include/openvswitch/ofpbuf.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2015, 2016 Nicira, Inc.
   3  *
   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:
   7  *
   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.
  15  */
  16
  17 #ifndef OPENVSWITCH_OFPBUF_H
  18 #define OPENVSWITCH_OFPBUF_H 1
  19
  20 #include <stddef.h>
  21 #include <stdint.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include "openvswitch/dynamic-string.h"
  25 #include "openvswitch/list.h"
  26 #include "openvswitch/util.h"
  27
  28 #ifdef  __cplusplus
  29 extern "C" {
  30 #endif
  31
  32 enum OVS_PACKED_ENUM ofpbuf_source {
  33     OFPBUF_MALLOC,              /* Obtained via malloc(). */
  34     OFPBUF_STACK,               /* Un-movable stack space or static buffer. */
  35     OFPBUF_STUB,                /* Starts on stack, may expand into heap. */
  36 };
  37
  38 /* Buffer for holding arbitrary data.  An ofpbuf is automatically reallocated
  39  * as necessary if it grows too large for the available memory.
  40  *
  41  * 'header' and 'msg' conventions:
  42  *
  43  * OpenFlow messages: 'header' points to the start of the OpenFlow
  44  *    header, while 'msg' is the OpenFlow msg body.
  45  *    When parsing, the 'data' will move past these, as data is being
  46  *    pulled from the OpenFlow message.
  47  *
  48  *    Caution: buffer manipulation of 'struct ofpbuf' must always update
  49  *             the 'header' and 'msg' pointers.
  50  *
  51  *
  52  * Actions: When encoding OVS action lists, the 'header' is used
  53  *    as a pointer to the beginning of the current action (see ofpact_put()).
  54  *
  55  * rconn: Reuses 'header' as a private pointer while queuing.
  56  */
  57 struct ofpbuf {
  58     void *base;                 /* First byte of allocated space. */
  59     void *data;                 /* First byte actually in use. */
  60     uint32_t size;              /* Number of bytes in use. */
  61     uint32_t allocated;         /* Number of bytes allocated. */
  62
  63     void *header;               /* OpenFlow header. */
  64     void *msg;                  /* message's body */
  65     struct ovs_list list_node;  /* Private list element for use by owner. */
  66     enum ofpbuf_source source;  /* Source of memory allocated as 'base'. */
  67 };
  68
  69 /* An initializer for a struct ofpbuf that will be initially empty and uses the
  70  * space in STUB (which should be an array) as a stub.  This is the initializer
  71  * form of ofpbuf_use_stub().
  72  *
  73  * Usage example:
  74  *
  75  *     uint64_t stub[1024 / 8]; // 1 kB stub properly aligned for 64-bit data.
  76  *     struct ofpbuf ofpbuf = OFPBUF_STUB_INITIALIZER(stub);
  77  */
  78 #define OFPBUF_STUB_INITIALIZER(STUB) {         \
  79         .base = (STUB),                         \
  80         .data = (STUB),                         \
  81         .size = 0,                              \
  82         .allocated = sizeof (STUB),             \
  83         .header = NULL,                         \
  84         .msg = NULL,                            \
  85         .list_node = OVS_LIST_POISON,           \
  86         .source = OFPBUF_STUB,                  \
  87     }
  88
  89 /* An initializer for a struct ofpbuf whose data starts at DATA and continues
  90  * for SIZE bytes.  This is appropriate for an ofpbuf that will be used to
  91  * inspect existing data, without moving it around or reallocating it, and
  92  * generally without modifying it at all.  This is the initializer form of
  93  * ofpbuf_use_const().
