feat: bind signed rosters to assignments

server/store/assignment_sql.go

@@ -3,8 +3,13 @@ package store
 import (
 	"context"
 	"database/sql"
+	"encoding/base64"
+	"encoding/json"
 	"fmt"
+	"strconv"
 	"time"
+
+	"github.com/cosmic-clash/cosmic-clash/server/domain"
 )
 
 // DurableAssignment is the persistence form of a verified assignment-ready
@@ -124,6 +129,36 @@ func SaveAssignments(ctx context.Context, db *sql.DB, assignments []DurableAssig
 	return tx.Commit()
 }
 
+// SaveVerifiedAssignmentRoster converts the backend-verified signed roster to
+// player-scoped rows. It rechecks the claims at this persistence boundary so a
+// caller cannot accidentally publish a token for another match or slot.
+func SaveVerifiedAssignmentRoster(ctx context.Context, db *sql.DB, assignment domain.Assignment, roster []domain.SignedJoinAuthorisation) error {
+	if assignment.Allocation.State != domain.ServerAllocated || len(roster) == 0 {
+		return fmt.Errorf("invalid verified assignment roster")
+	}
+	digest := domain.ManifestDigest(assignment.Manifest)
+	rows := make([]DurableAssignment, 0, len(roster))
+	for _, signed := range roster {
+		auth := signed.Authorisation
+		if len(signed.Signature) == 0 || auth.MatchID != assignment.Allocation.MatchID || auth.ServerID != assignment.Allocation.ServerID || auth.Protocol != strconv.Itoa(assignment.Allocation.Protocol) || auth.PlayerID == "" || auth.Slot < 0 || auth.Slot > 5 || auth.ExpiresAt.IsZero() {
+			return fmt.Errorf("invalid signed assignment roster")
+		}
+		envelope, err := json.Marshal(signed)
+		if err != nil {
+			return fmt.Errorf("encode signed assignment roster: %w", err)
+		}
+		rows = append(rows, DurableAssignment{
+			MatchID: assignment.Allocation.MatchID, PlayerID: auth.PlayerID,
+			AllocationID: assignment.Allocation.AllocationID, ServerID: assignment.Allocation.ServerID,
+			Slot: auth.Slot, Region: assignment.Allocation.Region, ClientBuild: assignment.Allocation.Build,
+			ProtocolVersion: assignment.Allocation.Protocol, Transport: assignment.Allocation.Transport,
+			Endpoint: assignment.Endpoint, JoinAuthorisation: base64.RawURLEncoding.EncodeToString(envelope),
+			ManifestDigest: digest[:], ExpiresAt: auth.ExpiresAt, Revision: 1,
+		})
+	}
+	return SaveAssignments(ctx, db, rows)
+}
+
 func GetAssignment(ctx context.Context, db *sql.DB, playerID, matchID string, now time.Time) (DurableAssignment, error) {
 	if db == nil || playerID == "" || matchID == "" || now.IsZero() {
 		return DurableAssignment{}, fmt.Errorf("invalid assignment recovery arguments")