HTTPS with openssl on linux in C/C++ - c++

Question

I have a project where I need to create a secure http server in C/C++ on Linux and I've chosen to use openssl, however, when I try to include the applinker.c from their github I see a lot of errors, mostly because the file seems to be written for Windows.I would like to know if there is an alternative for Linux or how should I deal with this.
Here is the applinker.c code:
/*
* Copyright 2004-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (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
*/
#define APPLINK_STDIN 1
#define APPLINK_STDOUT 2
#define APPLINK_STDERR 3
#define APPLINK_FPRINTF 4
#define APPLINK_FGETS 5
#define APPLINK_FREAD 6
#define APPLINK_FWRITE 7
#define APPLINK_FSETMOD 8
#define APPLINK_FEOF 9
#define APPLINK_FCLOSE 10 /* should not be used */
#define APPLINK_FOPEN 11 /* solely for completeness */
#define APPLINK_FSEEK 12
#define APPLINK_FTELL 13
#define APPLINK_FFLUSH 14
#define APPLINK_FERROR 15
#define APPLINK_CLEARERR 16
#define APPLINK_FILENO 17 /* to be used with below */
#define APPLINK_OPEN 18 /* formally can't be used, as flags can vary */
#define APPLINK_READ 19
#define APPLINK_WRITE 20
#define APPLINK_LSEEK 21
#define APPLINK_CLOSE 22
#define APPLINK_MAX 22 /* always same as last macro */
#ifndef APPMACROS_ONLY
# include <stdio.h>
# include <io.h>
# include <fcntl.h>
static void *app_stdin(void)
{
return stdin;
}
static void *app_stdout(void)
{
return stdout;
}
static void *app_stderr(void)
{
return stderr;
}
static int app_feof(FILE *fp)
{
return feof(fp);
}
static int app_ferror(FILE *fp)
{
return ferror(fp);
}
static void app_clearerr(FILE *fp)
{
clearerr(fp);
}
static int app_fileno(FILE *fp)
{
return _fileno(fp);
}
static int app_fsetmod(FILE *fp, char mod)
{
return _setmode(_fileno(fp), mod == 'b' ? _O_BINARY : _O_TEXT);
}
#ifdef __cplusplus
extern "C" {
#endif
__declspec(dllexport)
void **
# if defined(__BORLANDC__)
/*
* __stdcall appears to be the only way to get the name
* decoration right with Borland C. Otherwise it works
* purely incidentally, as we pass no parameters.
*/
__stdcall
# else
__cdecl
# endif
OPENSSL_Applink(void)
{
static int once = 1;
static void *OPENSSL_ApplinkTable[APPLINK_MAX + 1] =
{ (void *)APPLINK_MAX };
if (once) {
OPENSSL_ApplinkTable[APPLINK_STDIN] = app_stdin;
OPENSSL_ApplinkTable[APPLINK_STDOUT] = app_stdout;
OPENSSL_ApplinkTable[APPLINK_STDERR] = app_stderr;
OPENSSL_ApplinkTable[APPLINK_FPRINTF] = fprintf;
OPENSSL_ApplinkTable[APPLINK_FGETS] = fgets;
OPENSSL_ApplinkTable[APPLINK_FREAD] = fread;
OPENSSL_ApplinkTable[APPLINK_FWRITE] = fwrite;
OPENSSL_ApplinkTable[APPLINK_FSETMOD] = app_fsetmod;
OPENSSL_ApplinkTable[APPLINK_FEOF] = app_feof;
OPENSSL_ApplinkTable[APPLINK_FCLOSE] = fclose;
OPENSSL_ApplinkTable[APPLINK_FOPEN] = fopen;
OPENSSL_ApplinkTable[APPLINK_FSEEK] = fseek;
OPENSSL_ApplinkTable[APPLINK_FTELL] = ftell;
OPENSSL_ApplinkTable[APPLINK_FFLUSH] = fflush;
OPENSSL_ApplinkTable[APPLINK_FERROR] = app_ferror;
OPENSSL_ApplinkTable[APPLINK_CLEARERR] = app_clearerr;
OPENSSL_ApplinkTable[APPLINK_FILENO] = app_fileno;
OPENSSL_ApplinkTable[APPLINK_OPEN] = _open;
OPENSSL_ApplinkTable[APPLINK_READ] = _read;
