lib/stream.h

   1 /*
   2  * Packet interface
   3  * Copyright (C) 1999 Kunihiro Ishiguro
   4  *
   5  * This file is part of GNU Zebra.
   6  *
   7  * GNU Zebra is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation; either version 2, or (at your option) any
  10  * later version.
  11  *
  12  * GNU Zebra is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; see the file COPYING; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef _ZEBRA_STREAM_H
  23 #define _ZEBRA_STREAM_H
  24
  25 #include <pthread.h>
  26
  27 #include "frratomic.h"
  28 #include "mpls.h"
  29 #include "prefix.h"
  30
  31 #ifdef __cplusplus
  32 extern "C" {
  33 #endif
  34
  35 /*
  36  * A stream is an arbitrary buffer, whose contents generally are assumed to
  37  * be in network order.
  38  *
  39  * A stream has the following attributes associated with it:
  40  *
  41  * - size: the allocated, invariant size of the buffer.
  42  *
  43  * - getp: the get position marker, denoting the offset in the stream where
  44  *         the next read (or 'get') will be from. This getp marker is
  45  *         automatically adjusted when data is read from the stream, the
  46  *         user may also manipulate this offset as they wish, within limits
  47  *         (see below)
  48  *
  49  * - endp: the end position marker, denoting the offset in the stream where
  50  *         valid data ends, and if the user attempted to write (or
  51  *         'put') data where that data would be written (or 'put') to.
  52  *
  53  * These attributes are all size_t values.
  54  *
  55  * Constraints:
  56  *
  57  * 1. getp can never exceed endp
  58  *
  59  * - hence if getp is equal to endp, there is no more valid data that can be
  60  *   gotten from the stream (though, the user may reposition getp to earlier in
  61  *   the stream, if they wish).
  62  *
  63  * 2. endp can never exceed size
  64  *
  65  * - hence, if endp is equal to size, then the stream is full, and no more
  66  *   data can be written to the stream.
  67  *
  68  * In other words the following must always be true, and the stream
  69  * abstraction is allowed internally to assert that the following property
  70  * holds true for a stream, as and when it wishes:
  71  *
  72  *        getp <= endp <= size
  73  *
  74  * It is the users responsibility to ensure this property is never violated.
  75  *
  76  * A stream therefore can be thought of like this:
  77  *
  78  *      ---------------------------------------------------
  79  *      |XXXXXXXXXXXXXXXXXXXXXXXX                         |
  80  *      ---------------------------------------------------
  81  *               ^               ^                        ^
  82  *               getp            endp                     size
  83  *
  84  * This shows a stream containing data (shown as 'X') up to the endp offset.
  85  * The stream is empty from endp to size. Without adjusting getp, there are
  86  * still endp-getp bytes of valid data to be read from the stream.
  87  *
  88  * Methods are provided to get and put to/from the stream, as well as
  89  * retrieve the values of the 3 markers and manipulate the getp marker.
  90  *
  91  * Note:
  92  * At the moment, newly allocated streams are zero filled. Hence, one can
  93  * use stream_forward_endp() to effectively create arbitrary zero-fill
  94  * padding. However, note that stream_reset() does *not* zero-out the
  95  * stream. This property should **not** be relied upon.
  96  *
  97  * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out
  98  * any part of a stream which isn't otherwise written to.
  99  */
 100
 101 /* Stream buffer. */
 102 struct stream {
 103         struct stream *next;
 104
 105         /*
 106          * Remainder is ***private*** to stream
 107          * direct access is frowned upon!
