#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/cbcmac.h>

struct CBCMAC_CTX_st {
	EVP_CIPHER_CTX cipher_ctx;
	unsigned char cbcstate[EVP_MAX_BLOCK_LENGTH];
	unsigned char workspace[EVP_MAX_BLOCK_LENGTH];
	int worklen;
};


CBCMAC_CTX *CBCMAC_CTX_new(void)
{
	CBCMAC_CTX *ret;

	if (!(ret = OPENSSL_malloc(sizeof(*ret)))) {
		return NULL;
	}

	EVP_CIPHER_CTX_init(&ret->cipher_ctx);

	return ret;
}

void CBCMAC_CTX_cleanup(CBCMAC_CTX *ctx)
{
	EVP_CIPHER_CTX_cleanup(&ctx->cipher_ctx);
	OPENSSL_cleanse(ctx->cbcstate, EVP_MAX_BLOCK_LENGTH);
	OPENSSL_cleanse(ctx->workspace, EVP_MAX_BLOCK_LENGTH);
}

EVP_CIPHER_CTX *CBCMAC_CTX_get0_cipher_ctx(CBCMAC_CTX *ctx)
{
	return &ctx->cipher_ctx;
}

void CBCMAC_CTX_free(CBCMAC_CTX *ctx)
{
	if (ctx) {
		CBCMAC_CTX_cleanup(ctx);
		OPENSSL_free(ctx);
	}
}

int CBCMAC_CTX_copy(CBCMAC_CTX *to, const CBCMAC_CTX *from)
{
	return 0;
}

int CBCMAC_Init(CBCMAC_CTX *ctx, const void *key, size_t keylen,
	const EVP_CIPHER *cipher, ENGINE *eng)
{
	int i, block_size;
	
	if (!EVP_EncryptInit_ex(&ctx->cipher_ctx, cipher, eng, key, NULL)) {
		CBCMACerr(CBCMAC_F_CBCMAC_INIT, CBCMAC_R_CIPHER_CTX_INIT_FAILED);
		return 0;
	}
	if (EVP_CIPHER_CTX_mode(&ctx->cipher_ctx) != EVP_CIPH_ECB_MODE) {
		CBCMACerr(CBCMAC_F_CBCMAC_INIT, CBCMAC_R_CIPHER_NOT_ECB_MODE);
		return 0;
	}
	ctx->worklen = 0;
	block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
	bzero(ctx->cbcstate, block_size);
	return 0;
}

int CBCMAC_Update(CBCMAC_CTX *ctx, const void *data, size_t datalen)
{
	int block_size;
	int i, n, len;
	const unsigned char *in = (const unsigned char *)data;

	block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);

	
	if (ctx->worklen) {
		n = block_size - ctx->worklen;
		if (datalen < n) {
			for (i = 0; i < datalen; i++) {
				ctx->workspace[ctx->worklen + i] = in[i];
			}
			ctx->worklen += datalen;
			return 0;
		} else {
			for (i = 0; i < n; i++) {
				ctx->workspace[ctx->worklen + i] = in[i] ^ ctx->cbcstate[i];
			}
			if (!EVP_EncryptUpdate(&ctx->cipher_ctx, ctx->cbcstate, &len,
				ctx->workspace, block_size)) {
				CBCMACerr(CBCMAC_F_CBCMAC_UPDATE, ERR_R_EVP_LIB);
				return 0;
			}
		}

		while (n < datalen) {
			for (i = 0; i < block_size; i++) {
				ctx->workspace[i] = in[n + i] ^ ctx->cbcstate[i];
			}
			n += block_size;
		
			if (!EVP_EncryptUpdate(&ctx->cipher_ctx, ctx->cbcstate, &len,
				ctx->workspace, block_size)) {
				return 0;
			}
		}

		ctx->worklen = datalen - n;
		
		for (i = 0; i < ctx->worklen; i++) {
			ctx->workspace[i] = in[n + i];
		}

	}


	return 0;
}

int CBCMAC_Final(CBCMAC_CTX *ctx, unsigned char *out, size_t *outlen)
{
	int i;
	int block_size = EVP_CIPHER_CTX_block_size(&(ctx->cipher_ctx));

	if (ctx->worklen) {
		for (i = ctx->worklen; i < block_size; i++) {
			ctx->workspace[i] = ctx->cbcstate[i];
		}
		if (!EVP_EncryptUpdate(&(ctx->cipher_ctx), out, outlen, ctx->workspace, block_size)) {
			CBCMACerr(CBCMAC_F_CBCMAC_FINAL, ERR_R_EVP_LIB);
			return 0;
		}

	} else {
		for (i = 0; i < block_size; i++) {
			out[i] = ctx->cbcstate[i];
		}
	}

	return 1;
}

int CBCMAC_resume(CBCMAC_CTX *ctx)
{
	return 0;
}