/src/openssl/include/internal/ring_buf.h

Source
/*
 * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#ifndef OSSL_INTERNAL_RING_BUF_H
# define OSSL_INTERNAL_RING_BUF_H
# pragma once

# include <openssl/e_os2.h>              /* For 'ossl_inline' */
# include "internal/safe_math.h"

/*
 * ==================================================================
 * Byte-wise ring buffer which supports pushing and popping blocks of multiple
 * bytes at a time. The logical offset of each byte for the purposes of a QUIC
 * stream is tracked. Bytes can be popped from the ring buffer in two stages;
 * first they are popped, and then they are culled. Bytes which have been popped
 * but not yet culled will not be overwritten, and can be restored.
 */
struct ring_buf {
    void       *start;
    size_t      alloc;        /* size of buffer allocation in bytes */

    /*
     * Logical offset of the head (where we append to). This is the current size
     * of the QUIC stream. This increases monotonically.
     */
    uint64_t    head_offset;

    /*
     * Logical offset of the cull tail. Data is no longer needed and is
     * deallocated as the cull tail advances, which occurs as data is
     * acknowledged. This increases monotonically.
     */
    uint64_t    ctail_offset;
};

OSSL_SAFE_MATH_UNSIGNED(u64, uint64_t)

#define MAX_OFFSET   (((uint64_t)1) << 62) /* QUIC-imposed limit */

static ossl_inline int ring_buf_init(struct ring_buf *r)
{
    r->start = NULL;
    r->alloc = 0;
    r->head_offset = r->ctail_offset = 0;
    return 1;
}

static ossl_inline void ring_buf_destroy(struct ring_buf *r, int cleanse)
{
    if (cleanse)
        OPENSSL_clear_free(r->start, r->alloc);
    else
        OPENSSL_free(r->start);
    r->start = NULL;
    r->alloc = 0;
}

static ossl_inline size_t ring_buf_used(struct ring_buf *r)
{
    return (size_t)(r->head_offset - r->ctail_offset);
}

static ossl_inline size_t ring_buf_avail(struct ring_buf *r)
{
    return r->alloc - ring_buf_used(r);
}

static ossl_inline int ring_buf_write_at(struct ring_buf *r,
                                         uint64_t logical_offset,
                                         const unsigned char *buf,
                                         size_t buf_len)
{
    size_t avail, idx, l;
    unsigned char *start = r->start;
    int i, err = 0;

    avail = ring_buf_avail(r);
    if (logical_offset < r->ctail_offset
        || safe_add_u64(logical_offset, buf_len, &err)
           > safe_add_u64(r->head_offset, avail, &err)
        || safe_add_u64(r->head_offset, buf_len, &err)
           > MAX_OFFSET
        || err)
        return 0;

    for (i = 0; buf_len > 0 && i < 2; ++i) {
        idx = logical_offset % r->alloc;
        l = r->alloc - idx;
        if (buf_len < l)
            l = buf_len;

        memcpy(start + idx, buf, l);
        if (r->head_offset < logical_offset + l)
            r->head_offset = logical_offset + l;

        logical_offset += l;
        buf += l;
        buf_len -= l;
    }

    assert(buf_len == 0);

    return 1;
}

static ossl_inline size_t ring_buf_push(struct ring_buf *r,
                                        const unsigned char *buf,
                                        size_t buf_len)
{
    size_t pushed = 0, avail, idx, l;
    unsigned char *start = r->start;

    for (;;) {
        avail = ring_buf_avail(r);
        if (buf_len > avail)
            buf_len = avail;

        if (buf_len > MAX_OFFSET - r->head_offset)
            buf_len = (size_t)(MAX_OFFSET - r->head_offset);

        if (buf_len == 0)
            break;

        idx = r->head_offset % r->alloc;
        l = r->alloc - idx;
        if (buf_len < l)
            l = buf_len;

        memcpy(start + idx, buf, l);
        r->head_offset  += l;
        buf             += l;
        buf_len         -= l;
        pushed          += l;
    }

    return pushed;
}

static ossl_inline const unsigned char *ring_buf_get_ptr(const struct ring_buf *r,
                                                         uint64_t logical_offset,
                                                         size_t *max_len)
{
    unsigned char *start = r->start;
    size_t idx;

    if (logical_offset >= r->head_offset || logical_offset < r->ctail_offset)
        return NULL;
    idx = logical_offset % r->alloc;
    *max_len = r->alloc - idx;
    return start + idx;
}

