--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cli-agentfwd.c	Sat Feb 27 11:53:18 2010 +0000
@@ -0,0 +1,311 @@
+/*
+ * Dropbear - a SSH2 server
+ * 
+ * Copyright (c) 2005 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"
+
+#ifdef ENABLE_CLI_AGENTFWD
+
+#include "agentfwd.h"
+#include "session.h"
+#include "ssh.h"
+#include "dbutil.h"
+#include "chansession.h"
+#include "channel.h"
+#include "packet.h"
+#include "buffer.h"
+#include "random.h"
+#include "listener.h"
+#include "runopts.h"
+#include "atomicio.h"
+#include "signkey.h"
+#include "auth.h"
+
+/* The protocol implemented to talk to OpenSSH's SSH2 agent is documented in
+   PROTOCOL.agent in recent OpenSSH source distributions (5.1p1 has it). */
+
+static int new_agent_chan(struct Channel * channel);
+
+const struct ChanType cli_chan_agent = {
+	0, /* sepfds */
+	"[email protected]",
+	new_agent_chan,
+	NULL,
+	NULL,
+	NULL
+};
+
+static int connect_agent() {
+
+	int fd = -1;
+	char* agent_sock = NULL;
+
+	agent_sock = getenv("SSH_AUTH_SOCK");
+	if (agent_sock == NULL)
+		return -1;
+
+	fd = connect_unix(agent_sock);
+
+	if (fd < 0) {
+		dropbear_log(LOG_INFO, "Failed to connect to agent");
+	}
+
+	return fd;
+}
+
+// handle a request for a connection to the locally running ssh-agent
+// or forward.
+static int new_agent_chan(struct Channel * channel) {
+
+	int fd = -1;
+
+	if (!cli_opts.agent_fwd)
+		return SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
+
+	fd = connect_agent();
+	if (cli_opts.agent_fd < 0) {
+		return SSH_OPEN_CONNECT_FAILED;
+	}
+
+	setnonblocking(fd);
+
+	ses.maxfd = MAX(ses.maxfd, fd);
+
+	channel->readfd = fd;
+	channel->writefd = fd;
+
+	// success
+	return 0;
+}
+
+/* Sends a request to the agent, returning a newly allocated buffer
+ * with the response */
+/* This function will block waiting for a response - it will
+ * only be used by client authentication (not for forwarded requests)
+ * won't cause problems for interactivity. */
+/* Packet format (from draft-ylonen)
+   4 bytes     Length, msb first.  Does not include length itself.
+   1 byte      Packet type.  The value 255 is reserved for future extensions.
+   data        Any data, depending on packet type.  Encoding as in the ssh packet
+               protocol.
+*/
+static buffer * agent_request(unsigned char type, buffer *data) {
+
+	buffer * payload = NULL;
+	buffer * inbuf = NULL;
+	size_t readlen = 0;
+	ssize_t ret;
+	const int fd = cli_opts.agent_fd;
+	unsigned int data_len = 0;
+	if (data)
+	{
+		data_len = data->len;
+	}
+
+	payload = buf_new(4 + 1 + data_len);
+
+	buf_putint(payload, 1 + data_len);
+	buf_putbyte(payload, type);
+	if (data) {
+		buf_putbytes(payload, data->data, data->len);
+	}
+	buf_setpos(payload, 0);
+
+	ret = atomicio(write, fd, buf_getptr(payload, payload->len), payload->len);
+	if ((size_t)ret != payload->len) {
+		TRACE(("write failed fd %d for agent_request, %s", fd, strerror(errno)))
+		goto out;
+	}
+
+	buf_free(payload);
+	payload = NULL;
+	TRACE(("Wrote out bytes for agent_request"))
+	/* Now we read the response */
+	inbuf = buf_new(4);
+	ret = atomicio(read, fd, buf_getwriteptr(inbuf, 4), 4);
+	if (ret != 4) {
+		TRACE(("read of length failed for agent_request"))
+		goto out;
+	}
+	buf_setpos(inbuf, 0);
+	buf_setlen(inbuf, ret);
+
+	readlen = buf_getint(inbuf);
+	if (readlen > MAX_AGENT_REPLY) {
+		TRACE(("agent reply is too big"));
+		goto out;
+	}
+	
+	TRACE(("agent_request readlen is %d", readlen))
+
+	buf_resize(inbuf, readlen);
+	buf_setpos(inbuf, 0);
+	ret = atomicio(read, fd, buf_getwriteptr(inbuf, readlen), readlen);
+	if ((size_t)ret != readlen) {
