diff options
Diffstat (limited to 'crypto/openssl/ssl/quic/uint_set.c')
| -rw-r--r-- | crypto/openssl/ssl/quic/uint_set.c | 332 |
1 files changed, 332 insertions, 0 deletions
diff --git a/crypto/openssl/ssl/quic/uint_set.c b/crypto/openssl/ssl/quic/uint_set.c new file mode 100644 index 000000000000..faca906003b0 --- /dev/null +++ b/crypto/openssl/ssl/quic/uint_set.c @@ -0,0 +1,332 @@ +/* + * 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 + */ + +#include "internal/uint_set.h" +#include "internal/common.h" +#include <assert.h> + +/* + * uint64_t Integer Sets + * ===================== + * + * This data structure supports the following operations: + * + * Insert Range: Adds an inclusive range of integers [start, end] + * to the set. Equivalent to Insert for each number + * in the range. + * + * Remove Range: Removes an inclusive range of integers [start, end] + * from the set. Not all of the range need already be in + * the set, but any part of the range in the set is removed. + * + * Query: Is an integer in the data structure? + * + * The data structure can be iterated. + * + * For greater efficiency in tracking large numbers of contiguous integers, we + * track integer ranges rather than individual integers. The data structure + * manages a list of integer ranges [[start, end]...]. Internally this is + * implemented as a doubly linked sorted list of range structures, which are + * automatically split and merged as necessary. + * + * This data structure requires O(n) traversal of the list for insertion, + * removal and query when we are not adding/removing ranges which are near the + * beginning or end of the set of ranges. For the applications for which this + * data structure is used (e.g. QUIC PN tracking for ACK generation), it is + * expected that the number of integer ranges needed at any given time will + * generally be small and that most operations will be close to the beginning or + * end of the range. + * + * Invariant: The data structure is always sorted in ascending order by value. + * + * Invariant: No two adjacent ranges ever 'border' one another (have no + * numerical gap between them) as the data structure always ensures + * such ranges are merged. + * + * Invariant: No two ranges ever overlap. + * + * Invariant: No range [a, b] ever has a > b. + * + * Invariant: Since ranges are represented using inclusive bounds, no range + * item inside the data structure can represent a span of zero + * integers. + */ +void ossl_uint_set_init(UINT_SET *s) +{ + ossl_list_uint_set_init(s); +} + +void ossl_uint_set_destroy(UINT_SET *s) +{ + UINT_SET_ITEM *x, *xnext; + + for (x = ossl_list_uint_set_head(s); x != NULL; x = xnext) { + xnext = ossl_list_uint_set_next(x); + OPENSSL_free(x); + } +} + +/* Possible merge of x, prev(x) */ +static void uint_set_merge_adjacent(UINT_SET *s, UINT_SET_ITEM *x) +{ + UINT_SET_ITEM *xprev = ossl_list_uint_set_prev(x); + + if (xprev == NULL) + return; + + if (x->range.start - 1 != xprev->range.end) + return; + + x->range.start = xprev->range.start; + ossl_list_uint_set_remove(s, xprev); + OPENSSL_free(xprev); +} + +static uint64_t u64_min(uint64_t x, uint64_t y) +{ + return x < y ? x : y; +} + +static uint64_t u64_max(uint64_t x, uint64_t y) +{ + return x > y ? x : y; +} + +/* + * Returns 1 if there exists an integer x which falls within both ranges a and + * b. + */ +static int uint_range_overlaps(const UINT_RANGE *a, + const UINT_RANGE *b) +{ + return u64_min(a->end, b->end) + >= u64_max(a->start, b->start); +} + +static UINT_SET_ITEM *create_set_item(uint64_t start, uint64_t end) +{ + UINT_SET_ITEM *x = OPENSSL_malloc(sizeof(UINT_SET_ITEM)); + + if (x == NULL) + return NULL; + + ossl_list_uint_set_init_elem(x); + x->range.start = start; + x->range.end = end; + return x; +} + +int ossl_uint_set_insert(UINT_SET *s, const UINT_RANGE *range) +{ + UINT_SET_ITEM *x, *xnext, *z, *zprev, *f; + uint64_t start = range->start, end = range->end; + + if (!ossl_assert(start <= end)) + return 0; + + if (ossl_list_uint_set_is_empty(s)) { + /* Nothing in the set yet, so just add this range. */ + x = create_set_item(start, end); + if (x == NULL) + return 0; + ossl_list_uint_set_insert_head(s, x); + return 1; + } + + z = ossl_list_uint_set_tail(s); + if (start > z->range.end) { + /* + * Range is after the latest range in the set, so append. + * + * Note: The case where the range is before the earliest range in the + * set is handled as a degenerate case of the final case below. See + * optimization note (*) below. + */ + if (z->range.end + 1 == start) { + z->range.end = end; + return 1; + } + + x = create_set_item(start, end); + if (x == NULL) + return 0; + ossl_list_uint_set_insert_tail(s, x); + return 