/*
 * Retrieves data out of the read side of the ring buffer starting at the given
 * logical offset. *buf is set to point to a contiguous span of bytes and
 * *buf_len is set to the number of contiguous bytes. After this function
 * returns, there may or may not be more bytes available at the logical offset
 * of (logical_offset + *buf_len) by calling this function again. If the logical
 * offset is out of the range retained by the ring buffer, returns 0, else
 * returns 1. A logical offset at the end of the range retained by the ring
 * buffer is not considered an error and is returned with a *buf_len of 0.
 *
 * The ring buffer state is not changed.
 */
static ossl_inline int ring_buf_get_buf_at(const struct ring_buf *r,
                                           uint64_t logical_offset,
                                           const unsigned char **buf,
                                           size_t *buf_len)
{
    const unsigned char *start = r->start;
    size_t idx, l;

    if (logical_offset > r->head_offset || logical_offset < r->ctail_offset)
        return 0;

    if (r->alloc == 0) {
        *buf        = NULL;
        *buf_len    = 0;
        return 1;
    }

    idx = logical_offset % r->alloc;
    l   = (size_t)(r->head_offset - logical_offset);
    if (l > r->alloc - idx)
        l = r->alloc - idx;

    *buf        = start + idx;
    *buf_len    = l;
    return 1;
}

static ossl_inline void ring_buf_cpop_range(struct ring_buf *r,
                                            uint64_t start, uint64_t end,
                                            int cleanse)
{
    assert(end >= start);

    if (start > r->ctail_offset || end >= MAX_OFFSET)
        return;

    if (cleanse && r->alloc > 0 && end > r->ctail_offset) {
        size_t idx = r->ctail_offset % r->alloc;
        uint64_t cleanse_end = end + 1;
        size_t l;

        if (cleanse_end > r->head_offset)
            cleanse_end = r->head_offset;
        l = (size_t)(cleanse_end - r->ctail_offset);
        if (l > r->alloc - idx) {
            OPENSSL_cleanse((unsigned char *)r->start + idx, r->alloc - idx);
            l -= r->alloc - idx;
            idx = 0;
        }
        if (l > 0)
            OPENSSL_cleanse((unsigned char *)r->start + idx, l);
    }

    r->ctail_offset = end + 1;
    /* Allow culling unpushed data */
    if (r->head_offset < r->ctail_offset)
        r->head_offset = r->ctail_offset;
}

static ossl_inline int ring_buf_resize(struct ring_buf *r, size_t num_bytes,
                                       int cleanse)
{
    struct ring_buf rnew = {0};
    const unsigned char *src = NULL;
    size_t src_len = 0, copied = 0;

    if (num_bytes == r->alloc)
        return 1;

    if (num_bytes < ring_buf_used(r))
        return 0;

    rnew.start = OPENSSL_malloc(num_bytes);
    if (rnew.start == NULL)
        return 0;

    rnew.alloc          = num_bytes;
    rnew.head_offset    = r->head_offset - ring_buf_used(r);
    rnew.ctail_offset   = rnew.head_offset;

    for (;;) {
        if (!ring_buf_get_buf_at(r, r->ctail_offset + copied, &src, &src_len)) {
            OPENSSL_free(rnew.start);
            return 0;
        }

        if (src_len == 0)
            break;

        if (ring_buf_push(&rnew, src, src_len) != src_len) {
            OPENSSL_free(rnew.start);
            return 0;
        }

        copied += src_len;
    }

    assert(rnew.head_offset == r->head_offset);
    rnew.ctail_offset = r->ctail_offset;

