Mercurial > hg > nginx
view src/http/v3/ngx_http_v3_encode.c @ 9282:acb8548c00e9
HTTP/3: fixed dynamic table overflow.
While inserting a new entry into the dynamic table, first the entry is added,
and then older entries are evicted until table size is within capacity. After
the first step, the number of entries may temporarily exceed the maximum
calculated from capacity by one entry, which previously caused table overflow.
The easiest way to trigger the issue is to keep adding entries with empty names
and values until first eviction.
The issue was introduced by 987bee4363d1.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Tue, 28 May 2024 17:18:50 +0400 |
parents | 5c86189a1c1b |
children |
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/* * Copyright (C) Roman Arutyunyan * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> uintptr_t ngx_http_v3_encode_varlen_int(u_char *p, uint64_t value) { if (value <= 63) { if (p == NULL) { return 1; } *p++ = value; return (uintptr_t) p; } if (value <= 16383) { if (p == NULL) { return 2; } *p++ = 0x40 | (value >> 8); *p++ = value; return (uintptr_t) p; } if (value <= 1073741823) { if (p == NULL) { return 4; } *p++ = 0x80 | (value >> 24); *p++ = (value >> 16); *p++ = (value >> 8); *p++ = value; return (uintptr_t) p; } if (p == NULL) { return 8; } *p++ = 0xc0 | (value >> 56); *p++ = (value >> 48); *p++ = (value >> 40); *p++ = (value >> 32); *p++ = (value >> 24); *p++ = (value >> 16); *p++ = (value >> 8); *p++ = value; return (uintptr_t) p; } uintptr_t ngx_http_v3_encode_prefix_int(u_char *p, uint64_t value, ngx_uint_t prefix) { ngx_uint_t thresh, n; thresh = (1 << prefix) - 1; if (value < thresh) { if (p == NULL) { return 1; } *p++ |= value; return (uintptr_t) p; } value -= thresh; if (p == NULL) { for (n = 2; value >= 128; n++) { value >>= 7; } return n; } *p++ |= thresh; while (value >= 128) { *p++ = 0x80 | value; value >>= 7; } *p++ = value; return (uintptr_t) p; } uintptr_t ngx_http_v3_encode_field_section_prefix(u_char *p, ngx_uint_t insert_count, ngx_uint_t sign, ngx_uint_t delta_base) { if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, insert_count, 8) + ngx_http_v3_encode_prefix_int(NULL, delta_base, 7); } *p = 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, insert_count, 8); *p = sign ? 0x80 : 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, delta_base, 7); return (uintptr_t) p; } uintptr_t ngx_http_v3_encode_field_ri(u_char *p, ngx_uint_t dynamic, ngx_uint_t index) { /* Indexed Field Line */ if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, index, 6); } *p = dynamic ? 0x80 : 0xc0; return ngx_http_v3_encode_prefix_int(p, index, 6); } uintptr_t ngx_http_v3_encode_field_lri(u_char *p, ngx_uint_t dynamic, ngx_uint_t index, u_char *data, size_t len) { size_t hlen; u_char *p1, *p2; /* Literal Field Line With Name Reference */ if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, index, 4) + ngx_http_v3_encode_prefix_int(NULL, len, 7) + len; } *p = dynamic ? 0x40 : 0x50; p = (u_char *) ngx_http_v3_encode_prefix_int(p, index, 4); p1 = p; *p = 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, len, 7); if (data) { p2 = p; hlen = ngx_http_huff_encode(data, len, p, 0); if (hlen) { p = p1; *p = 0x80; p = (u_char *) ngx_http_v3_encode_prefix_int(p, hlen, 7); if (p != p2) { ngx_memmove(p, p2, hlen); } p += hlen; } else { p = ngx_cpymem(p, data, len); } } return (uintptr_t) p; } uintptr_t ngx_http_v3_encode_field_l(u_char *p, ngx_str_t *name, ngx_str_t *value) { size_t hlen; u_char *p1, *p2; /* Literal Field Line With Literal Name */ if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, name->len, 3) + name->len + ngx_http_v3_encode_prefix_int(NULL, value->len, 7) + value->len; } p1 = p; *p = 0x20; p = (u_char *) ngx_http_v3_encode_prefix_int(p, name->len, 3); p2 = p; hlen = ngx_http_huff_encode(name->data, name->len, p, 1); if (hlen) { p = p1; *p = 0x28; p = (u_char *) ngx_http_v3_encode_prefix_int(p, hlen, 3); if (p != p2) { ngx_memmove(p, p2, hlen); } p += hlen; } else { ngx_strlow(p, name->data, name->len); p += name->len; } p1 = p; *p = 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, value->len, 7); p2 = p; hlen = ngx_http_huff_encode(value->data, value->len, p, 0); if (hlen) { p = p1; *p = 0x80; p = (u_char *) ngx_http_v3_encode_prefix_int(p, hlen, 7); if (p != p2) { ngx_memmove(p, p2, hlen); } p += hlen; } else { p = ngx_cpymem(p, value->data, value->len); } return (uintptr_t) p; } uintptr_t ngx_http_v3_encode_field_pbi(u_char *p, ngx_uint_t index) { /* Indexed Field Line With Post-Base Index */ if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, index, 4); } *p = 0x10; return ngx_http_v3_encode_prefix_int(p, index, 4); } uintptr_t ngx_http_v3_encode_field_lpbi(u_char *p, ngx_uint_t index, u_char *data, size_t len) { size_t hlen; u_char *p1, *p2; /* Literal Field Line With Post-Base Name Reference */ if (p == NULL) { return ngx_http_v3_encode_prefix_int(NULL, index, 3) + ngx_http_v3_encode_prefix_int(NULL, len, 7) + len; } *p = 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, index, 3); p1 = p; *p = 0; p = (u_char *) ngx_http_v3_encode_prefix_int(p, len, 7); if (data) { p2 = p; hlen = ngx_http_huff_encode(data, len, p, 0); if (hlen) { p = p1; *p = 0x80; p = (u_char *) ngx_http_v3_encode_prefix_int(p, hlen, 7); if (p != p2) { ngx_memmove(p, p2, hlen); } p += hlen; } else { p = ngx_cpymem(p, data, len); } } return (uintptr_t) p; }