/*
 * 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 <sddl.h>

#define MAX_KEY_LENGTH 255
#define MAX_VALUE_NAME 16383

static int
get_user_root(struct agent_connection* con, HKEY *root){
	int r = 0;
	if (ImpersonateNamedPipeClient(con->connection) == FALSE)
		return ERROR_INTERNAL_ERROR;
	
	r = RegOpenCurrentUser(KEY_ALL_ACCESS, root);

	RevertToSelf();
	return r;
}

static int
convert_blob(struct agent_connection* con, char *blob, DWORD blen, char **eblob, DWORD *eblen, int encrypt) {
	int r = 0;
	DATA_BLOB in, out;
	if (ImpersonateNamedPipeClient(con->connection) == FALSE)
		return ERROR_INTERNAL_ERROR;

	in.cbData = blen;
	in.pbData = blob;
	out.cbData = 0;
	out.pbData = NULL;

	if (encrypt) {
		if (!CryptProtectData(&in, NULL, NULL, 0, NULL, 0, &out)) {
			r = GetLastError();
			goto done;
		}
	}
	else {
		if (!CryptUnprotectData(&in, NULL, NULL, 0, NULL, 0, &out)) {
			r = GetLastError();
			goto done;
		}
	}

	


	*eblob = malloc(out.cbData);
	if (*eblob == NULL) {
		r = ERROR_OUTOFMEMORY;
		goto done;
	}

	memcpy(*eblob, out.pbData, out.cbData);
	*eblen = out.cbData;
done:
	if (out.pbData)
		LocalFree(out.pbData);
	RevertToSelf();
	return r;
}

int
process_add_identity(struct sshbuf* request, struct sshbuf* response, struct agent_connection* con) {
	struct sshkey* key = NULL;
	int r = 0, r1 = 0, blob_len, eblob_len;
	size_t comment_len, pubkey_blob_len;
	u_char *pubkey_blob = NULL;
	char *thumbprint = NULL, *comment;
	const char *blob;
	char* eblob = NULL;
	HKEY reg = 0, sub = 0, user_root = 0;
	PSECURITY_DESCRIPTOR sd = NULL;
	wchar_t* str = L"O:SYG:BAD:P(A;;GA;;;SY)";
	SECURITY_ATTRIBUTES sa;
	ConvertStringSecurityDescriptorToSecurityDescriptorW(str, SDDL_REVISION_1, &sd, NULL);
	sa.nLength = sizeof(sa);
	sa.lpSecurityDescriptor = sd;
	sa.bInheritHandle = FALSE;

	blob = sshbuf_ptr(request);
	if ((r = sshkey_private_deserialize(request, &key)) != 0)
		goto done;
	blob_len = (sshbuf_ptr(request) - blob) & 0xffffffff;

	if ((r = sshkey_to_blob(key, &pubkey_blob, &pubkey_blob_len)) != 0)
		goto done;

	if ((r = convert_blob(con, blob, blob_len, &eblob, &eblob_len, 1)) != 0)
		goto done;

	if (((r = sshbuf_peek_string_direct(request, &comment, &comment_len)) != 0) ||
	    ((thumbprint = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) ||
	    ((r = get_user_root(con, &user_root)) != 0) ||
	    ((r = RegCreateKeyExW(user_root, SSHD_KEYS_ROOT, 0, 0, 0, KEY_WRITE, NULL, &reg, NULL)) != 0) ||
	    ((r = RegCreateKeyExA(reg, thumbprint, 0, 0, 0, KEY_WRITE, NULL, &sub, NULL)) != 0) ||
	    ((r = RegSetValueExW(sub, NULL, 0, REG_BINARY, eblob, eblob_len)) != 0) ||
	    ((r = RegSetValueExW(sub, L"pub", 0, REG_BINARY, pubkey_blob, pubkey_blob_len)) != 0) ||
	    ((r = RegSetValueExW(sub, L"type", 0, REG_DWORD, (BYTE*)&key->type, 4)) != 0) ||
	    ((r = RegSetValueExW(sub, L"comment", 0, REG_BINARY, comment, comment_len)) != 0) )
		goto done;

done:

	/* TODO if r failed the delete reg entries*/

	r1 = sshbuf_put_u8(response, (r==0) ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);

	if (eblob)
		free(eblob);
	if (sd)
		LocalFree(sd);
	if (key)
		sshkey_free(key);
	if (thumbprint)
		free(thumbprint);
	if (user_root)
		RegCloseKey(user_root);
	if (reg)
		RegCloseKey(reg);
	if (sub)
		RegCloseKey(sub);
	if (pubkey_blob)
		free(pubkey_blob);
	return r1;
}

static int sign_blob(const struct sshkey *pubkey, u_char ** sig, size_t *siglen,
	const u_char *blob, size_t blen, u_int flags, struct agent_connection* con) {
	HKEY reg = 0, sub = 0, user_root = 0;
	int r = 0;
	struct sshkey* prikey = NULL;
	char *thumbprint = NULL, *regdata = NULL;
	DWORD regdatalen = 0, keyblob_len = 0;;
	struct sshbuf* tmpbuf = NULL;
	char *keyblob = NULL;

	regdata = malloc(4);
	regdatalen = 4;

	*sig = NULL;
	*siglen = 0;

	if ((thumbprint = sshkey_fingerprint(pubkey, SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL)
		goto done;
	
	if ((r = get_user_root(con, &user_root)) != 0)
		goto done;

	if ((r = RegOpenKeyExW(user_root, SSHD_KEYS_ROOT,
		0, STANDARD_RIGHTS_READ | KEY_QUERY_VALUE | KEY_ENUMERATE_SUB_KEYS, &reg)) != 0)
		goto done;

	if ((r = RegOpenKeyExA(reg, thumbprint, 0, STANDARD_RIGHTS_READ | KEY_QUERY_VALUE | KEY_ENUMERATE_SUB_KEYS, 
		&sub)) != 0)
		goto done;

	if ((RegQueryValueExW(sub, NULL, 0, NULL, regdata, &regdatalen)) != ERROR_MORE_DATA) {
		r = EOTHER;
		goto done;
	}

	if ((regdata = malloc(regdatalen)) == NULL) {
		r = ENOMEM;
		goto done;
	}

	if ((r = RegQueryValueExW(sub, NULL, 0, NULL, regdata, &regdatalen)) != 0)
		goto done;

	if ((r = convert_blob(con, regdata, regdatalen, &keyblob, &keyblob_len, FALSE)) != 0)
		goto done;

	if ((tmpbuf = sshbuf_from(keyblob, keyblob_len)) == NULL) {
		r = ENOMEM;
		goto done;
	}
	
	if ( ((r = sshkey_private_deserialize(tmpbuf, &prikey)) != 0) ||
		((r = sshkey_sign(prikey, sig, siglen, blob, blen, 0)) != 0) )
		goto done;

done:
	if (keyblob)
		free(keyblob);
	if (regdata)
		free(regdata);
	if (tmpbuf)
		sshbuf_free(tmpbuf);
	if (prikey)
		sshkey_free(prikey);
	if (thumbprint)
		free(thumbprint);
	if (user_root)
		RegCloseKey(user_root);
	if (reg)
		RegCloseKey(reg);
	if (sub)
		RegCloseKey(sub);

	return r;
}

int
process_sign_request(struct sshbuf* request, struct sshbuf* response, struct agent_connection* con) {
	u_char *blob, *data, *signature = NULL;
	size_t blen, dlen, slen = 0;
	u_int flags = 0;
	int r, r1;
	struct sshkey *key;

	if ((r = sshbuf_get_string(request, &blob, &blen)) != 0 ||
		(r = sshbuf_get_string(request, &data, &dlen)) != 0 ||
		(r = sshbuf_get_u32(request, &flags)) != 0)
		goto done;