    ring_buf_destroy(r, cleanse);
    memcpy(r, &rnew, sizeof(*r));
    return 1;
}

#endif                          /* OSSL_INTERNAL_RING_BUF_H */

Coverage Report

Created: 2025-10-28 06:56

Line	Count	Source
1		/*
2		* Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
3		*
4		* Licensed under the Apache License 2.0 (the "License"). You may not use
5		* this file except in compliance with the License. You can obtain a copy
6		* in the file LICENSE in the source distribution or at
7		* https://www.openssl.org/source/license.html
8		*/
9
10		#ifndef OSSL_INTERNAL_RING_BUF_H
11		# define OSSL_INTERNAL_RING_BUF_H
12		# pragma once
13
14		# include <openssl/e_os2.h> /* For 'ossl_inline' */
15		# include "internal/safe_math.h"
16
17		/*
18		* ==================================================================
19		* Byte-wise ring buffer which supports pushing and popping blocks of multiple
20		* bytes at a time. The logical offset of each byte for the purposes of a QUIC
21		* stream is tracked. Bytes can be popped from the ring buffer in two stages;
22		* first they are popped, and then they are culled. Bytes which have been popped
23		* but not yet culled will not be overwritten, and can be restored.
24		*/
25		struct ring_buf {
26		void *start;
27		size_t alloc; /* size of buffer allocation in bytes */
28
29		/*
30		* Logical offset of the head (where we append to). This is the current size
31		* of the QUIC stream. This increases monotonically.
32		*/
33		uint64_t head_offset;
34
35		/*
36		* Logical offset of the cull tail. Data is no longer needed and is
37		* deallocated as the cull tail advances, which occurs as data is
38		* acknowledged. This increases monotonically.
39		*/
40		uint64_t ctail_offset;
41		};
42
43		OSSL_SAFE_MATH_UNSIGNED(u64, uint64_t)
44
45	0	#define MAX_OFFSET (((uint64_t)1) << 62) /* QUIC-imposed limit */
46
47		static ossl_inline int ring_buf_init(struct ring_buf *r)
48	0	{
49	0	r->start = NULL;
50	0	r->alloc = 0;
51	0	r->head_offset = r->ctail_offset = 0;
52	0	return 1;
53	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_init Unexecuted instantiation: quic_sstream.c:ring_buf_init
54
55		static ossl_inline void ring_buf_destroy(struct ring_buf *r, int cleanse)
56	0	{
57	0	if (cleanse)
58	0	OPENSSL_clear_free(r->start, r->alloc);
59	0	else
60	0	OPENSSL_free(r->start);
61	0	r->start = NULL;
62	0	r->alloc = 0;
63	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_destroy Unexecuted instantiation: quic_sstream.c:ring_buf_destroy
64
65		static ossl_inline size_t ring_buf_used(struct ring_buf *r)
66	0	{
67	0	return (size_t)(r->head_offset - r->ctail_offset);
68	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_used Unexecuted instantiation: quic_sstream.c:ring_buf_used
69
70		static ossl_inline size_t ring_buf_avail(struct ring_buf *r)
71	0	{
72	0	return r->alloc - ring_buf_used(r);
73	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_avail Unexecuted instantiation: quic_sstream.c:ring_buf_avail
74
75		static ossl_inline int ring_buf_write_at(struct ring_buf *r,
76		uint64_t logical_offset,
77		const unsigned char *buf,
78		size_t buf_len)
79	0	{
80	0	size_t avail, idx, l;
81	0	unsigned char *start = r->start;
82	0	int i, err = 0;
83
84	0	avail = ring_buf_avail(r);
85	0	if (logical_offset < r->ctail_offset
86	0	\|\| safe_add_u64(logical_offset, buf_len, &err)
87	0	> safe_add_u64(r->head_offset, avail, &err)
88	0	\|\| safe_add_u64(r->head_offset, buf_len, &err)
89	0	> MAX_OFFSET
90	0	\|\| err)
91	0	return 0;
92
93	0	for (i = 0; buf_len > 0 && i < 2; ++i) {
94	0	idx = logical_offset % r->alloc;
95	0	l = r->alloc - idx;
96	0	if (buf_len < l)
97	0	l = buf_len;
98
99	0	memcpy(start + idx, buf, l);
100	0	if (r->head_offset < logical_offset + l)
101	0	r->head_offset = logical_offset + l;
102
103	0	logical_offset += l;
104	0	buf += l;
105	0	buf_len -= l;
106	0	}
107
108	0	assert(buf_len == 0);
109
110	0	return 1;
111	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_write_at Unexecuted instantiation: quic_sstream.c:ring_buf_write_at
112
113		static ossl_inline size_t ring_buf_push(struct ring_buf *r,
114		const unsigned char *buf,
115		size_t buf_len)
116	0	{
117	0	size_t pushed = 0, avail, idx, l;
118	0	unsigned char *start = r->start;
119
120	0	for (;;) {
121	0	avail = ring_buf_avail(r);
122	0	if (buf_len > avail)
123	0	buf_len = avail;
124
125	0	if (buf_len > MAX_OFFSET - r->head_offset)
126	0	buf_len = (size_t)(MAX_OFFSET - r->head_offset);
127
128	0	if (buf_len == 0)
129	0	break;
130
131	0	idx = r->head_offset % r->alloc;
132	0	l = r->alloc - idx;
133	0	if (buf_len < l)
134	0	l = buf_len;
135