1; + } + + f = ossl_list_uint_set_head(s); + if (start <= f->range.start && end >= z->range.end) { + /* + * New range dwarfs all ranges in our set. + * + * Free everything except the first range in the set, which we scavenge + * and reuse. + */ + x = ossl_list_uint_set_head(s); + x->range.start = start; + x->range.end = end; + for (x = ossl_list_uint_set_next(x); x != NULL; x = xnext) { + xnext = ossl_list_uint_set_next(x); + ossl_list_uint_set_remove(s, x); + } + return 1; + } + + /* + * Walk backwards since we will most often be inserting at the end. As an + * optimization, test the head node first and skip iterating over the + * entire list if we are inserting at the start. The assumption is that + * insertion at the start and end of the space will be the most common + * operations. (*) + */ + z = end < f->range.start ? f : z; + + for (; z != NULL; z = zprev) { + zprev = ossl_list_uint_set_prev(z); + + /* An existing range dwarfs our new range (optimisation). */ + if (z->range.start <= start && z->range.end >= end) + return 1; + + if (uint_range_overlaps(&z->range, range)) { + /* + * Our new range overlaps an existing range, or possibly several + * existing ranges. + */ + UINT_SET_ITEM *ovend = z; + + ovend->range.end = u64_max(end, z->range.end); + + /* Get earliest overlapping range. */ + while (zprev != NULL && uint_range_overlaps(&zprev->range, range)) { + z = zprev; + zprev = ossl_list_uint_set_prev(z); + } + + ovend->range.start = u64_min(start, z->range.start); + + /* Replace sequence of nodes z..ovend with updated ovend only. */ + while (z != ovend) { + z = ossl_list_uint_set_next(x = z); + ossl_list_uint_set_remove(s, x); + OPENSSL_free(x); + } + break; + } else if (end < z->range.start + && (zprev == NULL || start > zprev->range.end)) { + if (z->range.start == end + 1) { + /* We can extend the following range backwards. */ + z->range.start = start; + + /* + * If this closes a gap we now need to merge + * consecutive nodes. + */ + uint_set_merge_adjacent(s, z); + } else if (zprev != NULL && zprev->range.end + 1 == start) { + /* We can extend the preceding range forwards. */ + zprev->range.end = end; + + /* + * If this closes a gap we now need to merge + * consecutive nodes. + */ + uint_set_merge_adjacent(s, z); + } else { + /* + * The new interval is between intervals without overlapping or + * touching them, so insert between, preserving sort. + */ + x = create_set_item(start, end); + if (x == NULL) + return 0; + ossl_list_uint_set_insert_before(s, z, x); + } + break; + } + } + + return 1; +} + +int ossl_uint_set_remove(UINT_SET *s, const UINT_RANGE *range) +{ + UINT_SET_ITEM *z, *zprev, *y; + uint64_t start = range->start, end = range->end; + + if (!ossl_assert(start <= end)) + return 0; + + /* Walk backwards since we will most often be removing at the end. */ + for (z = ossl_list_uint_set_tail(s); z != NULL; z = zprev) { + zprev = ossl_list_uint_set_prev(z); + + if (start > z->range.end) + /* No overlapping ranges can exist beyond this point, so stop. */ + break; + + if (start <= z->range.start && end >= z->range.end) { + /* + * The range being removed dwarfs this range, so it should be + * removed. + */ + ossl_list_uint_set_remove(s, z); + OPENSSL_free(z); + } else if (start <= z->range.start && end >= z->range.start) { + /* + * The range being removed includes start of this range, but does + * not cover the entire range (as this would be caught by the case + * above). Shorten the range. + */ + assert(end < z->range.end); + z->range.start = end + 1; + } else if (end >= z->range.end) { + /* + * The range being removed includes the end of this range, but does + * not cover the entire range (as this would be caught by the case + * above). Shorten the range. We can also stop iterating. + */ + assert(start > z->range.start); + assert(start > 0); + z->range.end = start - 1; + break; + } else if (start > z->range.start && end < z->range.end) { + /* + * The range being removed falls entirely in this range, so cut it + * into two. Cases where a zero-length range would be created are + * handled by the above cases. + */ + y = create_set_item(end + 1, z->range.end); + ossl_list_uint_set_insert_after(s, z, y); + z->range.end = start - 1; + break; + } else { + /* Assert no partial overlap; all cases should be covered above. */ + assert(!uint_range_overlaps(&z->range, range)); + } + } + + return 1; +} + +int ossl_uint_set_query(const UINT_SET *s, uint64_t v) +{ + UINT_SET_ITEM *x; + + if (ossl_list_uint_set_is_empty(s)) + return 0; + + for (x = ossl_list_uint_set_tail(s); x != NULL; x = ossl_list_uint_set_prev(x)) + if (x->range.start <= v && x->range.end >= v) + return 1; + else if (x->range.end < v) + return 0; + + return 0; +} |