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. */
95: struct 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. */
110: struct 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: */
141: extern struct stream *stream_new (size_t);
142: extern void stream_free (struct stream *);
143: extern struct stream * stream_copy (struct stream *, struct stream *src);
144: extern struct stream *stream_dup (struct stream *);
145: extern size_t stream_resize (struct stream *, size_t);
146: extern size_t stream_get_getp (struct stream *);
147: extern size_t stream_get_endp (struct stream *);
148: extern size_t stream_get_size (struct stream *);
149: extern 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: */
156: extern struct stream *stream_dupcat(struct stream *s1, struct stream *s2,
157: size_t offset);
158:
159: extern void stream_set_getp (struct stream *, size_t);
160: extern void stream_set_endp (struct stream *, size_t);
161: extern void stream_forward_getp (struct stream *, size_t);
162: extern void stream_forward_endp (struct stream *, size_t);
163:
164: /* steam_put: NULL source zeroes out size_t bytes of stream */
165: extern void stream_put (struct stream *, const void *, size_t);
166: extern int stream_putc (struct stream *, u_char);
167: extern int stream_putc_at (struct stream *, size_t, u_char);
168: extern int stream_putw (struct stream *, u_int16_t);
169: extern int stream_putw_at (struct stream *, size_t, u_int16_t);
170: extern int stream_putl (struct stream *, u_int32_t);
171: extern int stream_putl_at (struct stream *, size_t, u_int32_t);
172: extern int stream_putq (struct stream *, uint64_t);
173: extern int stream_putq_at (struct stream *, size_t, uint64_t);
174: extern int stream_put_ipv4 (struct stream *, u_int32_t);
175: extern int stream_put_in_addr (struct stream *, struct in_addr *);
176: extern int stream_put_prefix (struct stream *, struct prefix *);
177:
178: extern void stream_get (void *, struct stream *, size_t);
179: extern u_char stream_getc (struct stream *);
180: extern u_char stream_getc_from (struct stream *, size_t);
181: extern u_int16_t stream_getw (struct stream *);
182: extern u_int16_t stream_getw_from (struct stream *, size_t);
183: extern u_int32_t stream_getl (struct stream *);
184: extern u_int32_t stream_getl_from (struct stream *, size_t);
185: extern uint64_t stream_getq (struct stream *);
186: extern uint64_t stream_getq_from (struct stream *, size_t);
187: extern 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. */
194: extern 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: */
204: extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
205:
206: extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *,
207: int flags, size_t size);
208: extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len,
209: int flags, struct sockaddr *from,
210: socklen_t *fromlen);
211: extern size_t stream_write (struct stream *, const void *, size_t);
212:
213: /* reset the stream. See Note above */
214: extern void stream_reset (struct stream *);
215: extern int stream_flush (struct stream *, int);
216: extern int stream_empty (struct stream *); /* is the stream empty? */
217:
218: /* deprecated */
219: extern u_char *stream_pnt (struct stream *);
220:
221: /* Stream fifo. */
222: extern struct stream_fifo *stream_fifo_new (void);
223: extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
224: extern struct stream *stream_fifo_pop (struct stream_fifo *fifo);
225: extern struct stream *stream_fifo_head (struct stream_fifo *fifo);
226: extern void stream_fifo_clean (struct stream_fifo *fifo);
227: extern void stream_fifo_free (struct stream_fifo *fifo);
228:
229: #endif /* _ZEBRA_STREAM_H */
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