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 /* this macro is deprecated, but not slated for removal anytime soon */
 137 #define STREAM_DATA(S)  ((S)->data)
 138
 139 /* Stream prototypes.
 140  * For stream_{put,get}S, the S suffix mean:
 141  *
 142  * c: character (unsigned byte)
 143  * w: word (two bytes)
 144  * l: long (two words)
 145  * q: quad (four words)
 146  */
 147 extern struct stream *stream_new(size_t);
 148 extern void stream_free(struct stream *);
 149 extern struct stream *stream_copy(struct stream *, struct stream *src);
 150 extern struct stream *stream_dup(struct stream *);
 151
 152 #if CONFDATE > 20190821
 153 CPP_NOTICE("lib: time to remove stream_resize_orig")
 154 #endif
 155 extern size_t stream_resize_orig(struct stream *s, size_t newsize);
 156 #define stream_resize stream_resize_orig
 157 extern size_t stream_resize_inplace(struct stream **sptr, size_t newsize);
 158
 159 extern size_t stream_get_getp(struct stream *);
 160 extern size_t stream_get_endp(struct stream *);
 161 extern size_t stream_get_size(struct stream *);
 162 extern uint8_t *stream_get_data(struct stream *);
 163
 164 /**
 165  * Create a new stream structure; copy offset bytes from s1 to the new
 166  * stream; copy s2 data to the new stream; copy rest of s1 data to the
 167  * new stream.
 168  */
 169 extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
 170                                     size_t offset);
 171
 172 extern void stream_set_getp(struct stream *, size_t);
 173 extern void stream_set_endp(struct stream *, size_t);
 174 extern void stream_forward_getp(struct stream *, size_t);
 175 extern void stream_forward_endp(struct stream *, size_t);
 176
 177 /* steam_put: NULL source zeroes out size_t bytes of stream */
 178 extern void stream_put(struct stream *, const void *, size_t);
 179 extern int stream_putc(struct stream *, uint8_t);
 180 extern int stream_putc_at(struct stream *, size_t, uint8_t);
 181 extern int stream_putw(struct stream *, uint16_t);
 182 extern int stream_putw_at(struct stream *, size_t, uint16_t);
 183 extern int stream_put3(struct stream *, uint32_t);
 184 extern int stream_put3_at(struct stream *, size_t, uint32_t);
 185 extern int stream_putl(struct stream *, uint32_t);
 186 extern int stream_putl_at(struct stream *, size_t, uint32_t);
 187 extern int stream_putq(struct stream *, uint64_t);
 188 extern int stream_putq_at(struct stream *, size_t, uint64_t);
 189 extern int stream_put_ipv4(struct stream *, uint32_t);
 190 extern int stream_put_in_addr(struct stream *, struct in_addr *);
 191 extern int stream_put_in_addr_at(struct stream *, size_t, struct in_addr *);
 192 extern int stream_put_in6_addr_at(struct stream *, size_t, struct in6_addr *);
 193 extern int stream_put_prefix_addpath(struct stream *, struct prefix *,
 194                                      int addpath_encode,
 195                                      uint32_t addpath_tx_id);
 196 extern int stream_put_prefix(struct stream *, struct prefix *);
 197 extern int stream_put_labeled_prefix(struct stream *, struct prefix *,
 198                                      mpls_label_t *);
 199 extern void stream_get(void *, struct stream *, size_t);
 200 extern bool stream_get2(void *data, struct stream *s, size_t size);
 201 extern void stream_get_from(void *, struct stream *, size_t, size_t);
 202 extern uint8_t stream_getc(struct stream *);
 203 extern bool stream_getc2(struct stream *s, uint8_t *byte);
 204 extern uint8_t stream_getc_from(struct stream *, size_t);
 205 extern uint16_t stream_getw(struct stream *);
 206 extern bool stream_getw2(struct stream *s, uint16_t *word);
 207 extern uint16_t stream_getw_from(struct stream *, size_t);
 208 extern uint32_t stream_get3(struct stream *);
 209 extern uint32_t stream_get3_from(struct stream *, size_t);
 210 extern uint32_t stream_getl(struct stream *);
 211 extern bool stream_getl2(struct stream *s, uint32_t *l);
 212 extern uint32_t stream_getl_from(struct stream *, size_t);
 213 extern uint64_t stream_getq(struct stream *);
 214 extern uint64_t stream_getq_from(struct stream *, size_t);
 215 extern uint32_t stream_get_ipv4(struct stream *);
 216
 217 /* IEEE-754 floats */
 218 extern float stream_getf(struct stream *);
 219 extern double stream_getd(struct stream *);
 220 extern int stream_putf(struct stream *, float);
 221 extern int stream_putd(struct stream *, double);
 222
 223 #undef stream_read
 224 #undef stream_write
 225
 226 /* Deprecated: assumes blocking I/O.  Will be removed.
