housecarl/internal/server/h_config.go

package server

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/netip"
	"sort"
	"strconv"
	"strings"

	udiff "github.com/aymanbagabas/go-udiff"

	"housecarl/internal/api"
	"housecarl/internal/auth"
	"housecarl/internal/engine"
	"housecarl/internal/matrix"
	"housecarl/internal/model"
	"housecarl/internal/nft"
	"housecarl/internal/store"
)

// change makes an operation: at once through the engine, or, with a
// changeset named (?changeset=ID or X-Housecarl-Changeset), staged in it.
// A network change starts (or joins) the probation.
func (s *Server) change(w http.ResponseWriter, r *http.Request, p *auth.Principal, op model.Op) error {
	if err := require(p, auth.ResConfig, true); err != nil {
		return err
	}
	if op.Op == model.OpCreate && op.ID == 0 {
		ids, err := s.store.AllocateIDs(r.Context(), 1)
		if err != nil {
			return err
		}
		op.ID = ids[0]
	}
	csID, err := changesetParam(r)
	if err != nil {
		return err
	}
	if csID != 0 {
		return s.stage(w, r, p, csID, op)
	}
	var id int64
	res, err := s.eng.Apply(r.Context(), p, "", engine.Options{DryRun: queryBool(r, "dry_run"), Via: via(r, p)}, func(st *model.State, _ func() int64) error {
		var err error
		id, err = applyOp(st, &op)
		return err
	})
	if err != nil {
		s.writeErr(w, r, err, res)
		return nil
	}
	s.afterChange(r.Context(), p, res)
	out := s.mutation(res, objectOf(&op, id))
	out.ConfirmToken = s.issueCheck(w, r, p, res)
	writeJSON(w, s.mutationStatus(res, op.Op == model.OpCreate), out)
	return nil
}

// mutation is the answer to a change: what changed, warnings, the object
// (as it is after the change), the probation, and for a dry run the
// ruleset's diff.
func (s *Server) mutation(res *engine.Result, object func(st *model.State) any) api.MutationResponse {
	out := api.MutationResponse{Applied: res.Applied, DryRun: res.DryRun, HistoryID: res.HistoryID, Changes: res.Changes, Warnings: res.Warnings}
	if out.Changes == nil {
		out.Changes = []model.Change{}
	}
	if pr := s.probationStatus(); res.Applied && (len(pr.Pending) > 0 || pr.Takeovers > 0) {
		out.ConfirmBy = &pr.Deadline
	}
	if object != nil && res.After != nil && (res.Applied || res.DryRun) {
		if v := object(res.After); v != nil {
			out.Object, _ = json.Marshal(v)
		}
	}
	if res.DryRun && len(res.Changes) > 0 {
		out.Diff = s.rulesetDiff(res.Before, res.After)
	}
	return out
}

// mutationStatus is 201 for an applied create, else 200.
func (s *Server) mutationStatus(res *engine.Result, creates bool) int {
	if res.Applied && creates {
		return http.StatusCreated
	}
	return http.StatusOK
}

// respondChange answers a change made without an operation (undo).
func (s *Server) respondChange(w http.ResponseWriter, r *http.Request, p *auth.Principal, res *engine.Result, object func(st *model.State) any, creates bool) {
	out := s.mutation(res, object)
	out.ConfirmToken = s.issueCheck(w, r, p, res)
	writeJSON(w, s.mutationStatus(res, creates), out)
}

// rulesetDiff is the unified diff of the rulesets two configurations
// make: the file housecarl-ruleset.service loads, now and after.
func (s *Server) rulesetDiff(before, after *model.State) string {
	return s.labeledDiff(before, after, "now", "after")
}

// labeledDiff is rulesetDiff with its own names for the two sides.
func (s *Server) labeledDiff(before, after *model.State, from, to string) string {
	if before == nil || after == nil {
		return ""
	}
	now, then := s.fw.Render(before).Text, s.fw.Render(after).Text
	diff := hunkStarts(udiff.Unified("ruleset.nft ("+from+")", "ruleset.nft ("+to+")", now, then))
	return blockHeaders(diff, now, then)
}

