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1/* $OpenBSD: sshbuf.h,v 1.34 2025/12/29 23:52:09 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
25#ifdef WITH_OPENSSL
26#include <openssl/bn.h>
27#include <openssl/ec.h>
28#include <openssl/ecdsa.h>
29#include <openssl/evp.h>
30#else /* OPENSSL */
31#define BIGNUM void
32#define EC_KEY void
33#define EC_GROUP void
34#define EC_POINT void
35#define EVP_PKEY void
36#endif /* WITH_OPENSSL */
37
38#define SSHBUF_SIZE_MAX 0x8000000 /* Hard maximum size */
39#define SSHBUF_REFS_MAX 0x100000 /* Max child buffers */
40#define SSHBUF_MAX_BIGNUM (16384 / 8) /* Max bignum *bytes* */
41#define SSHBUF_MAX_ECPOINT ((528 * 2 / 8) + 1) /* Max EC point *bytes* */
42
43struct sshbuf;
44
45/*
46 * Create a new sshbuf buffer.
47 * Returns pointer to buffer on success, or NULL on allocation failure.
48 */
49struct sshbuf *sshbuf_new(void);
50
51/*
52 * Create a new, read-only sshbuf buffer from existing data.
53 * Returns pointer to buffer on success, or NULL on allocation failure.
54 */
55struct sshbuf *sshbuf_from(const void *blob, size_t len);
56
57/*
58 * Create a new, read-only sshbuf buffer from the contents of an existing
59 * buffer. The contents of "buf" must not change in the lifetime of the
60 * resultant buffer.
61 * Returns pointer to buffer on success, or NULL on allocation failure.
62 */
63struct sshbuf *sshbuf_fromb(struct sshbuf *buf);
64
65/*
66 * Create a new, read-only sshbuf buffer from the contents of a string in
67 * an existing buffer (the string is consumed in the process).
68 * The contents of "buf" must not change in the lifetime of the resultant
69 * buffer.
70 * On success, a pointer to the newly allocated buffer is placed in *bufp.
71 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
72 */
73int sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp);
74
75/*
76 * Clear and free buf
77 */
78void sshbuf_free(struct sshbuf *buf);
79
80/*
81 * Reset buf, clearing its contents. NB. max_size is preserved.
82 */
83void sshbuf_reset(struct sshbuf *buf);
84
85/*
86 * Return the maximum size of buf
87 */
88size_t sshbuf_max_size(const struct sshbuf *buf);
89
90/*
91 * Set the maximum size of buf
92 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
93 */
94int sshbuf_set_max_size(struct sshbuf *buf, size_t max_size);
95
96/*
97 * Returns the length of data in buf
98 */
99size_t sshbuf_len(const struct sshbuf *buf);
100
101/*
102 * Returns number of bytes left in buffer before hitting max_size.
103 */
104size_t sshbuf_avail(const struct sshbuf *buf);
105
106/*
107 * Returns a read-only pointer to the start of the data in buf
108 */
109const u_char *sshbuf_ptr(const struct sshbuf *buf);
110
111/*
112 * Returns a mutable pointer to the start of the data in buf, or
113 * NULL if the buffer is read-only.
114 */
115u_char *sshbuf_mutable_ptr(const struct sshbuf *buf);
116
117/*
118 * Check whether a reservation of size len will succeed in buf
119 * Safer to use than direct comparisons again sshbuf_avail as it copes
120 * with unsigned overflows correctly.
121 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
122 */
123int sshbuf_check_reserve(const struct sshbuf *buf, size_t len);
124
125/*
126 * Preallocates len additional bytes in buf.
127 * Useful for cases where the caller knows how many bytes will ultimately be
128 * required to avoid realloc in the buffer code.
129 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
130 */
131int sshbuf_allocate(struct sshbuf *buf, size_t len);
132
133/*
134 * Reserve len bytes in buf.
135 * Returns 0 on success and a pointer to the first reserved byte via the
136 * optional dpp parameter or a negative SSH_ERR_* error code on failure.
