/*
 * Simple GnuTLS client used for testing.
 *
 * Copyright (C) 2011-2013  Simon Ruderich
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include <gnutls/gnutls.h>
#include <gnutls/x509.h>


#define MAX_REQUEST_LINE 4096

static int connect_to_host(const char *hostname, const char *port);
static int read_http_request(FILE *client_fd, char *request, size_t length);


int main (int argc, char *argv[]) {
    int result, response;
    unsigned int status;
    char buffer[MAX_REQUEST_LINE];
    int server;
    FILE *fd;

    gnutls_session_t session;
    gnutls_certificate_credentials_t xcred;

    gnutls_x509_crt_t cert;
    const gnutls_datum_t *cert_list;
    unsigned int cert_list_size;

    if (5 != argc) {
        fprintf(stderr,
                "Usage: %s <ca-file> <hostname> <port> <hostname-verify>\n",
                argv[0]);
        return EXIT_FAILURE;
    }

    gnutls_global_init();
    gnutls_certificate_allocate_credentials(&xcred);

    gnutls_certificate_set_x509_trust_file(xcred,
                                           argv[1], GNUTLS_X509_FMT_PEM);

    gnutls_init(&session, GNUTLS_CLIENT);
    gnutls_priority_set_direct(session, "NORMAL", NULL);
    gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);

    server = connect_to_host("localhost", "4711");
    if (-1 == server) {
        return EXIT_FAILURE;
    }
    fd = fdopen(server, "a+");
    if (NULL == fd) {
        perror("fdopen()");
        return EXIT_FAILURE;
    }

    /* Talk to tlsproxy. */
    fprintf(fd, "CONNECT %s:%s HTTP/1.0\r\n", argv[2], argv[3]);
    fprintf(fd, "\r\n");
    fflush(fd);
    if (-1 == read_http_request(fd, buffer, sizeof(buffer))) {
        fprintf(stderr, "invalid proxy response\n");
        return EXIT_FAILURE;
    }

    printf("response: %s\n", buffer);

    if (1 != sscanf(buffer, "HTTP/1.0 %d", &response)) {
        fprintf(stderr, "invalid proxy response: %s\n", buffer);
        return EXIT_FAILURE;
    }

    if (200 != response) {
        fprintf(stderr, "proxy failure\n");
        return EXIT_FAILURE;
    }

    gnutls_transport_set_ptr(session, (gnutls_transport_ptr_t)server);

    result = gnutls_handshake(session);
    if (GNUTLS_E_SUCCESS != result) {
        fprintf(stderr, "gnutls_handshake() failed\n");
        gnutls_perror(result);
        return EXIT_FAILURE;
    }

    /* Verify the proxy certificate. */
    result = gnutls_certificate_verify_peers2(session, &status);
    if (0 > result) {
        fprintf(stderr, "gnutls_certificate_verify_peers2() failed\n");
        gnutls_perror(result);
        return EXIT_FAILURE;
    }

    if (status & GNUTLS_CERT_INVALID) {
        fprintf(stderr, "certificate invalid\n");
    }

    /* Get proxy certificate. */
    if (0 > (result = gnutls_x509_crt_init(&cert))) {
        fprintf(stderr, "gnutls_x509_crt_init() failed");
        gnutls_perror(result);
        return EXIT_FAILURE;
    }

    cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
    if (NULL == cert_list) {
        fprintf(stderr, "gnutls_certificate_get_peers() failed");
        return EXIT_FAILURE;
    }

    if (0 > (result = gnutls_x509_crt_import(cert, &cert_list[0],
                                             GNUTLS_X509_FMT_DER))) {
        fprintf(stderr, "gnutls_x509_crt_import() failed");
        gnutls_perror(result);
        return EXIT_FAILURE;
    }

    /* Check hostname. */
    if (!gnutls_x509_crt_check_hostname(cert, argv[4])) {
        fprintf(stderr, "hostname didn't match '%s'\n", argv[4]);
        return EXIT_FAILURE;
    }

    gnutls_x509_crt_deinit(cert);

    gnutls_bye(session, GNUTLS_SHUT_RDWR);
    fclose(fd);

    gnutls_deinit(session);
    gnutls_certificate_free_credentials(xcred);
    gnutls_global_deinit();

    return EXIT_SUCCESS;
}


/* Copied from src/connection.c (and removed LOG_* stuff)! Don't modify. */

static int connect_to_host(const char *hostname, const char *port) {
    struct addrinfo gai_hints;
    struct addrinfo *gai_result;
    int gai_return;

    int server_socket;
    struct addrinfo *server;

    if (NULL == hostname || NULL == port) {
        return -1;
    }

    /* Get IP of hostname server. */
    memset(&gai_hints, 0, sizeof(gai_hints));
    gai_hints.ai_family   = AF_UNSPEC;
    gai_hints.ai_socktype = SOCK_STREAM;
    gai_hints.ai_protocol = 0;
    gai_hints.ai_flags    = AI_NUMERICSERV /* given port is numeric */
                          | AI_ADDRCONFIG  /* supported by this computer */
                          | AI_V4MAPPED;   /* support IPv4 through IPv6 */
    gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
    if (0 != gai_return) {
        perror("connect_to_host(): getaddrinfo()");
        return -1;
    }

    /* Now try to connect to each server returned by getaddrinfo(), use the
     * first successful connect. */
    for (server = gai_result; NULL != server; server = server->ai_next) {
        server_socket = socket(server->ai_family,
                               server->ai_socktype,
                               server->ai_protocol);
        if (-1 == server_socket) {
            perror("connect_to_host(): socket(), trying next");
            continue;
        }

        if (-1 != connect(server_socket, server->ai_addr,
                                         server->ai_addrlen)) {
            break;
        }
        perror("connect_to_host(): connect(), trying next");

        close(server_socket);
    }
    /* Make sure we free the result from getaddrinfo(). */
    freeaddrinfo(gai_result);

    if (NULL == server) {
        perror("connect_to_host(): no server found, abort");
        return -1;
    }

    return server_socket;
}

static int read_http_request(FILE *client_fd, char *request, size_t length) {
    char buffer[MAX_REQUEST_LINE];

    if (NULL == fgets(request, (int)length, client_fd)) {
        if (ferror(client_fd)) {
            perror("read_http_request(): fgets()");
            return -1;
        }

        return -2;
    }

    while (NULL != fgets(buffer, MAX_REQUEST_LINE, client_fd)) {
        /* End of header. */
        if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) {
            break;
        }
    }
    if (ferror(client_fd)) {
        perror("read_http_request(): fgets()");
        return -1;
    }

    return 0;
}