// hunkStarts numbers each hunk's new side again, from its old side and
// the lines the hunks before it added and removed. go-udiff (v0.4.1)
// leaves out of its count the unchanged lines between two edits of one
// hunk, so after a hunk like a moved line every later one started too
// early ("@@ -76,9 +74,9 @@" for "+76,9"), and blockHeaders named the
// chain before it.
func hunkStarts(diff string) string {
	lines := strings.SplitAfter(diff, "\n")
	delta := 0
	for i := 0; i < len(lines); i++ {
		f := strings.Fields(lines[i])
		if !strings.HasPrefix(lines[i], "@@ ") || len(f) < 4 || f[3] != "@@" {
			continue
		}
		start, _, _ := strings.Cut(f[1][1:], ",")
		from, err := strconv.Atoi(start)
		if err != nil {
			continue
		}
		oldN, newN := 0, 0
		for _, l := range lines[i+1:] {
			if strings.HasPrefix(l, "@@ ") {
				break
			}
			switch {
			case strings.HasPrefix(l, "-"):
				oldN++
			case strings.HasPrefix(l, "+"):
				newN++
			case strings.HasPrefix(l, " "):
				oldN++
				newN++
			}
		}
		// An empty side is numbered by the line before it.
		first := from
		if oldN == 0 {
			first++
		}
		to := first + delta
		if newN == 0 {
			to--
		}
		side := "+" + strconv.Itoa(to)
		if newN > 1 {
			side += "," + strconv.Itoa(newN)
		}
		f[2] = side
		lines[i] = strings.Join(f, " ") + "\n"
		delta += newN - oldN
	}
	return strings.Join(lines, "")
}

// blockHeaders names, after each hunk's @@ line, the chain (or other
// block of the table) the hunk starts in, as git names the function:
// "@@ -40,6 +40,8 @@ chain forward". Without it a change deep in a long
// chain doesn't say which chain it is in.
func blockHeaders(diff, now, then string) string {
	if diff == "" {
		return diff
	}
	oldBlocks, newBlocks := enclosingBlocks(now), enclosingBlocks(then)
	lines := strings.SplitAfter(diff, "\n")
	for i, l := range lines {
		if !strings.HasPrefix(l, "@@ ") {
			continue
		}
		// "@@ -a,b +c,d @@": the new side's start, or the old side's
		// when nothing of the hunk is left.
		f := strings.Fields(l)
		if len(f) < 4 || f[3] != "@@" {
			continue
		}
		block := blockAt(newBlocks, f[2])
		if block == "" {
			block = blockAt(oldBlocks, f[1])
		}
		if block != "" {
			lines[i] = strings.TrimRight(l, "\n") + " " + block + "\n"
		}
	}
	return strings.Join(lines, "")
}

// enclosingBlocks gives each line of a rendered ruleset the block of the
// table it is in ("chain input"), "" outside one. A block opens with a
// line of one tab ending in "{" and closes with "\t}".
func enclosingBlocks(text string) []string {
	var out []string
	cur := ""
	for _, l := range strings.Split(text, "\n") {
		if strings.HasPrefix(l, "\t") && !strings.HasPrefix(l, "\t\t") && strings.HasSuffix(l, "{") {
			cur = strings.TrimSpace(strings.TrimSuffix(l, "{"))
		}
		out = append(out, cur)
		if l == "\t}" {
			cur = ""
		}
	}
	return out
}

// blockAt is the block at a hunk side's start ("+40,8" or "-40"); lines
// count from 1, and an empty side (",0") sits after its line.
func blockAt(blocks []string, side string) string {
	start, _, _ := strings.Cut(side[1:], ",")
	n, err := strconv.Atoi(start)
	if err != nil || n < 1 || n > len(blocks) {
		return ""
	}
	return blocks[n-1]
}

