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064af421 | 1 | /* |
608efb41 | 2 | * Copyright (c) 2008, 2009, 2010 Nicira Networks. |
064af421 | 3 | * |
a14bc59f BP |
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: | |
064af421 | 7 | * |
a14bc59f BP |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * | |
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. | |
064af421 BP |
15 | */ |
16 | ||
17 | #include <config.h> | |
18 | #include "pktbuf.h" | |
19 | #include <inttypes.h> | |
20 | #include <stdlib.h> | |
21 | #include "coverage.h" | |
fa37b408 | 22 | #include "ofp-util.h" |
064af421 BP |
23 | #include "ofpbuf.h" |
24 | #include "timeval.h" | |
25 | #include "util.h" | |
26 | #include "vconn.h" | |
064af421 BP |
27 | #include "vlog.h" |
28 | ||
5136ce49 BP |
29 | VLOG_DEFINE_THIS_MODULE(pktbuf) |
30 | ||
064af421 BP |
31 | /* Buffers are identified by a 32-bit opaque ID. We divide the ID |
32 | * into a buffer number (low bits) and a cookie (high bits). The buffer number | |
33 | * is an index into an array of buffers. The cookie distinguishes between | |
34 | * different packets that have occupied a single buffer. Thus, the more | |
35 | * buffers we have, the lower-quality the cookie... */ | |
36 | #define PKTBUF_BITS 8 | |
37 | #define PKTBUF_MASK (PKTBUF_CNT - 1) | |
38 | #define PKTBUF_CNT (1u << PKTBUF_BITS) | |
39 | ||
40 | #define COOKIE_BITS (32 - PKTBUF_BITS) | |
41 | #define COOKIE_MAX ((1u << COOKIE_BITS) - 1) | |
42 | ||
43 | #define OVERWRITE_MSECS 5000 | |
44 | ||
45 | struct packet { | |
46 | struct ofpbuf *buffer; | |
47 | uint32_t cookie; | |
48 | long long int timeout; | |
49 | uint16_t in_port; | |
50 | }; | |
51 | ||
52 | struct pktbuf { | |
53 | struct packet packets[PKTBUF_CNT]; | |
54 | unsigned int buffer_idx; | |
7778bd15 | 55 | unsigned int null_idx; |
064af421 BP |
56 | }; |
57 | ||
58 | int | |
59 | pktbuf_capacity(void) | |
60 | { | |
61 | return PKTBUF_CNT; | |
62 | } | |
63 | ||
64 | struct pktbuf * | |
65 | pktbuf_create(void) | |
66 | { | |
ec6fde61 | 67 | return xzalloc(sizeof *pktbuf_create()); |
064af421 BP |
68 | } |
69 | ||
70 | void | |
71 | pktbuf_destroy(struct pktbuf *pb) | |
72 | { | |
73 | if (pb) { | |
74 | size_t i; | |
75 | ||
76 | for (i = 0; i < PKTBUF_CNT; i++) { | |
77 | ofpbuf_delete(pb->packets[i].buffer); | |
78 | } | |
79 | free(pb); | |
80 | } | |
81 | } | |
82 | ||
7778bd15 BP |
83 | static unsigned int |
84 | make_id(unsigned int buffer_idx, unsigned int cookie) | |
85 | { | |
86 | return buffer_idx | (cookie << PKTBUF_BITS); | |
87 | } | |
88 | ||
89 | /* Attempts to allocate an OpenFlow packet buffer id within 'pb'. The packet | |
90 | * buffer will store a copy of 'buffer' and the port number 'in_port', which | |
91 | * should be the datapath port number on which 'buffer' was received. | |
92 | * | |
93 | * If successful, returns the packet buffer id (a number other than | |
94 | * UINT32_MAX). pktbuf_retrieve() can later be used to retrieve the buffer and | |
95 | * its input port number (buffers do expire after a time, so this is not | |
96 | * guaranteed to be true forever). On failure, returns UINT32_MAX. | |
97 | * | |
98 | * The caller retains ownership of 'buffer'. */ | |
064af421 BP |
99 | uint32_t |
100 | pktbuf_save(struct pktbuf *pb, struct ofpbuf *buffer, uint16_t in_port) | |
101 | { | |
102 | struct packet *p = &pb->packets[pb->buffer_idx]; | |
103 | pb->buffer_idx = (pb->buffer_idx + 1) & PKTBUF_MASK; | |
104 | if (p->buffer) { | |
105 | if (time_msec() < p->timeout) { | |
106 | return UINT32_MAX; | |
107 | } | |
108 | ofpbuf_delete(p->buffer); | |
109 | } | |
110 | ||
111 | /* Don't use maximum cookie value since all-1-bits ID is special. */ | |
112 | if (++p->cookie >= COOKIE_MAX) { | |
113 | p->cookie = 0; | |
114 | } | |
750638bb BP |
115 | p->buffer = ofpbuf_new(sizeof(struct ofp_packet_in) + buffer->size); |
116 | ofpbuf_reserve(p->buffer, sizeof(struct ofp_packet_in)); | |
117 | ofpbuf_put(p->buffer, buffer->data, buffer->size); | |
064af421 BP |
118 | p->timeout = time_msec() + OVERWRITE_MSECS; |
119 | p->in_port = in_port; | |
7778bd15 BP |
120 | return make_id(p - pb->packets, p->cookie); |
121 | } | |
122 | ||
123 | /* | |
