[Server] Add deck share links and public deck visibility (#7241)

* [Server] Add deck share links and public deck visibility

* Address server review comments for deck share links

* Document transaction teardown in deck share rollback paths

* Address second round of deck share review comments

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_protocol/libcockatrice/protocol/pb/CMakeLists.txt

@@ -15,9 +15,17 @@ set(PROTO_FILES
     command_deck_del.proto
     command_deck_del_dir.proto
     command_deck_download.proto
+    command_deck_download_public.proto
     command_deck_list.proto
+    command_deck_list_other_user.proto
     command_deck_new_dir.proto
     command_deck_select.proto
+    command_deck_set_visibility.proto
+    command_deck_share_create.proto
+    command_deck_share_download.proto
+    command_deck_share_list.proto
+    command_deck_share_list_mine.proto
+    command_deck_share_remove.proto
     command_deck_upload.proto
     command_del_counter.proto
     command_delete_arrow.proto
@@ -137,6 +145,10 @@ set(PROTO_FILES
     response_card_art_rule_entry.proto
     response_deck_download.proto
     response_deck_list.proto
+    response_deck_share_create.proto
+    response_deck_share_download.proto
+    response_deck_share_list.proto
+    response_deck_share_list_mine.proto
     response_deck_upload.proto
     response_dump_zone.proto
     response_forgotpasswordrequest.proto
@@ -175,6 +187,8 @@ set(PROTO_FILES
     serverinfo_cardcounter.proto
     serverinfo_chat_message.proto
     serverinfo_counter.proto
+    serverinfo_deck_share_item.proto
+    serverinfo_deck_share_summary.proto
     serverinfo_deckstorage.proto
     serverinfo_game.proto
     serverinfo_gametype.proto

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_download_public.proto

@@ -0,0 +1,9 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message Command_DeckDownloadPublic {
+    extend SessionCommand {
+        optional Command_DeckDownloadPublic ext = 1031;
+    }
+    optional uint32 deck_id = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_list_other_user.proto

@@ -0,0 +1,9 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message Command_DeckListOtherUser {
+    extend SessionCommand {
+        optional Command_DeckListOtherUser ext = 1029;
+    }
+    optional string user_name = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_set_visibility.proto

@@ -0,0 +1,13 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message Command_DeckSetVisibility {
+    extend SessionCommand {
+        optional Command_DeckSetVisibility ext = 1030;
+    }
+    // Set the public visibility of a single deck (mutually exclusive with folder_path).
+    optional uint32 deck_id = 1;
+    // Set the public visibility of a folder (all decks under it inherit).
+    optional string folder_path = 2;
+    optional bool is_public = 3;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_share_create.proto

@@ -0,0 +1,24 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message DeckShareItem {
+    // Reference an existing deck in the sharer's personal deck storage.
+    // Mutually exclusive with deck_list.
+    optional uint32 deck_id = 1;
+    // Inline deck content in the native format.
+    // Mutually exclusive with deck_id.
+    optional string deck_list = 2;
+    // Color identity of the deck (e.g. "WUBRG"), computed by the sharing client.
+    optional string color_identity = 3;
+}
+
+message Command_DeckShareCreate {
+    extend SessionCommand {
+        optional Command_DeckShareCreate ext = 1026;
+    }
+    optional string name = 1;
+    repeated DeckShareItem items = 2;
+    // Path of a folder in the sharer's personal deck storage. When set, all
+    // decks in that folder are shared (resolved by the server).
+    optional string folder_path = 3;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_share_download.proto

@@ -0,0 +1,10 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message Command_DeckShareDownload {
+    extend SessionCommand {
+        optional Command_DeckShareDownload ext = 1028;
+    }
+    optional string token = 1;
+    optional uint32 item_id = 2;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_share_list.proto

@@ -0,0 +1,9 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+message Command_DeckShareList {
+    extend SessionCommand {
+        optional Command_DeckShareList ext = 1027;
+    }
+    optional string token = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_share_list_mine.proto

@@ -0,0 +1,10 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+// Requests the list of share bundles created by the calling user, so they can
+// be reviewed and revoked before they expire.
+message Command_DeckShareListMine {
+    extend SessionCommand {
+        optional Command_DeckShareListMine ext = 1032;
+    }
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_share_remove.proto

@@ -0,0 +1,11 @@
+syntax = "proto2";
+import "session_commands.proto";
+
+// Revokes one of the calling user's own share bundles. The referenced items
+// are removed by cascade.
+message Command_DeckShareRemove {
+    extend SessionCommand {
+        optional Command_DeckShareRemove ext = 1033;
+    }
+    optional uint32 share_id = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/command_deck_upload.proto