// kindOf maps the API's plural path names to kinds.
var kindOf = map[string]string{
	"zones": model.KindZone, "sets": model.KindSet, "services": model.KindService, "rules": model.KindRule,
	"forwards": model.KindForward, "snats": model.KindSNAT, "redirects": model.KindRedirect,
	"banlists": model.KindBanList,
}

func pathKind(r *http.Request) (string, error) {
	k, ok := kindOf[r.PathValue("kind")]
	if !ok {
		return "", &httpError{status: http.StatusNotFound, code: "not_found", msg: "no such API endpoint: " + r.URL.Path}
	}
	return k, nil
}

func findObject(st *model.State, kind, ref string) (model.Object, error) {
	if o := st.Find(kind, ref); o != nil {
		return o, nil
	}
	return nil, notFound("no %s %s", kind, ref)
}

// ---- objects

func (s *Server) listObjects(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	if kind == model.KindBanList && !p.Can(auth.ResConfig, false) {
		return s.listOwnBanLists(w, p)
	}
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	cur, st, draft, err := s.viewState(w, r)
	if err != nil {
		return err
	}
	out := []any{}
	c := r.URL.Query().Get("chain")
	if draft {
		// Marked new, changed or deleted.
		for _, o := range withPending(cur, st, kind) {
			if c != "" && kind == model.KindRule && o.(map[string]any)["chain"] != c {
				continue
			}
			out = append(out, o)
		}
	} else {
		for _, o := range st.Objects(kind) {
			if c != "" {
				if rule, ok := o.(*model.Rule); ok && rule.Chain != c {
					continue
				}
			}
			out = append(out, o)
		}
	}
	// Services: the built-in ones too, unless overridden.
	if kind == model.KindService && !queryBool(r, "own") {
		for _, b := range model.BuiltinServices() {
			if mine := st.Find(kind, b.Name); mine == nil {
				out = append(out, b)
			}
		}
		name := func(x any) string {
			if m, ok := x.(map[string]any); ok {
				n, _ := m["name"].(string)
				return n
			}
			return x.(*model.Service).Name
		}
		sort.SliceStable(out, func(i, j int) bool { return name(out[i]) < name(out[j]) })
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) getObject(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	// A program that bans into a list may read it (its grouping, times).
	if kind == model.KindBanList && !p.Can(auth.ResConfig, false) {
		b, err := s.banList(r, p, false)
		if err != nil {
			return err
		}
		writeJSON(w, http.StatusOK, b)
		return nil
	}
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	_, st, _, err := s.viewState(w, r)
	if err != nil {
		return err
	}
	o, err := findObject(st, kind, r.PathValue("ref"))
	if err != nil && kind == model.KindService {
		if b := model.BuiltinService(r.PathValue("ref")); b != nil {
			writeJSON(w, http.StatusOK, b)
			return nil
		}
	}
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, o)
	return nil
}

// decodeObject reads a kind's object from JSON (unknown fields refused).
func decodeObject(kind string, data []byte) (model.Object, error) {
	var o model.Object
	switch kind {
	case model.KindZone:
		o = &model.Zone{}
	case model.KindSet:
		o = &model.AddressSet{}
	case model.KindService:
		o = &model.Service{}
	case model.KindRule:
		o = &model.Rule{}
	case model.KindForward:
		o = &model.PortForward{}
	case model.KindSNAT:
		o = &model.SourceNAT{}
	case model.KindRedirect:
		o = &model.Redirect{}
	case model.KindBanList:
		o = &model.BanList{}
	}
	dec := json.NewDecoder(strings.NewReader(string(data)))
	dec.DisallowUnknownFields()
	if err := dec.Decode(o); err != nil {
		return nil, badRequest("%s: %v", kind, err)
	}
	return o, nil
}