	/* TODO - flags?*/

	if (((r = sshkey_from_blob(blob, blen, &key)) != 0)
		|| ((r = sign_blob(key, &signature, &slen,
			data, dlen, 0, con)) != 0))
		goto done;

done:
	if (r == 0) {
		if ((r = sshbuf_put_u8(response, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
			(r = sshbuf_put_string(response, signature, slen)) != 0) {
		}
	}
	else 
		r = sshbuf_put_u8(response, SSH_AGENT_FAILURE);

	free(data);
	free(blob);
	free(signature);
	return r;
}

int
process_request_identities(struct sshbuf* request, struct sshbuf* response, struct agent_connection* con) {
	int r, r1, count = 0, index = 0;
	HKEY root = NULL, sub = NULL, user_root = 0;
	char* count_ptr = NULL;
	wchar_t sub_name[MAX_KEY_LENGTH];
	DWORD sub_name_len = MAX_KEY_LENGTH;
	char *regdata = NULL;
	DWORD regdatalen = 0, key_count = 0;
	struct sshbuf* identities;

	regdata = malloc(4);
	regdatalen = 4;

	identities = sshbuf_new();

	if ((identities == NULL) || (regdata == NULL))
		goto done;

	if ((r = get_user_root(con, &user_root)) != 0)
		goto done;

	if ((r = RegOpenKeyExW(user_root, SSHD_KEYS_ROOT,
		0, STANDARD_RIGHTS_READ | KEY_ENUMERATE_SUB_KEYS, &root)) != 0)
		goto done;

	while (1) {
		sub_name_len = MAX_KEY_LENGTH;
		if (sub) {
			RegCloseKey(sub);
			sub = NULL;
		}
		if ((r = RegEnumKeyExW(root, index++, sub_name, &sub_name_len, NULL, NULL, NULL, NULL)) == 0) {
			if ((r = RegOpenKeyExW(root, sub_name, 0, KEY_QUERY_VALUE, &sub)) == 0) {
				if ((r = RegQueryValueExW(sub, L"pub", 0, NULL, regdata, &regdatalen)) != 0) {
					if (r == ERROR_MORE_DATA) {
						r = 0;
						if (regdata)
							free(regdata);
						if ((regdata = malloc(regdatalen)) == NULL) {
							r = ENOMEM;
							goto done;
						}
						if ((r = RegQueryValueExW(sub, L"pub", 0, NULL, regdata, &regdatalen)) != 0)
							goto done;

					}
					else {
						r = EOTHER;
						goto done;
					}
				}
				
				if ((r = sshbuf_put_string(identities, regdata, regdatalen)) != 0)
					goto done;
				
				if ((r = RegQueryValueExW(sub, L"comment", 0, NULL, regdata, &regdatalen)) != 0) {
					if (r == ERROR_MORE_DATA) {
						r = 0;
						if (regdata)
							free(regdata);
						if ((regdata = malloc(regdatalen)) == NULL) {
							r = ENOMEM;
							goto done;
						}
						if ((r = RegQueryValueExW(sub, L"comment", 0, NULL, regdata, &regdatalen)) != 0)
							goto done;

					}
					else {
						r = EOTHER;
						goto done;
					}
				}
				if ((r = sshbuf_put_string(identities, regdata, regdatalen)) != 0)
					goto done;
				key_count++;
				
			}
			else if (r == ERROR_FILE_NOT_FOUND) {
				r = 0;
				continue;
			}
			else
				goto done;
		}
		else if (r == ERROR_NO_MORE_ITEMS) {
			r = 0;
			break;
		}
		else
			goto done;

	}

	if (((r = sshbuf_put_u8(response, SSH2_AGENT_IDENTITIES_ANSWER)) != 0)
	   || ((r = sshbuf_put_u32(response, key_count)) != 0)
	   || ((r = sshbuf_putb(response, identities)) != 0))
		goto done;


done:
	if (regdata)
		free(regdata);
	if (identities)
		sshbuf_free(identities);
	if (user_root)
		RegCloseKey(user_root);
	if (root)
		RegCloseKey(root);
	if (sub)
		RegCloseKey(sub);
	return r;
}


int process_keyagent_request(struct sshbuf* request, struct sshbuf* response, struct agent_connection* con) {
	int r;
	u_char type;

	if ((r = sshbuf_get_u8(request, &type)) != 0)
		return r;
	switch (type) {
	case SSH2_AGENTC_ADD_IDENTITY:
		return process_add_identity(request, response, con);
	case SSH2_AGENTC_REQUEST_IDENTITIES:
		return process_request_identities(request, response, con);
	case SSH2_AGENTC_SIGN_REQUEST:
		return process_sign_request(request, response, con);
	default:
		return EINVAL;		
	}
}