+		TRACE(("read of data failed for agent_request"))
+		goto out;
+	}
+	buf_incrwritepos(inbuf, readlen);
+	buf_setpos(inbuf, 0);
+	TRACE(("agent_request success, length %d", readlen))
+
+out:
+	if (payload)
+		buf_free(payload);
+
+	return inbuf;
+}
+
+static void agent_get_key_list(m_list * ret_list)
+{
+	buffer * inbuf = NULL;
+	unsigned int num = 0;
+	unsigned char packet_type;
+	unsigned int i;
+	int ret;
+
+	inbuf = agent_request(SSH2_AGENTC_REQUEST_IDENTITIES, NULL);
+	if (!inbuf) {
+		TRACE(("agent_request failed returning identities"))
+		goto out;
+	}
+
+	/* The reply has a format of:
+		byte			SSH2_AGENT_IDENTITIES_ANSWER
+		uint32			num_keys
+  	   Followed by zero or more consecutive keys, encoded as:
+       	 string			key_blob
+    	 string			key_comment
+	 */
+	packet_type = buf_getbyte(inbuf);
+	if (packet_type != SSH2_AGENT_IDENTITIES_ANSWER) {
+		goto out;
+	}
+
+	num = buf_getint(inbuf);
+	for (i = 0; i < num; i++) {
+		sign_key * pubkey = NULL;
+		int key_type = DROPBEAR_SIGNKEY_ANY;
+		buffer * key_buf;
+
+		/* each public key is encoded as a string */
+		key_buf = buf_getstringbuf(inbuf);
+		pubkey = new_sign_key();
+		ret = buf_get_pub_key(key_buf, pubkey, &key_type);
+		buf_free(key_buf);
+		if (ret != DROPBEAR_SUCCESS) {
+			/* This is slack, properly would cleanup vars etc */
+			dropbear_exit("Bad pubkey received from agent");
+		}
+		pubkey->type = key_type;
+		pubkey->source = SIGNKEY_SOURCE_AGENT;
+
+		list_append(ret_list, pubkey);
+
+		/* We'll ignore the comment for now. might want it later.*/
+		buf_eatstring(inbuf);
+	}
+
+out:
+	if (inbuf) {
+		buf_free(inbuf);
+		inbuf = NULL;
+	}
+}
+
+void cli_setup_agent(struct Channel *channel) {
+	if (!getenv("SSH_AUTH_SOCK")) {
+		return;
+	}
+	
+	cli_start_send_channel_request(channel, "[email protected]");
+	/* Don't want replies */
+	buf_putbyte(ses.writepayload, 0);
+	encrypt_packet();
+}
+
+/* Returned keys are prepended to ret_list, which will
+   be updated. */
+void cli_load_agent_keys(m_list *ret_list) {
+	/* agent_fd will be closed after successful auth */
+	cli_opts.agent_fd = connect_agent();
+	if (cli_opts.agent_fd < 0) {
+		return;
+	}
+
+	agent_get_key_list(ret_list);
+}
+
+void agent_buf_sign(buffer *sigblob, sign_key *key, 
+		const unsigned char *data, unsigned int len) {
+	buffer *request_data = buf_new(MAX_PUBKEY_SIZE + len + 12);
+	buffer *response;
+	unsigned int keylen, siglen;
+	int packet_type;
+	
+	/* Request format
+	byte			SSH2_AGENTC_SIGN_REQUEST
+	string			key_blob
+	string			data
+	uint32			flags
+	*/
+	/* We write the key, then figure how long it was and write that */
+	//buf_putint(request_data, 0);
+	buf_put_pub_key(request_data, key, key->type);
+	keylen = request_data->len - 4;
+	//buf_setpos(request_data, 0);
+	//buf_putint(request_data, keylen);
+	
+	//buf_setpos(request_data, request_data->len);
+	buf_putstring(request_data, data, len);
+	buf_putint(request_data, 0);
+	
+	response = agent_request(SSH2_AGENTC_SIGN_REQUEST, request_data);
+	buf_free(request_data);
+	
+	if (!response) {
+		goto fail;
+	}
+	
+	packet_type = buf_getbyte(response);
+	if (packet_type != SSH2_AGENT_SIGN_RESPONSE) {
+		goto fail;
+	}
+	
+	/* Response format
+	byte			SSH2_AGENT_SIGN_RESPONSE
+	string			signature_blob
+	*/
+	siglen = buf_getint(response);
+	buf_putbytes(sigblob, buf_getptr(response, siglen), siglen);
+	buf_free(response);
+	
+	return;
+fail:
+	/* XXX don't fail badly here. instead propagate a failure code back up to
+	   the cli auth pubkey code, and just remove this key from the list of 
+	   ones to try. */
+	dropbear_exit("Agent failed signing key");
+}
+
+#endif