Function pg_hmac_create

src/common/hmac.c:66–122

* pg_hmac_create * * Allocate a hash context. Returns NULL on failure for an OOM. The * backend issues an error, without returning. */

 * backend issues an error, without returning.
 */
pg_hmac_ctx *
pg_hmac_create(pg_cryptohash_type type)
{
	pg_hmac_ctx *ctx;

	ctx = ALLOC(sizeof(pg_hmac_ctx));
	if (ctx == NULL)
		return NULL;
	memset(ctx, 0, sizeof(pg_hmac_ctx));
	ctx->type = type;

	/*
	 * Initialize the context data.  This requires to know the digest and
	 * block lengths, that depend on the type of hash used.
	 */
	switch (type)
	{
		case PG_MD5:
			ctx->digest_size = MD5_DIGEST_LENGTH;
			ctx->block_size = MD5_BLOCK_SIZE;
			break;
		case PG_SHA1:
			ctx->digest_size = SHA1_DIGEST_LENGTH;
			ctx->block_size = SHA1_BLOCK_SIZE;
			break;
		case PG_SHA224:
			ctx->digest_size = PG_SHA224_DIGEST_LENGTH;
			ctx->block_size = PG_SHA224_BLOCK_LENGTH;
			break;
		case PG_SHA256:
			ctx->digest_size = PG_SHA256_DIGEST_LENGTH;
			ctx->block_size = PG_SHA256_BLOCK_LENGTH;
			break;
		case PG_SHA384:
			ctx->digest_size = PG_SHA384_DIGEST_LENGTH;
			ctx->block_size = PG_SHA384_BLOCK_LENGTH;
			break;
		case PG_SHA512:
			ctx->digest_size = PG_SHA512_DIGEST_LENGTH;
			ctx->block_size = PG_SHA512_BLOCK_LENGTH;
			break;
		case PG_SM3:
			ctx->digest_size = PG_SM3_DIGEST_LENGTH;
			ctx->block_size = PG_SM3_BLOCK_LENGTH;
			break;
	}

	ctx->hash = pg_cryptohash_create(type);
	if (ctx->hash == NULL)
	{
		explicit_bzero(ctx, sizeof(pg_hmac_ctx));
		FREE(ctx);
		return NULL;
	}

	return ctx;
}