 108          * Use the appropriate functions/macros
 109          */
 110         size_t getp;           /* next get position */
 111         size_t endp;           /* last valid data position */
 112         size_t size;           /* size of data segment */
 113         unsigned char data[0]; /* data pointer */
 114 };
 115
 116 /* First in first out queue structure. */
 117 struct stream_fifo {
 118         /* lock for mt-safe operations */
 119         pthread_mutex_t mtx;
 120
 121         /* number of streams in this fifo */
 122         atomic_size_t count;
 123 #if defined DEV_BUILD
 124         atomic_size_t max_count;
 125 #endif
 126
 127         struct stream *head;
 128         struct stream *tail;
 129 };
 130
 131 /* Utility macros. */
 132 #define STREAM_SIZE(S)  ((S)->size)
 133 /* number of bytes which can still be written */
 134 #define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
 135 /* number of bytes still to be read */
 136 #define STREAM_READABLE(S) ((S)->endp - (S)->getp)
 137
 138 #define STREAM_CONCAT_REMAIN(S1, S2, size) ((size) - (S1)->endp - (S2)->endp)
 139
 140 /* this macro is deprecated, but not slated for removal anytime soon */
 141 #define STREAM_DATA(S)  ((S)->data)
 142
 143 /* Stream prototypes.
 144  * For stream_{put,get}S, the S suffix mean:
 145  *
 146  * c: character (unsigned byte)
 147  * w: word (two bytes)
 148  * l: long (two words)
 149  * q: quad (four words)
 150  */
 151 extern struct stream *stream_new(size_t);
 152 extern void stream_free(struct stream *);
 153 extern struct stream *stream_copy(struct stream *, struct stream *src);
 154 extern struct stream *stream_dup(struct stream *);
 155
 156 extern size_t stream_resize_inplace(struct stream **sptr, size_t newsize);
 157
 158 extern size_t stream_get_getp(struct stream *);
 159 extern size_t stream_get_endp(struct stream *);
 160 extern size_t stream_get_size(struct stream *);
 161 extern uint8_t *stream_get_data(struct stream *);
 162
 163 /**
 164  * Create a new stream structure; copy offset bytes from s1 to the new
 165  * stream; copy s2 data to the new stream; copy rest of s1 data to the
 166  * new stream.
 167  */
 168 extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
 169                                     size_t offset);
 170
 171 extern void stream_set_getp(struct stream *, size_t);
 172 extern void stream_set_endp(struct stream *, size_t);
 173 extern void stream_forward_getp(struct stream *, size_t);
 174 extern void stream_forward_endp(struct stream *, size_t);
 175
 176 /* steam_put: NULL source zeroes out size_t bytes of stream */
 177 extern void stream_put(struct stream *, const void *, size_t);
 178 extern int stream_putc(struct stream *, uint8_t);
 179 extern int stream_putc_at(struct stream *, size_t, uint8_t);
 180 extern int stream_putw(struct stream *, uint16_t);
 181 extern int stream_putw_at(struct stream *, size_t, uint16_t);
 182 extern int stream_put3(struct stream *, uint32_t);
 183 extern int stream_put3_at(struct stream *, size_t, uint32_t);
 184 extern int stream_putl(struct stream *, uint32_t);
 185 extern int stream_putl_at(struct stream *, size_t, uint32_t);
 186 extern int stream_putq(struct stream *, uint64_t);
 187 extern int stream_putq_at(struct stream *, size_t, uint64_t);
 188 extern int stream_put_ipv4(struct stream *, uint32_t);
 189 extern int stream_put_in_addr(struct stream *s, const struct in_addr *addr);
 190 extern int stream_put_in_addr_at(struct stream *s, size_t putp,
 191                                  const struct in_addr *addr);
 192 extern int stream_put_in6_addr_at(struct stream *s, size_t putp,
 193                                   const struct in6_addr *addr);
 194 extern int stream_put_prefix_addpath(struct stream *s,
 195                                      const struct prefix *p,
 196                                      int addpath_encode,
 197                                      uint32_t addpath_tx_id);
 198 extern int stream_put_prefix(struct stream *s, const struct prefix *p);
 199 extern int stream_put_labeled_prefix(struct stream *, struct prefix *,
 200                                      mpls_label_t *, int addpath_encode,
 201                                      uint32_t addpath_tx_id);
 202 extern void stream_get(void *, struct stream *, size_t);
 203 extern bool stream_get2(void *data, struct stream *s, size_t size);
 204 extern void stream_get_from(void *, struct stream *, size_t, size_t);
 205 extern uint8_t stream_getc(struct stream *);
 206 extern bool stream_getc2(struct stream *s, uint8_t *byte);
 207 extern uint8_t stream_getc_from(struct stream *, size_t);
 208 extern uint16_t stream_getw(struct stream *);
 209 extern bool stream_getw2(struct stream *s, uint16_t *word);
 210 extern uint16_t stream_getw_from(struct stream *, size_t);
 211 extern uint32_t stream_get3(struct stream *);
 212 extern uint32_t stream_get3_from(struct stream *, size_t);
 213 extern uint32_t stream_getl(struct stream *);
 214 extern bool stream_getl2(struct stream *s, uint32_t *l);
 215 extern uint32_t stream_getl_from(struct stream *, size_t);
 216 extern uint64_t stream_getq(struct stream *);
 217 extern uint64_t stream_getq_from(struct stream *, size_t);
 218 extern uint32_t stream_get_ipv4(struct stream *);
 219
 220 /* IEEE-754 floats */
 221 extern float stream_getf(struct stream *);
 222 extern double stream_getd(struct stream *);
 223 extern int stream_putf(struct stream *, float);
 224 extern int stream_putd(struct stream *, double);
 225
 226 #undef stream_read
 227 #undef stream_write
 228
 229 /* Deprecated: assumes blocking I/O.  Will be removed.