137 */
138int sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp);
139
140/*
141 * Consume len bytes from the start of buf
142 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
143 */
144int sshbuf_consume(struct sshbuf *buf, size_t len);
145
146/*
147 * Consume len bytes from the end of buf
148 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
149 */
150int sshbuf_consume_end(struct sshbuf *buf, size_t len);
151
152/*
153 * Consume data from a parent buffer up to that of a child buffer (i.e.
154 * one created by sshbuf_fromb()).
155 *
156 * Intended to be used in a pattern like:
157 *
158 * b = sshbuf_fromb(parent);
159 * sshbuf_get_string(b, &foo, &foostr);
160 * sshbuf_get_u32(b, &bar);
161 * sshbuf_consume_upto_child(parent, b);
162 *
163 * After which, both "b" and "parent" will point to the same data.
164 *
165 * "child" must be a direct child of "buf" (i.e. neither an unrelated buffer
166 * nor a grandchild) which has consumed data past that of "buf".
167 */
168int sshbuf_consume_upto_child(struct sshbuf *buf, const struct sshbuf *child);
169
170/* Extract or deposit some bytes */
171int sshbuf_get(struct sshbuf *buf, void *v, size_t len);
172int sshbuf_put(struct sshbuf *buf, const void *v, size_t len);
173int sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v);
174
175/* Append using a printf(3) format */
176int sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
177 __attribute__((format(printf, 2, 3)));
178int sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap);
179
180/* Functions to extract or store big-endian words of various sizes */
181int sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp);
182int sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp);
183int sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp);
184int sshbuf_get_u8(struct sshbuf *buf, u_char *valp);
185int sshbuf_put_u64(struct sshbuf *buf, u_int64_t val);
186int sshbuf_put_u32(struct sshbuf *buf, u_int32_t val);
187int sshbuf_put_u16(struct sshbuf *buf, u_int16_t val);
188int sshbuf_put_u8(struct sshbuf *buf, u_char val);
189
190/* Functions to peek at the contents of a buffer without modifying it. */
191int sshbuf_peek_u64(const struct sshbuf *buf, size_t offset,
192 u_int64_t *valp);
193int sshbuf_peek_u32(const struct sshbuf *buf, size_t offset,
194 u_int32_t *valp);
195int sshbuf_peek_u16(const struct sshbuf *buf, size_t offset,
196 u_int16_t *valp);
197int sshbuf_peek_u8(const struct sshbuf *buf, size_t offset,
198 u_char *valp);
199
200/*
201 * Functions to poke values into an existing buffer (e.g. a length header
202 * to a packet). The destination bytes must already exist in the buffer.
203 */
204int sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val);
205int sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val);
206int sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val);
207int sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val);
208int sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len);
209
210/*
211 * Functions to extract or store SSH wire encoded strings (u32 len || data)
212 * The "cstring" variants admit no \0 characters in the string contents.
213 * Caller must free *valp.
214 */
215int sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp);
216int sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp);
217int sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v);
218int sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len);
219int sshbuf_put_cstring(struct sshbuf *buf, const char *v);
220int sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v);
221
222/*
223 * "Direct" variant of sshbuf_get_string, returns pointer into the sshbuf to
224 * avoid an malloc+memcpy. The pointer is guaranteed to be valid until the
225 * next sshbuf-modifying function call. Caller does not free.
226 */
227int sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
228 size_t *lenp);
229
230/* Skip past a string */
231#define sshbuf_skip_string(buf) sshbuf_get_string_direct(buf, NULL, NULL)
232
233/* Another variant: "peeks" into the buffer without modifying it */
234int sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
235 size_t *lenp);
236
237/*
238 * Functions to extract or store SSH wire encoded bignums and elliptic
239 * curve points.
