/*-
 * Copyright (c) 2006 Verdens Gang AS
 * Copyright (c) 2006-2015 Varnish Software AS
 * All rights reserved.
 *
 * Author: Poul-Henning Kamp <phk@phk.freebsd.dk>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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 "cache_varnishd.h"
#include "cache_filter.h"
#include "cache_objhead.h"

void
VDP_Panic(struct vsb *vsb, const struct vdp_ctx *vdc)
{
	struct vdp_entry *vde;

	if (PAN_dump_struct(vsb, vdc, VDP_CTX_MAGIC, "vdc"))
		return;
	VSB_printf(vsb, "nxt = %p,\n", vdc->nxt);
	VSB_printf(vsb, "retval = %d,\n", vdc->retval);

	if (!VTAILQ_EMPTY(&vdc->vdp)) {
		VSB_cat(vsb, "filters = {\n");
		VSB_indent(vsb, 2);
		VTAILQ_FOREACH(vde, &vdc->vdp, list)
			VSB_printf(vsb, "%s = %p { priv = %p }\n",
			    vde->vdp->name, vde, vde->priv);
		VSB_indent(vsb, -2);
		VSB_cat(vsb, "},\n");
	}

	VSB_indent(vsb, -2);
	VSB_cat(vsb, "},\n");
}

/*
 * Ensure that transports have called VDP_Close()
 * to avoid leaks in VDPs
 */
void
VDP_Fini(const struct vdp_ctx *vdc)
{
	assert(VTAILQ_EMPTY(&vdc->vdp));
}

void
VDP_Init(struct vdp_ctx *vdc, struct worker *wrk, struct vsl_log *vsl,
    const struct req *req, const struct busyobj *bo, intmax_t *clen)
{
	AN(vdc);
	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
	AN(vsl);

	AN(clen);

	assert((req ? 1 : 0) ^ (bo ? 1 : 0));

	AN(clen);
	assert(*clen >= -1);

	INIT_OBJ(vdc, VDP_CTX_MAGIC);
	VTAILQ_INIT(&vdc->vdp);
	vdc->wrk = wrk;
	vdc->vsl = vsl;
	vdc->clen = clen;

	if (req != NULL) {
		CHECK_OBJ(req, REQ_MAGIC);
		vdc->oc = req->objcore;
		vdc->hp = req->resp;
	}
	else {
		CHECK_OBJ_NOTNULL(bo, BUSYOBJ_MAGIC);
		vdc->oc = bo->bereq_body;
		vdc->hp = bo->bereq;
	}
}

/* VDP_bytes
 *
 * Pushes len bytes at ptr down the delivery processor list.
 *
 * This function picks and calls the next delivery processor from the
 * list. The return value is the return value of the delivery
 * processor. Upon seeing a non-zero return value, that lowest value
 * observed is latched in ->retval and all subsequent calls to
 * VDP_bytes will return that value directly without calling the next
 * processor.
 *
 * VDP_END marks the end of successful processing, it is issued by
 * VDP_DeliverObj() and may also be sent downstream by processors ending the
 * stream (for return value != 0)
 *
 * VDP_END must at most be received once per processor, so any VDP sending it
 * downstream must itself not forward it a second time.
 *
 * Valid return values (of VDP_bytes and any VDP function):
 * r < 0:  Error, breaks out early on an error condition
 * r == 0: Continue
 * r > 0:  Stop, breaks out early without error condition
 */

int
VDP_bytes(struct vdp_ctx *vdc, enum vdp_action act,
    const void *ptr, ssize_t len)
{
	int retval;
	struct vdp_entry *vdpe;

	CHECK_OBJ_NOTNULL(vdc, VDP_CTX_MAGIC);
	if (vdc->retval)
		return (vdc->retval);
	vdpe = vdc->nxt;
	CHECK_OBJ_NOTNULL(vdpe, VDP_ENTRY_MAGIC);

	/* at most one VDP_END call */
	assert(vdpe->end == VDP_NULL);

	if (act == VDP_NULL)
		assert(len > 0);
	else if (act == VDP_END)
		vdpe->end = VDP_END;
	else
		assert(act == VDP_FLUSH);

	/* Call the present layer, while pointing to the next layer down */
	vdc->nxt = VTAILQ_NEXT(vdpe, list);
	vdpe->calls++;
	vdc->bytes_done = len;
	retval = vdpe->vdp->bytes(vdc, act, &vdpe->priv, ptr, len);
	vdpe->bytes_in += vdc->bytes_done;
	if (retval && (vdc->retval == 0 || retval < vdc->retval))
		vdc->retval = retval; /* Latch error value */
	vdc->nxt = vdpe;
	return (vdc->retval);
}

int
VDP_Push(VRT_CTX, struct vdp_ctx *vdc, struct ws *ws, const struct vdp *vdp,
    void *priv)
{
	struct vdp_entry *vdpe;

