在Windows上C++使用OpenSSL库自动获取服务器证书

#include <iostream>
#include <openssl/ssl.h>
#include <openssl/bio.h>
#include <openssl/err.h>

void initializeOpenSSL() {
    SSL_load_error_strings();
    OpenSSL_add_ssl_algorithms();
}

void cleanupOpenSSL() {
    EVP_cleanup();
}

SSL_CTX* createSSLContext() {
    const SSL_METHOD* method = SSLv23_client_method();
    SSL_CTX* ctx = SSL_CTX_new(method);
    if (!ctx) {
        std::cerr << "Unable to create SSL context" << std::endl;
        ERR_print_errors_fp(stderr);
        exit(EXIT_FAILURE);
    }
    return ctx;
}

void getServerCertificate(const char* hostname, const char* port) {
    SSL_CTX* ctx = createSSLContext();
    SSL* ssl;
    BIO* bio;

    std::string host = std::string(hostname) + ":" + port;
    bio = BIO_new_ssl_connect(ctx);

    if (BIO_set_conn_hostname(bio, host.c_str()) <= 0) {
        std::cerr << "Error setting up connection to " << host << std::endl;
        ERR_print_errors_fp(stderr);
        return;
    }

    BIO_get_ssl(bio, &ssl);
    if (!ssl) {
        std::cerr << "Unable to locate SSL pointer" << std::endl;
        ERR_print_errors_fp(stderr);
        return;
    }

    SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);

    if (BIO_do_connect(bio) <= 0) {
        std::cerr << "Error attempting to connect" << std::endl;
        ERR_print_errors_fp(stderr);
        return;
    }

    if (BIO_do_handshake(bio) <= 0) {
        std::cerr << "Error attempting to handshake" << std::endl;
        ERR_print_errors_fp(stderr);
        return;
    }

    X509* cert = SSL_get_peer_certificate(ssl);
    if (cert) {
        std::cout << "Successfully retrieved server certificate:" << std::endl;
        X509_print_fp(stdout, cert);
        X509_free(cert);
    } else {
        std::cerr << "Error: No certificate retrieved" << std::endl;
    }

    BIO_free_all(bio);
    SSL_CTX_free(ctx);
}

int main() {
    initializeOpenSSL();

    const char* hostname = "www.example.com";
    const char* port = "443";

    getServerCertificate(hostname, port);

    cleanupOpenSSL();
    return 0;
}