// lastPosition is after the last rule of the chain (or NAT rule of the
// kind).
func lastPosition(st *model.State, kind, chain string) float64 {
	max := 0.0
	for _, o := range st.Objects(kind) {
		var pos float64
		switch x := o.(type) {
		case *model.Rule:
			if x.Chain != chain {
				continue
			}
			pos = x.Position
		case *model.PortForward:
			pos = x.Position
		case *model.SourceNAT:
			pos = x.Position
		case *model.Redirect:
			pos = x.Position
		}
		if pos > max {
			max = pos
		}
	}
	return max + 1
}

func setID(o model.Object, id int64) {
	switch x := o.(type) {
	case *model.Zone:
		x.ID = id
	case *model.AddressSet:
		x.ID = id
	case *model.Service:
		x.ID = id
	case *model.Rule:
		x.ID = id
	case *model.PortForward:
		x.ID = id
	case *model.SourceNAT:
		x.ID = id
	case *model.Redirect:
		x.ID = id
	case *model.BanList:
		x.ID = id
	}
}

func position(o model.Object) *float64 {
	switch x := o.(type) {
	case *model.Rule:
		return &x.Position
	case *model.PortForward:
		return &x.Position
	case *model.SourceNAT:
		return &x.Position
	case *model.Redirect:
		return &x.Position
	}
	return nil
}

func chainOf(o model.Object) string {
	if r, ok := o.(*model.Rule); ok {
		return r.Chain
	}
	return ""
}

func (s *Server) createObject(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	var raw json.RawMessage
	if err := decodeJSON(r, &raw); err != nil {
		return err
	}
	// Refuse a bad object now, not when it is applied.
	if _, err := decodeObject(kind, raw); err != nil {
		return err
	}
	op := model.Op{Op: model.OpCreate, Kind: kind, Data: raw}
	// ?before=ID, ?after=ID or ?first=1: where it goes in its order.
	q := r.URL.Query()
	var place api.MoveInput
	place.Before, _ = strconv.ParseInt(q.Get("before"), 10, 64)
	place.After, _ = strconv.ParseInt(q.Get("after"), 10, 64)
	if queryBool(r, "first") {
		place.To = "start"
	}
	if place.Before != 0 || place.After != 0 || place.To != "" {
		op.Place, _ = json.Marshal(place)
	}
	return s.change(w, r, p, op)
}

func (s *Server) updateObject(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	var patch map[string]json.RawMessage
	if err := decodeJSON(r, &patch); err != nil {
		return err
	}
	data, _ := json.Marshal(patch)
	return s.change(w, r, p, model.Op{Op: model.OpUpdate, Kind: kind, Ref: r.PathValue("ref"), Data: data})
}

func (s *Server) deleteObject(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	return s.change(w, r, p, model.Op{Op: model.OpDelete, Kind: kind, Ref: r.PathValue("ref")})
}

// usedBy names an object that refers to o (zones, sets and services are
// referred to by name), or "".
func usedBy(st *model.State, kind string, o model.Object) string {
	name := o.Label()
	has := func(list []string) bool {
		for _, x := range list {
			if strings.EqualFold(x, name) {
				return true
			}
		}
		return false
	}
	uses := func(m model.Match) bool {
		switch kind {
		case model.KindZone:
			return has(m.InZones) || has(m.OutZones)
		case model.KindSet:
			return has(m.Sources) || has(m.Destinations)
		case model.KindService:
			return has(m.Services)
		}
		return false
	}
	for _, x := range st.Rules {
		if uses(x.Match) {
			return x.Label()
		}
	}
	for _, x := range st.SNATs {
		if uses(x.Match) {
			return x.Label()
		}
	}
	for _, x := range st.Redirects {
		if uses(x.Match) {
			return x.Label()
		}
	}
	if kind == model.KindSet {
		for _, f := range st.Forwards {
			if has(f.Sources) || has(f.PublicAddresses) || has(f.HairpinSources) {
				return f.Label()
			}
		}
		for _, b := range st.BanLists {
			if has(b.Hosts) || has(b.Never) {
				return "ban list " + b.Name
			}
		}
	}
	return ""
}