 227    Use stream_read_try instead.  */
 228 extern int stream_read(struct stream *, int, size_t);
 229
 230 /* Read up to size bytes into the stream.
 231    Return code:
 232      >0: number of bytes read
 233      0: end-of-file
 234      -1: fatal error
 235      -2: transient error, should retry later (i.e. EAGAIN or EINTR)
 236    This is suitable for use with non-blocking file descriptors.
 237  */
 238 extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
 239
 240 extern ssize_t stream_recvmsg(struct stream *s, int fd, struct msghdr *,
 241                               int flags, size_t size);
 242 extern ssize_t stream_recvfrom(struct stream *s, int fd, size_t len, int flags,
 243                                struct sockaddr *from, socklen_t *fromlen);
 244 extern size_t stream_write(struct stream *, const void *, size_t);
 245
 246 /* reset the stream. See Note above */
 247 extern void stream_reset(struct stream *);
 248 extern int stream_flush(struct stream *, int);
 249 extern int stream_empty(struct stream *); /* is the stream empty? */
 250
 251 /* deprecated */
 252 extern uint8_t *stream_pnt(struct stream *);
 253
 254 /*
 255  * Operations on struct stream_fifo.
 256  *
 257  * Each function has a safe variant, which ensures that the operation performed
 258  * is atomic with respect to the operations performed by all other safe
 259  * variants. In other words, the safe variants lock the stream_fifo's mutex
 260  * before performing their action. These are provided for convenience when
 261  * using stream_fifo in a multithreaded context, to alleviate the need for the
 262  * caller to implement their own synchronization around the stream_fifo.
 263  *
 264  * The following functions do not have safe variants. The caller must ensure
 265  * that these operations are performed safely in a multithreaded context:
 266  * - stream_fifo_new
 267  * - stream_fifo_free
 268  */
 269
 270 /*
 271  * Create a new stream_fifo.
 272  *
 273  * Returns:
 274  *    newly created stream_fifo
 275  */
 276 extern struct stream_fifo *stream_fifo_new(void);
 277
 278 /*
 279  * Push a stream onto a stream_fifo.
 280  *
 281  * fifo
 282  *    the stream_fifo to push onto
 283  *
 284  * s
 285  *    the stream to push onto the stream_fifo
 286  */
 287 extern void stream_fifo_push(struct stream_fifo *fifo, struct stream *s);
 288 extern void stream_fifo_push_safe(struct stream_fifo *fifo, struct stream *s);
 289
 290 /*
 291  * Pop a stream off a stream_fifo.
 292  *
 293  * fifo
 294  *    the stream_fifo to pop from
 295  *
 296  * Returns:
 297  *    the next stream in the stream_fifo
 298  */
 299 extern struct stream *stream_fifo_pop(struct stream_fifo *fifo);
 300 extern struct stream *stream_fifo_pop_safe(struct stream_fifo *fifo);
 301
 302 /*
 303  * Retrieve the next stream from a stream_fifo without popping it.
