openssl3.2 - 官方demo学习 - server-arg.c

概述

TLS服务器, 等客户端来连接; 如果客户端断开了, 通过释放bio来释放客户端socket, 然后继续通过bio读来aceept.

笔记

对于开源工程, 不可能有作者那么熟悉, 变量命名需要改下有利于理解逻辑.
VS2019带的变量改名功能挺好的.

过了一遍的程序:

/*!
\file server-arg.c
\brief TLS服务器, 等客户端来连接; 如果客户端断开了, 通过释放bio来释放客户端socket, 然后继续通过bio读来aceept.
*/

/*
 * Copyright 2013-2017 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * A minimal program to serve an SSL connection. It uses blocking. It use the
 * SSL_CONF API with the command line. cc -I../../include server-arg.c
 * -L../.. -lssl -lcrypto -ldl
 */

#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <openssl/err.h>
#include <openssl/ssl.h>

#include "my_openSSL_lib.h"

int main(int argc, char *argv[])
{
    char *psz_port = "*:4433";
    BIO *bio_ssl, *bio_tmp;
    SSL_CTX *ctx_ssl;
    SSL_CONF_CTX *ctx_ssl_cfg;
    char buf[512];
    BIO *bio_in = NULL;
    int ret = EXIT_FAILURE, i;
    char **args = argv + 1;
    int nargs = argc - 1;

    ctx_ssl = SSL_CTX_new(TLS_server_method());

    ctx_ssl_cfg = SSL_CONF_CTX_new();
    SSL_CONF_CTX_set_flags(ctx_ssl_cfg, SSL_CONF_FLAG_SERVER);
    SSL_CONF_CTX_set_flags(ctx_ssl_cfg, SSL_CONF_FLAG_CERTIFICATE);
    SSL_CONF_CTX_set_ssl_ctx(ctx_ssl_cfg, ctx_ssl);
    while (*args && **args == '-') {
        int rv;
        /* Parse standard arguments */
        rv = SSL_CONF_cmd_argv(ctx_ssl_cfg, &nargs, &args);
        if (rv == -3) {
            fprintf(stderr, "Missing argument for %s\n", *args);
            goto err;
        }
        if (rv < 0) {
            fprintf(stderr, "Error in command %s\n", *args);
            ERR_print_errors_fp(stderr);
            goto err;
        }
        /* If rv > 0 we processed something so proceed to next arg */
        if (rv > 0)
            continue;
        /* Otherwise application specific argument processing */
        if (strcmp(*args, "-port") == 0) {
            psz_port = args[1];
            if (psz_port == NULL) {
                fprintf(stderr, "Missing -port argument\n");
                goto err;
            }
            args += 2;
            nargs -= 2;
            continue;
        } else {
            fprintf(stderr, "Unknown argument %s\n", *args);
            goto err;
        }
    }

    if (!SSL_CONF_CTX_finish(ctx_ssl_cfg)) {
        fprintf(stderr, "Finish error\n");
        ERR_print_errors_fp(stderr);
        goto err;
    }
#ifdef ITERATE_CERTS
    /*
     * Demo of how to iterate over all certificates in an SSL_CTX structure.
     */
    {
        X509 *x;
        int rv;
        rv = SSL_CTX_set_current_cert(ctx, SSL_CERT_SET_FIRST);
        while (rv) {
            X509 *x = SSL_CTX_get0_certificate(ctx);
            X509_NAME_print_ex_fp(stdout, X509_get_subject_name(x), 0,
                                  XN_FLAG_ONELINE);
            printf("\n");
            rv = SSL_CTX_set_current_cert(ctx, SSL_CERT_SET_NEXT);
        }
        fflush(stdout);
    }
#endif
    /* Setup server side SSL bio */
    bio_ssl = BIO_new_ssl(ctx_ssl, 0);

    if ((bio_in = BIO_new_accept(psz_port)) == NULL)
        goto err;

    /*
     * This means that when a new connection is accepted on 'in', The ssl_bio
     * will be 'duplicated' and have the new socket BIO push into it.
     * Basically it means the SSL BIO will be automatically setup
     */
    BIO_set_accept_bios(bio_in, bio_ssl);

 again:
    /*
     * The first call will setup the accept socket, and the second will get a
     * socket.  In this loop, the first actual accept will occur in the
     * BIO_read() function.
     */

    if (BIO_do_accept(bio_in) <= 0)
        goto err;

    for (;;) {
        i = BIO_read(bio_in, buf, 512); /*! 阻塞的读客户端连上服务器发来的信息, 如果此时没有客户端连接, 阻塞在这里 */
        if (i == 0) {
            /*
             * If we have finished, remove the underlying BIO stack so the
             * next time we call any function for this BIO, it will attempt
             * to do an accept
             */
            printf("Done\n");
            bio_tmp = BIO_pop(bio_in);
            BIO_free_all(bio_tmp);
            goto again;
        }
        if (i < 0)
            goto err;
        fwrite(buf, 1, i, stdout);
        fflush(stdout);
    }

    ret = EXIT_SUCCESS;
 err:
    if (ret != EXIT_SUCCESS)
        ERR_print_errors_fp(stderr);
    BIO_free(bio_in);
    return ret;
}

备注

如果只是为了将库用起来, 库实现, 我们不用去看.
在官方给的demo中, 哪个API不知道啥意思, 去本地帮助中去查, 或者去网上去查. 知道意思就行. 防止逻辑理解不正确.

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