@@ -8,4 +8,10 @@ message Command_DeckUpload {
     optional string path = 1;    // to upload a new deck
     optional uint32 deck_id = 2; // to replace an existing deck
     optional string deck_list = 3;
+    optional bool is_public = 4; // mark the deck public on upload (publish)
+    // The server derives the banner card and tags from deck_list, so clients only
+    // need to send the color identity, which cannot be computed server-side.
+    reserved 5, 6, 8;
+    reserved "banner_card_name", "banner_card_provider", "tags";
+    optional string color_identity = 7;
 }

libcockatrice_protocol/libcockatrice/protocol/pb/response.proto

@@ -81,6 +81,10 @@ message Response {
         REPLAY_LIST = 1100;             // Response listing replays
         REPLAY_DOWNLOAD = 1101;         // Response for replay download
         REPLAY_GET_CODE = 1102;         // Response containing replay code
+        DECK_SHARE_CREATE = 1103;       // Response to deck share creation
+        DECK_SHARE_LIST = 1104;         // Response listing shared decks
+        DECK_SHARE_DOWNLOAD = 1105;     // Response for shared deck download
+        DECK_SHARE_LIST_MINE = 1106;    // Response listing the caller's own shares
         CARD_ART_RULE_LIST = 1200;      // Response containing a list of card art rules
     }
 

libcockatrice_protocol/libcockatrice/protocol/pb/response_deck_share_create.proto

@@ -0,0 +1,11 @@
+syntax = "proto2";
+import "response.proto";
+
+message Response_DeckShareCreate {
+    extend Response {
+        optional Response_DeckShareCreate ext = 1103;
+    }
+    optional string token = 1;
+    optional uint64 expires_at = 2;
+    optional uint32 item_count = 3;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/response_deck_share_download.proto

@@ -0,0 +1,9 @@
+syntax = "proto2";
+import "response.proto";
+
+message Response_DeckShareDownload {
+    extend Response {
+        optional Response_DeckShareDownload ext = 1105;
+    }
+    optional string deck = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/response_deck_share_list.proto

@@ -0,0 +1,12 @@
+syntax = "proto2";
+import "response.proto";
+import "serverinfo_deck_share_item.proto";
+
+message Response_DeckShareList {
+    extend Response {
+        optional Response_DeckShareList ext = 1104;
+    }
+    optional string name = 1;
+    optional uint64 expires_at = 2;
+    repeated ServerInfo_DeckShareItem items = 3;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/response_deck_share_list_mine.proto

@@ -0,0 +1,10 @@
+syntax = "proto2";
+import "response.proto";
+import "serverinfo_deck_share_summary.proto";
+
+message Response_DeckShareListMine {
+    extend Response {
+        optional Response_DeckShareListMine ext = 1106;
+    }
+    repeated ServerInfo_DeckShareSummary shares = 1;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/serverinfo_deck_share_item.proto

@@ -0,0 +1,10 @@
+syntax = "proto2";
+
+message ServerInfo_DeckShareItem {
+    optional uint32 id = 1;
+    optional string name = 2;
+    repeated string tags = 3;
+    optional string banner_card = 4;
+    optional string game_format = 5;
+    optional string color_identity = 6;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/serverinfo_deck_share_summary.proto

@@ -0,0 +1,10 @@
+syntax = "proto2";
+
+// A share bundle created by a user, as reported by a "list my shares" query.
+message ServerInfo_DeckShareSummary {
+    optional uint32 id = 1;
+    optional string name = 2;
+    optional uint64 creation_time = 3;
+    optional uint64 expires_at = 4;
+    optional uint32 item_count = 5;
+}

libcockatrice_protocol/libcockatrice/protocol/pb/serverinfo_deckstorage.proto

@@ -1,10 +1,21 @@
 syntax = "proto2";
 message ServerInfo_DeckStorage_File {
     optional uint32 creation_time = 1;
+    optional bool is_public = 2;
+    // Preview metadata computed by the uploading client, so other clients can
+    // render this deck (e.g. in a visual storage grid) without downloading the
+    // full deck list. Empty for decks uploaded before the metadata columns.
+    optional string banner_card_name = 3;
+    optional string banner_card_provider = 4;
+    optional string color_identity = 5;
+    // Tag names associated with the deck. Empty for decks uploaded before the
+    // tags column existed.
+    repeated string tags = 6;
 }
 
 message ServerInfo_DeckStorage_Folder {
     repeated ServerInfo_DeckStorage_TreeItem items = 1;
+    optional bool is_public = 2;
 }
 
 message ServerInfo_DeckStorage_TreeItem {

libcockatrice_protocol/libcockatrice/protocol/pb/session_commands.proto

@@ -28,6 +28,14 @@ message SessionCommand {
         FORGOT_PASSWORD_CHALLENGE = 1023;
         REQUEST_PASSWORD_SALT = 1024;
         SET_CARD_ART_PARAMS = 1025;
+        DECK_SHARE_CREATE = 1026;
+        DECK_SHARE_LIST = 1027;
+        DECK_SHARE_DOWNLOAD = 1028;
+        DECK_LIST_OTHER_USER = 1029;
+        DECK_SET_VISIBILITY = 1030;
+        DECK_DOWNLOAD_PUBLIC = 1031;
+        DECK_SHARE_LIST_MINE = 1032;
+        DECK_SHARE_REMOVE = 1033;
         REPLAY_LIST = 1100;
         REPLAY_DOWNLOAD = 1101;
         REPLAY_MODIFY_MATCH = 1102;

