#include "net/tls13_utils.h"

#include <span>

#include <ngtcp2/ngtcp2_crypto.h>

#include <openssl/evp.h>

#include "common/defs.h"

extern "C" void ngtcp2_crypto_ctx_initial(ngtcp2_crypto_ctx *ctx);

namespace ag::tls13_utils {

bool hkdf_extract(std::span<uint8_t> dest, std::span<const uint8_t> secret, std::span<const uint8_t> salt) {

// SHA256 is used for QUIC [rfc 9001 5.2]

const EVP_MD *prf = EVP_sha256();

size_t dest_len = EVP_MD_size(prf);

if (dest.size() < dest_len) {

return false;

}

ngtcp2_crypto_ctx ctx;

ngtcp2_crypto_ctx_initial(&ctx);

return ngtcp2_crypto_hkdf_extract(dest.data(), &ctx.md, secret.data(), secret.size(), salt.data(), salt.size())

== 0;

}

bool hkdf_expand_label(std::span<uint8_t> dest, std::span<const uint8_t> secret, std::string_view label,

std::span<const uint8_t> context) {

std::string full_label = std::string("tls13 ") + label.data();

Uint8Vector info;

// 2 first bytes store out key length

info.push_back((uint8_t) (dest.size() >> CHAR_BIT));

info.push_back((uint8_t) dest.size());

// 3rd byte stores label length

info.push_back((uint8_t) full_label.size());

info.insert(info.end(), full_label.begin(), full_label.end());

// Context length

info.push_back((uint8_t) context.size());

info.insert(info.end(), context.begin(), context.end());

ngtcp2_crypto_ctx ctx;

ngtcp2_crypto_ctx_initial(&ctx);

return ngtcp2_crypto_hkdf_expand(

dest.data(), dest.size(), &ctx.md, secret.data(), secret.size(), info.data(), info.size())

== 0;

}

} // namespace ag::tls13_utils