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 /*
  32  * A stream is an arbitrary buffer, whose contents generally are assumed to
  33  * be in network order.
  34  *
  35  * A stream has the following attributes associated with it:
  36  *
  37  * - size: the allocated, invariant size of the buffer.
  38  *
  39  * - getp: the get position marker, denoting the offset in the stream where
  40  *         the next read (or 'get') will be from. This getp marker is
  41  *         automatically adjusted when data is read from the stream, the
  42  *         user may also manipulate this offset as they wish, within limits
  43  *         (see below)
  44  *
  45  * - endp: the end position marker, denoting the offset in the stream where
  46  *         valid data ends, and if the user attempted to write (or
  47  *         'put') data where that data would be written (or 'put') to.
  48  *
  49  * These attributes are all size_t values.
  50  *
  51  * Constraints:
  52  *
  53  * 1. getp can never exceed endp
  54  *
  55  * - hence if getp is equal to endp, there is no more valid data that can be
  56  *   gotten from the stream (though, the user may reposition getp to earlier in
  57  *   the stream, if they wish).
  58  *
  59  * 2. endp can never exceed size
  60  *
  61  * - hence, if endp is equal to size, then the stream is full, and no more
  62  *   data can be written to the stream.
  63  *
  64  * In other words the following must always be true, and the stream
  65  * abstraction is allowed internally to assert that the following property
  66  * holds true for a stream, as and when it wishes:
  67  *
  68  *        getp <= endp <= size
  69  *
  70  * It is the users responsibility to ensure this property is never violated.
  71  *
  72  * A stream therefore can be thought of like this:
  73  *
  74  *      ---------------------------------------------------
  75  *      |XXXXXXXXXXXXXXXXXXXXXXXX                         |
  76  *      ---------------------------------------------------
  77  *               ^               ^                        ^
  78  *               getp            endp                     size
  79  *
  80  * This shows a stream containing data (shown as 'X') up to the endp offset.
  81  * The stream is empty from endp to size. Without adjusting getp, there are
  82  * still endp-getp bytes of valid data to be read from the stream.
  83  *
  84  * Methods are provided to get and put to/from the stream, as well as
  85  * retrieve the values of the 3 markers and manipulate the getp marker.
  86  *
  87  * Note:
  88  * At the moment, newly allocated streams are zero filled. Hence, one can
  89  * use stream_forward_endp() to effectively create arbitrary zero-fill
  90  * padding. However, note that stream_reset() does *not* zero-out the
  91  * stream. This property should **not** be relied upon.
  92  *
  93  * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out
  94  * any part of a stream which isn't otherwise written to.
  95  */
  96
  97 /* Stream buffer. */
  98 struct stream {
  99         struct stream *next;
 100
 101         /*
 102          * Remainder is ***private*** to stream
 103          * direct access is frowned upon!
 104          * Use the appropriate functions/macros
 105          */
 106         size_t getp;           /* next get position */
 107         size_t endp;           /* last valid data position */
 108         size_t size;           /* size of data segment */
 109         unsigned char data[0]; /* data pointer */
 110 };
 111
 112 /* First in first out queue structure. */
 113 struct stream_fifo {
 114         /* lock for mt-safe operations */
 115         pthread_mutex_t mtx;
 116
 117         /* number of streams in this fifo */
 118         _Atomic size_t count;
 119 #if defined DEV_BUILD
 120         _Atomic size_t max_count;
 121 #endif
 122
 123         struct stream *head;
 124         struct stream *tail;
 125 };
 126
 127 /* Utility macros. */
 128 #define STREAM_SIZE(S)  ((S)->size)
 129 /* number of bytes which can still be written */
 130 #define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
 131 /* number of bytes still to be read */
 132 #define STREAM_READABLE(S) ((S)->endp - (S)->getp)
 133
 134 #define STREAM_CONCAT_REMAIN(S1, S2, size) ((size) - (S1)->endp - (S2)->endp)
 135
 136 /* deprecated macros - do not use in new code */
 137 #if CONFDATE > 20181128
 138 CPP_NOTICE("lib: time to remove deprecated stream.h macros")
 139 #endif
 140 #define STREAM_PNT(S)   stream_pnt((S))
 141 #define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
 142
 143 /* this macro is deprecated, but not slated for removal anytime soon */
 144 #define STREAM_DATA(S)  ((S)->data)
 145
 146 /* Stream prototypes.
