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sshbuf.h
1 /* $OpenBSD: sshbuf.h,v 1.8 2016/11/25 23:22:04 djm Exp $ */
2 /*
3  * Copyright (c) 2011 Damien Miller
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #ifndef _SSHBUF_H
19 #define _SSHBUF_H
20 
21 #include <sys/types.h>
22 #include <stdarg.h>
23 #include <stdio.h>
24 #ifdef WITH_OPENSSL
25 # include <openssl/bn.h>
26 # ifdef OPENSSL_HAS_ECC
27 # include <openssl/ec.h>
28 # endif /* OPENSSL_HAS_ECC */
29 #endif /* WITH_OPENSSL */
30 
31 #define SSHBUF_SIZE_MAX 0xF000000 /* Hard maximum size 256MB */
32 #define SSHBUF_REFS_MAX 0x100000 /* Max child buffers */
33 #define SSHBUF_MAX_BIGNUM (16384 / 8) /* Max bignum *bytes* */
34 #define SSHBUF_MAX_ECPOINT ((528 * 2 / 8) + 1) /* Max EC point *bytes* */
35 
36 /*
37  * NB. do not depend on the internals of this. It will be made opaque
38  * one day.
39  */
40 struct sshbuf {
41  u_char *d; /* Data */
42  const u_char *cd; /* Const data */
43  size_t off; /* First available byte is buf->d + buf->off */
44  size_t size; /* Last byte is buf->d + buf->size - 1 */
45  size_t max_size; /* Maximum size of buffer */
46  size_t alloc; /* Total bytes allocated to buf->d */
47  int readonly; /* Refers to external, const data */
48  int dont_free; /* Kludge to support sshbuf_init */
49  u_int refcount; /* Tracks self and number of child buffers */
50  struct sshbuf *parent; /* If child, pointer to parent */
51 };
52 
53 #ifndef SSHBUF_NO_DEPREACTED
54 /*
55  * NB. Please do not use sshbuf_init() in new code. Please use sshbuf_new()
56  * instead. sshbuf_init() is deprectated and will go away soon (it is
57  * only included to allow compat with buffer_* in OpenSSH)
58  */
59 void sshbuf_init(struct sshbuf *buf);
60 #endif
61 
62 /*
63  * Create a new sshbuf buffer.
64  * Returns pointer to buffer on success, or NULL on allocation failure.
65  */
66 struct sshbuf *sshbuf_new(void);
67 
68 /*
69  * Create a new, read-only sshbuf buffer from existing data.
70  * Returns pointer to buffer on success, or NULL on allocation failure.
71  */
72 struct sshbuf *sshbuf_from(const void *blob, size_t len);
73 
74 /*
75  * Create a new, read-only sshbuf buffer from the contents of an existing
76  * buffer. The contents of "buf" must not change in the lifetime of the
77  * resultant buffer.
78  * Returns pointer to buffer on success, or NULL on allocation failure.
79  */
80 struct sshbuf *sshbuf_fromb(struct sshbuf *buf);
81 
82 /*
83  * Create a new, read-only sshbuf buffer from the contents of a string in
84  * an existing buffer (the string is consumed in the process).
85  * The contents of "buf" must not change in the lifetime of the resultant
86  * buffer.
87  * Returns pointer to buffer on success, or NULL on allocation failure.
88  */
89 int sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp);
90 
91 /*
92  * Clear and free buf
93  */
94 void sshbuf_free(struct sshbuf *buf);
95 
96 /*
97  * Reset buf, clearing its contents. NB. max_size is preserved.
98  */
99 void sshbuf_reset(struct sshbuf *buf);
100 
101 /*
102  * Return the maximum size of buf
103  */
104 size_t sshbuf_max_size(const struct sshbuf *buf);
105 
106 /*
107  * Set the maximum size of buf
108  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
109  */
110 int sshbuf_set_max_size(struct sshbuf *buf, size_t max_size);
111 
112 /*
113  * Returns the length of data in buf
114  */
115 size_t sshbuf_len(const struct sshbuf *buf);
116 
117 /*
118  * Returns number of bytes left in buffer before hitting max_size.
119  */
120 size_t sshbuf_avail(const struct sshbuf *buf);
121 
122 /*
123  * Returns a read-only pointer to the start of the data in buf
124  */
125 const u_char *sshbuf_ptr(const struct sshbuf *buf);
126 
127 /*
128  * Returns a mutable pointer to the start of the data in buf, or
129  * NULL if the buffer is read-only.
130  */
131 u_char *sshbuf_mutable_ptr(const struct sshbuf *buf);
132 
133 /*
134  * Check whether a reservation of size len will succeed in buf
135  * Safer to use than direct comparisons again sshbuf_avail as it copes
136  * with unsigned overflows correctly.