 304  *
 305  * fifo
 306  *    the stream_fifo to operate on
 307  *
 308  * Returns:
 309  *    the next stream that would be returned from stream_fifo_pop
 310  */
 311 extern struct stream *stream_fifo_head(struct stream_fifo *fifo);
 312 extern struct stream *stream_fifo_head_safe(struct stream_fifo *fifo);
 313
 314 /*
 315  * Remove all streams from a stream_fifo.
 316  *
 317  * fifo
 318  *    the stream_fifo to clean
 319  */
 320 extern void stream_fifo_clean(struct stream_fifo *fifo);
 321 extern void stream_fifo_clean_safe(struct stream_fifo *fifo);
 322
 323 /*
 324  * Retrieve number of streams on a stream_fifo.
 325  *
 326  * fifo
 327  *    the stream_fifo to retrieve the count for
 328  *
 329  * Returns:
 330  *    the number of streams on the stream_fifo
 331  */
 332 extern size_t stream_fifo_count_safe(struct stream_fifo *fifo);
 333
 334 /*
 335  * Free a stream_fifo.
 336  *
 337  * Calls stream_fifo_clean, then deinitializes the stream_fifo and frees it.
 338  *
 339  * fifo
 340  *    the stream_fifo to free
 341  */
 342 extern void stream_fifo_free(struct stream_fifo *fifo);
 343
 344 /* This is here because "<< 24" is particularly problematic in C.
 345  * This is because the left operand of << is integer-promoted, which means
 346  * an uint8_t gets converted into a *signed* int.  Shifting into the sign
 347  * bit of a signed int is theoretically undefined behaviour, so - the left
 348  * operand needs to be cast to unsigned.
 349  *
 350  * This is not a problem for 16- or 8-bit values (they don't reach the sign
 351  * bit), for 64-bit values (you need to cast them anyway), and neither for
 352  * encoding (because it's downcasted.)
 353  */
 354 static inline uint8_t *ptr_get_be32(uint8_t *ptr, uint32_t *out)
 355 {
 356         uint32_t tmp;
 357         memcpy(&tmp, ptr, sizeof(tmp));
 358         *out = ntohl(tmp);
 359         return ptr + 4;
 360 }
 361
 362 /*
 363  * so Normal stream_getX functions assert.  Which is anathema
 364  * to keeping a daemon up and running when something goes south
 365  * Provide a stream_getX2 functions that do not assert.
 366  * In addition provide these macro's that upon failure
 367  * goto stream_failure.  This is modeled upon some NL_XX
 368  * macros in the linux kernel.
 369  *
 370  * This change allows for proper memory freeing
 371  * after we've detected an error.
 372  *
 373  * In the future we will be removing the assert in
 374  * the stream functions but we need a transition
 375  * plan.
 376  */
 377 #define STREAM_GETC(S, P)                                                      \
 378         do {                                                                   \
 379                 uint8_t _pval;                                                 \
 380                 if (!stream_getc2((S), &_pval))                                \
 381                         goto stream_failure;                                   \
 382                 (P) = _pval;                                                   \
 383         } while (0)
 384
 385 #define STREAM_GETW(S, P)                                                      \
 386         do {                                                                   \
 387                 uint16_t _pval;                                                \
 388                 if (!stream_getw2((S), &_pval))                                \
 389                         goto stream_failure;                                   \
 390                 (P) = _pval;                                                   \
 391         } while (0)
 392
 393 #define STREAM_GETL(S, P)                                                      \
 394         do {                                                                   \
 395                 uint32_t _pval;                                                \
 396                 if (!stream_getl2((S), &_pval))                                \
 397                         goto stream_failure;                                   \
 398                 (P) = _pval;                                                   \
 399         } while (0)
 400
 401 #define STREAM_GET(P, STR, SIZE)                                               \
 402         do {                                                                   \
 403                 if (!stream_get2((P), (STR), (SIZE)))                          \
 404                         goto stream_failure;                                   \
 405         } while (0)
 406
 407 #endif /* _ZEBRA_STREAM_H */