2 * Copyright (c) 2008, 2009, 2010 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' and the port number 'in_port', which
96 * should be the datapath port number on which 'buffer' was received.
98 * If successful, returns the packet buffer id (a number other than
99 * UINT32_MAX). pktbuf_retrieve() can later be used to retrieve the buffer and
100 * its input port number (buffers do expire after a time, so this is not
101 * guaranteed to be true forever). On failure, returns UINT32_MAX.
103 * The caller retains ownership of 'buffer'. */
105 pktbuf_save(struct pktbuf *pb, struct ofpbuf *buffer, uint16_t in_port)
107 struct packet *p = &pb->packets[pb->buffer_idx];
108 pb->buffer_idx = (pb->buffer_idx + 1) & PKTBUF_MASK;
110 if (time_msec() < p->timeout) {
113 ofpbuf_delete(p->buffer);
116 /* Don't use maximum cookie value since all-1-bits ID is special. */
117 if (++p->cookie >= COOKIE_MAX) {
120 p->buffer = ofpbuf_new_with_headroom(buffer->size,
121 sizeof(struct ofp_packet_in));
122 ofpbuf_put(p->buffer, buffer->data, buffer->size);
123 p->timeout = time_msec() + OVERWRITE_MSECS;
124 p->in_port = in_port;
125 return make_id(p - pb->packets, p->cookie);
129 * Allocates and returns a "null" packet buffer id. The returned packet buffer
130 * id is considered valid by pktbuf_retrieve(), but it is not associated with
131 * actual buffered data.
133 * This function is always successful.
135 * This is useful in one special case: with the current OpenFlow design, the
136 * "fail-open" code cannot always know whether a connection to a controller is
137 * actually valid until it receives a OFPT_PACKET_OUT or OFPT_FLOW_MOD request,
138 * but at that point the packet in question has already been forwarded (since
139 * we are still in "fail-open" mode). If the packet was buffered in the usual
140 * way, then the OFPT_PACKET_OUT or OFPT_FLOW_MOD would cause a duplicate
141 * packet in the network. Null packet buffer ids identify such a packet that
142 * has already been forwarded, so that Open vSwitch can quietly ignore the
143 * request to re-send it. (After that happens, the switch exits fail-open
146 * See the top-level comment in fail-open.c for an overview.
149 pktbuf_get_null(void)
151 return make_id(0, COOKIE_MAX);
154 /* Attempts to retrieve a saved packet with the given 'id' from 'pb'. Returns
155 * 0 if successful, otherwise an OpenFlow error code constructed with
158 * On success, ordinarily stores the buffered packet in '*bufferp' and the
159 * datapath port number on which the packet was received in '*in_port'. The
160 * caller becomes responsible for freeing the buffer. However, if 'id'
161 * identifies a "null" packet buffer (created with pktbuf_get_null()), stores
162 * NULL in '*bufferp' and UINT16_max in '*in_port'.
164 * A returned packet will have at least sizeof(struct ofp_packet_in) bytes of
167 * On failure, stores NULL in in '*bufferp' and UINT16_MAX in '*in_port'. */
169 pktbuf_retrieve(struct pktbuf *pb, uint32_t id, struct ofpbuf **bufferp,
172 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 20);
177 VLOG_WARN_RL(&rl, "attempt to send buffered packet via connection "
179 return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN);
182 p = &pb->packets[id & PKTBUF_MASK];
183 if (p->cookie == id >> PKTBUF_BITS) {
184 struct ofpbuf *buffer = p->buffer;
187 *in_port = p->in_port;
189 COVERAGE_INC(pktbuf_retrieved);
192 COVERAGE_INC(pktbuf_reuse_error);
193 VLOG_WARN_RL(&rl, "attempt to reuse buffer %08"PRIx32, id);
194 error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_EMPTY);
196 } else if (id >> PKTBUF_BITS != COOKIE_MAX) {
197 COVERAGE_INC(pktbuf_buffer_unknown);
198 VLOG_WARN_RL(&rl, "cookie mismatch: %08"PRIx32" != %08"PRIx32,
199 id, (id & PKTBUF_MASK) | (p->cookie << PKTBUF_BITS));
200 error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN);
202 COVERAGE_INC(pktbuf_null_cookie);
203 VLOG_INFO_RL(&rl, "Received null cookie %08"PRIx32" (this is normal "
204 "if the switch was recently in fail-open mode)", id);
208 *in_port = UINT16_MAX;
213 pktbuf_discard(struct pktbuf *pb, uint32_t id)
215 struct packet *p = &pb->packets[id & PKTBUF_MASK];
216 if (p->cookie == id >> PKTBUF_BITS) {
217 ofpbuf_delete(p->buffer);