 147  * For stream_{put,get}S, the S suffix mean:
 148  *
 149  * c: character (unsigned byte)
 150  * w: word (two bytes)
 151  * l: long (two words)
 152  * q: quad (four words)
 153  */
 154 extern struct stream *stream_new(size_t);
 155 extern void stream_free(struct stream *);
 156 extern struct stream *stream_copy(struct stream *, struct stream *src);
 157 extern struct stream *stream_dup(struct stream *);
 158
 159 #if CONFDATE > 20190821
 160 CPP_NOTICE("lib: time to remove stream_resize_orig")
 161 #endif
 162 extern size_t stream_resize_orig(struct stream *s, size_t newsize);
 163 #define stream_resize stream_resize_orig
 164 extern size_t stream_resize_inplace(struct stream **sptr, size_t newsize);
 165
 166 extern size_t stream_get_getp(struct stream *);
 167 extern size_t stream_get_endp(struct stream *);
 168 extern size_t stream_get_size(struct stream *);
 169 extern uint8_t *stream_get_data(struct stream *);
 170
 171 /**
 172  * Create a new stream structure; copy offset bytes from s1 to the new
 173  * stream; copy s2 data to the new stream; copy rest of s1 data to the
 174  * new stream.
 175  */
 176 extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
 177                                     size_t offset);
 178
 179 extern void stream_set_getp(struct stream *, size_t);
 180 extern void stream_set_endp(struct stream *, size_t);
 181 extern void stream_forward_getp(struct stream *, size_t);
 182 extern void stream_forward_endp(struct stream *, size_t);
 183
 184 /* steam_put: NULL source zeroes out size_t bytes of stream */
 185 extern void stream_put(struct stream *, const void *, size_t);
 186 extern int stream_putc(struct stream *, uint8_t);
 187 extern int stream_putc_at(struct stream *, size_t, uint8_t);
 188 extern int stream_putw(struct stream *, uint16_t);
 189 extern int stream_putw_at(struct stream *, size_t, uint16_t);
 190 extern int stream_put3(struct stream *, uint32_t);
 191 extern int stream_put3_at(struct stream *, size_t, uint32_t);
 192 extern int stream_putl(struct stream *, uint32_t);
 193 extern int stream_putl_at(struct stream *, size_t, uint32_t);
 194 extern int stream_putq(struct stream *, uint64_t);
 195 extern int stream_putq_at(struct stream *, size_t, uint64_t);
 196 extern int stream_put_ipv4(struct stream *, uint32_t);
 197 extern int stream_put_in_addr(struct stream *, struct in_addr *);
 198 extern int stream_put_in_addr_at(struct stream *, size_t, struct in_addr *);
 199 extern int stream_put_in6_addr_at(struct stream *, size_t, struct in6_addr *);
 200 extern int stream_put_prefix_addpath(struct stream *, struct prefix *,
 201                                      int addpath_encode,
 202                                      uint32_t addpath_tx_id);
 203 extern int stream_put_prefix(struct stream *, struct prefix *);
 204 extern int stream_put_labeled_prefix(struct stream *, struct prefix *,
 205                                      mpls_label_t *);
 206 extern void stream_get(void *, struct stream *, size_t);
 207 extern bool stream_get2(void *data, struct stream *s, size_t size);
 208 extern void stream_get_from(void *, struct stream *, size_t, size_t);
 209 extern uint8_t stream_getc(struct stream *);
 210 extern bool stream_getc2(struct stream *s, uint8_t *byte);
 211 extern uint8_t stream_getc_from(struct stream *, size_t);
 212 extern uint16_t stream_getw(struct stream *);
 213 extern bool stream_getw2(struct stream *s, uint16_t *word);
 214 extern uint16_t stream_getw_from(struct stream *, size_t);
 215 extern uint32_t stream_get3(struct stream *);
 216 extern uint32_t stream_get3_from(struct stream *, size_t);
 217 extern uint32_t stream_getl(struct stream *);
 218 extern bool stream_getl2(struct stream *s, uint32_t *l);
 219 extern uint32_t stream_getl_from(struct stream *, size_t);
 220 extern uint64_t stream_getq(struct stream *);
 221 extern uint64_t stream_getq_from(struct stream *, size_t);
 222 extern uint32_t stream_get_ipv4(struct stream *);
 223
 224 /* IEEE-754 floats */
 225 extern float stream_getf(struct stream *);
 226 extern double stream_getd(struct stream *);
 227 extern int stream_putf(struct stream *, float);
 228 extern int stream_putd(struct stream *, double);
 229
 230 #undef stream_read
 231 #undef stream_write
 232
 233 /* Deprecated: assumes blocking I/O.  Will be removed.
