/* do ECDSA operations for IKEv2
 *
 * Copyright (C) 2018 Sahana Prasad <sahana.prasad07@gmail.com>
 * Copyright (C) 2018 Paul Wouters <pwouters@redhat.com>
 * Copyright (C) 2019 Andrew Cagney <cagney@gnu.org>
 * Copyright (C) 2019 D. Hugh Redelmeier <hugh@mimosa.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.   See <https://www.gnu.org/licenses/gpl2.txt>. 
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.   See the GNU General Public License
 * for more details. 
 *
 */

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "secitem.h"
#include "cryptohi.h"
#include "keyhi.h"


#include "sysdep.h"
#include "constants.h"

#include "defs.h"
#include "id.h"
#include "x509.h"
#include "certs.h"
#include "connections.h"        /* needs id.h */
#include "state.h"
#include "packet.h"
#include "crypto.h"
#include "ike_alg.h"
#include "ike_alg_hash.h"
#include "log.h"
#include "demux.h"      /* needs packet.h */
#include "pluto_crypt.h"  /* for pluto_crypto_req & pluto_crypto_req_cont */
#include "ikev2.h"
#include "server.h"
#include "vendor.h"
#include "keys.h"
#include "secrets.h"
#include "crypt_hash.h"
#include "ietf_constants.h"
#include "asn1.h"
#include "lswnss.h"
#include "ikev2_auth.h"

static try_signature_fn try_ECDSA_signature_v2; /* type assert */
static err_t try_ECDSA_signature_v2(const struct crypt_mac *hash,
				    const pb_stream *sig_pbs, struct pubkey *kr,
				    struct state *st,
				    const struct hash_desc *hash_algo_unused UNUSED)
{
	PRArenaPool *arena = PORT_NewArena(DER_DEFAULT_CHUNKSIZE);
	if (arena == NULL) {
		log_nss_error(RC_LOG, st->st_logger,
			      "allocating ECDSA arena using PORT_NewArena() failed");
		return "10" "NSS error: Not enough memory to create arena";
	}

	/*
	 * convert K(R) into a public key
	 */

	/* allocate the pubkey */
	const struct ECDSA_public_key *k = &kr->u.ecdsa;
	SECKEYPublicKey *publicKey = (SECKEYPublicKey *)
		PORT_ArenaZAlloc(arena, sizeof(SECKEYPublicKey));
	if (publicKey == NULL) {
		PORT_FreeArena(arena, PR_FALSE);
		log_nss_error(RC_LOG, st->st_logger,
			      "allocating ECDSA public key using PORT_ArenaZAlloc() failed");
		return "11" "NSS error: Not enough memory to create publicKey";
	}
	publicKey->arena = arena;
	publicKey->keyType = ecKey;
	publicKey->pkcs11Slot = NULL;
	publicKey->pkcs11ID = CK_INVALID_HANDLE;

	/* copy k's public key value into the arena / publicKey */
	SECItem k_pub = same_chunk_as_secitem(k->pub, siBuffer);
	if (SECITEM_CopyItem(arena, &publicKey->u.ec.publicValue, &k_pub) ! = SECSuccess) {
		log_nss_error(RC_LOG, st->st_logger,
			      "constructing ECDSA public value using SECITEM_CopyItem() failed");
		PORT_FreeArena(arena, PR_FALSE);
		return "10" "NSS error: copy failed";
	}

	/* construct the EC Parameters */
	SECItem k_ecParams = same_chunk_as_secitem(k->ecParams, siBuffer);
	if (SECITEM_CopyItem(arena,
			     &publicKey->u.ec. DEREncodedParams,
			     &k_ecParams) ! = SECSuccess) {
		log_nss_error(RC_LOG, st->st_logger,
			      "construction of ecParams using SECITEM_CopyItem() failed");
		PORT_FreeArena(arena, PR_FALSE);
		return "1" "NSS error: Not able to copy modulus or exponent or both while forming SECKEYPublicKey structure";
	}


	/*
	 * Convert the signature into raw form
	 */
	SECItem der_signature = {
		.type = siBuffer,
		.data = sig_pbs->cur,
		.len = pbs_left(sig_pbs),
	};
	LSWDBGP(DBG_BASE, buf) {
		jam(buf, "%d-byte DER encoded ECDSA signature: ",
		    der_signature.len);
		jam_nss_secitem(buf, &der_signature);
	}
	SECItem *raw_signature = DSAU_DecodeDerSigToLen(&der_signature,
							SECKEY_SignatureLen(publicKey));
	if (raw_signature == NULL) {
		log_nss_error(RC_LOG, st->st_logger,
			      "unpacking DER encoded ECDSA signature using DSAU_DecodeDerSigToLen() failed:");
		PORT_FreeArena(arena, PR_FALSE);
		return "1" "Decode failed";
	}
	LSWDBGP(DBG_BASE, buf) {
		jam(buf, "%d-byte raw ESCSA signature: ",
		    raw_signature->len);
		jam_nss_secitem(buf, raw_signature);
	}

	/*
	 * put the hash somewhere writable; so it can later be logged? 
	 *
	 * XXX: cast away const? 
	 */
	struct crypt_mac hash_data = *hash;
	SECItem hash_item = {
		.type = siBuffer,
		.data = hash_data.ptr,
		.len = hash_data.len,
	};

	if (PK11_Verify(publicKey, raw_signature, &hash_item,
			lsw_nss_get_password_context(st->st_logger)) ! = SECSuccess) {
		log_nss_error(RC_LOG, st->st_logger,
			      "verifying AUTH hash using PK11_Verify() failed:");
		PORT_FreeArena(arena, PR_FALSE);
		SECITEM_FreeItem(raw_signature, PR_TRUE);
		return "1" "NSS error: Not able to verify";
	}

	dbg("NSS: verified signature");

	SECITEM_FreeItem(raw_signature, PR_TRUE);
	unreference_key(&st->st_peer_pubkey);
	st->st_peer_pubkey = reference_key(kr);

	return NULL;
}

stf_status ikev2_verify_ecdsa_hash(struct ike_sa *ike,
				   const struct crypt_mac *idhash,
				   pb_stream *sig_pbs,
				   const struct hash_desc *hash_algo)
{
	if (hash_algo->common.ikev2_alg_id < 0) {
		return STF_FATAL;
	}

	struct crypt_mac calc_hash = v2_calculate_sighash(ike, idhash, hash_algo,
							  REMOTE_PERSPECTIVE);
	return check_signature_gen(&ike->sa, &calc_hash, sig_pbs, hash_algo,
				   &pubkey_type_ecdsa, try_ECDSA_signature_v2);
}
