/*
 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <limits.h>
#include <string.h>

#include <openssl/ct.h>
#include <openssl/err.h>
#include <openssl/evp.h>

#include "ct_local.h"

/*
 * Decodes the base64 string |in| into |out|.
 * A new string will be malloc'd and assigned to |out|. This will be owned by
 * the caller. Do not provide a pre-allocated string in |out|.
 */
static int ct_base64_decode(const char *in, unsigned char **out)
{
    size_t inlen = strlen(in);
    int outlen, i;
    unsigned char *outbuf = NULL;

    if (inlen == 0) {
        *out = NULL;
        return 0;
    }

    outlen = (inlen / 4) * 3;
    outbuf = OPENSSL_malloc(outlen);
    if (outbuf == NULL) {
        CTerr(CT_F_CT_BASE64_DECODE, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    outlen = EVP_DecodeBlock(outbuf, (unsigned char *)in, inlen);
    if (outlen < 0) {
        CTerr(CT_F_CT_BASE64_DECODE, CT_R_BASE64_DECODE_ERROR);
        goto err;
    }

    /* Subtract padding bytes from |outlen|.  Any more than 2 is malformed. */
    i = 0;
    while (in[--inlen] == '=') {
        --outlen;
        if (++i > 2)
            goto err;
    }

    *out = outbuf;
    return outlen;
err:
    OPENSSL_free(outbuf);
    return -1;
}

SCT *SCT_new_from_base64(unsigned char version, const char *logid_base64,
                         ct_log_entry_type_t entry_type, uint64_t timestamp,
                         const char *extensions_base64,
                         const char *signature_base64)
{
    SCT *sct = SCT_new();
    unsigned char *dec = NULL;
    const unsigned char* p = NULL;
    int declen;

    if (sct == NULL) {
        CTerr(CT_F_SCT_NEW_FROM_BASE64, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    /*
     * RFC6962 section 4.1 says we "MUST NOT expect this to be 0", but we
     * can only construct SCT versions that have been defined.
     */
    if (!SCT_set_version(sct, version)) {
        CTerr(CT_F_SCT_NEW_FROM_BASE64, CT_R_SCT_UNSUPPORTED_VERSION);
        goto err;
    }

    declen = ct_base64_decode(logid_base64, &dec);
    if (declen < 0) {
        CTerr(CT_F_SCT_NEW_FROM_BASE64, X509_R_BASE64_DECODE_ERROR);
        goto err;
    }
    if (!SCT_set0_log_id(sct, dec, declen))
        goto err;
    dec = NULL;

    declen = ct_base64_decode(extensions_base64, &dec);
    if (declen < 0) {
        CTerr(CT_F_SCT_NEW_FROM_BASE64, X509_R_BASE64_DECODE_ERROR);
        goto err;
    }
    SCT_set0_extensions(sct, dec, declen);
    dec = NULL;

    declen = ct_base64_decode(signature_base64, &dec);
    if (declen < 0) {
        CTerr(CT_F_SCT_NEW_FROM_BASE64, X509_R_BASE64_DECODE_ERROR);
        goto err;
    }

    p = dec;
    if (o2i_SCT_signature(sct, &p, declen) <= 0)
        goto err;
    OPENSSL_free(dec);
    dec = NULL;

    SCT_set_timestamp(sct, timestamp);

    if (!SCT_set_log_entry_type(sct, entry_type))
        goto err;

    return sct;

 err:
    OPENSSL_free(dec);
    SCT_free(sct);
    return NULL;
}

/*
 * Allocate, build and returns a new |ct_log| from input |pkey_base64|
 * It returns 1 on success,
 * 0 on decoding failure, or invalid parameter if any
 * -1 on internal (malloc) failure
 */
int CTLOG_new_from_base64(CTLOG **ct_log, const char *pkey_base64, const char *name)
{
    unsigned char *pkey_der = NULL;
    int pkey_der_len;
    const unsigned char *p;
    EVP_PKEY *pkey = NULL;

    if (ct_log == NULL) {
        CTerr(CT_F_CTLOG_NEW_FROM_BASE64, ERR_R_PASSED_INVALID_ARGUMENT);
        return 0;
    }

    pkey_der_len = ct_base64_decode(pkey_base64, &pkey_der);
    if (pkey_der_len < 0) {
        CTerr(CT_F_CTLOG_NEW_FROM_BASE64, CT_R_LOG_CONF_INVALID_KEY);
        return 0;
    }

    p = pkey_der;
    pkey = d2i_PUBKEY(NULL, &p, pkey_der_len);
    OPENSSL_free(pkey_der);
    if (pkey == NULL) {
        CTerr(CT_F_CTLOG_NEW_FROM_BASE64, CT_R_LOG_CONF_INVALID_KEY);
        return 0;
    }

    *ct_log = CTLOG_new(pkey, name);
    if (*ct_log == NULL) {
        EVP_PKEY_free(pkey);
        return 0;
    }

    return 1;
}