 234    Use stream_read_try instead.  */
 235 extern int stream_read(struct stream *, int, size_t);
 236
 237 /* Read up to size bytes into the stream.
 238    Return code:
 239      >0: number of bytes read
 240      0: end-of-file
 241      -1: fatal error
 242      -2: transient error, should retry later (i.e. EAGAIN or EINTR)
 243    This is suitable for use with non-blocking file descriptors.
 244  */
 245 extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
 246
 247 extern ssize_t stream_recvmsg(struct stream *s, int fd, struct msghdr *,
 248                               int flags, size_t size);
 249 extern ssize_t stream_recvfrom(struct stream *s, int fd, size_t len, int flags,
 250                                struct sockaddr *from, socklen_t *fromlen);
 251 extern size_t stream_write(struct stream *, const void *, size_t);
 252
 253 /* reset the stream. See Note above */
 254 extern void stream_reset(struct stream *);
 255 extern int stream_flush(struct stream *, int);
 256 extern int stream_empty(struct stream *); /* is the stream empty? */
 257
 258 /* deprecated */
 259 extern uint8_t *stream_pnt(struct stream *);
 260
 261 /*
 262  * Operations on struct stream_fifo.
 263  *
 264  * Each function has a safe variant, which ensures that the operation performed
 265  * is atomic with respect to the operations performed by all other safe
 266  * variants. In other words, the safe variants lock the stream_fifo's mutex
 267  * before performing their action. These are provided for convenience when
 268  * using stream_fifo in a multithreaded context, to alleviate the need for the
 269  * caller to implement their own synchronization around the stream_fifo.
 270  *
 271  * The following functions do not have safe variants. The caller must ensure
 272  * that these operations are performed safely in a multithreaded context:
 273  * - stream_fifo_new
 274  * - stream_fifo_free
 275  */
 276
 277 /*
 278  * Create a new stream_fifo.
 279  *
 280  * Returns:
 281  *    newly created stream_fifo
 282  */
 283 extern struct stream_fifo *stream_fifo_new(void);
 284
 285 /*
 286  * Push a stream onto a stream_fifo.
 287  *
 288  * fifo
 289  *    the stream_fifo to push onto
 290  *
 291  * s
 292  *    the stream to push onto the stream_fifo
 293  */
 294 extern void stream_fifo_push(struct stream_fifo *fifo, struct stream *s);
 295 extern void stream_fifo_push_safe(struct stream_fifo *fifo, struct stream *s);
 296
 297 /*
 298  * Pop a stream off a stream_fifo.
 299  *
 300  * fifo
 301  *    the stream_fifo to pop from
 302  *
 303  * Returns:
 304  *    the next stream in the stream_fifo
 305  */
 306 extern struct stream *stream_fifo_pop(struct stream_fifo *fifo);
 307 extern struct stream *stream_fifo_pop_safe(struct stream_fifo *fifo);
 308
 309 /*
 310  * Retrieve the next stream from a stream_fifo without popping it.
