openssl3.2 - 官方demo学习 - server-conf.c

openssl3.2 - 官方demo学习 - server-conf.c

概述

建立TLS服务器, 参数从配置文件中来.通过SSL_CONF_CTX_set_flags()来决定读那些TLS参数
遍历配置文件, 通过SSL_CONF_cmd()来读取预期的配置项.
如果不是TLS直接用的参数(e.g. BIO), 自己从配置文件Item中赋值到变量.

笔记

/*!
\file server-conf.c
\brief 建立TLS服务器, 参数从配置文件中来.通过SSL_CONF_CTX_set_flags()来决定读那些TLS参数
        遍历配置文件, 通过SSL_CONF_cmd()来读取预期的配置项. 
        如果不是TLS直接用的参数(e.g. BIO), 自己从配置文件Item中赋值到变量.
*/

/*
 * 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 uses
 * the SSL_CONF API with a configuration file. cc -I../../include saccept.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 <openssl/conf.h>

#include "my_openSSL_lib.h"

int main(int argc, char *argv[])
{
    char *psz_port = "*:4433";
    BIO *bio_in = NULL;
    BIO *bio_ssl, *bio_tmp;
    SSL_CTX *ctx_ssl;
    SSL_CONF_CTX *ctx_ssl_cfg = NULL;
    CONF *conf = NULL;
    STACK_OF(CONF_VALUE) *sk_of_conf_value = NULL;
    CONF_VALUE *conf_value;
    long errline = -1;
    char buf[512];
    int ret = EXIT_FAILURE, i;
    int iCfgItemCnt = 0;

    ctx_ssl = SSL_CTX_new(TLS_server_method());

    conf = NCONF_new(NULL);

    if (NCONF_load(conf, "accept.cnf", &errline) <= 0) {
        if (errline <= 0)
            fprintf(stderr, "Error processing config file\n");
        else
            fprintf(stderr, "Error on line %ld\n", errline);
        goto err;
    }

    sk_of_conf_value = NCONF_get_section(conf, "default");

    if (sk_of_conf_value == NULL) {
        fprintf(stderr, "Error retrieving default section\n");
        goto err;
    }

    ctx_ssl_cfg = SSL_CONF_CTX_new();

    // 如果需要SSL_CONF_cmd处理的配置项, 先设置标志, 告诉 SSL_CONF_cmd需要从配置文件中读什么预想的配置项名称
    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_flags(ctx_ssl_cfg, SSL_CONF_FLAG_FILE);
    SSL_CONF_CTX_set_ssl_ctx(ctx_ssl_cfg, ctx_ssl);

    iCfgItemCnt = sk_CONF_VALUE_num(sk_of_conf_value);
    for (i = 0; i < iCfgItemCnt; i++) {
        int rv;
        conf_value = sk_CONF_VALUE_value(sk_of_conf_value, i);
        rv = SSL_CONF_cmd(ctx_ssl_cfg, conf_value->name, conf_value->value);
        if (rv > 0)
        {
            /*! 如果是SSL配置项中指定的配置, 就会处理为true */
            continue;
        }
            
        /*! 如果是非法的配置项名称, 就会报错 */
        if (rv != -2) {
            fprintf(stderr, "Error processing %s = %s\n",
                    conf_value->name, conf_value->value);
            ERR_print_errors_fp(stderr);
            goto err;
        }

        /*! 如果是合法的配置名称, 又不是SSL配置中需要的项目, 需要自己单独处理 */
        if (strcmp(conf_value->name, "Port") == 0) {
            psz_port = conf_value->value;
        } else {
            fprintf(stderr, "Unknown configuration option %s\n", conf_value->name);
            /*! 如果不是预想的配置名称, 需要继续遍历(多行时, 预想的配置项可能没写在第一行), 而不是报错退出 */
            // goto err;
        }
    }

    if (!SSL_CONF_CTX_finish(ctx_ssl_cfg)) {
        fprintf(stderr, "Finish error\n");
        ERR_print_errors_fp(stderr);
        goto err;
    }

    /* 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); /*! 阻塞等待客户端来连接 */
        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) {
            if (BIO_should_retry(bio_in))
                continue;
            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;
}

END