/*
 * 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"
#include "config.h"

#pragma warning(push, 3)

int process_request(struct agent_connection*);

#define ABORT_CONNECTION_RETURN(c) do {	\
	c->state = DONE;		\
	agent_cleanup_connection(c);	\
	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 */
	debug3("connection io %p #bytes:%d state:%d", con, bytes, con->state);
	if ((bytes == 0) && (GetOverlappedResult(con->pipe_handle, ol, &bytes, FALSE) == FALSE))
		ABORT_CONNECTION_RETURN(con);
	if (con->state == DONE)
		debug_assert_internal();

	switch (con->state) {		
	case LISTENING:
	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)
			debug_assert_internal();
		con->state = READING_HEADER;
		ZeroMemory(&con->io_buf, sizeof(con->io_buf));
		if (!ReadFile(con->pipe_handle, con->io_buf.buf,
			HEADER_SIZE,  NULL, &con->ol) && (GetLastError() != ERROR_IO_PENDING)) 
			ABORT_CONNECTION_RETURN(con);
		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(con);

			con->state = READING;
			if (!ReadFile(con->pipe_handle, con->io_buf.buf,
				con->io_buf.num_bytes, NULL, &con->ol)&&(GetLastError() != ERROR_IO_PENDING)) 
				ABORT_CONNECTION_RETURN(con);
		} else {
			if (!ReadFile(con->pipe_handle, 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(con);
		}
		break;
	case READING:
		con->io_buf.transferred += bytes;
		if (con->io_buf.transferred == con->io_buf.num_bytes) {
			if (process_request(con) != 0) {
				ABORT_CONNECTION_RETURN(con);
			}
			con->state = WRITING;
			if (!WriteFile(con->pipe_handle, con->io_buf.buf,
				con->io_buf.num_bytes, NULL, &con->ol)&& (GetLastError() != ERROR_IO_PENDING) )
				ABORT_CONNECTION_RETURN(con);
		} else {
			if (!ReadFile(con->pipe_handle, 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(con);
		}
		break;
	default:
		debug_assert_internal();
	}		
}

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

static int
process_request(struct agent_connection* con) 
{
	int r = -1;
	struct sshbuf *request = NULL, *response = NULL;
	u_char type;
	errno_t err = 0;

	request = sshbuf_from(con->io_buf.buf, con->io_buf.num_bytes);
	response = sshbuf_new();
	if ((request == NULL) || (response == NULL))
		goto done;

	if (sshbuf_get_u8(request, &type) != 0)
		return -1;
	debug("process agent request type %d", type);

	switch (type) {
	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
	case SSH_AGENTC_RSA_CHALLENGE:
	case SSH_AGENTC_ADD_RSA_IDENTITY:
	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
		r = process_unsupported_request(request, response, con);
		break;
	case SSH2_AGENTC_ADD_IDENTITY:
	case SSH2_AGENTC_ADD_ID_CONSTRAINED:
		r =  process_add_identity(request, response, con);
		break;
	case SSH2_AGENTC_REQUEST_IDENTITIES:
		r = process_request_identities(request, response, con);
		break;
	case SSH2_AGENTC_SIGN_REQUEST:
		r = process_sign_request(request, response, con);
		break;
	case SSH2_AGENTC_REMOVE_IDENTITY:
		r = process_remove_key(request, response, con);
		break;
	case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
		r = process_remove_all(request, response, con);
		break;
#ifdef ENABLE_PKCS11
	case SSH_AGENTC_ADD_SMARTCARD_KEY:
	case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
		r = process_add_smartcard_key(request, response, con);
		break;
	case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
		r = process_remove_smartcard_key(request, response, con);
		break;
#endif /* ENABLE_PKCS11 */
	case SSH_AGENTC_EXTENSION:
		r = process_extension(request, response, con);
		break;
	default:
		debug("unknown agent request %d", type);
		r = -1;
		break;
	}

done:
	if (request)
		sshbuf_free(request);

	ZeroMemory(&con->io_buf, sizeof(con->io_buf));
	if (r == 0) {
		POKE_U32(con->io_buf.buf, (u_int32_t)sshbuf_len(response));
		if ((err = memcpy_s(con->io_buf.buf + 4, sizeof(con->io_buf.buf) - 4, sshbuf_ptr(response), sshbuf_len(response))) != 0) {
			debug("memcpy_s failed with error: %d.", err);
			r = -1;
		}
		con->io_buf.num_bytes = (DWORD)sshbuf_len(response) + 4;
	}
	
	if (response)
		sshbuf_free(response);

	return r;
}

#pragma warning(pop)