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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Functions for manipulating fifo buffers (that can grow if needed). | |
6 | * | |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
12 | */ | |
13 | ||
14 | #include "includes.h" | |
15 | RCSID("$OpenBSD: buffer.c,v 1.21 2003/11/21 11:57:03 djm Exp $"); | |
16 | ||
17 | #include "xmalloc.h" | |
18 | #include "buffer.h" | |
19 | #include "log.h" | |
20 | ||
21 | /* Initializes the buffer structure. */ | |
22 | ||
23 | void | |
24 | buffer_init(Buffer *buffer) | |
25 | { | |
26 | const u_int len = 4096; | |
27 | ||
28 | buffer->alloc = 0; | |
29 | buffer->buf = xmalloc(len); | |
30 | buffer->alloc = len; | |
31 | buffer->offset = 0; | |
32 | buffer->end = 0; | |
33 | } | |
34 | ||
35 | /* Frees any memory used for the buffer. */ | |
36 | ||
37 | void | |
38 | buffer_free(Buffer *buffer) | |
39 | { | |
40 | if (buffer->alloc > 0) { | |
41 | memset(buffer->buf, 0, buffer->alloc); | |
42 | buffer->alloc = 0; | |
43 | xfree(buffer->buf); | |
44 | } | |
45 | } | |
46 | ||
47 | /* | |
48 | * Clears any data from the buffer, making it empty. This does not actually | |
49 | * zero the memory. | |
50 | */ | |
51 | ||
52 | void | |
53 | buffer_clear(Buffer *buffer) | |
54 | { | |
55 | buffer->offset = 0; | |
56 | buffer->end = 0; | |
57 | } | |
58 | ||
59 | /* Appends data to the buffer, expanding it if necessary. */ | |
60 | ||
61 | void | |
62 | buffer_append(Buffer *buffer, const void *data, u_int len) | |
63 | { | |
64 | void *p; | |
65 | p = buffer_append_space(buffer, len); | |
66 | memcpy(p, data, len); | |
67 | } | |
68 | ||
69 | /* | |
70 | * Appends space to the buffer, expanding the buffer if necessary. This does | |
71 | * not actually copy the data into the buffer, but instead returns a pointer | |
72 | * to the allocated region. | |
73 | */ | |
74 | ||
75 | void * | |
76 | buffer_append_space(Buffer *buffer, u_int len) | |
77 | { | |
78 | u_int newlen; | |
79 | void *p; | |
80 | ||
81 | if (len > 0x100000) | |
82 | fatal("buffer_append_space: len %u not supported", len); | |
83 | ||
84 | /* If the buffer is empty, start using it from the beginning. */ | |
85 | if (buffer->offset == buffer->end) { | |
86 | buffer->offset = 0; | |
87 | buffer->end = 0; | |
88 | } | |
89 | restart: | |
90 | /* If there is enough space to store all data, store it now. */ | |
91 | if (buffer->end + len < buffer->alloc) { | |
92 | p = buffer->buf + buffer->end; | |
93 | buffer->end += len; | |
94 | return p; | |
95 | } | |
96 | /* | |
97 | * If the buffer is quite empty, but all data is at the end, move the | |
98 | * data to the beginning and retry. | |
99 | */ | |
100 | if (buffer->offset > buffer->alloc / 2) { | |
101 | memmove(buffer->buf, buffer->buf + buffer->offset, | |
102 | buffer->end - buffer->offset); | |
103 | buffer->end -= buffer->offset; | |
104 | buffer->offset = 0; | |
105 | goto restart; | |
106 | } | |
107 | /* Increase the size of the buffer and retry. */ | |
108 | ||
109 | newlen = buffer->alloc + len + 32768; | |
110 | if (newlen > 0xa00000) | |
111 | fatal("buffer_append_space: alloc %u not supported", | |
112 | newlen); | |
113 | buffer->buf = xrealloc(buffer->buf, newlen); | |
114 | buffer->alloc = newlen; | |
115 | goto restart; | |
116 | /* NOTREACHED */ | |
117 | } | |
118 | ||
119 | /* Returns the number of bytes of data in the buffer. */ | |
120 | ||
121 | u_int | |
122 | buffer_len(Buffer *buffer) | |
123 | { | |
124 | return buffer->end - buffer->offset; | |
125 | } | |
126 | ||
127 | /* Gets data from the beginning of the buffer. */ | |
128 | ||
129 | void | |
130 | buffer_get(Buffer *buffer, void *buf, u_int len) | |
131 | { | |
132 | if (len > buffer->end - buffer->offset) | |
133 | fatal("buffer_get: trying to get more bytes %d than in buffer %d", | |
134 | len, buffer->end - buffer->offset); | |
135 | memcpy(buf, buffer->buf + buffer->offset, len); | |
136 | buffer->offset += len; | |
137 | } | |
138 | ||
139 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
140 | ||
141 | void | |
142 | buffer_consume(Buffer *buffer, u_int bytes) | |
143 | { | |
144 | if (bytes > buffer->end - buffer->offset) | |
145 | fatal("buffer_consume: trying to get more bytes than in buffer"); | |
146 | buffer->offset += bytes; | |
147 | } | |
148 | ||
149 | /* Consumes the given number of bytes from the end of the buffer. */ | |
150 | ||
151 | void | |
152 | buffer_consume_end(Buffer *buffer, u_int bytes) | |
153 | { | |
154 | if (bytes > buffer->end - buffer->offset) | |
155 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); | |
156 | buffer->end -= bytes; | |
157 | } | |
158 | ||
159 | /* Returns a pointer to the first used byte in the buffer. */ | |
160 | ||
161 | void * | |
162 | buffer_ptr(Buffer *buffer) | |
163 | { | |
164 | return buffer->buf + buffer->offset; | |
165 | } | |
166 | ||
167 | /* Dumps the contents of the buffer to stderr. */ | |
168 | ||
169 | void | |
170 | buffer_dump(Buffer *buffer) | |
171 | { | |
172 | u_int i; | |
173 | u_char *ucp = buffer->buf; | |
174 | ||
175 | for (i = buffer->offset; i < buffer->end; i++) { | |
176 | fprintf(stderr, "%02x", ucp[i]); | |
177 | if ((i-buffer->offset)%16==15) | |
178 | fprintf(stderr, "\r\n"); | |
179 | else if ((i-buffer->offset)%2==1) | |
180 | fprintf(stderr, " "); | |
181 | } | |
182 | fprintf(stderr, "\r\n"); | |
183 | } |