137  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
138  */
139 int sshbuf_check_reserve(const struct sshbuf *buf, size_t len);
140 
141 /*
142  * Preallocates len additional bytes in buf.
143  * Useful for cases where the caller knows how many bytes will ultimately be
144  * required to avoid realloc in the buffer code.
145  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
146  */
147 int sshbuf_allocate(struct sshbuf *buf, size_t len);
148 
149 /*
150  * Reserve len bytes in buf.
151  * Returns 0 on success and a pointer to the first reserved byte via the
152  * optional dpp parameter or a negative * SSH_ERR_* error code on failure.
153  */
154 int sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp);
155 
156 /*
157  * Consume len bytes from the start of buf
158  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
159  */
160 int sshbuf_consume(struct sshbuf *buf, size_t len);
161 
162 /*
163  * Consume len bytes from the end of buf
164  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
165  */
166 int sshbuf_consume_end(struct sshbuf *buf, size_t len);
167 
168 /* Extract or deposit some bytes */
169 int sshbuf_get(struct sshbuf *buf, void *v, size_t len);
170 int sshbuf_put(struct sshbuf *buf, const void *v, size_t len);
171 int sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v);
172 
173 /* Append using a printf(3) format */
174 int sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
175  __attribute__((format(printf, 2, 3)));
176 int sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap);
177 
178 /* Functions to extract or store big-endian words of various sizes */
179 int sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp);
180 int sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp);
181 int sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp);
182 int sshbuf_get_u8(struct sshbuf *buf, u_char *valp);
183 int sshbuf_put_u64(struct sshbuf *buf, u_int64_t val);
184 int sshbuf_put_u32(struct sshbuf *buf, u_int32_t val);
185 int sshbuf_put_u16(struct sshbuf *buf, u_int16_t val);
186 int sshbuf_put_u8(struct sshbuf *buf, u_char val);
187 
188 /*
189  * Functions to extract or store SSH wire encoded strings (u32 len || data)
190  * The "cstring" variants admit no \0 characters in the string contents.
191  * Caller must free *valp.
192  */
193 int sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp);
194 int sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp);
195 int sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v);
196 int sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len);
197 int sshbuf_put_cstring(struct sshbuf *buf, const char *v);
198 int sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v);
199 
200 /*
201  * "Direct" variant of sshbuf_get_string, returns pointer into the sshbuf to
202  * avoid an malloc+memcpy. The pointer is guaranteed to be valid until the
203  * next sshbuf-modifying function call. Caller does not free.
204  */
205 int sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
206  size_t *lenp);
207 
208 /* Skip past a string */
209 #define sshbuf_skip_string(buf) sshbuf_get_string_direct(buf, NULL, NULL)
210 
211 /* Another variant: "peeks" into the buffer without modifying it */
212 int sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
213  size_t *lenp);
214 
215 /*
216  * Functions to extract or store SSH wire encoded bignums and elliptic
217  * curve points.
218  */
219 int sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len);
220 int sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
221  const u_char **valp, size_t *lenp);
222 #ifdef WITH_OPENSSL
223 int sshbuf_get_bignum2(struct sshbuf *buf, BIGNUM *v);
224 int sshbuf_get_bignum1(struct sshbuf *buf, BIGNUM *v);
225 int sshbuf_put_bignum2(struct sshbuf *buf, const BIGNUM *v);
226 int sshbuf_put_bignum1(struct sshbuf *buf, const BIGNUM *v);
227 # ifdef OPENSSL_HAS_ECC
228 int sshbuf_get_ec(struct sshbuf *buf, EC_POINT *v, const EC_GROUP *g);
229 int sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v);
230 int sshbuf_put_ec(struct sshbuf *buf, const EC_POINT *v, const EC_GROUP *g);
231 int sshbuf_put_eckey(struct sshbuf *buf, const EC_KEY *v);
232 # endif /* OPENSSL_HAS_ECC */
233 #endif /* WITH_OPENSSL */
234 
235 /* Dump the contents of the buffer in a human-readable format */
236 void sshbuf_dump(struct sshbuf *buf, FILE *f);
237 
238 /* Dump specified memory in a human-readable format */
239 void sshbuf_dump_data(const void *s, size_t len, FILE *f);
240 
241 /* Return the hexadecimal representation of the contents of the buffer */
242 char *sshbuf_dtob16(struct sshbuf *buf);
243 
244 /* Encode the contents of the buffer as base64 */
245 char *sshbuf_dtob64(struct sshbuf *buf);
246 
247 /* Decode base64 data and append it to the buffer */
248 int sshbuf_b64tod(struct sshbuf *buf, const char *b64);
249 
250 /*
251  * Duplicate the contents of a buffer to a string (caller to free).
252  * Returns NULL on buffer error, or if the buffer contains a premature
253  * nul character.