240 */
241int sshbuf_get_bignum2(struct sshbuf *buf, BIGNUM **valp);
242int sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
243 const u_char **valp, size_t *lenp);
244int sshbuf_put_bignum2(struct sshbuf *buf, const BIGNUM *v);
245int sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len);
246int sshbuf_get_ec(struct sshbuf *buf, EC_POINT *v, const EC_GROUP *g);
247int sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v);
248int sshbuf_put_ec(struct sshbuf *buf, const EC_POINT *v, const EC_GROUP *g);
249int sshbuf_put_eckey(struct sshbuf *buf, const EC_KEY *v);
250int sshbuf_put_ec_pkey(struct sshbuf *buf, EVP_PKEY *pkey);
251
252/* Functions to extract or store various non-SSH wire encoded values */
253int sshbuf_get_nulterminated_string(struct sshbuf *buf, size_t maxlen,
254 char **valp, size_t *lenp);
255
256/* Dump the contents of the buffer in a human-readable format */
257void sshbuf_dump(const struct sshbuf *buf, FILE *f);
258
259/* Dump specified memory in a human-readable format */
260void sshbuf_dump_data(const void *s, size_t len, FILE *f);
261
262/* Return the hexadecimal representation of the contents of the buffer */
263char *sshbuf_dtob16(const struct sshbuf *buf);
264/* Make a sshbuf from a hex string */
265struct sshbuf *sshbuf_b16tod(const char *b16);
266
267/* Encode the contents of the buffer as base64 */
268char *sshbuf_dtob64_string(const struct sshbuf *buf, int wrap);
269int sshbuf_dtob64(const struct sshbuf *d, struct sshbuf *b64, int wrap);
270/* RFC4648 "base64url" encoding variant */
271int sshbuf_dtourlb64(const struct sshbuf *d, struct sshbuf *b64, int wrap);
272
273/* Decode base64 data and append it to the buffer */
274int sshbuf_b64tod(struct sshbuf *buf, const char *b64);
275
276/*
277 * Tests whether the buffer contains the specified byte sequence at the
278 * specified offset. Returns 0 on successful match, or a ssherr.h code
279 * otherwise. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
280 * present but the buffer contents did not match those supplied. Zero-
281 * length comparisons are not allowed.
282 *
283 * If sufficient data is present to make a comparison, then it is
284 * performed with timing independent of the value of the data. If
285 * insufficient data is present then the comparison is not attempted at
286 * all.
287 */
288int sshbuf_cmp(const struct sshbuf *b, size_t offset,
289 const void *s, size_t len);
290
291/*
292 * Test whether two buffers have identical contents.
293 * SSH_ERR_MESSAGE_INCOMPLETE indicates the buffers had differing size.
294 * SSH_ERR_INVALID_FORMAT indicates the buffers were the same size but
295 * had differing contents.
296 * Returns 0 on successful compare (comparing two empty buffers returns 0).
297 */
298int sshbuf_equals(const struct sshbuf *a, const struct sshbuf *b);
299
300/*
301 * Searches the buffer for the specified string. Returns 0 on success
302 * and updates *offsetp with the offset of the first match, relative to
303 * the start of the buffer. Otherwise sshbuf_find will return a ssherr.h
304 * error code. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
305 * present in the buffer for a match to be possible but none was found.
306 * Searches for zero-length data are not allowed.
307 */
308int
309sshbuf_find(const struct sshbuf *b, size_t start_offset,
310 const void *s, size_t len, size_t *offsetp);
311
312/*
313 * Duplicate the contents of a buffer to a string (caller to free).
314 * Returns NULL on buffer error, or if the buffer contains a premature
315 * nul character.
316 */
317char *sshbuf_dup_string(struct sshbuf *buf);
318
319/*
320 * Fill a buffer from a file descriptor or filename. Both allocate the
321 * buffer for the caller.
322 */
323int sshbuf_load_fd(int, struct sshbuf **)
324 __attribute__((__nonnull__ (2)));
325int sshbuf_load_file(const char *, struct sshbuf **)
326 __attribute__((__nonnull__ (2)));
327
328/*
329 * Write a buffer to a path, creating/truncating as needed (mode 0644,
330 * subject to umask). The buffer contents are not modified.