servatrice/migrations/servatrice_0036_to_0037.sql

@@ -0,0 +1,71 @@
+-- Servatrice db migration from version 36 to version 37
+
+-- Deck sharing (temporary share links + permanent public decks).
+--
+-- This feature was developed behind several intermediate migrations that have
+-- never shipped, so they are folded into this single 36 -> 37 migration:
+-- temporary share links, permanent public-deck visibility, preview metadata,
+-- and per-deck tags.
+
+-- 1. Temporary deck shares: a named bundle of decks that can be fetched by
+-- anyone who knows the (unguessable) token, until the share expires.
+CREATE TABLE IF NOT EXISTS `cockatrice_deck_share` (
+  `id` int(7) unsigned zerofill NOT NULL auto_increment,
+  `token` varchar(64) COLLATE utf8mb4_bin NOT NULL,
+  `name` varchar(64) NOT NULL,
+  `created_by` int(7) unsigned NULL,
+  `created_at` datetime NOT NULL,
+  `expires_at` datetime NOT NULL,
+  PRIMARY KEY  (`id`),
+  UNIQUE KEY `token` (`token`),
+  KEY `expires_at` (`expires_at`),
+  FOREIGN KEY(`created_by`) REFERENCES `cockatrice_users`(`id`) ON DELETE SET NULL ON UPDATE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
+
+-- Individual decks inside a share bundle. Content is materialized at share
+-- time so expiring/deleting a share can cascade cleanly. The metadata columns
+-- are nullable because Qt's MySQL driver binds empty QStrings as NULL when
+-- using prepared statements.
+CREATE TABLE IF NOT EXISTS `cockatrice_deck_share_item` (
+  `id` int(7) unsigned zerofill NOT NULL auto_increment,
+  `share_id` int(7) unsigned zerofill NOT NULL,
+  `name` varchar(50) NOT NULL,
+  `tags` text NULL,
+  `banner_card` varchar(255) NULL,
+  `game_format` varchar(50) NULL,
+  `color_identity` varchar(5) NULL,
+  `content` text NOT NULL,
+  `position` int(7) NOT NULL,
+  PRIMARY KEY  (`id`),
+  KEY `share_id` (`share_id`),
+  FOREIGN KEY(`share_id`) REFERENCES `cockatrice_deck_share`(`id`) ON DELETE CASCADE ON UPDATE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
+
+-- 2. Permanent deck sharing: add public visibility flags to the deck storage
+-- tables. A deck is visible to other users if it is marked public, or if any
+-- ancestor folder is marked public (inherited). Existing decks default to
+-- private, so the upgrade does not expose any data.
+ALTER TABLE `cockatrice_decklist_files`
+  ADD COLUMN `is_public` tinyint(1) NOT NULL DEFAULT 0 AFTER `content`;
+
+ALTER TABLE `cockatrice_decklist_folders`
+  ADD COLUMN `is_public` tinyint(1) NOT NULL DEFAULT 0 AFTER `name`;
+
+-- 3. Per-deck preview metadata so clients can render another user's public
+-- decks (e.g. in a visual deck storage grid) without downloading each deck
+-- list. The metadata is derived by the server from the deck content (the color
+-- identity is supplied by the uploading client); decks uploaded before this
+-- migration have empty values until they are re-uploaded.
+ALTER TABLE `cockatrice_decklist_files`
+  ADD COLUMN `banner_card_name` varchar(255) NULL AFTER `is_public`,
+  ADD COLUMN `banner_card_provider` varchar(32) NULL AFTER `banner_card_name`,
+  ADD COLUMN `color_identity` varchar(5) NULL AFTER `banner_card_provider`;
+
+-- 4. Per-deck tags for public decks. The server renders the deck's own tags
+-- into a JSON array, so another user's public decks can filter by tag without
+-- downloading each deck list. Decks uploaded before this migration have NULL
+-- tags until they are re-uploaded.
+ALTER TABLE `cockatrice_decklist_files`
+  ADD COLUMN `tags` text NULL AFTER `color_identity`;
+
+UPDATE cockatrice_schema_version SET version=37 WHERE version=36;

servatrice/servatrice.ini.example

@@ -452,3 +452,24 @@ ssl_cert=ssl_cert.pem
 
 ; Filename of the private key for the server-to-server certificate
 ssl_key=ssl_key.pem
+
+
+[deck_share]
+
+; How many days a created deck share link remains valid before it expires.
+; Default: 7
+expiry_days=7
+
+; How often (in minutes) the server checks for and removes expired deck shares.
+; A value of 0 disables the automatic cleanup.
+; Default: 60
+cleanup_interval=60
+
+; Maximum number of decks a single share link can contain.
+; Default: 50
+max_decks_per_share=50
+
+; Maximum number of share links a single user may create per day.
+; A value of 0 disables the limit.
+; Default: 50
+max_shares_per_day=50

servatrice/servatrice.sql

@@ -20,7 +20,7 @@ CREATE TABLE IF NOT EXISTS `cockatrice_schema_version` (
   PRIMARY KEY  (`version`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
 
-INSERT INTO cockatrice_schema_version VALUES(36);
+INSERT INTO cockatrice_schema_version VALUES(37);
 
 -- users and user data tables
 CREATE TABLE IF NOT EXISTS `cockatrice_users` (
@@ -66,16 +66,56 @@ CREATE TABLE IF NOT EXISTS `cockatrice_decklist_files` (
   `name` varchar(50) NOT NULL,
   `upload_time` datetime NOT NULL,
   `content` text NOT NULL,
+  `is_public` tinyint(1) NOT NULL DEFAULT 0,
+  `banner_card_name` varchar(255) NULL,
+  `banner_card_provider` varchar(32) NULL,
+  `color_identity` varchar(5) NULL,
+  `tags` text NULL,
   PRIMARY KEY  (`id`),
   KEY `FolderPlusUser` (`id_folder`,`id_user`),
   FOREIGN KEY(`id_user`) REFERENCES `cockatrice_users`(`id`)  ON DELETE CASCADE ON UPDATE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
 
