/*
  JS 2024-04-11 testovane s OpenSSL 3.3.0, liboqs 0.10.0 a oqs-provider 0.6.0
*/
/*
  JS 2024-04-11 testovane s OpenSSL 3.3.0, liboqs 0.10.0 a oqs-provider 0.5.3
*/
/*
   JS 2024-03-04 - doplnenie funkcii pre uvolnenie nacitanych providerov
*/

/*
   JS 2024-02-24 - funkcia initSSLContext() rozsirena o nacitanie OQS-providera
		   pre plne funkcne PQ algoritmy na kazdej platforme
		 - doplnene priklady nastavenia premennej DEFAULT_GROUPS
		 - testovane s oqsprovider 0.5.3
*/
/*
   JS 2024-02-18 - testovanie PQ algoritmov s pouzitim oqs-providera
		 - uprava vypisu o pripojeni klienta
		 - pridane vypisy s informaciami o pouzivanych algoritmoch
		   pre KEX a certifikaty
		 - oprava kontroly navratovej hodnoty funkcii 
			SSL_CTX_use_certificate_file() a SSL_CTX_use_PrivateKey_file
*/

/*
   JS 2024-02-08 testovane s aktualnou najnovsou verziou OpenSSL 3.2.1
*/

/*
   MJ 2023-05-18 - Uprava funkcie printHeader()
                     -> Zmazanie SSL metody
                     -> Upraveny vypis ako spustit program
               - Uprava funkcie initSSLContext() aby realizovala fixne iba TLS spojenie
                     -> pridanie argumentov do funkcie na nacitanie client.key,  client.pem
               - Uprava hlavnej funkcie main() na zaklade predoslej upravy (nastavenie fixne TLS)
                    -> Zmazanie premennej ctxMethod
                    -> Uprava argumentov [argv] - zmazanie TLS metody, pridanie suborov s klucmi
                    -> Pridanie premennych na nacitanie klucov: client_key, client_pem
 (vid. komentare MJ) 
*/

/* 
   MD 2021-03-29 testovane s aktualne najnovsou verziou OpenSSL v 1.1.1k
   MD 2018-11-06 upravene pre linkovanie s OpenSSL 1.1.1
                 (pouzita metoda TLS_client_method)
   MD 2018-11-02 vlozene upravy na odstraneie varovania a autentizaciu servera 
                 vlozene upravy na realizaciu autentizacie klienta (nacitanie potrebnych certifikatov 
                 a kluca)
                 odstranenie varovania o poradi hlavickovych suborov
                 (vid. komentare // MD)
*/

/** SSL/TLS Client
 * SSL/TLS client demonstration. This source code is cross-plateforme Windows and Linux.
 */

// __unix__ is usually defined by compilers targeting Unix systems
#ifdef __unix__         
#   include <unistd.h>
#   include <sys/socket.h>
#   include <resolv.h>
#   include <netdb.h>
#   define SOCKLEN_T socklen_t
#   define CLOSESOCKET close
     // _Win32 is usually defined by compilers targeting 32 or 64 bit Windows systems
#elif defined _WIN32   
     // MD odstrani varovanie o potrebe prehodit poradie hlavickovych suborov
#   define WIN32_LEAN_AND_MEAN
#   include <windows.h>
#   include <winsock2.h>
#   define SOCKLEN_T int
#   define CLOSESOCKET closesocket
#endif

#include <stdio.h>
#include <errno.h>
#include <malloc.h>
#include <string.h>

#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/provider.h>

#ifdef _WIN32
WSADATA wsa;    // Winsock data
#endif

/* JS
Premenna na definovanie "exchange groups", algoritmov na vymenu klucov
Server moze podporovat viacero KEX/KEM algoritmov, v premennej musi byt kazdy
algoritmus oddeleny dvojbodkou, napr. "kyber512:bikel1"
Podporovane algoritmy je mozne ziskat prikazom "openssl list -kem-algorithms"
Prazdna premenna alebo naplnena neplatnymi protokolmi sposobi prerusenie aplikacie

Ak server a klient nenajdu spolocny KEX/KEM protokol, tak
SSL vyhodi chybu SSL routines:final_key_share:no suitable key share

Priklad pouzitia:
- klasicke algoritmy: "x25519:x448:prime256v1:secp521r1:secp384r1:ffdhe2048:ffdhe3072"
- PQ algoritmy: "kyber512:kyber768:kyber1024:bikel1:bikel3:bikel5:hqc128:hqc192:hqc256:frodo640aes:frodo640shake:frodo976aes:frodo976shake:frodo1344aes:frodo1344shake"
- hybrid algoritmy: "x25519_kyber768:x25519_frodo640aes:x25519_hqc128:x448_bikel3:x448_kyber768:p256_kyber768"

