view listener.c @ 994:5c5ade336926

Prefer stronger algorithms in algorithm negotiation. Prefer diffie-hellman-group14-sha1 (2048 bit) over diffie-hellman-group1-sha1 (1024 bit). Due to meet-in-the-middle attacks the effective key length of three key 3DES is 112 bits. AES is stronger and faster then 3DES. Prefer to delay the start of compression until after authentication has completed. This avoids exposing compression code to attacks from unauthenticated users. (github pull request #9)
author Fedor Brunner <fedor.brunner@azet.sk>
date Fri, 23 Jan 2015 23:00:25 +0800
parents 0cfba3034be5
children 2b4fd440399d
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/*
 * Dropbear SSH
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * 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 "listener.h"
#include "session.h"
#include "dbutil.h"

void listeners_initialise() {

	/* just one slot to start with */
	ses.listeners = (struct Listener**)m_malloc(sizeof(struct Listener*));
	ses.listensize = 1;
	ses.listeners[0] = NULL;

}

void set_listener_fds(fd_set * readfds) {

	unsigned int i, j;
	struct Listener *listener;

	/* check each in turn */
	for (i = 0; i < ses.listensize; i++) {
		listener = ses.listeners[i];
		if (listener != NULL) {
			for (j = 0; j < listener->nsocks; j++) {
				FD_SET(listener->socks[j], readfds);
			}
		}
	}
}


void handle_listeners(fd_set * readfds) {

	unsigned int i, j;
	struct Listener *listener;
	int sock;

	/* check each in turn */
	for (i = 0; i < ses.listensize; i++) {
		listener = ses.listeners[i];
		if (listener != NULL) {
			for (j = 0; j < listener->nsocks; j++) {
				sock = listener->socks[j];
				if (FD_ISSET(sock, readfds)) {
					listener->acceptor(listener, sock);
				}
			}
		}
	}
} /* Woo brace matching */


/* acceptor(int fd, void* typedata) is a function to accept connections, 
 * cleanup(void* typedata) happens when cleaning up */
struct Listener* new_listener(int socks[], unsigned int nsocks,
		int type, void* typedata, 
		void (*acceptor)(struct Listener* listener, int sock), 
		void (*cleanup)(struct Listener*)) {

	unsigned int i, j;
	struct Listener *newlisten = NULL;
	/* try get a new structure to hold it */
	for (i = 0; i < ses.listensize; i++) {
		if (ses.listeners[i] == NULL) {
			break;
		}
	}

	/* or create a new one */
	if (i == ses.listensize) {
		if (ses.listensize > MAX_LISTENERS) {
			TRACE(("leave newlistener: too many already"))
			for (j = 0; j < nsocks; j++) {
				close(socks[i]);
			}
			return NULL;
		}
		
		ses.listeners = (struct Listener**)m_realloc(ses.listeners,
				(ses.listensize+LISTENER_EXTEND_SIZE)
				*sizeof(struct Listener*));

		ses.listensize += LISTENER_EXTEND_SIZE;

		for (j = i; j < ses.listensize; j++) {
			ses.listeners[j] = NULL;
		}
	}

	for (j = 0; j < nsocks; j++) {
		ses.maxfd = MAX(ses.maxfd, socks[j]);
	}

	TRACE(("new listener num %d ", i))

	newlisten = (struct Listener*)m_malloc(sizeof(struct Listener));
	newlisten->index = i;
	newlisten->type = type;
	newlisten->typedata = typedata;
	newlisten->nsocks = nsocks;
	memcpy(newlisten->socks, socks, nsocks * sizeof(int));
	newlisten->acceptor = acceptor;
	newlisten->cleanup = cleanup;

	ses.listeners[i] = newlisten;
	return newlisten;
}

/* Return the first listener which matches the type-specific comparison
 * function. Particularly needed for global requests, like tcp */
struct Listener * get_listener(int type, void* typedata,
		int (*match)(void*, void*)) {

	unsigned int i;
	struct Listener* listener;

	for (i = 0, listener = ses.listeners[i]; i < ses.listensize; i++) {
		if (listener->type == type
				&& match(typedata, listener->typedata)) {
			return listener;
		}
	}

	return NULL;
}

void remove_listener(struct Listener* listener) {

	unsigned int j;

	if (listener->cleanup) {
		listener->cleanup(listener);
	}

	for (j = 0; j < listener->nsocks; j++) {
		close(listener->socks[j]);
	}
	ses.listeners[listener->index] = NULL;
	m_free(listener);

}