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#ifndef _PX5G_OPENSSL_HPP
#define _PX5G_OPENSSL_HPP
// #define OPENSSL_API_COMPAT 0x10102000L
#include <fcntl.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <unistd.h>
#include <memory>
#include <stdexcept>
#include <string>
static constexpr auto rsa_min_modulus_bits = 512;
using EVP_PKEY_ptr = std::unique_ptr<EVP_PKEY, decltype(&::EVP_PKEY_free)>;
using X509_NAME_ptr = std::unique_ptr<X509_NAME, decltype(&::X509_NAME_free)>;
auto checkend(const std::string& crtpath, time_t seconds = 0, bool use_pem = true) -> bool;
auto gen_eckey(int curve) -> EVP_PKEY_ptr;
auto gen_rsakey(int keysize, BN_ULONG exponent = RSA_F4) -> EVP_PKEY_ptr;
void write_key(const EVP_PKEY_ptr& pkey, const std::string& keypath = "", bool use_pem = true);
auto subject2name(const std::string& subject) -> X509_NAME_ptr;
void selfsigned(const EVP_PKEY_ptr& pkey,
int days,
const std::string& subject = "",
const std::string& crtpath = "",
bool use_pem = true);
// ------------------------- implementation: ----------------------------------
inline auto print_error(const char* str, const size_t /*len*/, void* errmsg) -> int
{
*static_cast<std::string*>(errmsg) += str;
return 0;
}
// wrapper for clang-tidy:
inline auto _BIO_new_fp(FILE* stream, const bool use_pem, const bool close = false) -> BIO*
{
return BIO_new_fp(stream, // NOLINTNEXTLINE(hicpp-signed-bitwise) macros:
(use_pem ? BIO_FP_TEXT : 0) | (close ? BIO_CLOSE : BIO_NOCLOSE));
}
auto checkend(const std::string& crtpath, const time_t seconds, const bool use_pem) -> bool
{
BIO* bio = crtpath.empty() ? _BIO_new_fp(stdin, use_pem)
: BIO_new_file(crtpath.c_str(), (use_pem ? "r" : "rb"));
X509* x509 = nullptr;
if (bio != nullptr) {
x509 = use_pem ? PEM_read_bio_X509_AUX(bio, nullptr, nullptr, nullptr)
: d2i_X509_bio(bio, nullptr);
BIO_free(bio);
}
if (x509 == nullptr) {
std::string errmsg{"checkend error: unable to load certificate\n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
time_t checktime = time(nullptr) + seconds;
auto cmp = X509_cmp_time(X509_get0_notAfter(x509), &checktime);
X509_free(x509);
return (cmp >= 0);
}
auto gen_eckey(const int curve) -> EVP_PKEY_ptr
{
EC_GROUP* group = curve != 0 ? EC_GROUP_new_by_curve_name(curve) : nullptr;
if (group == nullptr) {
std::string errmsg{"gen_eckey error: cannot build group for curve id "};
errmsg += std::to_string(curve) + "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
EC_GROUP_set_asn1_flag(group, OPENSSL_EC_NAMED_CURVE);
EC_GROUP_set_point_conversion_form(group, POINT_CONVERSION_UNCOMPRESSED);
auto* eckey = EC_KEY_new();
if (eckey != nullptr) {
if ((EC_KEY_set_group(eckey, group) == 0) || (EC_KEY_generate_key(eckey) == 0)) {
EC_KEY_free(eckey);
eckey = nullptr;
}
}
EC_GROUP_free(group);
if (eckey == nullptr) {
std::string errmsg{"gen_eckey error: cannot build key with curve id "};
errmsg += std::to_string(curve) + "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
EVP_PKEY_ptr pkey{EVP_PKEY_new(), ::EVP_PKEY_free};
// EVP_PKEY_assign_EC_KEY is a macro casting eckey to char *:
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-cstyle-cast)
if (!EVP_PKEY_assign_EC_KEY(pkey.get(), eckey)) {
EC_KEY_free(eckey);
std::string errmsg{"gen_eckey error: cannot assign EC key to EVP\n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
return pkey;
}
auto gen_rsakey(const int keysize, const BN_ULONG exponent) -> EVP_PKEY_ptr
{
if (keysize < rsa_min_modulus_bits || keysize > OPENSSL_RSA_MAX_MODULUS_BITS) {
std::string errmsg{"gen_rsakey error: RSA keysize ("};
errmsg += std::to_string(keysize) + ") out of range [512..";
errmsg += std::to_string(OPENSSL_RSA_MAX_MODULUS_BITS) + "]";