Podporovane algoritmy OQS-providerom: https://github.com/open-quantum-safe/oqs-provider/blob/0.6.0/ALGORITHMS.md  

POZOR - BIKE protokol nefunguje na Windows platforme (liboqs 0.10.0, oqs-provider 0.6.0)

*/
#define DEFAULT_GROUPS "kyber512:X25519:kyber768"

#define DEFAULT_PORT 443

/**
 * printUsage function who describe the utilisation of this script.
 * @param char* bin : the name of the current binary.
 */
void printHeader(char* bin){
    // JS update
    printf("[?] Usage : %s <hostname> <port> <client_private_key> <client_public_key>\n", bin);  
    return;
}

/** JS update navratove hodnoty pri chybe
 * makeClientSocket function who create a traditionnal client socket to the hostname throught the port.
 * @param char* hostname : the target to connect to
 * @param int port : the port to connect throught
 * @return int socket ; the socket number created
 */
int makeClientSocket(const char *hostname, int port){
    int                 sock;
    struct hostent      *host;
    struct sockaddr_in  addr;
    #ifdef _WIN32
    WSAStartup(MAKEWORD(2,0),&wsa);
    #endif
    if((host = gethostbyname(hostname)) == NULL ){
        perror(hostname);
        return -1;
    }
    sock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&addr, 0, sizeof(addr));
    addr.sin_family         = AF_INET;
    addr.sin_port           = htons(port);
    addr.sin_addr.s_addr    = *(long*)(host->h_addr);
    if(connect(sock, (struct sockaddr*)&addr, sizeof(addr)) != 0){
        CLOSESOCKET(sock);
        perror(hostname);
        return -1;
    }
    return sock;
}

/** JS update
 * initSSLContext function who initialize the SSL/TLS engine with right method/protocol
 * @param client_key name of file where is stored private key of client
 * @param client_pem name of file where is stored public key of client
 * @return SSL_CTX *ctx ; a pointer to the SSL context created
 */
SSL_CTX* initSSLContext(char* client_key, char* client_pem){
    const SSL_METHOD *method;
    SSL_CTX *ctx;

    // initialize the SSL library
    SSL_library_init();       
    SSL_load_error_strings();        
    OpenSSL_add_all_algorithms();

    // MJ only TLS connection
    method = TLS_client_method();
 
    // create new context from selected method
    ctx = SSL_CTX_new(method);                
    if(ctx == NULL){
        ERR_print_errors_fp(stderr);
        abort();
    }

    // MD zabezpecienie overenia certifikatu servera pomocou CA
    if (SSL_CTX_load_verify_locations(ctx, "myCA.pem", 0)) {
        printf("CA certificate loaded\n");
        SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
    }

    else {
        printf("\nCA certificate not loaded! Abort ...\n");
        abort();
    }

// MD nacitanie dat pre autentizaciu klineta
// MJ Update [Define Macro]
#ifdef AUTHENTICATION
    int res = 0;

    res = SSL_CTX_use_certificate_file(ctx, client_pem, SSL_FILETYPE_PEM);
    if (res <= 0) {
        // handle error
        printf("\nCLIENT certificate not loaded! Abort ...\n");
        abort();
    }
    
    res = SSL_CTX_use_PrivateKey_file(ctx, client_key, SSL_FILETYPE_PEM);
    if (res <= 0) {
        // handle error

        printf("\nCLIENT key not loaded! Abort ...\n");
        abort();
    }

    /* verify private key */
    if ( !SSL_CTX_check_private_key(ctx) )
    {
        fprintf(stderr, "Private key does not match the public certificate\n");
        abort();
    }
    printf("Certificate attached\n");
    printf("\n");
#endif

    return ctx;
}

/**
 * showCerts function who catch and print out certificat's data from the server
 * @param SSL* ssl : the SSL/TLS connection
 */
void showCerts(SSL* ssl){
    X509 *cert;
    char *subject, *issuer;

    // get the server's certificate
    cert = SSL_get_peer_certificate(ssl);                               
    if(cert != NULL){

	// JS get server's certificate algorithm name
	int nid;
	SSL_get_peer_signature_type_nid(ssl, &nid);
	printf("Server signature algorithm: %s\n", OBJ_nid2sn(nid));