+-- Temporary deck shares: a named bundle of decks that can be fetched by
+-- anyone who knows the (unguessable) token, until the share expires.
+CREATE TABLE IF NOT EXISTS `cockatrice_deck_share` (
+  `id` int(7) unsigned zerofill NOT NULL auto_increment,
+  `token` varchar(64) COLLATE utf8mb4_bin NOT NULL,
+  `name` varchar(64) NOT NULL,
+  `created_by` int(7) unsigned NULL,
+  `created_at` datetime NOT NULL,
+  `expires_at` datetime NOT NULL,
+  PRIMARY KEY  (`id`),
+  UNIQUE KEY `token` (`token`),
+  KEY `expires_at` (`expires_at`),
+  FOREIGN KEY(`created_by`) REFERENCES `cockatrice_users`(`id`) ON DELETE SET NULL ON UPDATE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
+
+-- Individual decks inside a share bundle. Content is materialized at share
+-- time so expiring/deleting a share can cascade cleanly. The metadata columns
+-- are nullable because Qt's MySQL driver binds empty QStrings as NULL when
+-- using prepared statements.
+CREATE TABLE IF NOT EXISTS `cockatrice_deck_share_item` (
+  `id` int(7) unsigned zerofill NOT NULL auto_increment,
+  `share_id` int(7) unsigned zerofill NOT NULL,
+  `name` varchar(50) NOT NULL,
+  `tags` text NULL,
+  `banner_card` varchar(255) NULL,
+  `game_format` varchar(50) NULL,
+  `color_identity` varchar(5) NULL,
+  `content` text NOT NULL,
+  `position` int(7) NOT NULL,
+  PRIMARY KEY  (`id`),
+  KEY `share_id` (`share_id`),
+  FOREIGN KEY(`share_id`) REFERENCES `cockatrice_deck_share`(`id`) ON DELETE CASCADE ON UPDATE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;
+
 CREATE TABLE IF NOT EXISTS `cockatrice_decklist_folders` (
   `id` int(7) unsigned zerofill NOT NULL auto_increment,
   `id_parent` int(7) unsigned zerofill NOT NULL,
   `id_user` int(7) unsigned NULL,
   `name` varchar(30) NOT NULL,
+  `is_public` tinyint(1) NOT NULL DEFAULT 0,
   PRIMARY KEY  (`id`),
   KEY `ParentPlusUser` (`id_parent`,`id_user`),
   FOREIGN KEY(`id_user`) REFERENCES `cockatrice_users`(`id`)  ON DELETE CASCADE ON UPDATE CASCADE

servatrice/src/deck_tag_serialization.h

@@ -0,0 +1,39 @@
+#ifndef DECK_TAG_SERIALIZATION_H
+#define DECK_TAG_SERIALIZATION_H
+
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonValue>
+#include <QString>
+#include <QStringList>
+
+/**
+ * @brief Encodes deck tags as a compact JSON array for storage in a text column.
+ *
+ * Deck tags are stored as JSON (rather than a delimited string) so tag names may
+ * contain any character, and decoded uniformly everywhere they are read.
+ */
+inline QString serializeDeckTags(const QStringList &tags)
+{
+    QJsonArray array;
+    for (const QString &tag : tags) {
+        array.append(tag);
+    }
+    return QString::fromUtf8(QJsonDocument(array).toJson(QJsonDocument::Compact));
+}
+
+/** @brief Decodes deck tags previously written by serializeDeckTags. */
+inline QStringList deserializeDeckTags(const QString &serialized)
+{
+    QStringList tags;
+    if (serialized.isEmpty()) {
+        return tags;
+    }
+    const QJsonArray array = QJsonDocument::fromJson(serialized.toUtf8()).array();
+    for (const QJsonValue &tag : array) {
+        tags.append(tag.toString());
+    }
+    return tags;
+}
+
+#endif // DECK_TAG_SERIALIZATION_H

servatrice/src/servatrice.cpp

@@ -437,6 +437,14 @@ bool Servatrice::initServer()
         statusUpdateClock->start(getServerStatusUpdateTime());
     }
 
+    deckShareCleanupClock = new QTimer(this);
+    connect(deckShareCleanupClock, SIGNAL(timeout()), this, SLOT(cleanupExpiredDeckShares()));
+    const int deckShareCleanupInterval = getDeckShareCleanupInterval();
+    if (deckShareCleanupInterval > 0) {
+        qDebug() << "Starting deck share cleanup clock, interval" << deckShareCleanupInterval << "ms";
+        deckShareCleanupClock->start(deckShareCleanupInterval);
+    }
+
     // SOCKET SERVER
     if (getNumberOfTCPPools() > 0) {
         gameServer =
@@ -655,6 +663,11 @@ void Servatrice::setRequiredFeatures(const QString &featureList)
     qDebug() << "Set required client features to:" << serverRequiredFeatureList;
 }
 