// renameRefs makes every object that refers to a zone, set or service by
// its old name use the new one: renaming it changes them in the same
// change, so the history shows (and undoes) them together.
func renameRefs(st *model.State, kind, old, now string) {
	fix := func(list []string) {
		for i, x := range list {
			if strings.EqualFold(x, old) {
				list[i] = now
			}
		}
	}
	match := func(m *model.Match) {
		switch kind {
		case model.KindZone:
			fix(m.InZones)
			fix(m.OutZones)
		case model.KindSet:
			fix(m.Sources)
			fix(m.Destinations)
		case model.KindService:
			fix(m.Services)
		}
	}
	for _, x := range st.Rules {
		match(&x.Match)
	}
	for _, x := range st.SNATs {
		match(&x.Match)
	}
	for _, x := range st.Redirects {
		match(&x.Match)
	}
	if kind == model.KindSet {
		for _, f := range st.Forwards {
			fix(f.Sources)
			fix(f.PublicAddresses)
			fix(f.HairpinSources)
		}
		for _, b := range st.BanLists {
			fix(b.Hosts)
			fix(b.Never)
		}
	}
}

// moveObject reorders a rule or NAT rule (moveOp).
func (s *Server) moveObject(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	kind, err := pathKind(r)
	if err != nil {
		return err
	}
	var in api.MoveInput
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	data, _ := json.Marshal(in)
	return s.change(w, r, p, model.Op{Op: model.OpMove, Kind: kind, Ref: r.PathValue("ref"), Data: data})
}

// ---- settings

func (s *Server) getSettings(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	_, st, _, err := s.viewState(w, r)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, st.Settings)
	return nil
}

func (s *Server) updateSettings(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	var patch map[string]json.RawMessage
	if err := decodeJSON(r, &patch); err != nil {
		return err
	}
	data, _ := json.Marshal(patch)
	return s.change(w, r, p, model.Op{Op: model.OpSettings, Data: data})
}

// ---- the zone matrix

// zoneMatrix answers what the rules do to new connections between zones
// (internal/matrix); with a changeset named, as it will make them.
func (s *Server) zoneMatrix(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	_, st, _, err := s.viewState(w, r)
	if err != nil {
		return err
	}
	m := matrix.Build(st, matrix.Options{Connected: s.connected(st)})
	if t, err := s.fw.Table(r.Context()); err == nil {
		matrixHits(&m, t.Counters)
	}
	writeJSON(w, http.StatusOK, m)
	return nil
}

// matrixHits fills in the hits of the matrix's rules, built-ins and
// policies from the counters.
func matrixHits(m *api.Matrix, counters map[string]nft.Counter) {
	hits := func(marks []string) *uint64 {
		var n uint64
		found := false
		for _, mk := range marks {
			if c, ok := counters[mk]; ok {
				n, found = n+c.Packets, true
			}
		}
		if !found {
			return nil
		}
		return &n
	}
	for i := range m.Cells {
		c := &m.Cells[i]
		c.Hits = hits(c.Marks)
		for j := range c.Exceptions {
			c.Exceptions[j].Hits = hits(c.Exceptions[j].Marks)
		}
	}
}

// connected maps the networks on the firewall's interfaces (link-local
// and loopback aside) to their zones.
// Connected are the networks connected to the firewall's interfaces,
// with their zones (link-local and loopback left out).
func (s *Server) Connected(st *model.State) map[netip.Prefix]string { return s.connected(st) }

func (s *Server) connected(st *model.State) map[netip.Prefix]string {
	out := map[netip.Prefix]string{}
	for _, i := range s.hostInterfaces(st) {
		if i.Zone == "" {
			continue
		}
		for _, a := range i.Addresses {
			p, err := netip.ParsePrefix(a)
			if err != nil || p.Addr().IsLinkLocalUnicast() || p.Addr().IsLoopback() {
				continue
			}
			out[p.Masked()] = i.Zone
		}
	}
	return out
}

// ---- the ruleset

func (s *Server) ruleset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	_, st, _, err := s.viewState(w, r)
	if err != nil {
		return err
	}
	rs := s.fw.Render(st)
	// In shadow mode: what would be loaded once it is off.
	if queryBool(r, "enforcing") {
		rs = s.fw.RenderEnforcing(st)
	}
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Write([]byte(rs.Text))
	return nil
}