 230    Use stream_read_try instead.  */
 231 extern int stream_read(struct stream *, int, size_t);
 232
 233 /* Read up to size bytes into the stream.
 234    Return code:
 235      >0: number of bytes read
 236      0: end-of-file
 237      -1: fatal error
 238      -2: transient error, should retry later (i.e. EAGAIN or EINTR)
 239    This is suitable for use with non-blocking file descriptors.
 240  */
 241 extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
 242
 243 extern ssize_t stream_recvmsg(struct stream *s, int fd, struct msghdr *,
 244                               int flags, size_t size);
 245 extern ssize_t stream_recvfrom(struct stream *s, int fd, size_t len, int flags,
 246                                struct sockaddr *from, socklen_t *fromlen);
 247 extern size_t stream_write(struct stream *, const void *, size_t);
 248
 249 /* reset the stream. See Note above */
 250 extern void stream_reset(struct stream *);
 251 extern int stream_flush(struct stream *, int);
 252 extern int stream_empty(struct stream *); /* is the stream empty? */
 253
 254 /* deprecated */
 255 extern uint8_t *stream_pnt(struct stream *);
 256
 257 /*
 258  * Operations on struct stream_fifo.
 259  *
 260  * Each function has a safe variant, which ensures that the operation performed
 261  * is atomic with respect to the operations performed by all other safe
 262  * variants. In other words, the safe variants lock the stream_fifo's mutex
 263  * before performing their action. These are provided for convenience when
 264  * using stream_fifo in a multithreaded context, to alleviate the need for the
 265  * caller to implement their own synchronization around the stream_fifo.
 266  *
 267  * The following functions do not have safe variants. The caller must ensure
 268  * that these operations are performed safely in a multithreaded context:
 269  * - stream_fifo_new
 270  * - stream_fifo_free
 271  */
 272
 273 /*
 274  * Create a new stream_fifo.
 275  *
 276  * Returns:
 277  *    newly created stream_fifo
 278  */
 279 extern struct stream_fifo *stream_fifo_new(void);
 280
 281 /*
 282  * Push a stream onto a stream_fifo.
 283  *
 284  * fifo
 285  *    the stream_fifo to push onto
 286  *
 287  * s
 288  *    the stream to push onto the stream_fifo
 289  */
 290 extern void stream_fifo_push(struct stream_fifo *fifo, struct stream *s);
 291 extern void stream_fifo_push_safe(struct stream_fifo *fifo, struct stream *s);
 292
 293 /*
 294  * Pop a stream off a stream_fifo.
 295  *
 296  * fifo
 297  *    the stream_fifo to pop from
 298  *
 299  * Returns:
 300  *    the next stream in the stream_fifo
 301  */
 302 extern struct stream *stream_fifo_pop(struct stream_fifo *fifo);
 303 extern struct stream *stream_fifo_pop_safe(struct stream_fifo *fifo);
 304
 305 /*
 306  * Retrieve the next stream from a stream_fifo without popping it.
