SocketReader.cpp

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/*
 * SNode.C - a slim toolkit for network communication
 * Copyright (C) Volker Christian <me@vchrist.at>
 *               2020, 2021, 2022, 2023, 2024, 2025
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "core/socket/stream/tls/SocketReader.h"
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include "core/socket/stream/tls/ssl_utils.h"
#include "log/Logger.h"
#include "utils/PreserveErrno.h"
 
#include <cerrno>
#include <limits>
#include <openssl/ssl.h>
#include <string>
 
#endif // DOXYGEN_SHOULD_SKIP_THIS
 
namespace core::socket::stream::tls {
 
    ssize_t SocketReader::read(char* chunk, std::size_t chunkLen) {
        ssize_t ret = 0;
 
        if ((SSL_get_shutdown(ssl) & SSL_RECEIVED_SHUTDOWN) != 0) {
            ret = Super::read(chunk, chunkLen);
        } else {
            chunkLen = chunkLen > std::numeric_limits<int>::max() ? std::numeric_limits<int>::max() : chunkLen;
            ret = SSL_read(ssl, chunk, static_cast<int>(chunkLen));
 
            if (ret <= 0) {
                const int ssl_err = SSL_get_error(ssl, static_cast<int>(ret));
 
                switch (ssl_err) {
                    case SSL_ERROR_WANT_READ:
                        errno = EAGAIN;
                        ret = -1;
                        break;
                    case SSL_ERROR_WANT_WRITE:
                        LOG(TRACE) << getName() << " SSL/TLS: Start renegotiation on read";
                        doSSLHandshake(
                            [this]() {
                                LOG(DEBUG) << getName() << " SSL/TLS: Renegotiation on read success";
                            },
                            [this]() {
                                LOG(WARNING) << getName() << " SSL/TLS: Renegotiation on read timed out";
                            },
                            [this](int ssl_err) {
                                ssl_log(getName() + " SSL/TLS: Renegotiation on read", ssl_err);
                            });
                        errno = EAGAIN;
                        ret = -1;
                        break;
                    case SSL_ERROR_ZERO_RETURN: // received close_notify
                        LOG(DEBUG) << getName() << " SSL/TLS: Close_notify is" << (closeNotifyIsEOF ? " " : " not ") << "EOF";
                        onReadShutdown();
                        errno = closeNotifyIsEOF ? 0 : EAGAIN;
                        ret = closeNotifyIsEOF ? 0 : -1;
                        break;
                    case SSL_ERROR_SYSCALL: // When SSL_get_error(ssl, ret) returns SSL_ERROR_SYSCALL
                                            // and ret is 0, it indicates that the underlying TCP connection
                                            // was closed unexpectedly by the peer. This situation typically
                                            // happens when the peer closes (FIN) the connection without
                                            // sending a close_notify alert, which violates the SSL/TLS
                                            // protocol’s  graceful shutdown procedure.
                        // In case ret is -1 a real syscall error (RST = ECONNRESET)
                        {
                            const utils::PreserveErrno pe;
 
                            if (ret == 0) {
                                PLOG(DEBUG) << getName() << " SSL/TLS: EOF detected: Connection closed by peer.";
                            } else {
                                PLOG(WARNING) << getName() + " SSL/TLS: Syscall error on read";
                            }
                        }
                        ret = -1;
                        break;
                    case SSL_ERROR_SSL:
                        ssl_log(getName() + " SSL/TLS: Read failed", ssl_err);
                        onReadShutdown();
                        ret = -1;
                        break;
                    default:
                        ssl_log(getName() + " SSL/TLS: Unexpected error", ssl_err);
                        onReadShutdown();
                        errno = EIO;
                        ret = -1;
                        break;
                }
            }
        }
 
        return ret;
    }
 
} // namespace core::socket::stream::tls