text: /*-
   * Copyright (c) 2013 Varnish Software AS
   * All rights reserved.
   *
   * Author: Poul-Henning Kamp <phk@FreeBSD.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include "config.h"
  
  #include <math.h>
  #include <stdlib.h>
  
  #include "cache/cache.h"
  #include "cache/cache_backend.h"
  
  #include "vrt.h"
  #include "vbm.h"
  #include "vend.h"
  #include "vsha256.h"
  
  #include "vdir.h"
  
  #include "vcc_if.h"
  
  struct vmod_directors_hash {
  	unsigned				magic;
  #define VMOD_DIRECTORS_HASH_MAGIC		0xc08dd611
  	struct vdir				*vd;
  	unsigned				nloops;
  	struct vbitmap				*vbm;
  };
  
  VCL_VOID __match_proto__()
  vmod_hash__init(const struct vrt_ctx *ctx, struct vmod_directors_hash **rrp,
      const char *vcl_name)
  {
  	struct vmod_directors_hash *rr;
  
  	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
  	AN(rrp);
  	AZ(*rrp);
  	ALLOC_OBJ(rr, VMOD_DIRECTORS_HASH_MAGIC);
  	AN(rr);
  	rr->vbm = vbit_init(8);
  	AN(rr->vbm);
  	rr->nloops = 3; //
  	*rrp = rr;
  	vdir_new(&rr->vd, vcl_name, NULL, NULL, rr);
  }
  
  VCL_VOID __match_proto__()
  vmod_hash__fini(struct vmod_directors_hash **rrp)
  {
  	struct vmod_directors_hash *rr;
  
  	rr = *rrp;
  	*rrp = NULL;
  	CHECK_OBJ_NOTNULL(rr, VMOD_DIRECTORS_HASH_MAGIC);
  	vdir_delete(&rr->vd);
  	vbit_destroy(rr->vbm);
  	FREE_OBJ(rr);
  }
  
  VCL_VOID __match_proto__()
  vmod_hash_add_backend(const struct vrt_ctx *ctx,
      struct vmod_directors_hash *rr, VCL_BACKEND be, double w)
  {
  
  	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
  	CHECK_OBJ_NOTNULL(rr, VMOD_DIRECTORS_HASH_MAGIC);
  	(void)vdir_add_backend(rr->vd, be, w);
  }
  
  VCL_BACKEND __match_proto__()
  vmod_hash_backend(const struct vrt_ctx *ctx, struct vmod_directors_hash *rr,
      const char *arg, ...)
  {
  	struct SHA256Context sha_ctx;
  	va_list ap;
  	const char *p;
  	unsigned char sha256[SHA256_LEN];
  	VCL_BACKEND be;
  	double r;
  
  	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
  
  	CHECK_OBJ_NOTNULL(rr, VMOD_DIRECTORS_HASH_MAGIC);
  	SHA256_Init(&sha_ctx);
  	va_start(ap, arg);
  	p = arg;
  	while (p != vrt_magic_string_end) {
  		SHA256_Update(&sha_ctx, arg, strlen(arg));
  		p = va_arg(ap, const char *);
  	}
  	va_end(ap);
  	SHA256_Final(sha256, &sha_ctx);
  
  	r = vbe32dec(sha256);
  	r = scalbn(r, -32);
  	assert(r >= 0 && r <= 1.0);
  	be = vdir_pick_be(rr->vd, r, rr->nloops);
  	return (be);
  }
  