Grcov report - character_set

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#pragma once

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#include <array>

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#include <cstdint>

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// A set of tables for validating that a character is in a specific

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// character set. Used to validate RFC compliance for various HTTP protocol elements.

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namespace Envoy {

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namespace Http {

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inline constexpr bool testCharInTable(const std::array<uint32_t, 8>& table, char c) {

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  // CPU cache friendly version of a lookup in a bit table of size 256.

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  // The table is organized as 8 32 bit words.

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  // This function looks up a bit from the `table` at the index `c`.

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  // This function is used to test whether a character `c` is allowed

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  // or not based on the value of a bit at index `c`.

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  uint8_t tmp = static_cast<uint8_t>(c);

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  // The `tmp >> 5` determines which of the 8 uint32_t words has the bit at index `uc`.

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  // The `0x80000000 >> (tmp & 0x1f)` determines the index of the bit within the 32 bit word.

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  return (table[tmp >> 5] & (0x80000000 >> (tmp & 0x1f))) != 0;

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8908963

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// Header name character table.

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// From RFC 9110, https://www.rfc-editor.org/rfc/rfc9110.html#section-5.1:

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//

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// SPELLCHECKER(off)

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// header-field   = field-name ":" OWS field-value OWS

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// field-name     = token

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// token          = 1*tchar

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//

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// tchar          = "!" / "#" / "$" / "%" / "&" / "'" / "*"

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//                / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"

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//                / DIGIT / ALPHA

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// SPELLCHECKER(on)

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inline constexpr std::array<uint32_t, 8> kGenericHeaderNameCharTable = {

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    // control characters

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    0b00000000000000000000000000000000,

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    // !"#$%&'()*+,-./0123456789:;<=>?

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    0b01011111001101101111111111000000,

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    //@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_

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    0b01111111111111111111111111100011,

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    //`abcdefghijklmnopqrstuvwxyz{|}~

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    0b11111111111111111111111111101010,

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    // extended ascii

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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};

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// A URI query and fragment character table. From RFC 3986:

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// https://datatracker.ietf.org/doc/html/rfc3986#section-3.4

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//

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// SPELLCHECKER(off)

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// query       = *( pchar / "/" / "?" )

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// fragment    = *( pchar / "/" / "?" )

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// SPELLCHECKER(on)

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inline constexpr std::array<uint32_t, 8> kUriQueryAndFragmentCharTable = {

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    // control characters

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    0b00000000000000000000000000000000,

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    // !"#$%&'()*+,-./0123456789:;<=>?

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    0b01001111111111111111111111110101,

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    //@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_

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    0b11111111111111111111111111100001,

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    //`abcdefghijklmnopqrstuvwxyz{|}~

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    0b01111111111111111111111111100010,

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    // extended ascii

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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    0b00000000000000000000000000000000,

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};

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} // namespace Http

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} // namespace Envoy