OPENSSL_ApplinkTable[APPLINK_WRITE] = _write;
OPENSSL_ApplinkTable[APPLINK_LSEEK] = _lseek;
OPENSSL_ApplinkTable[APPLINK_CLOSE] = _close;
once = 0;
}
return OPENSSL_ApplinkTable;
}
#ifdef __cplusplus
}
#endif
#endif
And here is a little snippet I prepared for testing the connection:
#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <cstring>
#include <cstdlib>
#include <cerrno>
#include <arpa/inet.h>
#include <cstdio>
#include <sys/stat.h>
#include <unordered_map>
#include <string>
#include <algorithm>
#include <fstream>
#include <thread>
#include "openssl-master/ms/applink.c"
#include "openssl-master/include/openssl/bio.h"
#include "openssl-master/include/openssl/ssl.h"
#include "openssl-master/include/openssl/err.h"
#define PORT 2024
void InitializeSSL()
{
SSL_load_error_strings();
SSL_library_init();
OpenSSL_add_all_algorithms();
}
void DestroySSL()
{
ERR_free_strings();
EVP_cleanup();
}
void ShutdownSSL(SSL *ssl)
{
SSL_shutdown(ssl);
SSL_free(ssl);
}
int main(int argc, const char * argv[]) {
int sockfd, newsockfd;
SSL_CTX *sslctx;
SSL *cSSL;
InitializeSSL();
struct sockaddr_in server;
struct sockaddr_in from;
SSL_CTX_set_options(sslctx, SSL_OP_SINGLE_DH_USE);
int use_cert = SSL_CTX_use_certificate_file(sslctx, "/serverCertificate.pem" , SSL_FILETYPE_PEM);
int use_prv = SSL_CTX_use_PrivateKey_file(sslctx, "/serverCertificate.pem", SSL_FILETYPE_PEM);
int sd;
if ((sd = socket (AF_INET, SOCK_STREAM, 0)) == -1)
{
perror ("socket() error.\n");
return errno;
}
bzero (&server, sizeof (server));
bzero (&from, sizeof (from));
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl (INADDR_ANY);
server.sin_port = htons (PORT);
if (bind (sd, (struct sockaddr *) &server, sizeof (struct sockaddr)) == -1)
{
perror ("bind() error.\n");
return errno;
}
if (listen (sd, 5) == -1)
{
perror ("listen() error.\n");
return errno;
}
int client;
socklen_t length = sizeof (from);
printf ("Waiting on port %d...\n",PORT);
fflush (stdout);
client = accept (sd, (struct sockaddr *) &from, &length);
if (client < 0)
{
perror ("accept() error.\n");
return 0;
}
cSSL = SSL_new(sslctx);
SSL_set_fd(cSSL, client);
int ssl_err = SSL_accept(cSSL);
if(ssl_err <= 0)
{
ShutdownSSL(cSSL);
}
return 0;
}
And I compile it like this: g++ withssl.cpp libssl.a libcrypto.a -lssl -lcrypto -o server.bin

Answer 1

Code looks good, I used Suse Leap 4.2.2 and performed these commands:
openssl version
OpenSSL 1.0.2j-fips 26 Sep 2016
sudo zypper in openssl-devel
g++ -std=c++11 main.cpp -lssl -lcrypto -o server
Because I am using the distro provided openssl I changed your code to include the standard headers like this:
#include <openssl/ssl.h>
#include <openssl/err.h>
// DONT NEED
// suggest instead of including C code, link to the libraries
// for example, /usr/lib64/libssl.so contains referenced functions
// observe the provided functions using a command like this
// readelf -a /usr/lib64/libssl.so | grep FUNC
// #include "openssl-master/ms/applink.c"
// WRONG PATH?
// suggest you use a distro provided openssl instead of building your own
// #include "openssl-master/include/openssl/bio.h"
// #include "openssl-master/include/openssl/ssl.h"
// #include "openssl-master/include/openssl/err.h"