136	0	memcpy(start + idx, buf, l);
137	0	r->head_offset += l;
138	0	buf += l;
139	0	buf_len -= l;
140	0	pushed += l;
141	0	}
142
143	0	return pushed;
144	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_push Unexecuted instantiation: quic_sstream.c:ring_buf_push
145
146		static ossl_inline const unsigned char ring_buf_get_ptr(const struct ring_buf r,
147		uint64_t logical_offset,
148		size_t *max_len)
149	0	{
150	0	unsigned char *start = r->start;
151	0	size_t idx;
152
153	0	if (logical_offset >= r->head_offset \|\| logical_offset < r->ctail_offset)
154	0	return NULL;
155	0	idx = logical_offset % r->alloc;
156	0	*max_len = r->alloc - idx;
157	0	return start + idx;
158	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_get_ptr Unexecuted instantiation: quic_sstream.c:ring_buf_get_ptr
159
160		/*
161		* Retrieves data out of the read side of the ring buffer starting at the given
162		* logical offset. *buf is set to point to a contiguous span of bytes and
163		* *buf_len is set to the number of contiguous bytes. After this function
164		* returns, there may or may not be more bytes available at the logical offset
165		* of (logical_offset + *buf_len) by calling this function again. If the logical
166		* offset is out of the range retained by the ring buffer, returns 0, else
167		* returns 1. A logical offset at the end of the range retained by the ring
168		* buffer is not considered an error and is returned with a *buf_len of 0.
169		*
170		* The ring buffer state is not changed.
171		*/
172		static ossl_inline int ring_buf_get_buf_at(const struct ring_buf *r,
173		uint64_t logical_offset,
174		const unsigned char **buf,
175		size_t *buf_len)
176	0	{
177	0	const unsigned char *start = r->start;
178	0	size_t idx, l;
179
180	0	if (logical_offset > r->head_offset \|\| logical_offset < r->ctail_offset)
181	0	return 0;
182
183	0	if (r->alloc == 0) {
184	0	*buf = NULL;
185	0	*buf_len = 0;
186	0	return 1;
187	0	}
188
189	0	idx = logical_offset % r->alloc;
190	0	l = (size_t)(r->head_offset - logical_offset);
191	0	if (l > r->alloc - idx)
192	0	l = r->alloc - idx;
193
194	0	*buf = start + idx;
195	0	*buf_len = l;
196	0	return 1;
197	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_get_buf_at Unexecuted instantiation: quic_sstream.c:ring_buf_get_buf_at
198
199		static ossl_inline void ring_buf_cpop_range(struct ring_buf *r,
200		uint64_t start, uint64_t end,
201		int cleanse)
202	0	{
203	0	assert(end >= start);
204
205	0	if (start > r->ctail_offset \|\| end >= MAX_OFFSET)
206	0	return;
207
208	0	if (cleanse && r->alloc > 0 && end > r->ctail_offset) {
209	0	size_t idx = r->ctail_offset % r->alloc;
210	0	uint64_t cleanse_end = end + 1;
211	0	size_t l;
212
213	0	if (cleanse_end > r->head_offset)
214	0	cleanse_end = r->head_offset;
215	0	l = (size_t)(cleanse_end - r->ctail_offset);
216	0	if (l > r->alloc - idx) {
217	0	OPENSSL_cleanse((unsigned char *)r->start + idx, r->alloc - idx);
218	0	l -= r->alloc - idx;
219	0	idx = 0;
220	0	}
221	0	if (l > 0)
222	0	OPENSSL_cleanse((unsigned char *)r->start + idx, l);
223	0	}
224
225	0	r->ctail_offset = end + 1;
226		/* Allow culling unpushed data */
227	0	if (r->head_offset < r->ctail_offset)
228	0	r->head_offset = r->ctail_offset;
229	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_cpop_range Unexecuted instantiation: quic_sstream.c:ring_buf_cpop_range
230
231		static ossl_inline int ring_buf_resize(struct ring_buf *r, size_t num_bytes,
232		int cleanse)
233	0	{
234	0	struct ring_buf rnew = {0};
235	0	const unsigned char *src = NULL;
236	0	size_t src_len = 0, copied = 0;
237
238	0	if (num_bytes == r->alloc)
239	0	return 1;
240
241	0	if (num_bytes < ring_buf_used(r))
242	0	return 0;
243
244	0	rnew.start = OPENSSL_malloc(num_bytes);
245	0	if (rnew.start == NULL)
246	0	return 0;
247
248	0	rnew.alloc = num_bytes;
249	0	rnew.head_offset = r->head_offset - ring_buf_used(r);
250	0	rnew.ctail_offset = rnew.head_offset;
251
252	0	for (;;) {
253	0	if (!ring_buf_get_buf_at(r, r->ctail_offset + copied, &src, &src_len)) {
254	0	OPENSSL_free(rnew.start);
255	0	return 0;
256	0	}
257
258	0	if (src_len == 0)
259	0	break;
260
261	0	if (ring_buf_push(&rnew, src, src_len) != src_len) {
262	0	OPENSSL_free(rnew.start);
263	0	return 0;
264	0	}
265
266	0	copied += src_len;
267	0	}
268
269	0	assert(rnew.head_offset == r->head_offset);
270	0	rnew.ctail_offset = r->ctail_offset;
271
272	0	ring_buf_destroy(r, cleanse);
273	0	memcpy(r, &rnew, sizeof(*r));
274	0	return 1;
275	0	} Unexecuted instantiation: quic_rstream.c:ring_buf_resize Unexecuted instantiation: quic_sstream.c:ring_buf_resize
276
277		#endif /* OSSL_INTERNAL_RING_BUF_H */