  94  */
  95 static inline struct ofpbuf
  96 ofpbuf_const_initializer(const void *data, size_t size)
  97 {
  98     return (struct ofpbuf) {
  99         .base = CONST_CAST(void *, data),
 100         .data = CONST_CAST(void *, data),
 101         .size = size,
 102         .allocated = size,
 103         .header = NULL,
 104         .msg = NULL,
 105         .list_node = OVS_LIST_POISON,
 106         .source = OFPBUF_STACK,
 107     };
 108 }
 109
 110 void ofpbuf_use_ds(struct ofpbuf *, const struct ds *);
 111 void ofpbuf_use_stack(struct ofpbuf *, void *, size_t);
 112 void ofpbuf_use_stub(struct ofpbuf *, void *, size_t);
 113 void ofpbuf_use_const(struct ofpbuf *, const void *, size_t);
 114
 115 void ofpbuf_init(struct ofpbuf *, size_t);
 116 void ofpbuf_uninit(struct ofpbuf *);
 117 void ofpbuf_reinit(struct ofpbuf *, size_t);
 118
 119 struct ofpbuf *ofpbuf_new(size_t);
 120 struct ofpbuf *ofpbuf_new_with_headroom(size_t, size_t headroom);
 121 struct ofpbuf *ofpbuf_clone(const struct ofpbuf *);
 122 struct ofpbuf *ofpbuf_clone_with_headroom(const struct ofpbuf *,
 123                                           size_t headroom);
 124 struct ofpbuf *ofpbuf_clone_data(const void *, size_t);
 125 struct ofpbuf *ofpbuf_clone_data_with_headroom(const void *, size_t,
 126                                                size_t headroom);
 127 static inline void ofpbuf_delete(struct ofpbuf *);
 128
 129 static inline void *ofpbuf_at(const struct ofpbuf *, size_t offset,
 130                               size_t size);
 131 static inline void *ofpbuf_at_assert(const struct ofpbuf *, size_t offset,
 132                                      size_t size);
 133 static inline void *ofpbuf_tail(const struct ofpbuf *);
 134 static inline void *ofpbuf_end(const struct ofpbuf *);
 135
 136 void *ofpbuf_put_uninit(struct ofpbuf *, size_t);
 137 void *ofpbuf_put_zeros(struct ofpbuf *, size_t);
 138 void *ofpbuf_put(struct ofpbuf *, const void *, size_t);
 139 char *ofpbuf_put_hex(struct ofpbuf *, const char *s, size_t *n);
 140 void ofpbuf_reserve(struct ofpbuf *, size_t);
 141 void *ofpbuf_push_uninit(struct ofpbuf *b, size_t);
 142 void *ofpbuf_push_zeros(struct ofpbuf *, size_t);
 143 void *ofpbuf_push(struct ofpbuf *b, const void *, size_t);
 144
 145 static inline size_t ofpbuf_headroom(const struct ofpbuf *);
 146 static inline size_t ofpbuf_tailroom(const struct ofpbuf *);
 147 static inline size_t ofpbuf_msgsize(const struct ofpbuf *);
 148 void ofpbuf_prealloc_headroom(struct ofpbuf *, size_t);
 149 void ofpbuf_prealloc_tailroom(struct ofpbuf *, size_t);
 150 void ofpbuf_trim(struct ofpbuf *);
 151 void ofpbuf_padto(struct ofpbuf *, size_t);
 152 void ofpbuf_shift(struct ofpbuf *, int);
 153
 154 static inline void ofpbuf_clear(struct ofpbuf *);
 155 static inline void *ofpbuf_pull(struct ofpbuf *, size_t);
 156 static inline void *ofpbuf_try_pull(struct ofpbuf *, size_t);
 157
 158 void *ofpbuf_steal_data(struct ofpbuf *);
 159
 160 char *ofpbuf_to_string(const struct ofpbuf *, size_t maxbytes);
 161 static inline struct ofpbuf *ofpbuf_from_list(const struct ovs_list *);
 162 void ofpbuf_list_delete(struct ovs_list *);
 163 static inline bool ofpbuf_equal(const struct ofpbuf *, const struct ofpbuf *);
 164
 165 \f
 166 /* Frees memory that 'b' points to, as well as 'b' itself. */
 167 static inline void ofpbuf_delete(struct ofpbuf *b)
 168 {
 169     if (b) {
 170         ofpbuf_uninit(b);
 171         free(b);
 172     }
 173 }
 174
 175 /* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
 176  * byte 'offset'.  Otherwise, returns a null pointer. */
