/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

#include "squid.h"
#include "anyp/PortCfg.h"
#include "fatal.h"
#include "security/Certificate.h"
#include "security/KeyData.h"
#include "SquidConfig.h"
#include "ssl/bio.h"
#include "ssl/gadgets.h"

#include <algorithm>

/// load the signing certificate and its chain, if any, from certFile
/// \return true if the signing certificate was obtained
bool
Security::KeyData::loadCertificates()
{
    debugs(83, 2, "from " << certFile);
    cert.reset(); // paranoid: ensure cert is unset

#if USE_OPENSSL
    const char *certFilename = certFile.c_str();
    Ssl::BIO_Pointer bio(BIO_new(BIO_s_file()));
    if (!bio || !BIO_read_filename(bio.get(), certFilename)) {
        const auto x = ERR_get_error();
        debugs(83, DBG_IMPORTANT, "ERROR: unable to load certificate file '" << certFile << "': " << ErrorString(x));
        return false;
    }

    try {
        cert = Ssl::ReadCertificate(bio);
        debugs(83, DBG_PARSE_NOTE(2), "Loaded signing certificate: " << *cert);
    }
    catch (...) {
        // TODO: Convert the rest of this method to throw on errors instead.
        debugs(83, DBG_IMPORTANT, "ERROR: unable to load certificate file '" << certFile << "':" <<
               Debug::Extra << "problem: " << CurrentException);
        return false;
    }

    try {
        // Squid sends `cert` (loaded above) followed by certificates in `chain`
        // (formed below by loading and sorting the remaining certificates).

        // load all the remaining configured certificates
        CertList candidates;
        while (const auto c = Ssl::ReadOptionalCertificate(bio))
            candidates.emplace_back(c);

        // Push certificates into `chain` in on-the-wire order, as defined by
        // RFC 8446 Section 4.4.2: "Each following certificate SHOULD directly
        // certify the one immediately preceding it."
        while (!candidates.empty()) {
            const auto precedingCert = chain.empty() ? cert : chain.back();

            // We cannot chain any certificate after a self-signed certificate.
            // This check also protects the IssuedBy() search below from adding
            // duplicated (i.e. listed multiple times) self-signed certificates.
            if (SelfSigned(*precedingCert))
                break;

            const auto issuerPos = std::find_if(candidates.begin(), candidates.end(), [&](const CertPointer &i) {
                return IssuedBy(*precedingCert, *i);
            });
            if (issuerPos == candidates.end())
                break;

            const auto &issuer = *issuerPos;
            debugs(83, DBG_PARSE_NOTE(3), "Adding CA certificate: " << *issuer);
            chain.emplace_back(issuer);
            candidates.erase(issuerPos);
        }

        for (const auto &c: candidates)
            debugs(83, DBG_IMPORTANT, "WARNING: Ignoring certificate that does not extend the chain: " << *c);
    }
    catch (...) {
        // TODO: Reject configs with malformed intermediate certs instead.
        debugs(83, DBG_IMPORTANT, "ERROR: Failure while loading intermediate certificate(s) from '" << certFile << "':" <<
               Debug::Extra << "problem: " << CurrentException);
    }

#elif HAVE_LIBGNUTLS
    const char *certFilename = certFile.c_str();
    gnutls_datum_t data;
    Security::LibErrorCode x = gnutls_load_file(certFilename, &data);
    if (x != GNUTLS_E_SUCCESS) {
        debugs(83, DBG_IMPORTANT, "ERROR: unable to load certificate file '" << certFile << "': " << ErrorString(x));
        return false;
    }

    gnutls_pcert_st pcrt;
    x = gnutls_pcert_import_x509_raw(&pcrt, &data, GNUTLS_X509_FMT_PEM, 0);
    if (x != GNUTLS_E_SUCCESS) {
        debugs(83, DBG_IMPORTANT, "ERROR: unable to import certificate from '" << certFile << "': " << ErrorString(x));
        return false;
    }
    gnutls_free(data.data);

    gnutls_x509_crt_t certificate;
    x = gnutls_pcert_export_x509(&pcrt, &certificate);
    if (x != GNUTLS_E_SUCCESS) {
        debugs(83, DBG_IMPORTANT, "ERROR: unable to X.509 convert certificate from '" << certFile << "': " << ErrorString(x));
        return false;
    }

    if (certificate) {
        cert = Security::CertPointer(certificate, [](gnutls_x509_crt_t p) {
            debugs(83, 5, "gnutls_x509_crt_deinit cert=" << (void*)p);
            gnutls_x509_crt_deinit(p);
        });
    }

    // XXX: implement chain loading
    debugs(83, 2, "Loading certificate chain from PEM files not implemented in this Squid.");

#else
    // do nothing.
#endif

    if (!cert) {
        debugs(83, DBG_IMPORTANT, "ERROR: unable to load certificate from '" << certFile << "'");
    }

    return bool(cert);
}

/**
 * Read X.509 private key from file.
 */
bool
Security::KeyData::loadX509PrivateKeyFromFile()
{
    debugs(83, 2, "from " << privateKeyFile);

#if USE_OPENSSL
    const char *keyFilename = privateKeyFile.c_str();
    // XXX: Ssl::AskPasswordCb needs SSL_CTX_set_default_passwd_cb_userdata()
    // so this may not fully work iff Config.Program.ssl_password is set.
    pem_password_cb *cb = ::Config.Program.ssl_password ? &Ssl::AskPasswordCb : nullptr;
    Ssl::ReadPrivateKeyFromFile(keyFilename, pkey, cb);

    if (pkey && !X509_check_private_key(cert.get(), pkey.get())) {
        debugs(83, DBG_IMPORTANT, "WARNING: '" << privateKeyFile << "' X509_check_private_key() failed");
        pkey.reset();
    }

#elif HAVE_LIBGNUTLS
    const char *keyFilename = privateKeyFile.c_str();
    gnutls_datum_t data;
    if (gnutls_load_file(keyFilename, &data) == GNUTLS_E_SUCCESS) {
        gnutls_privkey_t key;
        (void)gnutls_privkey_init(&key);
        Security::ErrorCode x = gnutls_privkey_import_x509_raw(key, &data, GNUTLS_X509_FMT_PEM, nullptr, 0);
        if (x == GNUTLS_E_SUCCESS) {
            gnutls_x509_privkey_t xkey;
            gnutls_privkey_export_x509(key, &xkey);
            gnutls_privkey_deinit(key);
            pkey = Security::PrivateKeyPointer(xkey, [](gnutls_x509_privkey_t p) {
                debugs(83, 5, "gnutls_x509_privkey_deinit pkey=" << (void*)p);
                gnutls_x509_privkey_deinit(p);
            });
        }
    }
    gnutls_free(data.data);

#else
    // nothing to do.
#endif

    return bool(pkey);
}

void
Security::KeyData::loadFromFiles(const AnyP::PortCfg &port, const char *portType)
{
    char buf[128];
    if (!loadCertificates()) {
        debugs(83, DBG_IMPORTANT, "WARNING: '" << portType << "_port " << port.s.toUrl(buf, sizeof(buf)) << "' missing certificate in '" << certFile << "'");
        return;
    }

    // pkey is mandatory, not having it makes cert and chain pointless.
    if (!loadX509PrivateKeyFromFile()) {
        debugs(83, DBG_IMPORTANT, "WARNING: '" << portType << "_port " << port.s.toUrl(buf, sizeof(buf)) << "' missing private key in '" << privateKeyFile << "'");
        cert.reset();
        chain.clear();
    }
}