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 18 * along with GNU Zebra; see the file COPYING. If not, write to the Free 19 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 20 * 02111-1307, USA. 21 */ 22 23#ifndef _ZEBRA_STREAM_H 24#define _ZEBRA_STREAM_H 25 26#include "prefix.h" 27 28/* 29 * A stream is an arbitrary buffer, whose contents generally are assumed to 30 * be in network order. 31 * 32 * A stream has the following attributes associated with it: 33 * 34 * - size: the allocated, invariant size of the buffer. 35 * 36 * - getp: the get position marker, denoting the offset in the stream where 37 * the next read (or 'get') will be from. This getp marker is 38 * automatically adjusted when data is read from the stream, the 39 * user may also manipulate this offset as they wish, within limits 40 * (see below) 41 * 42 * - endp: the end position marker, denoting the offset in the stream where 43 * valid data ends, and if the user attempted to write (or 44 * 'put') data where that data would be written (or 'put') to. 45 * 46 * These attributes are all size_t values. 47 * 48 * Constraints: 49 * 50 * 1. getp can never exceed endp 51 * 52 * - hence if getp is equal to endp, there is no more valid data that can be 53 * gotten from the stream (though, the user may reposition getp to earlier in 54 * the stream, if they wish). 55 * 56 * 2. endp can never exceed size 57 * 58 * - hence, if endp is equal to size, then the stream is full, and no more 59 * data can be written to the stream. 60 * 61 * In other words the following must always be true, and the stream 62 * abstraction is allowed internally to assert that the following property 63 * holds true for a stream, as and when it wishes: 64 * 65 * getp <= endp <= size 66 * 67 * It is the users responsibility to ensure this property is never violated. 68 * 69 * A stream therefore can be thought of like this: 70 * 71 * --------------------------------------------------- 72 * |XXXXXXXXXXXXXXXXXXXXXXXX | 73 * --------------------------------------------------- 74 * ^ ^ ^ 75 * getp endp size 76 * 77 * This shows a stream containing data (shown as 'X') up to the endp offset. 78 * The stream is empty from endp to size. Without adjusting getp, there are 79 * still endp-getp bytes of valid data to be read from the stream. 80 * 81 * Methods are provided to get and put to/from the stream, as well as 82 * retrieve the values of the 3 markers and manipulate the getp marker. 83 * 84 * Note: 85 * At the moment, newly allocated streams are zero filled. Hence, one can 86 * use stream_forward_endp() to effectively create arbitrary zero-fill 87 * padding. However, note that stream_reset() does *not* zero-out the 88 * stream. This property should **not** be relied upon. 89 * 90 * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out 91 * any part of a stream which isn't otherwise written to. 92 */ 93 94/* Stream buffer. */ 95struct stream 96{ 97 struct stream *next; 98 99 /* Remainder is ***private*** to stream 100 * direct access is frowned upon! 101 * Use the appropriate functions/macros 102 */ 103 size_t getp; /* next get position */ 104 size_t endp; /* last valid data position */ 105 size_t size; /* size of data segment */ 106 unsigned char *data; /* data pointer */ 107}; 108 109/* First in first out queue structure. */ 110struct stream_fifo 111{ 112 size_t count; 113 114 struct stream *head; 115 struct stream *tail; 116}; 117 118/* Utility macros. */ 119#define STREAM_SIZE(S) ((S)->size) 120 /* number of bytes which can still be written */ 121#define STREAM_WRITEABLE(S) ((S)->size - (S)->endp) 122 /* number of bytes still to be read */ 123#define STREAM_READABLE(S) ((S)->endp - (S)->getp) 124 125#define STREAM_CONCAT_REMAIN(S1, S2, size) \ 126 ((size) - (S1)->endp - (S2)->endp) 127 128/* deprecated macros - do not use in new code */ 129#define STREAM_PNT(S) stream_pnt((S)) 130#define STREAM_DATA(S) ((S)->data) 131#define STREAM_REMAIN(S) STREAM_WRITEABLE((S)) 132 133/* Stream prototypes. 