/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is PRIVATE to SSL.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef __tls13ech_h_
#define __tls13ech_h_

#include "pk11hpke.h"

/* draft-08, shared-mode only.
 * Notes on the implementation status:
 * - Padding (https://tools.ietf.org/html/draft-ietf-tls-esni-08#section-6.2),
 *   is not implemented (see bug 1677181).
 * - When multiple ECHConfigs are provided by the server, the first compatible
 *   config is selected by the client. Ciphersuite choices are limited and only
 *   the AEAD may vary (AES-128-GCM or ChaCha20Poly1305).
 * - Some of the buffering (construction/compression/decompression) could likely
 *   be optimized, but the spec is still evolving so that work is deferred.
 */
#define TLS13_ECH_VERSION 0xfe08
#define TLS13_ECH_SIGNAL_LEN 8

static const char kHpkeInfoEch[] = "tls ech";
static const char kHpkeInfoEchHrr[] = "tls ech hrr key";
static const char kHpkeLabelHrrPsk[] = "hrr key";
static const char hHkdfInfoEchConfigID[] = "tls ech config id";
static const char kHkdfInfoEchConfirm[] = "ech accept confirmation";

struct sslEchConfigContentsStr {
    char *publicName;
    SECItem publicKey; /* NULL on server. Use the keypair in sslEchConfig instead. */
    HpkeKemId kemId;
    HpkeKdfId kdfId;
    HpkeAeadId aeadId;
    SECItem suites; /* One or more HpkeCipherSuites. The selected s
                     * suite is placed in kdfId and aeadId. */
    PRUint16 maxNameLen;
    /* No supported extensions. */
};

struct sslEchConfigStr {
    PRCList link;
    SECItem raw;
    PRUint8 configId[32];
    PRUint16 version;
    sslEchConfigContents contents;
};

SECStatus SSLExp_EncodeEchConfig(const char *publicName, const PRUint32 *hpkeSuites,
                                 unsigned int hpkeSuiteCount, HpkeKemId kemId,
                                 const SECKEYPublicKey *pubKey, PRUint16 maxNameLen,
                                 PRUint8 *out, unsigned int *outlen, unsigned int maxlen);
SECStatus SSLExp_GetEchRetryConfigs(PRFileDesc *fd, SECItem *retryConfigs);
SECStatus SSLExp_SetClientEchConfigs(PRFileDesc *fd, const PRUint8 *echConfigs,
                                     unsigned int echConfigsLen);
SECStatus SSLExp_SetServerEchConfigs(PRFileDesc *fd,
                                     const SECKEYPublicKey *pubKey, const SECKEYPrivateKey *privKey,
                                     const PRUint8 *echConfigs, unsigned int numEchConfigs);
SECStatus SSLExp_RemoveEchConfigs(PRFileDesc *fd);

SECStatus tls13_ClientSetupEch(sslSocket *ss, sslClientHelloType type);
SECStatus tls13_ConstructClientHelloWithEch(sslSocket *ss, const sslSessionID *sid,
                                            PRBool freshSid, sslBuffer *chOuterBuf,
                                            sslBuffer *chInnerXtnsBuf);
SECStatus tls13_CopyEchConfigs(PRCList *oconfigs, PRCList *configs);
SECStatus tls13_DecodeEchConfigs(const SECItem *data, PRCList *configs);
void tls13_DestroyEchConfigs(PRCList *list);
SECStatus tls13_GetMatchingEchConfig(const sslSocket *ss, HpkeKdfId kdf, HpkeAeadId aead,
                                     const SECItem *configId, sslEchConfig **cfg);
SECStatus tls13_MaybeHandleEch(sslSocket *ss, const PRUint8 *msg, PRUint32 msgLen, SECItem *sidBytes,
                               SECItem *comps, SECItem *cookieBytes, SECItem *suites, SECItem **echInner);
SECStatus tls13_MaybeHandleEchSignal(sslSocket *ss);
SECStatus tls13_MaybeAcceptEch(sslSocket *ss, const SECItem *sidBytes, const PRUint8 *chOuter,
                               unsigned int chOuterLen, SECItem **chInner);
SECStatus tls13_MaybeGreaseEch(sslSocket *ss, unsigned int prefixLen, sslBuffer *buf);
SECStatus tls13_WriteServerEchSignal(sslSocket *ss);

#endif