// ---- history

func (s *Server) listHistory(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	hs, err := s.store.ListHistory(r.Context(), queryInt(r, "limit", 100), int64(queryInt(r, "before", 0)))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, hs)
	return nil
}

func (s *Server) getHistory(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	h, err := s.store.GetHistory(r.Context(), id)
	if errors.Is(err, store.ErrNotFound) {
		return notFound("history entry %d not found", id)
	}
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, h)
	return nil
}

// historyDiff is the ruleset's diff for one history entry: the
// configurations before and after it, got back by stepping back from
// the current one through every later entry, rendered by this version.
func (s *Server) historyDiff(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	hs, err := s.store.HistorySince(r.Context(), id)
	if err != nil {
		return err
	}
	if len(hs) == 0 || hs[len(hs)-1].ID != id {
		return notFound("history entry %d not found", id)
	}
	st := s.eng.State()
	var after *model.State
	for _, h := range hs {
		if h.ID == id {
			after = st.Clone()
		}
		if err := engine.Rewind(st, h); err != nil {
			return err
		}
	}
	before, done := fmt.Sprintf("before %d", id), fmt.Sprintf("after %d", id)
	writeJSON(w, http.StatusOK, map[string]string{"diff": s.labeledDiff(st, after, before, done)})
	return nil
}

func (s *Server) revertHistory(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, true); err != nil {
		return err
	}
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	// Staged, an undo is an operation of its own, reviewed like any.
	if csID, err := changesetParam(r); err != nil {
		return err
	} else if csID != 0 {
		h, err := s.store.GetHistory(r.Context(), id)
		if errors.Is(err, store.ErrNotFound) {
			return notFound("history entry %d not found", id)
		}
		if err != nil {
			return err
		}
		if h.RevertedBy != 0 {
			return conflict("history entry %d was already undone by entry %d", id, h.RevertedBy)
		}
		data, _ := json.Marshal(h)
		return s.stage(w, r, p, csID, model.Op{Op: model.OpRevert, ID: id, Data: data})
	}
	res, err := s.eng.Revert(r.Context(), p, id, engine.Options{DryRun: queryBool(r, "dry_run"), Via: via(r, p)})
	if err != nil {
		s.writeErr(w, r, err, res)
		return nil
	}
	s.afterChange(r.Context(), p, res)
	s.respondChange(w, r, p, res, nil, false)
	return nil
}

// ---- probation

func (s *Server) getProbation(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, false); err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, s.probationStatus())
	return nil
}

func (s *Server) confirmChanges(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, true); err != nil {
		return err
	}
	var in api.ConfirmInput
	if r.ContentLength != 0 {
		if err := decodeJSON(r, &in); err != nil {
			return err
		}
	}
	confirm := func() (int, error) { return s.confirm(r.Context(), p) }
	if in.Token != "" {
		confirm = func() (int, error) { return s.confirmToken(r, p, in.Token) }
	}
	n, err := confirm()
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]int{"confirmed": n})
	return nil
}

func (s *Server) rollbackChanges(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, true); err != nil {
		return err
	}
	ps := s.probationStatus()
	n := len(ps.Pending) + ps.Takeovers
	if n > 0 {
		s.rollback("rolled back by " + p.Name())
	}
	writeJSON(w, http.StatusOK, map[string]int{"rolled_back": n})
	return nil
}

// listOwnBanLists lists the ban lists a principal without config:read
// may use.
func (s *Server) listOwnBanLists(w http.ResponseWriter, p *auth.Principal) error {
	out := []*model.BanList{}
	for _, b := range s.eng.State().BanLists {
		if p.CanBan(b.Name, false) {
			out = append(out, b)
		}
	}
	if len(out) == 0 && !p.Can(auth.ResBans, false) {
		return require(p, auth.ResConfig, false)
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}