124 | * Allocates and returns a "null" packet buffer id. The returned packet buffer | |
125 | * id is considered valid by pktbuf_retrieve(), but it is not associated with | |
126 | * actual buffered data. | |
127 | * | |
128 | * This function is always successful. | |
129 | * | |
130 | * This is useful in one special case: with the current OpenFlow design, the | |
131 | * "fail-open" code cannot always know whether a connection to a controller is | |
132 | * actually valid until it receives a OFPT_PACKET_OUT or OFPT_FLOW_MOD request, | |
133 | * but at that point the packet in question has already been forwarded (since | |
134 | * we are still in "fail-open" mode). If the packet was buffered in the usual | |
135 | * way, then the OFPT_PACKET_OUT or OFPT_FLOW_MOD would cause a duplicate | |
136 | * packet in the network. Null packet buffer ids identify such a packet that | |
137 | * has already been forwarded, so that Open vSwitch can quietly ignore the | |
138 | * request to re-send it. (After that happens, the switch exits fail-open | |
139 | * mode.) | |
140 | * | |
141 | * See the top-level comment in fail-open.c for an overview. | |
142 | */ | |
143 | uint32_t | |
144 | pktbuf_get_null(void) | |
145 | { | |
146 | return make_id(0, COOKIE_MAX); | |
064af421 BP |
147 | } |
148 | ||
7778bd15 BP |
149 | /* Attempts to retrieve a saved packet with the given 'id' from 'pb'. Returns |
150 | * 0 if successful, otherwise an OpenFlow error code constructed with | |
151 | * ofp_mkerr(). | |
152 | * | |
153 | * On success, ordinarily stores the buffered packet in '*bufferp' and the | |
154 | * datapath port number on which the packet was received in '*in_port'. The | |
155 | * caller becomes responsible for freeing the buffer. However, if 'id' | |
156 | * identifies a "null" packet buffer (created with pktbuf_get_null()), stores | |
608efb41 | 157 | * NULL in '*bufferp' and UINT16_max in '*in_port'. |
7778bd15 | 158 | * |
750638bb BP |
159 | * A returned packet will have at least sizeof(struct ofp_packet_in) bytes of |
160 | * headroom. | |
161 | * | |
608efb41 | 162 | * On failure, stores NULL in in '*bufferp' and UINT16_MAX in '*in_port'. */ |
064af421 BP |
163 | int |
164 | pktbuf_retrieve(struct pktbuf *pb, uint32_t id, struct ofpbuf **bufferp, | |
165 | uint16_t *in_port) | |
166 | { | |
167 | static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 20); | |
168 | struct packet *p; | |
169 | int error; | |
170 | ||
171 | if (!pb) { | |
172 | VLOG_WARN_RL(&rl, "attempt to send buffered packet via connection " | |
173 | "without buffers"); | |
49bdc010 | 174 | return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN); |
064af421 BP |
175 | } |
176 | ||
177 | p = &pb->packets[id & PKTBUF_MASK]; | |
178 | if (p->cookie == id >> PKTBUF_BITS) { | |
179 | struct ofpbuf *buffer = p->buffer; | |
180 | if (buffer) { | |
181 | *bufferp = buffer; | |
182 | *in_port = p->in_port; | |
183 | p->buffer = NULL; | |
184 | COVERAGE_INC(pktbuf_retrieved); | |
185 | return 0; | |
186 | } else { | |
187 | COVERAGE_INC(pktbuf_reuse_error); | |
188 | VLOG_WARN_RL(&rl, "attempt to reuse buffer %08"PRIx32, id); | |
189 | error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_EMPTY); | |
190 | } | |
7778bd15 | 191 | } else if (id >> PKTBUF_BITS != COOKIE_MAX) { |
49bdc010 | 192 | COVERAGE_INC(pktbuf_buffer_unknown); |
064af421 BP |
193 | VLOG_WARN_RL(&rl, "cookie mismatch: %08"PRIx32" != %08"PRIx32, |
194 | id, (id & PKTBUF_MASK) | (p->cookie << PKTBUF_BITS)); | |
49bdc010 | 195 | error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BUFFER_UNKNOWN); |
7778bd15 BP |
196 | } else { |
197 | COVERAGE_INC(pktbuf_null_cookie); | |
198 | VLOG_INFO_RL(&rl, "Received null cookie %08"PRIx32" (this is normal " | |
199 | "if the switch was recently in fail-open mode)", id); | |
200 | error = 0; | |
064af421 BP |
201 | } |
202 | *bufferp = NULL; | |
608efb41 | 203 | *in_port = UINT16_MAX; |
064af421 BP |
204 | return error; |
205 | } | |
206 | ||
207 | void | |
208 | pktbuf_discard(struct pktbuf *pb, uint32_t id) | |
209 | { | |
210 | struct packet *p = &pb->packets[id & PKTBUF_MASK]; | |
211 | if (p->cookie == id >> PKTBUF_BITS) { | |
212 | ofpbuf_delete(p->buffer); | |
213 | p->buffer = NULL; | |
214 | } | |
215 | } |