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      1 /*
      2  * Copyright 2013-2025 The OpenSSL Project Authors. All Rights Reserved.
      3  *
      4  * Licensed under the Apache License 2.0 (the "License").  You may not use
      5  * this file except in compliance with the License.  You can obtain a copy
      6  * in the file LICENSE in the source distribution or at
      7  * https://www.openssl.org/source/license.html
      8  */
      9 
     10 /*
     11  * A minimal program to serve an SSL connection. It uses blocking. It uses
     12  * the SSL_CONF API with a configuration file. cc -I../../include saccept.c
     13  * -L../.. -lssl -lcrypto -ldl
     14  */
     15 
     16 #include <stdio.h>
     17 #include <string.h>
     18 #include <signal.h>
     19 #include <stdlib.h>
     20 #include <openssl/err.h>
     21 #include <openssl/ssl.h>
     22 #include <openssl/conf.h>
     23 
     24 int main(int argc, char *argv[])
     25 {
     26     char *port = "*:4433";
     27     BIO *in = NULL;
     28     BIO *ssl_bio = NULL;
     29     BIO *tmp;
     30     SSL_CTX *ctx;
     31     SSL_CONF_CTX *cctx = NULL;
     32     CONF *conf = NULL;
     33     STACK_OF(CONF_VALUE) *sect = NULL;
     34     CONF_VALUE *cnf;
     35     long errline = -1;
     36     char buf[512];
     37     int ret = EXIT_FAILURE, i;
     38 
     39     ctx = SSL_CTX_new(TLS_server_method());
     40 
     41     conf = NCONF_new(NULL);
     42 
     43     if (NCONF_load(conf, "accept.cnf", &errline) <= 0) {
     44         if (errline <= 0)
     45             fprintf(stderr, "Error processing config file\n");
     46         else
     47             fprintf(stderr, "Error on line %ld\n", errline);
     48         goto err;
     49     }
     50 
     51     sect = NCONF_get_section(conf, "default");
     52 
     53     if (sect == NULL) {
     54         fprintf(stderr, "Error retrieving default section\n");
     55         goto err;
     56     }
     57 
     58     cctx = SSL_CONF_CTX_new();
     59     SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_SERVER);
     60     SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CERTIFICATE);
     61     SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_FILE);
     62     SSL_CONF_CTX_set_ssl_ctx(cctx, ctx);
     63     for (i = 0; i < sk_CONF_VALUE_num(sect); i++) {
     64         int rv;
     65         cnf = sk_CONF_VALUE_value(sect, i);
     66         rv = SSL_CONF_cmd(cctx, cnf->name, cnf->value);
     67         if (rv > 0)
     68             continue;
     69         if (rv != -2) {
     70             fprintf(stderr, "Error processing %s = %s\n",
     71                 cnf->name, cnf->value);
     72             ERR_print_errors_fp(stderr);
     73             goto err;
     74         }
     75         if (strcmp(cnf->name, "Port") == 0) {
     76             port = cnf->value;
     77         } else {
     78             fprintf(stderr, "Unknown configuration option %s\n", cnf->name);
     79             goto err;
     80         }
     81     }
     82 
     83     if (!SSL_CONF_CTX_finish(cctx)) {
     84         fprintf(stderr, "Finish error\n");
     85         ERR_print_errors_fp(stderr);
     86         goto err;
     87     }
     88 
     89     /* Setup server side SSL bio */
     90     ssl_bio = BIO_new_ssl(ctx, 0);
     91 
     92     if ((in = BIO_new_accept(port)) == NULL)
     93         goto err;
     94 
     95     /*
     96      * This means that when a new connection is accepted on 'in', The ssl_bio
     97      * will be 'duplicated' and have the new socket BIO push into it.
     98      * Basically it means the SSL BIO will be automatically setup
     99      */
    100     BIO_set_accept_bios(in, ssl_bio);
    101     ssl_bio = NULL;
    102 
    103 again:
    104     /*
    105      * The first call will setup the accept socket, and the second will get a
    106      * socket.  In this loop, the first actual accept will occur in the
    107      * BIO_read() function.
    108      */
    109 
    110     if (BIO_do_accept(in) <= 0)
    111         goto err;
    112 
    113     for (;;) {
    114         i = BIO_read(in, buf, 512);
    115         if (i == 0) {
    116             /*
    117              * If we have finished, remove the underlying BIO stack so the
    118              * next time we call any function for this BIO, it will attempt
    119              * to do an accept
    120              */
    121             printf("Done\n");
    122             tmp = BIO_pop(in);
    123             BIO_free_all(tmp);
    124             goto again;
    125         }
    126         if (i < 0) {
    127             if (BIO_should_retry(in))
    128                 continue;
    129             goto err;
    130         }
    131         fwrite(buf, 1, i, stdout);
    132         fflush(stdout);
    133     }
    134 
    135     ret = EXIT_SUCCESS;
    136 err:
    137     if (ret != EXIT_SUCCESS)
    138         ERR_print_errors_fp(stderr);
    139     BIO_free(in);
    140     BIO_free_all(ssl_bio);
    141     return ret;
    142 }
    143