	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
	CHECK_OBJ_NOTNULL(vdc, VDP_CTX_MAGIC);
	CHECK_OBJ_ORNULL(vdc->oc, OBJCORE_MAGIC);
	CHECK_OBJ_NOTNULL(vdc->hp, HTTP_MAGIC);
	AN(vdc->clen);
	assert(*vdc->clen >= -1);
	AN(ws);
	AN(vdp);
	AN(vdp->name);

	if (vdc->retval)
		return (vdc->retval);

	if (DO_DEBUG(DBG_PROCESSORS))
		VSLb(vdc->vsl, SLT_Debug, "VDP_push(%s)", vdp->name);

	vdpe = WS_Alloc(ws, sizeof *vdpe);
	if (vdpe == NULL) {
		AZ(vdc->retval);
		vdc->retval = -1;
		return (vdc->retval);
	}
	INIT_OBJ(vdpe, VDP_ENTRY_MAGIC);
	vdpe->vdp = vdp;
	vdpe->priv = priv;
	VTAILQ_INSERT_TAIL(&vdc->vdp, vdpe, list);
	vdc->nxt = VTAILQ_FIRST(&vdc->vdp);

	AZ(vdc->retval);
	if (vdpe->vdp->init != NULL)
		vdc->retval = vdpe->vdp->init(ctx, vdc, &vdpe->priv);
	vdc->oc = NULL;

	if (vdc->retval > 0) {
		VTAILQ_REMOVE(&vdc->vdp, vdpe, list);
		vdc->nxt = VTAILQ_FIRST(&vdc->vdp);
		vdc->retval = 0;
	}
	else if (vdc->retval == 0)
		AN(vdp->bytes);
	return (vdc->retval);
}

uint64_t
VDP_Close(struct vdp_ctx *vdc, struct objcore *oc, struct boc *boc)
{
	struct vdp_entry *vdpe;
	uint64_t rv = 0;

	CHECK_OBJ_NOTNULL(vdc, VDP_CTX_MAGIC);
	CHECK_OBJ_NOTNULL(vdc->wrk, WORKER_MAGIC);
	CHECK_OBJ_ORNULL(oc, OBJCORE_MAGIC);
	CHECK_OBJ_ORNULL(boc, BOC_MAGIC);

	while ((vdpe = VTAILQ_FIRST(&vdc->vdp)) != NULL) {
		CHECK_OBJ(vdpe, VDP_ENTRY_MAGIC);
		rv = vdpe->bytes_in;
		VSLb(vdc->vsl, SLT_VdpAcct, "%s %ju %ju", vdpe->vdp->name,
		    (uintmax_t)vdpe->calls, (uintmax_t)rv);
		if (vdpe->vdp->fini != NULL)
			AZ(vdpe->vdp->fini(vdc, &vdpe->priv));
		AZ(vdpe->priv);
		VTAILQ_REMOVE(&vdc->vdp, vdpe, list);
		vdc->nxt = VTAILQ_FIRST(&vdc->vdp);
#ifdef VDP_PEDANTIC_ARMED
		// enable when we are confident to get VDP_END right
		if (vdc->nxt == NULL && vdc->retval >= 0)
			assert(vdpe->end == VDP_END);
#endif
	}
	if (oc != NULL)
		HSH_Cancel(vdc->wrk, oc, boc);
	return (rv);
}

/*--------------------------------------------------------------------*/

int v_matchproto_(objiterate_f)
VDP_ObjIterate(void *priv, unsigned flush, const void *ptr, ssize_t len)
{
	enum vdp_action act;

	if (flush == 0)
		act = VDP_NULL;
	else if ((flush & OBJ_ITER_END) != 0)
		act = VDP_END;
	else
		act = VDP_FLUSH;

	return (VDP_bytes(priv, act, ptr, len));
}


int
VDP_DeliverObj(struct vdp_ctx *vdc, struct objcore *oc)
{
	int r, final;

	CHECK_OBJ_NOTNULL(vdc, VDP_CTX_MAGIC);
	CHECK_OBJ_NOTNULL(oc, OBJCORE_MAGIC);
	CHECK_OBJ_NOTNULL(vdc->wrk, WORKER_MAGIC);
	AN(vdc->vsl);
	AZ(vdc->oc);
	vdc->hp = NULL;
	vdc->clen = NULL;
	final = oc->flags & OC_F_TRANSIENT ? 1 : 0;
	r = ObjIterate(vdc->wrk, oc, vdc, VDP_ObjIterate, final);
	if (r < 0)
		return (r);
	return (0);
}