throw std::runtime_error(errmsg);
}
auto* bignum = BN_new();
if (bignum == nullptr) {
std::string errmsg{"gen_rsakey error: cannot get big number struct\n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
auto* rsa = RSA_new();
if (rsa != nullptr) {
if ((BN_set_word(bignum, exponent) == 0) ||
(RSA_generate_key_ex(rsa, keysize, bignum, nullptr) == 0))
{
RSA_free(rsa);
rsa = nullptr;
}
}
BN_free(bignum);
if (rsa == nullptr) {
std::string errmsg{"gen_rsakey error: cannot create RSA key with size"};
errmsg += std::to_string(keysize) + " and exponent ";
errmsg += std::to_string(exponent) + "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
EVP_PKEY_ptr pkey{EVP_PKEY_new(), ::EVP_PKEY_free};
// EVP_PKEY_assign_RSA is a macro casting rsa to char *:
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-cstyle-cast)
if (!EVP_PKEY_assign_RSA(pkey.get(), rsa)) {
RSA_free(rsa);
std::string errmsg{"gen_rsakey error: cannot assign RSA key to EVP\n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
return pkey;
}
void write_key(const EVP_PKEY_ptr& pkey, const std::string& keypath, const bool use_pem)
{
BIO* bio = nullptr;
if (keypath.empty()) {
bio = _BIO_new_fp(stdout, use_pem);
}
else { // BIO_new_file(keypath.c_str(), (use_pem ? "w" : "wb") );
static constexpr auto mask = 0600;
// auto fd = open(keypath.c_str(), O_WRONLY | O_CREAT | O_TRUNC, mask);
// creat has no cloexec, alt. triggers cppcoreguidelines-pro-type-vararg
// NOLINTNEXTLINE(android-cloexec-creat)
auto fd = creat(keypath.c_str(), mask); // the same without va_args.
if (fd >= 0) {
auto* fp = fdopen(fd, (use_pem ? "w" : "wb"));
if (fp != nullptr) {
bio = _BIO_new_fp(fp, use_pem, true);
if (bio == nullptr) {
// NOLINTNEXTLINE(cppcoreguidelines-owning-memory) fp owns fd:
fclose(fp);
}
}
else {
close(fd);
}
}
}
if (bio == nullptr) {
std::string errmsg{"write_key error: cannot open "};
errmsg += keypath.empty() ? "stdout" : keypath;
errmsg += "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
int len = 0;
auto* key = pkey.get();
switch (EVP_PKEY_base_id(key)) { // use same format as px5g:
case EVP_PKEY_EC:
len = use_pem ? PEM_write_bio_ECPrivateKey(bio, EVP_PKEY_get0_EC_KEY(key), nullptr,
nullptr, 0, nullptr, nullptr)
: i2d_ECPrivateKey_bio(bio, EVP_PKEY_get0_EC_KEY(key));
break;
case EVP_PKEY_RSA:
len = use_pem ? PEM_write_bio_RSAPrivateKey(bio, EVP_PKEY_get0_RSA(key), nullptr,
nullptr, 0, nullptr, nullptr)
: i2d_RSAPrivateKey_bio(bio, EVP_PKEY_get0_RSA(key));
break;
default:
len = use_pem
? PEM_write_bio_PrivateKey(bio, key, nullptr, nullptr, 0, nullptr, nullptr)
: i2d_PrivateKey_bio(bio, key);
}
BIO_free_all(bio);
if (len == 0) {
std::string errmsg{"write_key error: cannot write EVP pkey to "};
errmsg += keypath.empty() ? "stdout" : keypath;
errmsg += "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
}
auto subject2name(const std::string& subject) -> X509_NAME_ptr
{
if (!subject.empty() && subject[0] != '/') {
throw std::runtime_error("subject2name errror: not starting with /");
}
X509_NAME_ptr name = {X509_NAME_new(), ::X509_NAME_free};
if (!name) {
std::string errmsg{"subject2name error: cannot create X509 name \n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
if (subject.empty()) {
return name;
}
int prev = 1;
std::string type{};
char chr = '=';
for (int i = 0; subject[i] != 0;) {
++i;
if (subject[i] == '\\' && subject[++i] == '\0') {
throw std::runtime_error("subject2name errror: escape at the end");
}
if (subject[i] != chr && subject[i] != '\0') {
continue;
}
if (chr == '=') {
type = subject.substr(prev, i - prev);
chr = '/';
}
else {
auto nid = OBJ_txt2nid(type.c_str());
if (nid == NID_undef) {
// skip unknown entries (silently?).
