openssl3.2 - 官方demo学习 - client-conf.c-Toy模板网

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openssl3.2 - 官方demo学习 - client-conf.c

笔记

client-conf.c

client-arg.c是从命令行参数中得到TLS服务器ip/port.
client-conf.c 从配置文件中读取TLS服务器ip/port, 其他相同.
openSSL附带赠送了好多有用的API(这个例子中, 演示了读取配置文件. 不过读取item时, 用的是遍历), 不仅仅是密码学相关.
官方demo中读取配置文件时, 只比对了第一项, 这是不对的, 如果连接处不在第一行, 逻辑就不对了. 修正了这个实现.

配置文件格式 - connect.cnf

注释行, 行首是’#’
配置项行, 名称 = 值
可以有任意个空行

经过 NCONF_get_section()后, sk_CONF_VALUE_num()时, 得到的就是配置项的条目数量.

例子 connect.cnf 的内容如下

# Example configuration file

# Comment out the next line to ignore configuration errors
config_diagnostics = 1

# Connects to the default port of s_server
Connect = localhost:4433

# Disable TLS v1.2 for test.
# Protocol = ALL, -TLSv1.2
# Only support 3 curves
Curves = P-521:P-384:P-256

# Restricted signature algorithms
SignatureAlgorithms = RSA+SHA512:ECDSA+SHA512

如果程序不做密码学任务, 带个openSSL库, 也能做好多其他事情.

/*! \file client-conf.c */

/*
 * Copyright 2013-2023 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
 */

#include <string.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/conf.h>

#pragma comment(lib, "libcrypto.lib")
#pragma comment(lib, "libssl.lib")

#include <openssl/applink.c> /*! for OPENSSL_Uplink(00007FF8B7EF0FE8,08): no OPENSSL_Applink */

int main(int argc, char **argv)
{
    BIO *sbio = NULL, *out = NULL;
    int i, len, rv;
    char tmpbuf[1024];
    SSL_CTX *ctx = NULL;
    SSL_CONF_CTX *cctx = NULL;
    SSL *ssl = NULL;
    CONF *conf = NULL;
    STACK_OF(CONF_VALUE) *sect = NULL;
    CONF_VALUE *cnf;
    const char *connect_str = "localhost:4433";
    long errline = -1;
    int ret = EXIT_FAILURE;
    int iCfgItemCnt = 0;

    /*!
    用编译完的OpenSSL3.2单步, 有pdb文件, 可以单步进入已经编译好的实现(.c)
    前提是, 编译好, 进行安装的openSSL源码包别动, 7z后备份一下好些
    */

    conf = NCONF_new(NULL);

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

    sect = NCONF_get_section(conf, "default");

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

    ctx = SSL_CTX_new(TLS_client_method());
    cctx = SSL_CONF_CTX_new();
    SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CLIENT);
    SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_FILE);
    SSL_CONF_CTX_set_ssl_ctx(cctx, ctx);

    /*! OpenSSL3.2 API中有对配置文件的读取
        即使不用openSSL3.2做密码学方面的编程, 也有很多附带功能啊
        
        配置文件格式
        # 注释
        xx_config_item_name = yy_config_item_value
    */

    iCfgItemCnt = sk_CONF_VALUE_num(sect);
    for (i = 0; i < iCfgItemCnt; i++) {
        cnf = sk_CONF_VALUE_value(sect, i);
        rv = SSL_CONF_cmd(cctx, cnf->name, cnf->value);
        if (rv > 0)
            continue;
        if (rv != -2) {
            fprintf(stderr, "Error processing %s = %s\n",
                    cnf->name, cnf->value);
            ERR_print_errors_fp(stderr);
            goto end;
        }
        if (strcmp(cnf->name, "Connect") == 0) {
            connect_str = cnf->value; /*!< 连接串从配置文件中来 */
            break;
        } else {
            /*! \bugfix 配置文件中还有多条配置项, 只有遍历完成后, 都没有找到, 才能说配置错误 */
            if ((iCfgItemCnt - 1) == i)
            {
                fprintf(stderr, "Unknown configuration option %s\n", cnf->name);
                goto end;
            }

            continue;
        }
    }

    /*!
    * 其他实现和 client - arg.c 相同
    */

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

    /*
     * We'd normally set some stuff like the verify paths and * mode here
     * because as things stand this will connect to * any server whose
     * certificate is signed by any CA.
     */

    sbio = BIO_new_ssl_connect(ctx);

    BIO_get_ssl(sbio, &ssl);

    if (!ssl) {
        fprintf(stderr, "Can't locate SSL pointer\n");
        goto end;
    }

    /* We might want to do other things with ssl here */

    BIO_set_conn_hostname(sbio, connect_str);

    out = BIO_new_fp(stdout, BIO_NOCLOSE);
    if (BIO_do_connect(sbio) <= 0) {
        fprintf(stderr, "Error connecting to server\n");
        ERR_print_errors_fp(stderr);
        goto end;
    }

    /* Could examine ssl here to get connection info */

    BIO_puts(sbio, "GET / HTTP/1.0\n\n");
    for (;;) {
        len = BIO_read(sbio, tmpbuf, 1024);
        if (len <= 0)
            break;
        BIO_write(out, tmpbuf, len);
    }
    ret = EXIT_SUCCESS;

 end:
    SSL_CONF_CTX_free(cctx);
    BIO_free_all(sbio);
    BIO_free(out);

    /*!
    * 由xx_new出来, 又没有附加到其他上下文的指针, 需要释放
    */
    NCONF_free(conf); /*! conf = NCONF_new() */
    return ret;
}