254  */
255 char *sshbuf_dup_string(struct sshbuf *buf);
256 
257 /* Macros for decoding/encoding integers */
258 #define PEEK_U64(p) \
259  (((u_int64_t)(((const u_char *)(p))[0]) << 56) | \
260  ((u_int64_t)(((const u_char *)(p))[1]) << 48) | \
261  ((u_int64_t)(((const u_char *)(p))[2]) << 40) | \
262  ((u_int64_t)(((const u_char *)(p))[3]) << 32) | \
263  ((u_int64_t)(((const u_char *)(p))[4]) << 24) | \
264  ((u_int64_t)(((const u_char *)(p))[5]) << 16) | \
265  ((u_int64_t)(((const u_char *)(p))[6]) << 8) | \
266  (u_int64_t)(((const u_char *)(p))[7]))
267 #define PEEK_U32(p) \
268  (((u_int32_t)(((const u_char *)(p))[0]) << 24) | \
269  ((u_int32_t)(((const u_char *)(p))[1]) << 16) | \
270  ((u_int32_t)(((const u_char *)(p))[2]) << 8) | \
271  (u_int32_t)(((const u_char *)(p))[3]))
272 #define PEEK_U16(p) \
273  (((u_int16_t)(((const u_char *)(p))[0]) << 8) | \
274  (u_int16_t)(((const u_char *)(p))[1]))
275 
276 #define POKE_U64(p, v) \
277  do { \
278  const u_int64_t __v = (v); \
279  ((u_char *)(p))[0] = (__v >> 56) & 0xff; \
280  ((u_char *)(p))[1] = (__v >> 48) & 0xff; \
281  ((u_char *)(p))[2] = (__v >> 40) & 0xff; \
282  ((u_char *)(p))[3] = (__v >> 32) & 0xff; \
283  ((u_char *)(p))[4] = (__v >> 24) & 0xff; \
284  ((u_char *)(p))[5] = (__v >> 16) & 0xff; \
285  ((u_char *)(p))[6] = (__v >> 8) & 0xff; \
286  ((u_char *)(p))[7] = __v & 0xff; \
287  } while (0)
288 #define POKE_U32(p, v) \
289  do { \
290  const u_int32_t __v = (v); \
291  ((u_char *)(p))[0] = (__v >> 24) & 0xff; \
292  ((u_char *)(p))[1] = (__v >> 16) & 0xff; \
293  ((u_char *)(p))[2] = (__v >> 8) & 0xff; \
294  ((u_char *)(p))[3] = __v & 0xff; \
295  } while (0)
296 #define POKE_U16(p, v) \
297  do { \
298  const u_int16_t __v = (v); \
299  ((u_char *)(p))[0] = (__v >> 8) & 0xff; \
300  ((u_char *)(p))[1] = __v & 0xff; \
301  } while (0)
302 
303 /* Internal definitions follow. Exposed for regress tests */
304 #ifdef SSHBUF_INTERNAL
305 
306 /*
307  * Return the allocation size of buf
308  */
309 size_t sshbuf_alloc(const struct sshbuf *buf);
310 
311 /*
312  * Increment the reference count of buf.
313  */
314 int sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent);
315 
316 /*
317  * Return the parent buffer of buf, or NULL if it has no parent.
318  */
319 const struct sshbuf *sshbuf_parent(const struct sshbuf *buf);
320 
321 /*
322  * Return the reference count of buf
323  */
324 u_int sshbuf_refcount(const struct sshbuf *buf);
325 
326 # define SSHBUF_SIZE_INIT 256 /* Initial allocation */
327 # define SSHBUF_SIZE_INC 256 /* Preferred increment length */
328 # define SSHBUF_PACK_MIN 8192 /* Minimim packable offset */
329 
330 /* # define SSHBUF_ABORT abort */
331 /* # define SSHBUF_DEBUG */
332 
333 # ifndef SSHBUF_ABORT
334 # define SSHBUF_ABORT()
335 # endif
336 
337 # ifdef SSHBUF_DEBUG
338 # define SSHBUF_TELL(what) do { \
339  printf("%s:%d %s: %s size %zu alloc %zu off %zu max %zu\n", \
340  __FILE__, __LINE__, __func__, what, \
341  buf->size, buf->alloc, buf->off, buf->max_size); \
342  fflush(stdout); \
343  } while (0)
344 # define SSHBUF_DBG(x) do { \
345  printf("%s:%d %s: ", __FILE__, __LINE__, __func__); \
346  printf x; \
347  printf("\n"); \
348  fflush(stdout); \
349  } while (0)
350 # else
351 # define SSHBUF_TELL(what)
352 # define SSHBUF_DBG(x)
353 # endif
354 #endif /* SSHBUF_INTERNAL */
355 
356 #endif /* _SSHBUF_H */
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