay && SCTP_IP_OVERHEAD == packet->size &&
|
613 |
|
|
q->outstanding_bytes && sctp_state(asoc, ESTABLISHED)) {
|
614 |
|
|
unsigned len = datasize + q->out_qlen;
|
615 |
|
|
|
616 |
|
|
/* Check whether this chunk and all the rest of pending
|
617 |
|
|
* data will fit or delay in hopes of bundling a full
|
618 |
|
|
* sized packet.
|
619 |
|
|
*/
|
620 |
|
|
if (len < asoc->pmtu - SCTP_IP_OVERHEAD) {
|
621 |
|
|
retval = SCTP_XMIT_NAGLE_DELAY;
|
622 |
|
|
goto finish;
|
623 |
|
|
}
|
624 |
|
|
}
|
625 |
|
|
|
626 |
|
|
/* Keep track of how many bytes are in flight over this transport. */
|
627 |
|
|
transport->flight_size += datasize;
|
628 |
|
|
|
629 |
|
|
/* Keep track of how many bytes are in flight to the receiver. */
|
630 |
|
|
asoc->outqueue.outstanding_bytes += datasize;
|
631 |
|
|
|
632 |
|
|
/* Update our view of the receiver's rwnd. */
|
633 |
|
|
if (datasize < rwnd)
|
634 |
|
|
rwnd -= datasize;
|
635 |
|
|
else
|
636 |
|
|
rwnd = 0;
|
637 |
|
|
|
638 |
|
|
asoc->peer.rwnd = rwnd;
|
639 |
|
|
/* Has been accepted for transmission. */
|
640 |
|
|
chunk->msg->can_expire = 0;
|
641 |
|
|
|
642 |
|
|
finish:
|
643 |
|
|
return retval;
|
644 |
|
|
}
|