}
else {
const auto* val = // X509_NAME_add_entry_by_NID wants it unsigned:
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
reinterpret_cast<const unsigned char*>(&subject[prev]);
int len = i - prev;
if (X509_NAME_add_entry_by_NID(
name.get(), nid,
MBSTRING_ASC, // NOLINT(hicpp-signed-bitwise) is macro
val, len, -1, 0) == 0)
{
std::string errmsg{"subject2name error: cannot add "};
errmsg += "/" + type + "=" + subject.substr(prev, len) + "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
}
chr = '=';
}
prev = i + 1;
}
return name;
}
void selfsigned(const EVP_PKEY_ptr& pkey,
const int days,
const std::string& subject,
const std::string& crtpath,
const bool use_pem)
{
auto* x509 = X509_new();
if (x509 == nullptr) {
std::string errmsg{"selfsigned error: cannot create X509 structure\n"};
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
auto freeX509_and_throw = [&x509](const std::string& what) {
X509_free(x509);
std::string errmsg{"selfsigned error: cannot set "};
errmsg += what + " in X509 certificate\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
};
if (X509_set_version(x509, 2) == 0) {
freeX509_and_throw("version");
}
if (X509_set_pubkey(x509, pkey.get()) == 0) {
freeX509_and_throw("pubkey");
}
if ((X509_gmtime_adj(X509_getm_notBefore(x509), 0) == nullptr) ||
(X509_time_adj_ex(X509_getm_notAfter(x509), days, 0, nullptr) == nullptr))
{
freeX509_and_throw("times");
}
X509_NAME_ptr name{nullptr, ::X509_NAME_free};
try {
name = subject2name(subject);
}
catch (...) {
X509_free(x509);
throw;
}
if (X509_set_subject_name(x509, name.get()) == 0) {
freeX509_and_throw("subject");
}
if (X509_set_issuer_name(x509, name.get()) == 0) {
freeX509_and_throw("issuer");
}
auto* bignum = BN_new();
if (bignum == nullptr) {
freeX509_and_throw("serial (creating big number struct)");
}
static const auto BITS = 159;
if (BN_rand(bignum, BITS, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY) == 0) {
BN_free(bignum);
freeX509_and_throw("serial (creating random number)");
}
if (BN_to_ASN1_INTEGER(bignum, X509_get_serialNumber(x509)) == nullptr) {
BN_free(bignum);
freeX509_and_throw("random serial");
}
BN_free(bignum);
if (X509_sign(x509, pkey.get(), EVP_sha256()) == 0) {
freeX509_and_throw("signing digest");
}
BIO* bio = crtpath.empty() ? _BIO_new_fp(stdout, use_pem)
: BIO_new_file(crtpath.c_str(), (use_pem ? "w" : "wb"));
int len = 0;
if (bio != nullptr) {
len = use_pem ? PEM_write_bio_X509(bio, x509) : i2d_X509_bio(bio, x509);
BIO_free_all(bio);
}
X509_free(x509);
if (len == 0) {
std::string errmsg{"selfsigned error: cannot write certificate to "};
errmsg += crtpath.empty() ? "stdout" : crtpath;
errmsg += "\n";
ERR_print_errors_cb(print_error, &errmsg);
throw std::runtime_error(errmsg);
}
}
#endif