Bans an admin makes or lifts: the admin cause, a reason, lifted bans kept (closes #86)

A bans.json entry without a cause gets the cause admin, written back so.
Bans whose cause is admin are never dropped and do not count toward
SWWAF_MAX_BANS, so setting a ban's cause to admin keeps it. Bans
smallwebwaf makes get a reason: the limit broken or the rule matched. A
lifted ban refuses nothing, is kept, and makes no later ban longer.
smallwebwaf_bans_made_total counts admin bans an edit adds while running;
earlier_bans counts admin in place of without_cause.

Judgement call: lifted lifts at once, whatever time it gives.
Judgement call: a lifted ban still counts in earlier_bans.
Known gap: a ban dropped from behind an admin's ban on its netblock leaves that netblock's later earlier_bans.

Model: opus-5-5

internal/state/state.go

@@ -48,7 +48,7 @@ var (
 	errVersion = errors.New("unknown version")
 	// errMissing is for an entry without a field it needs.
 	errMissing = errors.New("has no")
-	errCause   = errors.New("is not limit or attack")
+	errCause   = errors.New("is not limit, attack or admin")
 )
 
 // Params are what Load needs.
@@ -96,12 +96,15 @@ type bansFile struct {
 }
 
 // banEntry is a ban as bans.json holds it: a permanent ban's expires is
-// null, and a ban an admin added may have no cause.
+// null, a ban an admin added may have no cause, which makes it an
+// admin's, and lifted is left out until an admin lifts the ban.
 type banEntry struct {
 	Netblock netip.Prefix `json:"netblock"`
 	Start    time.Time    `json:"start"`
 	Expires  *time.Time   `json:"expires"`
-	Cause    string       `json:"cause,omitempty"`
+	Cause    string       `json:"cause"`
+	Reason   string       `json:"reason,omitempty"`
+	Lifted   *time.Time   `json:"lifted,omitempty"`
 	Notes    bans.Notes   `json:"notes"`
 }
 
@@ -262,7 +265,7 @@ func (f *Files) fileChanged(name string) {
 // runs, by Watch or by a write, is taken in here. An edit that does not
 // parse is neither counted nor logged, and takeIn's error returned.
 func (f *Files) takeInEdit(name string, data []byte) error {
-	_, err := f.takeIn(name, data)
+	_, err := f.takeIn(name, data, true)
 	if err != nil {
 		return err
 	}
@@ -284,7 +287,7 @@ func (f *Files) read(name string) (int, error) {
 		return 0, err
 	}
 
-	return f.takeIn(name, data)
+	return f.takeIn(name, data, false)
 }
 
 // readChanged returns what the state file name holds, and whether that
@@ -308,9 +311,11 @@ func (f *Files) readChanged(name string) ([]byte, bool, error) {
 
 // takeIn parses data, what the state file name holds, puts it into the
 // part that keeps that state, in place of what the part held, and returns
-// how many entries the file holds. An error names the file and, where the
-// JSON decoder tells it, the line and column, or else the entry.
-func (f *Files) takeIn(name string, data []byte) (int, error) {
+// how many entries the file holds. edit is whether data is an admin's
+// edit taken in while smallwebwaf runs, rather than the file read at the
+// start. An error names the file and, where the JSON decoder tells it,
+// the line and column, or else the entry.
+func (f *Files) takeIn(name string, data []byte, edit bool) (int, error) {
 	path := filepath.Join(f.params.Dir, name)
 
 	var entries int
@@ -329,7 +334,12 @@ func (f *Files) takeIn(name string, data []byte) (int, error) {
 			held = append(held, entry.ban())
 		}
 
-		f.params.Ledger.Load(held)
+		if edit {
+			f.params.Ledger.LoadEdit(held)
+		} else {
+			f.params.Ledger.Load(held)
+		}
+
 		entries = len(held)
 	case clientsJSON:
 		var file clientsFile
@@ -447,22 +457,34 @@ func (f *Files) encode(name string) ([]byte, error) {
 // newBanEntry returns ban as bans.json holds it.
 func newBanEntry(ban bans.Ban) banEntry {
 	entry := banEntry{
-		Netblock: ban.Netblock, Start: ban.Start, Cause: ban.Cause, Notes: ban.Notes,
+		Netblock: ban.Netblock, Start: ban.Start, Cause: ban.Cause, Reason: ban.Reason,
+		Notes: ban.Notes,
 	}
 	if !ban.Permanent() {
 		entry.Expires = &ban.Expires
 	}
 
+	if !ban.Lifted.IsZero() {
+		entry.Lifted = &ban.Lifted
+	}
+
 	return entry
 }
 
 // ban returns the ban an entry of bans.json holds.
 func (e banEntry) ban() bans.Ban {
-	ban := bans.Ban{Netblock: e.Netblock, Start: e.Start, Cause: e.Cause, Notes: e.Notes}
+	ban := bans.Ban{
+		Netblock: e.Netblock, Start: e.Start, Cause: e.Cause, Reason: e.Reason,
+		Notes: e.Notes,
+	}
 	if e.Expires != nil {
 		ban.Expires = *e.Expires
 	}
 
+	if e.Lifted != nil {
+		ban.Lifted = *e.Lifted
+	}
+
 	return ban
 }
 
@@ -470,8 +492,8 @@ func (e banEntry) ban() bans.Ban {
 // client, a start, from which the length of the netblock's next ban is
 // worked out, or an expires, which would make it permanent. A permanent
 // ban's expires is null, which Bans cannot tell from a missing one, so
-// each expires is read again as written. A cause other than limit or
-// attack, most likely misspelt, is refused too.
+// each expires is read again as written. A cause other than limit,
+// attack or admin, most likely misspelt, is refused too.
 func (f *bansFile) check(data []byte) error {
 	var written struct {
 		Bans []struct {
@@ -493,7 +515,7 @@ func (f *bansFile) check(data []byte) error {
 		case written.Bans[i].Expires == nil:
 			return missing(i, "expires")
 		case entry.Cause != "" && entry.Cause != bans.CauseLimit &&
-			entry.Cause != bans.CauseAttack:
+			entry.Cause != bans.CauseAttack && entry.Cause != bans.CauseAdmin:
 			return fmt.Errorf("entry %d's cause %q %w", i+1, entry.Cause, errCause)
 		}
 	}