1 /* SCTP kernel implementation 2 * Copyright (c) 1999-2000 Cisco, Inc. 3 * Copyright (c) 1999-2001 Motorola, Inc. 4 * Copyright (c) 2002 International Business Machines, Corp. 5 * 6 * This file is part of the SCTP kernel implementation 7 * 8 * These functions are the methods for accessing the SCTP inqueue. 9 * 10 * An SCTP inqueue is a queue into which you push SCTP packets 11 * (which might be bundles or fragments of chunks) and out of which you 12 * pop SCTP whole chunks. 13 * 14 * This SCTP implementation is free software; 15 * you can redistribute it and/or modify it under the terms of 16 * the GNU General Public License as published by 17 * the Free Software Foundation; either version 2, or (at your option) 18 * any later version. 19 * 20 * This SCTP implementation is distributed in the hope that it 21 * will be useful, but WITHOUT ANY WARRANTY; without even the implied 22 * ************************ 23 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 24 * See the GNU General Public License for more details. 25 * 26 * You should have received a copy of the GNU General Public License 27 * along with GNU CC; see the file COPYING. If not, see 28 * <http://www.gnu.org/licenses/>. 29 * 30 * Please send any bug reports or fixes you make to the 31 * email address(es): 32 * lksctp developers <linux-sctp@vger.kernel.org> 33 * 34 * Written or modified by: 35 * La Monte H.P. Yarroll <piggy@acm.org> 36 * Karl Knutson <karl@athena.chicago.il.us> 37 */ 38 39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 40 41 #include <net/sctp/sctp.h> 42 #include <net/sctp/sm.h> 43 #include <linux/interrupt.h> 44 #include <linux/slab.h> 45 46 /* Initialize an SCTP inqueue. */ 47 void sctp_inq_init(struct sctp_inq *queue) 48 { 49 INIT_LIST_HEAD(&queue->in_chunk_list); 50 queue->in_progress = NULL; 51 52 /* Create a task for delivering data. */ 53 INIT_WORK(&queue->immediate, NULL); 54 } 55 56 /* Release the memory associated with an SCTP inqueue. */ 57 void sctp_inq_free(struct sctp_inq *queue) 58 { 59 struct sctp_chunk *chunk, *tmp; 60 61 /* Empty the queue. */ 62 list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) { 63 list_del_init(&chunk->list); 64 sctp_chunk_free(chunk); 65 } 66 67 /* If there is a packet which is currently being worked on, 68 * free it as well. 69 */ 70 if (queue->in_progress) { 71 sctp_chunk_free(queue->in_progress); 72 queue->in_progress = NULL; 73 } 74 } 75 76 /* Put a new packet in an SCTP inqueue. 77 * We assume that packet->sctp_hdr is set and in host byte order. 78 */ 79 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk) 80 { 81 /* Directly call the packet handling routine. */ 82 if (chunk->rcvr->dead) { 83 sctp_chunk_free(chunk); 84 return; 85 } 86 87 /* We are now calling this either from the soft interrupt 88 * or from the backlog processing. 89 * Eventually, we should clean up inqueue to not rely 90 * on the BH related data structures. 91 */ 92 list_add_tail(&chunk->list, &q->in_chunk_list); 93 if (chunk->asoc) 94 chunk->asoc->stats.ipackets++; 95 q->immediate.func(&q->immediate); 96 } 97 98 /* Peek at the next chunk on the inqeue. */ 99 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue) 100 { 101 struct sctp_chunk *chunk; 102 sctp_chunkhdr_t *ch = NULL; 103 104 chunk = queue->in_progress; 105 /* If there is no more chunks in this packet, say so */ 106 if (chunk->singleton || 107 chunk->end_of_packet || 108 chunk->pdiscard) 109 return NULL; 110 111 ch = (sctp_chunkhdr_t *)chunk->chunk_end; 112 113 return ch; 114 } 115 116 117 /* Extract a chunk from an SCTP inqueue. 118 * 119 * WARNING: If you need to put the chunk on another queue, you need to 120 * make a shallow copy (clone) of it. 121 */ 122 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue) 123 { 124 struct sctp_chunk *chunk; 125 sctp_chunkhdr_t *ch = NULL; 126 127 /* The assumption is that we are safe to process the chunks 128 * at this time. 129 */ 130 131 if ((chunk = queue->in_progress)) { 132 /* There is a packet that we have been working on. 133 * Any post processing work to do before we move on? 134 */ 135 if (chunk->singleton || 136 chunk->end_of_packet || 137 chunk->pdiscard) { 138 sctp_chunk_free(chunk); 139 chunk = queue->in_progress = NULL; 140 } else { 141 /* Nothing to do. Next chunk in the packet, please. */ 142 ch = (sctp_chunkhdr_t *) chunk->chunk_end; 143 /* Force chunk->skb->data to chunk->chunk_end. */ 144 skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data); 145 /* We are guaranteed to pull a SCTP header. */ 146 } 147 } 148 149 /* Do we need to take the next packet out of the queue to process? */ 150 if (!chunk) { 151 struct list_head *entry; 152 153 /* Is the queue empty? */ 154 if (list_empty(&queue->in_chunk_list)) 155 return NULL; 156 157 entry = queue->in_chunk_list.next; 158 chunk = queue->in_progress = 159 list_entry(entry, struct sctp_chunk, list); 160 list_del_init(entry); 161 162 /* This is the first chunk in the packet. */ 163 chunk->singleton = 1; 164 ch = (sctp_chunkhdr_t *) chunk->skb->data; 165 chunk->data_accepted = 0; 166 } 167 168 chunk->chunk_hdr = ch; 169 chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 170 /* In the unlikely case of an IP reassembly, the skb could be 171 * non-linear. If so, update chunk_end so that it doesn't go past 172 * the skb->tail. 173 */ 174 if (unlikely(skb_is_nonlinear(chunk->skb))) { 175 if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) 176 chunk->chunk_end = skb_tail_pointer(chunk->skb); 177 } 178 skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t)); 179 chunk->subh.v = NULL; /* Subheader is no longer valid. */ 180 181 if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) < 182 skb_tail_pointer(chunk->skb)) { 183 /* This is not a singleton */ 184 chunk->singleton = 0; 185 } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) { 186 /* Discard inside state machine. */ 187 chunk->pdiscard = 1; 188 chunk->chunk_end = skb_tail_pointer(chunk->skb); 189 } else { 190 /* We are at the end of the packet, so mark the chunk 191 * in case we need to send a SACK. 192 */ 193 chunk->end_of_packet = 1; 194 } 195 196 pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n", 197 chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)), 198 ntohs(chunk->chunk_hdr->length), chunk->skb->len); 199 200 return chunk; 201 } 202 203 /* Set a top-half handler. 204 * 205 * Originally, we the top-half handler was scheduled as a BH. We now 206 * call the handler directly in sctp_inq_push() at a time that 207 * we know we are lock safe. 208 * The intent is that this routine will pull stuff out of the 209 * inqueue and process it. 210 */ 211 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback) 212 { 213 INIT_WORK(&q->immediate, callback); 214 } 215