 177 static inline void *ofpbuf_at(const struct ofpbuf *b, size_t offset,
 178                               size_t size)
 179 {
 180     return offset + size <= b->size ? (char *) b->data + offset : NULL;
 181 }
 182
 183 /* Returns a pointer to byte 'offset' in 'b', which must contain at least
 184  * 'offset + size' bytes of data. */
 185 static inline void *ofpbuf_at_assert(const struct ofpbuf *b, size_t offset,
 186                                      size_t size)
 187 {
 188     ovs_assert(offset + size <= b->size);
 189     return ((char *) b->data) + offset;
 190 }
 191
 192 /* Returns a pointer to byte following the last byte of data in use in 'b'. */
 193 static inline void *ofpbuf_tail(const struct ofpbuf *b)
 194 {
 195     return (char *) b->data + b->size;
 196 }
 197
 198 /* Returns a pointer to byte following the last byte allocated for use (but
 199  * not necessarily in use) in 'b'. */
 200 static inline void *ofpbuf_end(const struct ofpbuf *b)
 201 {
 202     return (char *) b->base + b->allocated;
 203 }
 204
 205 /* Returns the number of bytes of headroom in 'b', that is, the number of bytes
 206  * of unused space in ofpbuf 'b' before the data that is in use.  (Most
 207  * commonly, the data in a ofpbuf is at its beginning, and thus the ofpbuf's
 208  * headroom is 0.) */
 209 static inline size_t ofpbuf_headroom(const struct ofpbuf *b)
 210 {
 211     return (char*)b->data - (char*)b->base;
 212 }
 213
 214 /* Returns the number of bytes that may be appended to the tail end of ofpbuf
 215  * 'b' before the ofpbuf must be reallocated. */
 216 static inline size_t ofpbuf_tailroom(const struct ofpbuf *b)
 217 {
 218     return (char*)ofpbuf_end(b) - (char*)ofpbuf_tail(b);
 219 }
 220
 221 /* Returns the number of bytes from 'b->header' to 'b->msg', that is, the
 222  * length of 'b''s header. */
 223 static inline size_t
 224 ofpbuf_headersize(const struct ofpbuf *b)
 225 {
 226     return (char *)b->msg - (char *)b->header;
 227 }
 228
 229 /* Returns the number of bytes from 'b->msg' to 'b->data + b->size', that is,
 230  * the length of the used space in 'b' starting from 'msg'. */
 231 static inline size_t
 232 ofpbuf_msgsize(const struct ofpbuf *b)
 233 {
 234     return (char *)ofpbuf_tail(b) - (char *)b->msg;
 235 }
 236
 237 /* Clears any data from 'b'. */
 238 static inline void ofpbuf_clear(struct ofpbuf *b)
 239 {
 240     b->data = b->base;
 241     b->size = 0;
 242 }
 243
 244 /* Removes 'size' bytes from the head end of 'b', which must contain at least
 245  * 'size' bytes of data.  Returns the first byte of data removed. */
 246 static inline void *ofpbuf_pull(struct ofpbuf *b, size_t size)
 247 {
 248     void *data = b->data;
 249     b->data = (char*)b->data + size;
 250     b->size = b->size - size;
 251     return data;
 252 }
 253
 254 /* If 'b' has at least 'size' bytes of data, removes that many bytes from the
 255  * head end of 'b' and returns the first byte removed.  Otherwise, returns a
 256  * null pointer without modifying 'b'. */
 257 static inline void *ofpbuf_try_pull(struct ofpbuf *b, size_t size)
 258 {
 259     return b->size >= size ? ofpbuf_pull(b, size) : NULL;
 260 }
 261
 262 static inline struct ofpbuf *ofpbuf_from_list(const struct ovs_list *list)
 263 {
 264     return CONTAINER_OF(list, struct ofpbuf, list_node);
 265 }
 266
 267 static inline bool ofpbuf_equal(const struct ofpbuf *a, const struct ofpbuf *b)
 268 {
 269     return a->size == b->size &&
 270            memcmp(a->data, b->data, a->size) == 0;
 271 }
 272
 273 #ifdef  __cplusplus
 274 }
 275 #endif
 276
 277 #endif /* ofpbuf.h */