 307  *
 308  * fifo
 309  *    the stream_fifo to operate on
 310  *
 311  * Returns:
 312  *    the next stream that would be returned from stream_fifo_pop
 313  */
 314 extern struct stream *stream_fifo_head(struct stream_fifo *fifo);
 315 extern struct stream *stream_fifo_head_safe(struct stream_fifo *fifo);
 316
 317 /*
 318  * Remove all streams from a stream_fifo.
 319  *
 320  * fifo
 321  *    the stream_fifo to clean
 322  */
 323 extern void stream_fifo_clean(struct stream_fifo *fifo);
 324 extern void stream_fifo_clean_safe(struct stream_fifo *fifo);
 325
 326 /*
 327  * Retrieve number of streams on a stream_fifo.
 328  *
 329  * fifo
 330  *    the stream_fifo to retrieve the count for
 331  *
 332  * Returns:
 333  *    the number of streams on the stream_fifo
 334  */
 335 extern size_t stream_fifo_count_safe(struct stream_fifo *fifo);
 336
 337 /*
 338  * Free a stream_fifo.
 339  *
 340  * Calls stream_fifo_clean, then deinitializes the stream_fifo and frees it.
 341  *
 342  * fifo
 343  *    the stream_fifo to free
 344  */
 345 extern void stream_fifo_free(struct stream_fifo *fifo);
 346
 347 /* This is here because "<< 24" is particularly problematic in C.
 348  * This is because the left operand of << is integer-promoted, which means
 349  * an uint8_t gets converted into a *signed* int.  Shifting into the sign
 350  * bit of a signed int is theoretically undefined behaviour, so - the left
 351  * operand needs to be cast to unsigned.
 352  *
 353  * This is not a problem for 16- or 8-bit values (they don't reach the sign
 354  * bit), for 64-bit values (you need to cast them anyway), and neither for
 355  * encoding (because it's downcasted.)
 356  */
 357 static inline uint8_t *ptr_get_be32(uint8_t *ptr, uint32_t *out)
 358 {
 359         uint32_t tmp;
 360         memcpy(&tmp, ptr, sizeof(tmp));
 361         *out = ntohl(tmp);
 362         return ptr + 4;
 363 }
 364
 365 /*
 366  * so Normal stream_getX functions assert.  Which is anathema
 367  * to keeping a daemon up and running when something goes south
 368  * Provide a stream_getX2 functions that do not assert.
 369  * In addition provide these macro's that upon failure
 370  * goto stream_failure.  This is modeled upon some NL_XX
 371  * macros in the linux kernel.
 372  *
 373  * This change allows for proper memory freeing
 374  * after we've detected an error.
 375  *
 376  * In the future we will be removing the assert in
 377  * the stream functions but we need a transition
 378  * plan.
 379  */
 380 #define STREAM_GETC(S, P)                                                      \
 381         do {                                                                   \
 382                 uint8_t _pval;                                                 \
 383                 if (!stream_getc2((S), &_pval))                                \
 384                         goto stream_failure;                                   \
 385                 (P) = _pval;                                                   \
 386         } while (0)
 387
 388 #define STREAM_GETW(S, P)                                                      \
 389         do {                                                                   \
 390                 uint16_t _pval;                                                \
 391                 if (!stream_getw2((S), &_pval))                                \
 392                         goto stream_failure;                                   \
 393                 (P) = _pval;                                                   \
 394         } while (0)
 395
 396 #define STREAM_GETL(S, P)                                                      \
 397         do {                                                                   \
 398                 uint32_t _pval;                                                \
 399                 if (!stream_getl2((S), &_pval))                                \
 400                         goto stream_failure;                                   \
 401                 (P) = _pval;                                                   \
 402         } while (0)
 403
 404 #define STREAM_GET(P, STR, SIZE)                                               \
 405         do {                                                                   \
 406                 if (!stream_get2((P), (STR), (SIZE)))                          \
 407                         goto stream_failure;                                   \
 408         } while (0)
 409
 410 #ifdef __cplusplus
 411 }
 412 #endif
 413
 414 #endif /* _ZEBRA_STREAM_H */