134 * For stream_{put,get}S, the S suffix mean: 135 * 136 * c: character (unsigned byte) 137 * w: word (two bytes) 138 * l: long (two words) 139 * q: quad (four words) 140 */ 141extern struct stream *stream_new (size_t); 142extern void stream_free (struct stream *); 143extern struct stream * stream_copy (struct stream *, struct stream *src); 144extern struct stream *stream_dup (struct stream *); 145extern size_t stream_resize (struct stream *, size_t); 146extern size_t stream_get_getp (struct stream *); 147extern size_t stream_get_endp (struct stream *); 148extern size_t stream_get_size (struct stream *); 149extern u_char *stream_get_data (struct stream *); 150 151/** 152 * Create a new stream structure; copy offset bytes from s1 to the new 153 * stream; copy s2 data to the new stream; copy rest of s1 data to the 154 * new stream. 155 */ 156extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2, 157 size_t offset); 158 159extern void stream_set_getp (struct stream *, size_t); 160extern void stream_set_endp (struct stream *, size_t); 161extern void stream_forward_getp (struct stream *, size_t); 162extern void stream_forward_endp (struct stream *, size_t); 163 164/* steam_put: NULL source zeroes out size_t bytes of stream */ 165extern void stream_put (struct stream *, const void *, size_t); 166extern int stream_putc (struct stream *, u_char); 167extern int stream_putc_at (struct stream *, size_t, u_char); 168extern int stream_putw (struct stream *, u_int16_t); 169extern int stream_putw_at (struct stream *, size_t, u_int16_t); 170extern int stream_putl (struct stream *, u_int32_t); 171extern int stream_putl_at (struct stream *, size_t, u_int32_t); 172extern int stream_putq (struct stream *, uint64_t); 173extern int stream_putq_at (struct stream *, size_t, uint64_t); 174extern int stream_put_ipv4 (struct stream *, u_int32_t); 175extern int stream_put_in_addr (struct stream *, struct in_addr *); 176extern int stream_put_prefix (struct stream *, struct prefix *); 177 178extern void stream_get (void *, struct stream *, size_t); 179extern u_char stream_getc (struct stream *); 180extern u_char stream_getc_from (struct stream *, size_t); 181extern u_int16_t stream_getw (struct stream *); 182extern u_int16_t stream_getw_from (struct stream *, size_t); 183extern u_int32_t stream_getl (struct stream *); 184extern u_int32_t stream_getl_from (struct stream *, size_t); 185extern uint64_t stream_getq (struct stream *); 186extern uint64_t stream_getq_from (struct stream *, size_t); 187extern u_int32_t stream_get_ipv4 (struct stream *); 188 189#undef stream_read 190#undef stream_write 191 192/* Deprecated: assumes blocking I/O. Will be removed. 193 Use stream_read_try instead. */ 194extern int stream_read (struct stream *, int, size_t); 195 196/* Read up to size bytes into the stream. 197 Return code: 198 >0: number of bytes read 199 0: end-of-file 200 -1: fatal error 201 -2: transient error, should retry later (i.e. EAGAIN or EINTR) 202 This is suitable for use with non-blocking file descriptors. 203 */ 204extern ssize_t stream_read_try(struct stream *s, int fd, size_t size); 205 206extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *, 207 int flags, size_t size); 208extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len, 209 int flags, struct sockaddr *from, 210 socklen_t *fromlen); 211extern size_t stream_write (struct stream *, const void *, size_t); 212 213/* reset the stream. See Note above */ 214extern void stream_reset (struct stream *); 215extern int stream_flush (struct stream *, int); 216extern int stream_empty (struct stream *); /* is the stream empty? */ 217 218/* deprecated */ 219extern u_char *stream_pnt (struct stream *); 220 221/* Stream fifo. */ 222extern struct stream_fifo *stream_fifo_new (void); 223extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s); 224extern struct stream *stream_fifo_pop (struct stream_fifo *fifo); 225extern struct stream *stream_fifo_head (struct stream_fifo *fifo); 226extern void stream_fifo_clean (struct stream_fifo *fifo); 227extern void stream_fifo_free (struct stream_fifo *fifo); 228 229#endif /* _ZEBRA_STREAM_H */ 230