2 * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
29 VLOG_DEFINE_THIS_MODULE(pktbuf);
31 COVERAGE_DEFINE(pktbuf_buffer_unknown);
32 COVERAGE_DEFINE(pktbuf_null_cookie);
33 COVERAGE_DEFINE(pktbuf_retrieved);
34 COVERAGE_DEFINE(pktbuf_reuse_error);
36 /* Buffers are identified by a 32-bit opaque ID. We divide the ID
37 * into a buffer number (low bits) and a cookie (high bits). The buffer number
38 * is an index into an array of buffers. The cookie distinguishes between
39 * different packets that have occupied a single buffer. Thus, the more
40 * buffers we have, the lower-quality the cookie... */
42 #define PKTBUF_MASK (PKTBUF_CNT - 1)
43 #define PKTBUF_CNT (1u << PKTBUF_BITS)
45 #define COOKIE_BITS (32 - PKTBUF_BITS)
46 #define COOKIE_MAX ((1u << COOKIE_BITS) - 1)
48 #define OVERWRITE_MSECS 5000
51 struct ofpbuf *buffer;
53 long long int timeout;
58 struct packet packets[PKTBUF_CNT];
59 unsigned int buffer_idx;
60 unsigned int null_idx;
72 return xzalloc(sizeof *pktbuf_create());
76 pktbuf_destroy(struct pktbuf *pb)
81 for (i = 0; i < PKTBUF_CNT; i++) {
82 ofpbuf_delete(pb->packets[i].buffer);
89 make_id(unsigned int buffer_idx, unsigned int cookie)
91 return buffer_idx | (cookie << PKTBUF_BITS);
94 /* Attempts to allocate an OpenFlow packet buffer id within 'pb'. The packet
95 * buffer will store a copy of 'buffer_size' bytes in 'buffer' and the port
96 * number 'in_port', which should be the OpenFlow port number on which 'buffer'
99 * If successful, returns the packet buffer id (a number other than
100 * UINT32_MAX). pktbuf_retrieve() can later be used to retrieve the buffer and
101 * its input port number (buffers do expire after a time, so this is not
102 * guaranteed to be true forever). On failure, returns UINT32_MAX.
104 * The caller retains ownership of 'buffer'. */
106 pktbuf_save(struct pktbuf *pb, const void *buffer, size_t buffer_size,
109 struct packet *p = &pb->packets[pb->buffer_idx];
110 pb->buffer_idx = (pb->buffer_idx + 1) & PKTBUF_MASK;
112 if (time_msec() < p->timeout) {
115 ofpbuf_delete(p->buffer);
118 /* Don't use maximum cookie value since all-1-bits ID is special. */
119 if (++p->cookie >= COOKIE_MAX) {
122 p->buffer = ofpbuf_clone_data_with_headroom(buffer, buffer_size,
123 sizeof(struct ofp_packet_in));
126 p->timeout = time_msec() + OVERWRITE_MSECS;
127 p->in_port = in_port;
128 return make_id(p - pb->packets, p->cookie);
132 * Allocates and returns a "null" packet buffer id. The returned packet buffer
133 * id is considered valid by pktbuf_retrieve(), but it is not associated with
134 * actual buffered data.
136 * This function is always successful.
138 * This is useful in one special case: with the current OpenFlow design, the
139 * "fail-open" code cannot always know whether a connection to a controller is
140 * actually valid until it receives a OFPT_PACKET_OUT or OFPT_FLOW_MOD request,
141 * but at that point the packet in question has already been forwarded (since
142 * we are still in "fail-open" mode). If the packet was buffered in the usual
143 * way, then the OFPT_PACKET_OUT or OFPT_FLOW_MOD would cause a duplicate
144 * packet in the network. Null packet buffer ids identify such a packet that
145 * has already been forwarded, so that Open vSwitch can quietly ignore the
146 * request to re-send it. (After that happens, the switch exits fail-open
149 * See the top-level comment in fail-open.c for an overview.
152 pktbuf_get_null(void)
154 return make_id(0, COOKIE_MAX);
157 /* Attempts to retrieve a saved packet with the given 'id' from 'pb'. Returns
158 * 0 if successful, otherwise an OpenFlow error code.
160 * On success, ordinarily stores the buffered packet in '*bufferp' and the
161 * datapath port number on which the packet was received in '*in_port'. The
162 * caller becomes responsible for freeing the buffer. However, if 'id'
163 * identifies a "null" packet buffer (created with pktbuf_get_null()), stores
164 * NULL in '*bufferp' and UINT16_max in '*in_port'.
166 * 'in_port' may be NULL if the input port is not of interest.
168 * A returned packet will have at least sizeof(struct ofp_packet_in) bytes of
171 * On failure, stores NULL in in '*bufferp' and UINT16_MAX in '*in_port'. */
173 pktbuf_retrieve(struct pktbuf *pb, uint32_t id, struct ofpbuf **bufferp,
176 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 20);
180 if (id == UINT32_MAX) {
186 VLOG_WARN_RL(&rl, "attempt to send buffered packet via connection "
188 return OFPERR_OFPBRC_BUFFER_UNKNOWN;
191 p = &pb->packets[id & PKTBUF_MASK];
192 if (p->cookie == id >> PKTBUF_BITS) {
193 struct ofpbuf *buffer = p->buffer;
197 *in_port = p->in_port;
200 COVERAGE_INC(pktbuf_retrieved);
203 COVERAGE_INC(pktbuf_reuse_error);
204 VLOG_WARN_RL(&rl, "attempt to reuse buffer %08"PRIx32, id);
205 error = OFPERR_OFPBRC_BUFFER_EMPTY;
207 } else if (id >> PKTBUF_BITS != COOKIE_MAX) {
208 COVERAGE_INC(pktbuf_buffer_unknown);
209 VLOG_WARN_RL(&rl, "cookie mismatch: %08"PRIx32" != %08"PRIx32,
210 id, (id & PKTBUF_MASK) | (p->cookie << PKTBUF_BITS));
211 error = OFPERR_OFPBRC_BUFFER_UNKNOWN;
213 COVERAGE_INC(pktbuf_null_cookie);
214 VLOG_INFO_RL(&rl, "Received null cookie %08"PRIx32" (this is normal "
215 "if the switch was recently in fail-open mode)", id);
221 *in_port = UINT16_MAX;
227 pktbuf_discard(struct pktbuf *pb, uint32_t id)
229 struct packet *p = &pb->packets[id & PKTBUF_MASK];
230 if (p->cookie == id >> PKTBUF_BITS) {
231 ofpbuf_delete(p->buffer);