331 */
332int sshbuf_write_file(const char *path, struct sshbuf *buf)
333 __attribute__((__nonnull__ (2)));
334
335/* Read up to maxlen bytes from a fd directly to a buffer */
336int sshbuf_read(int, struct sshbuf *, size_t, size_t *)
337 __attribute__((__nonnull__ (2)));
338
339/* Macros for decoding/encoding integers */
340#define PEEK_U64(p) \
341 (((u_int64_t)(((const u_char *)(p))[0]) << 56) | \
342 ((u_int64_t)(((const u_char *)(p))[1]) << 48) | \
343 ((u_int64_t)(((const u_char *)(p))[2]) << 40) | \
344 ((u_int64_t)(((const u_char *)(p))[3]) << 32) | \
345 ((u_int64_t)(((const u_char *)(p))[4]) << 24) | \
346 ((u_int64_t)(((const u_char *)(p))[5]) << 16) | \
347 ((u_int64_t)(((const u_char *)(p))[6]) << 8) | \
348 (u_int64_t)(((const u_char *)(p))[7]))
349#define PEEK_U32(p) \
350 (((u_int32_t)(((const u_char *)(p))[0]) << 24) | \
351 ((u_int32_t)(((const u_char *)(p))[1]) << 16) | \
352 ((u_int32_t)(((const u_char *)(p))[2]) << 8) | \
353 (u_int32_t)(((const u_char *)(p))[3]))
354#define PEEK_U16(p) \
355 (((u_int16_t)(((const u_char *)(p))[0]) << 8) | \
356 (u_int16_t)(((const u_char *)(p))[1]))
357
358#define POKE_U64(p, v) \
359 do { \
360 const u_int64_t __v = (v); \
361 ((u_char *)(p))[0] = (__v >> 56) & 0xff; \
362 ((u_char *)(p))[1] = (__v >> 48) & 0xff; \
363 ((u_char *)(p))[2] = (__v >> 40) & 0xff; \
364 ((u_char *)(p))[3] = (__v >> 32) & 0xff; \
365 ((u_char *)(p))[4] = (__v >> 24) & 0xff; \
366 ((u_char *)(p))[5] = (__v >> 16) & 0xff; \
367 ((u_char *)(p))[6] = (__v >> 8) & 0xff; \
368 ((u_char *)(p))[7] = __v & 0xff; \
369 } while (0)
370#define POKE_U32(p, v) \
371 do { \
372 const u_int32_t __v = (v); \
373 ((u_char *)(p))[0] = (__v >> 24) & 0xff; \
374 ((u_char *)(p))[1] = (__v >> 16) & 0xff; \
375 ((u_char *)(p))[2] = (__v >> 8) & 0xff; \
376 ((u_char *)(p))[3] = __v & 0xff; \
377 } while (0)
378#define POKE_U16(p, v) \
379 do { \
380 const u_int16_t __v = (v); \
381 ((u_char *)(p))[0] = (__v >> 8) & 0xff; \
382 ((u_char *)(p))[1] = __v & 0xff; \
383 } while (0)
384
385/* Internal definitions follow. Exposed for regress tests */
386#ifdef SSHBUF_INTERNAL
387
388/*
389 * Return the allocation size of buf
390 */
391size_t sshbuf_alloc(const struct sshbuf *buf);
392
393/*
394 * Increment the reference count of buf.
395 */
396int sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent);
397
398/*
399 * Return the parent buffer of buf, or NULL if it has no parent.
400 */
401const struct sshbuf *sshbuf_parent(const struct sshbuf *buf);
402
403/*
404 * Return the reference count of buf
405 */
406u_int sshbuf_refcount(const struct sshbuf *buf);
407
408# define SSHBUF_SIZE_INIT 256 /* Initial allocation */
409# define SSHBUF_SIZE_INC 256 /* Preferred increment length */
410# define SSHBUF_PACK_MIN 8192 /* Minimum packable offset */
411
412/* # define SSHBUF_ABORT abort */
413/* # define SSHBUF_DEBUG */
414
415# ifndef SSHBUF_ABORT
416# define SSHBUF_ABORT()
417# endif
418
419# ifdef SSHBUF_DEBUG
420# define SSHBUF_DBG(x) do { \
421 printf("%s:%d %s: ", __FILE__, __LINE__, __func__); \
422 printf x; \
423 printf("\n"); \
424 fflush(stdout); \
425 } while (0)
426# else
427# define SSHBUF_DBG(x)
428# endif
429#endif /* SSHBUF_INTERNAL */
430
431#endif /* _SSHBUF_H */