+void Servatrice::cleanupExpiredDeckShares()
+{
+    servatriceDatabaseInterface->cleanupExpiredDeckShares();
+}
+
 void Servatrice::statusUpdate()
 {
     if (!servatriceDatabaseInterface->checkSql()) {
@@ -1067,6 +1080,27 @@ int Servatrice::getServerStatusUpdateTime() const
     return settingsCache->value("server/statusupdate", 15000).toInt();
 }
 
+int Servatrice::getDeckShareExpiryDays() const
+{
+    return qMax(1, settingsCache->value("deck_share/expiry_days", 7).toInt());
+}
+
+int Servatrice::getDeckShareCleanupInterval() const
+{
+    // default: every 60 minutes
+    return settingsCache->value("deck_share/cleanup_interval", 60).toInt() * 60000;
+}
+
+int Servatrice::getDeckShareMaxDecksPerShare() const
+{
+    return settingsCache->value("deck_share/max_decks_per_share", 50).toInt();
+}
+
+int Servatrice::getDeckShareMaxSharesPerDay() const
+{
+    return settingsCache->value("deck_share/max_shares_per_day", 50).toInt();
+}
+
 int Servatrice::getNumberOfTCPPools() const
 {
     return settingsCache->value("server/number_pools", 1).toInt();

servatrice/src/servatrice.h

@@ -146,6 +146,7 @@ public:
 private slots:
     void statusUpdate();
     void shutdownTimeout();
+    void cleanupExpiredDeckShares();
 
 protected:
     void doSendIslMessage(const IslMessage &msg, int _serverId) override;
@@ -159,6 +160,7 @@ private:
     AuthenticationMethod authenticationMethod;
     DatabaseType databaseType;
     QTimer *pingClock, *statusUpdateClock;
+    QTimer *deckShareCleanupClock;
     Servatrice_GameServer *gameServer;
     Servatrice_WebsocketGameServer *websocketGameServer;
     Servatrice_IslServer *islServer;
@@ -276,6 +278,10 @@ public:
     int getMaxGameInactivityTime() const override;
     int getMaxPlayerInactivityTime() const override;
     int getClientKeepAlive() const override;
+    int getDeckShareExpiryDays() const;
+    int getDeckShareCleanupInterval() const;
+    int getDeckShareMaxDecksPerShare() const;
+    int getDeckShareMaxSharesPerDay() const;
     int getMaxUsersPerAddress() const;
     int getMessageCountingInterval() const override;
     int getMaxMessageCountPerInterval() const override;

servatrice/src/servatrice_database_interface.cpp

@@ -1,5 +1,6 @@
 #include "servatrice_database_interface.h"
 
+#include "deck_tag_serialization.h"
 #include "servatrice.h"
 #include "serversocketinterface.h"
 #include "settingscache.h"
@@ -7,6 +8,7 @@
 #include <QChar>
 #include <QDateTime>
 #include <QDebug>
+#include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QLoggingCategory>
@@ -1079,6 +1081,183 @@ DeckList *Servatrice_DatabaseInterface::getDeckFromDatabase(int deckId, int user
     return deck;
 }
 
