Thread: Need help with OpenSSL

Hi,

I'm currently working on a project for a class in shcool, i need to develop a basic client to interact with the openssl server, using a trustore and CA's.

I simply run the openssl server with this command (I must be in /certs folder) in one terminal:
openssl s_server -cert crt.pem -key key.pem

and then I run my code to emulate the client:

Code:

#include "openssl/ssl.h"
#include "openssl/bio.h"
#include "openssl/err.h"

#include "stdio.h"
#include "string.h"

int main(int argc, char *argv[])
{ 

    BIO * bio;
    SSL * ssl;
    SSL_CTX * ctx;   

    char buffer1[1024], buffer2[1024];
    int j,p;	
    char *hostname, *port;

    /* Verificar se foram colocados todos os argumentos */
    if ( argc != 3 )
    {

        printf("Sintaxe: &#37;s <hostname> <portnum>\n", argv[0]);
        exit(0);
    }	

    hostname = argv[1];
    port = argv[2];

	

    /* Preparar a biblioteca */
    SSL_library_init();
    ERR_load_BIO_strings();
    SSL_load_error_strings();	/* Para o registo e msgs de erro */	

    OpenSSL_add_all_algorithms();
     ENGINE_load_builtin_engines();	

    /* Criar o contexto */
    ctx = SSL_CTX_new(SSLv23_client_method());

    /* Carregar o trust store */
    if(! SSL_CTX_load_verify_locations(ctx, "/root/Desktop/Trab2_cr/certs/TrustStore.pem", NULL))
    {
        fprintf(stderr, "Erro ao carregar o trust store\n");
        ERR_print_errors_fp(stderr);
        SSL_CTX_free(ctx);
        return 0;
    }



    /* Realizar a liga&#231;ao ao servidor */ 	
    bio = BIO_new_ssl_connect(ctx);


    /* Ligar a flag SSL_MODE_AUTO_RETRY */
    BIO_get_ssl(bio, & ssl);
    SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);

    /* Criar e configurar a liga&#231;ao */
    BIO_set_conn_hostname(bio, hostname);
    BIO_set_conn_port(bio, port);

    if(BIO_do_connect(bio) <= 0)

    {
        fprintf(stderr, "Erro ao tentar ligar ao servidor\n");
        ERR_print_errors_fp(stderr);
        BIO_free_all(bio);
        SSL_CTX_free(ctx);
        return 0;

    }

    /* Validar o certificado do servidor */
    if(SSL_get_verify_result(ssl) != X509_V_OK)
    {

        fprintf(stderr, "Erro ao validar o certificado: %i\n", SSL_get_verify_result(ssl));
        BIO_free_all(bio);
        SSL_CTX_free(ctx);
        return 0;

    }

    printf("Ligado com encriptacao do tipo %s \n", SSL_get_cipher(ssl));

    /* Enviar/receber mensagens */
    for(;;)
    {

		/* Enviar msg*/
		scanf("%s", buffer1);	
   		j = BIO_write(bio, buffer1, strlen(buffer1));
		if(j <= 0)
			break;
		buffer1[j] = 0;		

		/* Receber msg */
                p = BIO_read(bio, buffer2, 1023);
                if(p <= 0) 
			break;
                buffer2[p] = 0;
		printf("%s\n", buffer2);
    }

    /* Close the connection and free the context */
    BIO_free_all(bio);
    SSL_CTX_free(ctx);
    return 0;

}

The problem with this is that,when I send a message to server I must wait for his reply, or else things get messed up because of the for() cycle:

Code:

/* Send/receive messages */
for(;;)
{
		/* Enviar msg*/
		scanf("%s", buffer1);
   		j = BIO_write(bio, buffer1, strlen(buffer1));
		if(j <= 0)
			break;
		buffer1[j] = 0;		

		/* Receber msg */
                p = BIO_read(bio, buffer2, 1023);
                if(p <= 0)
			break;
                buffer2[p] = 0;
		printf("%s\n", buffer2);
    }

Do any of the experts have any sugestion to change this in a way that i don't need to wait for the server reply?!

I don't want my homework done, I just want sugestions so that i can then try to figure it out by my own.


Thanks in advance.

PS- sorry for the formating on the code, did my best for align it manually.