        // get certificat's subject
        subject = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);

        // get certificat's issuer
        issuer  = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);

        printf("[+] Server certificates :\n");
        printf("\tSubject: %s\n", subject);
        printf("\tIssuer: %s\n", issuer);

        // Free memory
        free(subject);
        free(issuer);
        X509_free(cert);

        // check certificat's trust
        if(SSL_get_verify_result(ssl) == X509_V_OK)
            printf("[+] Server certificates X509 is trust!\n");
        else
            printf("[-] Server certificates X509 is not trust...\n");
    }
    else
        printf("[-] No server's certificates\n");
    return;
}

/**
 * main function who coordinate the socket and SSL connection creation, then receive and emit 
   data to and from the server.
 */
int main(int argc, char **argv){
    int     sock, bytes, port;
    SSL_CTX *ctx;
    SSL     *ssl;
    char    buf[1024];
    char    *hostname;

    if(argc != 5){
        printHeader(argv[0]);
        exit(0);
    }

    // MJ Add keys for communication
    char *client_key = argv[3];
    char *client_pem = argv[4];

    hostname = argv[1];

    // Assign correct port number 
    port = (atoi(argv[2]) > 0 && atoi(argv[2]) < 65535) ? atoi(argv[2]) : DEFAULT_PORT;
    
    // JS update
    // Load default and OQS providers
    // Default provider must be loaded before OQS provider
    // Providers have to loaded before SSL/TLS engine initSSLContext()
    OSSL_PROVIDER* provider;
    provider = OSSL_PROVIDER_load(NULL, "default");
    if (provider == NULL) {
    	printf("Failed to load Default provider\n");
	    exit(0);
    }

    OSSL_PROVIDER* custom_provider = OSSL_PROVIDER_load(NULL, "oqsprovider");
    if (custom_provider == NULL){
	    printf("Failed to load OQS-provider\n");
        OSSL_PROVIDER_unload(provider);
	    exit(0);
    }

    // load SSL library and dependances
    ctx = initSSLContext(client_key, client_pem);  

    // make a classic socket to the hostname throught the port
    sock = makeClientSocket(hostname, port); 

    // create new SSL connection state
    ssl = SSL_new(ctx);      

    // JS set key exchange/encapsulation protocols supported by server
    // Without this function, client will use default X25519 protocol
    // First protocol supported by both server and client will be used for KEX/KEM
    // Empty DEFAULT_GROUPS or list of unsupported protocol by server will fail communication    
    if (SSL_set1_groups_list(ssl, DEFAULT_GROUPS) != 1){
	printf("KEX/KEM algorithms undefined - check DEFAULT_GROUPS variable\n");
    	ERR_print_errors_fp(stderr);
        SSL_free(ssl);
       	SSL_CTX_free(ctx);
        OSSL_PROVIDER_unload(provider);
        OSSL_PROVIDER_unload(custom_provider); 
    	exit(0);
    }

    // attach the socket descriptor
    SSL_set_fd(ssl, sock);    

    // make the SSL connection
    if(SSL_connect(ssl) == -1)                        
        ERR_print_errors_fp(stderr);
    else{

	// JS get chosen (negotiated) key exchange/encapsulation algorithm name
	printf("Used group (KEM): %s\n", SSL_group_to_name(ssl, SSL_get_negotiated_group(ssl)));

        /*
        if the server suddenly wants a new handshake,
        OpenSSL handles it in the background. Without this
        option, any read or write operation will return an
        error if the server wants a new handshake.
        */
        SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);     

        char msg[] = "ClientName";
        printf("[+] Cipher used : %s\n", SSL_get_cipher(ssl));
        
        // Show certificats data
        showCerts(ssl);                                
        
        // encrypt and send message
        SSL_write(ssl, msg, strlen(msg));            

        // get response and decrypt content
        bytes = SSL_read(ssl, buf, sizeof(buf));    
        buf[bytes] = 0;
        printf("[+] Server data received : %s\n", buf);
        
        // release SSL connection state
        SSL_shutdown(ssl);
        SSL_free(ssl);                                

    } 
    
    // close socket
    CLOSESOCKET(sock);                             
    #ifdef _WIN32
    WSACleanup();                              
    #endif

    // release SSL's context
    SSL_CTX_free(ctx);     
    // JS Unload both providers
    OSSL_PROVIDER_unload(provider);
    OSSL_PROVIDER_unload(custom_provider);                           
    return 0;
}