+bool Servatrice_DatabaseInterface::createDeckShare(const QString &token,
+                                                   const QString &name,
+                                                   int userId,
+                                                   const QList<DeckShareItemRecord> &items,
+                                                   int expiryDays,
+                                                   qint64 &expiresAt)
+{
+    checkSql();
+
+    if (items.isEmpty()) {
+        return false;
+    }
+
+    if (!sqlDatabase.transaction()) {
+        return false;
+    }
+
+    QSqlQuery *query = prepareQuery("insert into {prefix}_deck_share (token, name, created_by, created_at, expires_at) "
+                                    "values (:token, :name, :created_by, NOW(), DATE_ADD(NOW(), INTERVAL :days DAY))");
+    query->bindValue(":token", token);
+    query->bindValue(":name", name);
+    query->bindValue(":created_by", userId < 1 ? QVariant() : userId);
+    query->bindValue(":days", expiryDays);
+    if (!execSqlQuery(query)) {
+        // A failed execSqlQuery has already closed and reopened the connection,
+        // which implicitly discards the transaction; rollback below is a no-op.
+        sqlDatabase.rollback();
+        return false;
+    }
+
+    const int shareId = query->lastInsertId().toInt();
+
+    // Read the expiry back from the database so the value returned to the client
+    // matches the server clock rather than being approximated client-side.
+    QSqlQuery *expiryQuery = prepareQuery("select UNIX_TIMESTAMP(expires_at) from {prefix}_deck_share where id = :id");
+    expiryQuery->bindValue(":id", shareId);
+    if (!execSqlQuery(expiryQuery) || !expiryQuery->next()) {
+        // See the note above: after a failed execSqlQuery the transaction is
+        // already gone because the connection was torn down.
+        sqlDatabase.rollback();
+        return false;
+    }
+    expiresAt = expiryQuery->value(0).toLongLong();
+
+    for (int i = 0; i < items.size(); ++i) {
+        const DeckShareItemRecord &item = items.at(i);
+        QSqlQuery *itemQuery = prepareQuery("insert into {prefix}_deck_share_item (share_id, name, tags, banner_card, "
+                                            "game_format, color_identity, content, position) values (:share_id, :name, "
+                                            ":tags, :banner_card, :game_format, :color_identity, :content, :position)");
+        itemQuery->bindValue(":share_id", shareId);
+        itemQuery->bindValue(":name", item.name);
+        itemQuery->bindValue(":tags", serializeDeckTags(item.tags));
+        itemQuery->bindValue(":banner_card", item.bannerCard);
+        itemQuery->bindValue(":game_format", item.gameFormat);
+        itemQuery->bindValue(":color_identity", item.colorIdentity);
+        itemQuery->bindValue(":content", item.content);
+        itemQuery->bindValue(":position", i);
+        if (!execSqlQuery(itemQuery)) {
+            // See the note above: the transaction is already gone after the
+            // reconnect performed by a failed execSqlQuery.
+            sqlDatabase.rollback();
+            return false;
+        }
+    }
+
+    if (!sqlDatabase.commit()) {
+        sqlDatabase.rollback();
+        return false;
+    }
+    return true;
+}
+
+bool Servatrice_DatabaseInterface::getDeckShareList(const QString &token,
+                                                    QString &name,
+                                                    qint64 &expiresAt,
+                                                    QList<DeckShareItemRecord> &items)
+{
+    checkSql();
+
+    QSqlQuery *query =
+        prepareQuery("select id, name, UNIX_TIMESTAMP(expires_at) from {prefix}_deck_share where token = "
+                     ":token and expires_at > now()");
+    query->bindValue(":token", token);
+    execSqlQuery(query);
+    if (!query->next()) {
+        return false;
+    }
+
+    const int shareId = query->value(0).toInt();
+    name = query->value(1).toString();
+    expiresAt = query->value(2).toLongLong();
+    items.clear();
+
+    QSqlQuery *itemQuery =
+        prepareQuery("select id, name, tags, banner_card, game_format, color_identity from {prefix}_deck_share_item "
+                     "where share_id = :share_id order by position");
+    itemQuery->bindValue(":share_id", shareId);
+    execSqlQuery(itemQuery);
+    while (itemQuery->next()) {
+        DeckShareItemRecord item;
+        item.id = itemQuery->value(0).toInt();
+        item.name = itemQuery->value(1).toString();
+        item.tags = deserializeDeckTags(itemQuery->value(2).toString());
+        item.bannerCard = itemQuery->value(3).toString();
+        item.gameFormat = itemQuery->value(4).toString();
+        item.colorIdentity = itemQuery->value(5).toString();
+        items.append(item);
+    }
+
+    return true;
+}
+
+bool Servatrice_DatabaseInterface::getDeckShareItem(const QString &token, int itemId, QString &content)
+{
+    checkSql();
+
+    QSqlQuery *query = prepareQuery("select i.content from {prefix}_deck_share_item i join {prefix}_deck_share s on "
+                                    "s.id = i.share_id where s.token = :token and s.expires_at > now() and i.id = :id");
+    query->bindValue(":token", token);
+    query->bindValue(":id", itemId);
+    execSqlQuery(query);
+    if (!query->next()) {
+        return false;
+    }
+
+    content = query->value(0).toString();
+    return true;
+}
+
+void Servatrice_DatabaseInterface::cleanupExpiredDeckShares()
+{
+    checkSql();
+
+    QSqlQuery *query = prepareQuery("delete from {prefix}_deck_share where expires_at < now()");
+    execSqlQuery(query);
+}
+
+bool Servatrice_DatabaseInterface::getDeckSharesForUser(int userId, QList<DeckShareSummaryRecord> &shares)
+{
+    checkSql();
+
+    QSqlQuery *query = prepareQuery("select s.id, s.name, UNIX_TIMESTAMP(s.created_at), "
+                                    "UNIX_TIMESTAMP(s.expires_at), count(i.id) from {prefix}_deck_share s left join "
+                                    "{prefix}_deck_share_item i on i.share_id = s.id "
+                                    "where s.created_by = :created_by and s.expires_at > now() "
+                                    "group by s.id, s.name, s.created_at, s.expires_at order by s.created_at desc");
+    query->bindValue(":created_by", userId);
+    if (!execSqlQuery(query)) {
+        return false;
+    }
+
+    shares.clear();
+    while (query->next()) {
+        DeckShareSummaryRecord summary;
+        summary.id = query->value(0).toInt();
+        summary.name = query->value(1).toString();
+        summary.creationTime = query->value(2).toLongLong();
+        summary.expiresAt = query->value(3).toLongLong();
+        summary.itemCount = query->value(4).toInt();
+        shares.append(summary);
+    }
+    return true;
+}
+
+bool Servatrice_DatabaseInterface::deleteDeckShare(int shareId, int userId)
+{
+    checkSql();
+
+    QSqlQuery *query = prepareQuery("delete from {prefix}_deck_share where id = :id and created_by = :created_by");
+    query->bindValue(":id", shareId);
+    query->bindValue(":created_by", userId);
+    if (!execSqlQuery(query)) {
+        return false;
+    }
+    return query->numRowsAffected() > 0;
+}
+
 void Servatrice_DatabaseInterface::logMessage(const int senderId,
                                               const QString &senderName,
                                               const QString &senderIp,

servatrice/src/servatrice_database_interface.h

@@ -13,10 +13,32 @@
 #include <server.h>
 #include <server_database_interface.h>
 
-#define DATABASE_SCHEMA_VERSION 36
+#define DATABASE_SCHEMA_VERSION 37
 
 class Servatrice;
 
