/*
 * Author: Manoj Ampalam <manoj.ampalam@microsoft.com>
 * ssh-agent implementation on Windows
 * 
 * Copyright (c) 2015 Microsoft Corp.
 * All rights reserved
 *
 * Microsoft openssh win32 port
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "agent.h"
#include "agent-request.h"

void process_request(struct agent_connection*);

#define ABORT_CONNECTION_RETURN(c) do {	\
	con->state = DONE;		\
	agent_cleanup_connection(con);	\
	return;				\
} while (0)

void agent_connection_on_error(struct agent_connection* con, DWORD error) {
	ABORT_CONNECTION_RETURN(con);
}

void agent_connection_on_io(struct agent_connection* con, DWORD bytes, OVERLAPPED* ol) {
	
	/* process error */
	if ((bytes == 0) && (GetOverlappedResult(con->connection, ol, &bytes, FALSE) == FALSE))
		ABORT_CONNECTION_RETURN(c);

	if (con->state == DONE)
		DebugBreak();

	//while (1) 
	{
		switch (con->state) {		
		case LISTENING:
			agent_listen();
		case WRITING:
			/* Writing is done, read next request */
			/* assert on assumption that write always completes on sending all bytes*/
			if (bytes != con->io_buf.num_bytes)
				DebugBreak();
			con->state = READING_HEADER;
			ZeroMemory(&con->io_buf, sizeof(con->io_buf));
			if (!ReadFile(con->connection, con->io_buf.buf,
			    HEADER_SIZE,  NULL, &con->ol) && (GetLastError() != ERROR_IO_PENDING)) 
				ABORT_CONNECTION_RETURN(c);
			break;
		case READING_HEADER:
			con->io_buf.transferred += bytes;
			if (con->io_buf.transferred == HEADER_SIZE) {
				con->io_buf.num_bytes = PEEK_U32(con->io_buf.buf);
				con->io_buf.transferred = 0;
				if (con->io_buf.num_bytes > MAX_MESSAGE_SIZE)
					ABORT_CONNECTION_RETURN(c);

				con->state = READING;
				if (!ReadFile(con->connection, con->io_buf.buf,
				    con->io_buf.num_bytes, NULL, &con->ol)&&(GetLastError() != ERROR_IO_PENDING)) 
					ABORT_CONNECTION_RETURN(c);
			}
			else {
				if (!ReadFile(con->connection, con->io_buf.buf + con->io_buf.num_bytes,
				    HEADER_SIZE - con->io_buf.num_bytes, NULL, &con->ol)&& (GetLastError() != ERROR_IO_PENDING)) 
					ABORT_CONNECTION_RETURN(c);
			}
			break;
		case READING:
			con->io_buf.transferred += bytes;
			if (con->io_buf.transferred == con->io_buf.num_bytes) {
				process_request(con);
				con->state = WRITING;
				if (!WriteFile(con->connection, con->io_buf.buf,
				    con->io_buf.num_bytes, NULL, &con->ol)&& (GetLastError() != ERROR_IO_PENDING) )
					ABORT_CONNECTION_RETURN(c);
			}
			else {
				if (!ReadFile(con->connection, con->io_buf.buf + con->io_buf.transferred,
				    con->io_buf.num_bytes - con->io_buf.transferred, NULL, &con->ol)&& (GetLastError() != ERROR_IO_PENDING)) 
					ABORT_CONNECTION_RETURN(c);
			}
			break;
		default:
			DebugBreak();
		}		
	}
}

void agent_connection_disconnect(struct agent_connection* con) {
	CancelIoEx(con->connection, NULL);
	DisconnectNamedPipe(con->connection);
}

static void
process_request(struct agent_connection* con) {
	int r;
	struct sshbuf *request = NULL, *response = NULL;
	u_char type;
	
	request = sshbuf_from(con->io_buf.buf, con->io_buf.num_bytes);
	response = sshbuf_new();
	if ((request == NULL) || (response == NULL)) {
		r = ENOMEM;
		goto done;
	}

	if ((r = sshbuf_get_u8(request, &type)) != 0)
		goto done;

	switch (type) {
	case SSH2_AGENTC_ADD_IDENTITY:
		r = process_add_identity(request, response, con->client_token);
		break;
	case SSH2_AGENTC_REQUEST_IDENTITIES:
		r = process_request_identities(request, response, con->client_token);
		break;
	case SSH2_AGENTC_SIGN_REQUEST:
	default:
		r = EINVAL;
		goto done;
	}

done:
	if (request)
		sshbuf_free(request);

	ZeroMemory(&con->io_buf, sizeof(con->io_buf));
	if (r == 0) {
		POKE_U32(con->io_buf.buf, sshbuf_len(response));
		memcpy(con->io_buf.buf + 4, sshbuf_ptr(response), sshbuf_len(response));
		con->io_buf.num_bytes = sshbuf_len(response) + 4;
	}
	else {
		POKE_U32(con->io_buf.buf, 1);
		*(con->io_buf.buf + 4) = SSH_AGENT_FAILURE;
		con->io_buf.num_bytes = 5;
	}

	if (response)
		sshbuf_free(response);
}