/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002-2004 Matt Johnston
 * Copyright (c) 2004 by Mihnea Stoenescu
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#include "includes.h"
#include "session.h"
#include "dbutil.h"
#include "algo.h"
#include "buffer.h"
#include "session.h"
#include "kex.h"
#include "ssh.h"
#include "packet.h"
#include "bignum.h"
#include "random.h"
#include "runopts.h"
#include "signkey.h"


static void checkhostkey(unsigned char* keyblob, unsigned int keybloblen);
#define MAX_KNOWNHOSTS_LINE 4500

void send_msg_kexdh_init() {
	TRACE(("send_msg_kexdh_init()"))	
	if ((cli_ses.dh_e && cli_ses.dh_x 
				&& cli_ses.dh_val_algo == ses.newkeys->algo_kex)) {
		TRACE(("reusing existing dh_e from first_kex_packet_follows"))
	} else {
		if (!cli_ses.dh_e || !cli_ses.dh_e) {
			cli_ses.dh_e = (mp_int*)m_malloc(sizeof(mp_int));
			cli_ses.dh_x = (mp_int*)m_malloc(sizeof(mp_int));
			m_mp_init_multi(cli_ses.dh_e, cli_ses.dh_x, NULL);
		}

		gen_kexdh_vals(cli_ses.dh_e, cli_ses.dh_x);
		cli_ses.dh_val_algo = ses.newkeys->algo_kex;
	}

	CHECKCLEARTOWRITE();
	buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_INIT);
	buf_putmpint(ses.writepayload, cli_ses.dh_e);
	encrypt_packet();
	ses.requirenext[0] = SSH_MSG_KEXDH_REPLY;
	ses.requirenext[1] = SSH_MSG_KEXINIT;
}

/* Handle a diffie-hellman key exchange reply. */
void recv_msg_kexdh_reply() {

	DEF_MP_INT(dh_f);
	sign_key *hostkey = NULL;
	unsigned int type, keybloblen;
	unsigned char* keyblob = NULL;


	TRACE(("enter recv_msg_kexdh_reply"))

	if (cli_ses.kex_state != KEXDH_INIT_SENT) {
		dropbear_exit("Received out-of-order kexdhreply");
	}
	m_mp_init(&dh_f);
	type = ses.newkeys->algo_hostkey;
	TRACE(("type is %d", type))

	hostkey = new_sign_key();
	keybloblen = buf_getint(ses.payload);

	keyblob = buf_getptr(ses.payload, keybloblen);
	if (!ses.kexstate.donefirstkex) {
		/* Only makes sense the first time */
		checkhostkey(keyblob, keybloblen);
	}

	if (buf_get_pub_key(ses.payload, hostkey, &type) != DROPBEAR_SUCCESS) {
		TRACE(("failed getting pubkey"))
		dropbear_exit("Bad KEX packet");
	}

	if (buf_getmpint(ses.payload, &dh_f) != DROPBEAR_SUCCESS) {
		TRACE(("failed getting mpint"))
		dropbear_exit("Bad KEX packet");
	}

	kexdh_comb_key(cli_ses.dh_e, cli_ses.dh_x, &dh_f, hostkey);
	mp_clear(&dh_f);
	mp_clear_multi(cli_ses.dh_e, cli_ses.dh_x, NULL);
	m_free(cli_ses.dh_e);
	m_free(cli_ses.dh_x);
	cli_ses.dh_val_algo = DROPBEAR_KEX_NONE;

	if (buf_verify(ses.payload, hostkey, ses.hash, SHA1_HASH_SIZE) 
			!= DROPBEAR_SUCCESS) {
		dropbear_exit("Bad hostkey signature");
	}

	sign_key_free(hostkey);
	hostkey = NULL;

	send_msg_newkeys();
	ses.requirenext[0] = SSH_MSG_NEWKEYS;
	ses.requirenext[1] = 0;
	TRACE(("leave recv_msg_kexdh_init"))
}

static void ask_to_confirm(unsigned char* keyblob, unsigned int keybloblen) {

	char* fp = NULL;
	FILE *tty = NULL;
	char response = 'z';

	fp = sign_key_fingerprint(keyblob, keybloblen);
	if (cli_opts.always_accept_key) {
		fprintf(stderr, "\nHost '%s' key accepted unconditionally.\n(fingerprint %s)\n",
				cli_opts.remotehost,
				fp);
		m_free(fp);
		return;
	}
	fprintf(stderr, "\nHost '%s' is not in the trusted hosts file.\n(fingerprint %s)\nDo you want to continue connecting? (y/n) ", 
			cli_opts.remotehost, 
			fp);
	m_free(fp);

	tty = fopen(_PATH_TTY, "r");
	if (tty) {
		response = getc(tty);
		fclose(tty);
	} else {
		response = getc(stdin);
	}

	if (response == 'y') {
		return;
	}

	dropbear_exit("Didn't validate host key");
}

static FILE* open_known_hosts_file(int * readonly)
{
	FILE * hostsfile = NULL;
	char * filename = NULL;
	char * homedir = NULL;
	
	homedir = getenv("HOME");

	if (!homedir) {
		struct passwd * pw = NULL;
		pw = getpwuid(getuid());
		if (pw) {
			homedir = pw->pw_dir;
		}
	}