+/** @brief Metadata of a single deck inside a temporary deck share bundle. */
+struct DeckShareItemRecord
+{
+    int id = -1;           ///< Database id, used for downloads.
+    QString name;          ///< Deck name.
+    QStringList tags;      ///< Deck tags.
+    QString bannerCard;    ///< Banner card name (deck image).
+    QString gameFormat;    ///< Game format the deck was built for.
+    QString colorIdentity; ///< Color identity, e.g. "WUBRG".
+    QString content;       ///< Deck content (native format); empty in list queries.
+};
+
+/** @brief Summary of a share bundle owned by a user. */
+struct DeckShareSummaryRecord
+{
+    int id = -1;             ///< Database id, used for revocation.
+    QString name;            ///< Share name.
+    qint64 creationTime = 0; ///< Unix timestamp at which the share was created.
+    qint64 expiresAt = 0;    ///< Unix timestamp at which the share expires.
+    int itemCount = 0;       ///< Number of decks in the bundle.
+};
+
 class Servatrice_DatabaseInterface : public Server_DatabaseInterface
 {
     Q_OBJECT
@@ -80,6 +102,37 @@ public:
                               const QList<GameReplay *> &replayList) override;
     DeckList *getDeckFromDatabase(int deckId, int userId) override;
 
+    /**
+     * @brief Creates a new temporary deck share bundle.
+     * @param expiresAt Receives the actual expiry read back from the database.
+     * @return false on failure.
+     */
+    bool createDeckShare(const QString &token,
+                         const QString &name,
+                         int userId,
+                         const QList<DeckShareItemRecord> &items,
+                         int expiryDays,
+                         qint64 &expiresAt);
+    /** @brief Lists the share bundles created by a user, newest first. */
+    bool getDeckSharesForUser(int userId, QList<DeckShareSummaryRecord> &shares);
+    /**
+     * @brief Deletes one of a user's own share bundles (cascades to its items).
+     * @return false if no such bundle belongs to the user.
+     */
+    bool deleteDeckShare(int shareId, int userId);
+    /**
+     * @brief Looks up a valid (non-expired) share bundle by token.
+     * @return false if the token is unknown or expired.
+     */
+    bool getDeckShareList(const QString &token, QString &name, qint64 &expiresAt, QList<DeckShareItemRecord> &items);
+    /**
+     * @brief Fetches the content of one item of a valid share bundle.
+     * @return false if the token is unknown/expired or the item does not belong to the bundle.
+     */
+    bool getDeckShareItem(const QString &token, int itemId, QString &content);
+    /** @brief Deletes all expired share bundles (cascades to their items). */
+    void cleanupExpiredDeckShares();
+
     int getNextGameId() override;
     int getNextReplayId() override;
     int getActiveUserCount(QString connectionType = QString()) override;

servatrice/src/serversocketinterface.cpp

@@ -20,6 +20,7 @@
 
 #include "serversocketinterface.h"
 
+#include "deck_tag_serialization.h"
 #include "email_parser.h"
 #include "main.h"
 #include "servatrice.h"
@@ -35,10 +36,12 @@
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QLoggingCategory>
+#include <QRandomGenerator>
 #include <QRegularExpression>
 #include <QSqlError>
 #include <QSqlQuery>
 #include <QString>
+#include <algorithm>
 #include <game/server_player.h>
 #include <google/protobuf/descriptor.h>
 #include <iostream>
@@ -47,8 +50,16 @@
 #include <libcockatrice/protocol/pb/command_deck_del.pb.h>
 #include <libcockatrice/protocol/pb/command_deck_del_dir.pb.h>
 #include <libcockatrice/protocol/pb/command_deck_download.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_download_public.pb.h>
 #include <libcockatrice/protocol/pb/command_deck_list.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_list_other_user.pb.h>
 #include <libcockatrice/protocol/pb/command_deck_new_dir.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_set_visibility.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_share_create.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_share_download.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_share_list.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_share_list_mine.pb.h>
+#include <libcockatrice/protocol/pb/command_deck_share_remove.pb.h>
 #include <libcockatrice/protocol/pb/command_deck_upload.pb.h>
 #include <libcockatrice/protocol/pb/command_get_server_stats.pb.h>
 #include <libcockatrice/protocol/pb/command_replay_delete_match.pb.h>
@@ -81,6 +92,10 @@
 #include <libcockatrice/protocol/pb/response_card_art_rule_entry.pb.h>
 #include <libcockatrice/protocol/pb/response_deck_download.pb.h>
 #include <libcockatrice/protocol/pb/response_deck_list.pb.h>
+#include <libcockatrice/protocol/pb/response_deck_share_create.pb.h>
+#include <libcockatrice/protocol/pb/response_deck_share_download.pb.h>
+#include <libcockatrice/protocol/pb/response_deck_share_list.pb.h>
+#include <libcockatrice/protocol/pb/response_deck_share_list_mine.pb.h>
 #include <libcockatrice/protocol/pb/response_deck_upload.pb.h>
 #include <libcockatrice/protocol/pb/response_forgotpasswordrequest.pb.h>
 #include <libcockatrice/protocol/pb/response_get_admin_notes.pb.h>
@@ -277,6 +292,12 @@ Response::ResponseCode AbstractServerSocketInterface::processExtendedSessionComm
             return cmdRemoveFromList(cmd.GetExtension(Command_RemoveFromList::ext), rc);
         case SessionCommand::DECK_LIST:
             return cmdDeckList(cmd.GetExtension(Command_DeckList::ext), rc);
+        case SessionCommand::DECK_LIST_OTHER_USER:
+            return cmdDeckListOtherUser(cmd.GetExtension(Command_DeckListOtherUser::ext), rc);
+        case SessionCommand::DECK_SET_VISIBILITY:
+            return cmdDeckSetVisibility(cmd.GetExtension(Command_DeckSetVisibility::ext), rc);
+        case SessionCommand::DECK_DOWNLOAD_PUBLIC:
+            return cmdDeckDownloadPublic(cmd.GetExtension(Command_DeckDownloadPublic::ext), rc);
         case SessionCommand::DECK_NEW_DIR:
             return cmdDeckNewDir(cmd.GetExtension(Command_DeckNewDir::ext), rc);
         case SessionCommand::DECK_DEL_DIR:
@@ -320,6 +341,16 @@ Response::ResponseCode AbstractServerSocketInterface::processExtendedSessionComm
             return cmdAccountImage(cmd.GetExtension(Command_AccountImage::ext), rc);
         case SessionCommand::SET_CARD_ART_PARAMS:
             return cmdSetCardArtParams(cmd.GetExtension(Command_SetCardArtParams::ext), rc);
+        case SessionCommand::DECK_SHARE_CREATE:
+            return cmdDeckShareCreate(cmd.GetExtension(Command_DeckShareCreate::ext), rc);
+        case SessionCommand::DECK_SHARE_LIST:
+            return cmdDeckShareList(cmd.GetExtension(Command_DeckShareList::ext), rc);
+        case SessionCommand::DECK_SHARE_LIST_MINE:
+            return cmdDeckShareListMine(cmd.GetExtension(Command_DeckShareListMine::ext), rc);
+        case SessionCommand::DECK_SHARE_REMOVE:
+            return cmdDeckShareRemove(cmd.GetExtension(Command_DeckShareRemove::ext), rc);
+        case SessionCommand::DECK_SHARE_DOWNLOAD:
+            return cmdDeckShareDownload(cmd.GetExtension(Command_DeckShareDownload::ext), rc);
         case SessionCommand::ACCOUNT_PASSWORD:
             return cmdAccountPassword(cmd.GetExtension(Command_AccountPassword::ext), rc);
         case SessionCommand::REQUEST_PASSWORD_SALT:
@@ -566,46 +597,73 @@ int AbstractServerSocketInterface::getDeckPathId(const QString &path)
     return getDeckPathId(0, path.split("/"));
 }
 