 311  *
 312  * fifo
 313  *    the stream_fifo to operate on
 314  *
 315  * Returns:
 316  *    the next stream that would be returned from stream_fifo_pop
 317  */
 318 extern struct stream *stream_fifo_head(struct stream_fifo *fifo);
 319 extern struct stream *stream_fifo_head_safe(struct stream_fifo *fifo);
 320
 321 /*
 322  * Remove all streams from a stream_fifo.
 323  *
 324  * fifo
 325  *    the stream_fifo to clean
 326  */
 327 extern void stream_fifo_clean(struct stream_fifo *fifo);
 328 extern void stream_fifo_clean_safe(struct stream_fifo *fifo);
 329
 330 /*
 331  * Retrieve number of streams on a stream_fifo.
 332  *
 333  * fifo
 334  *    the stream_fifo to retrieve the count for
 335  *
 336  * Returns:
 337  *    the number of streams on the stream_fifo
 338  */
 339 extern size_t stream_fifo_count_safe(struct stream_fifo *fifo);
 340
 341 /*
 342  * Free a stream_fifo.
 343  *
 344  * Calls stream_fifo_clean, then deinitializes the stream_fifo and frees it.
 345  *
 346  * fifo
 347  *    the stream_fifo to free
 348  */
 349 extern void stream_fifo_free(struct stream_fifo *fifo);
 350
 351 /* This is here because "<< 24" is particularly problematic in C.
 352  * This is because the left operand of << is integer-promoted, which means
 353  * an uint8_t gets converted into a *signed* int.  Shifting into the sign
 354  * bit of a signed int is theoretically undefined behaviour, so - the left
 355  * operand needs to be cast to unsigned.
 356  *
 357  * This is not a problem for 16- or 8-bit values (they don't reach the sign
 358  * bit), for 64-bit values (you need to cast them anyway), and neither for
 359  * encoding (because it's downcasted.)
 360  */
 361 static inline uint8_t *ptr_get_be32(uint8_t *ptr, uint32_t *out)
 362 {
 363         uint32_t tmp;
 364         memcpy(&tmp, ptr, sizeof(tmp));
 365         *out = ntohl(tmp);
 366         return ptr + 4;
 367 }
 368
 369 /*
 370  * so Normal stream_getX functions assert.  Which is anathema
 371  * to keeping a daemon up and running when something goes south
 372  * Provide a stream_getX2 functions that do not assert.
 373  * In addition provide these macro's that upon failure
 374  * goto stream_failure.  This is modeled upon some NL_XX
 375  * macros in the linux kernel.
 376  *
 377  * This change allows for proper memory freeing
 378  * after we've detected an error.
 379  *
 380  * In the future we will be removing the assert in
 381  * the stream functions but we need a transition
 382  * plan.
 383  */
 384 #define STREAM_GETC(S, P)                                                      \
 385         do {                                                                   \
 386                 uint8_t _pval;                                                 \
 387                 if (!stream_getc2((S), &_pval))                                \
 388                         goto stream_failure;                                   \
 389                 (P) = _pval;                                                   \
 390         } while (0)
 391
 392 #define STREAM_GETW(S, P)                                                      \
 393         do {                                                                   \
 394                 uint16_t _pval;                                                \
 395                 if (!stream_getw2((S), &_pval))                                \
 396                         goto stream_failure;                                   \
 397                 (P) = _pval;                                                   \
 398         } while (0)
 399
 400 #define STREAM_GETL(S, P)                                                      \
 401         do {                                                                   \
 402                 uint32_t _pval;                                                \
 403                 if (!stream_getl2((S), &_pval))                                \
 404                         goto stream_failure;                                   \
 405                 (P) = _pval;                                                   \
 406         } while (0)
 407
 408 #define STREAM_GET(P, STR, SIZE)                                               \
 409         do {                                                                   \
 410                 if (!stream_get2((P), (STR), (SIZE)))                          \
 411                         goto stream_failure;                                   \
 412         } while (0)
 413
 414 #endif /* _ZEBRA_STREAM_H */