-bool AbstractServerSocketInterface::deckListHelper(int folderId, ServerInfo_DeckStorage_Folder *folder)
+bool AbstractServerSocketInterface::deckListHelper(int folderId,
+                                                   ServerInfo_DeckStorage_Folder *folder,
+                                                   int userId,
+                                                   bool inheritedPublic,
+                                                   bool publicOnly)
 {
-    QSqlQuery *query = sqlInterface->prepareQuery(
-        "select id, name from {prefix}_decklist_folders where id_parent = :id_parent and id_user = :id_user");
+    QSqlQuery *query = sqlInterface->prepareQuery("select id, name, is_public from {prefix}_decklist_folders where "
+                                                  "id_parent = :id_parent and id_user = :id_user");
     query->bindValue(":id_parent", folderId);
-    query->bindValue(":id_user", userInfo->id());
+    query->bindValue(":id_user", userId);
     if (!sqlInterface->execSqlQuery(query)) {
         return false;
     }
 
-    QMap<int, QString> results;
+    QList<std::pair<int, std::pair<QString, bool>>> folderRows;
     while (query->next()) {
-        results[query->value(0).toInt()] = query->value(1).toString();
+        folderRows.append({query->value(0).toInt(), {query->value(1).toString(), query->value(2).toBool()}});
     }
+    std::sort(folderRows.begin(), folderRows.end(), [](const auto &a, const auto &b) { return a.first < b.first; });
+
+    for (const auto &[folderIdValue, folderInfo] : folderRows) {
+        const QString name = folderInfo.first;
+        const bool ownPublic = folderInfo.second;
+        const bool effectivePublic = inheritedPublic || ownPublic;
 
-    for (int key : results.keys()) {
         ServerInfo_DeckStorage_TreeItem *newItem = folder->add_items();
-        newItem->set_id(key);
-        newItem->set_name(results.value(key).toStdString());
+        newItem->set_id(folderIdValue);
+        newItem->set_name(name.toStdString());
+        newItem->mutable_folder()->set_is_public(ownPublic);
 
-        if (!deckListHelper(newItem->id(), newItem->mutable_folder())) {
+        if (!deckListHelper(newItem->id(), newItem->mutable_folder(), userId, effectivePublic, publicOnly)) {
             return false;
         }
+
+        if (publicOnly && !effectivePublic && newItem->mutable_folder()->items_size() == 0) {
+            folder->mutable_items()->RemoveLast();
+        }
     }
 
-    query = sqlInterface->prepareQuery("select id, name, upload_time from {prefix}_decklist_files where id_folder = "
-                                       ":id_folder and id_user = :id_user");
+    query = sqlInterface->prepareQuery("select id, name, upload_time, is_public, banner_card_name, "
+                                       "banner_card_provider, color_identity, tags from {prefix}_decklist_files where "
+                                       "id_folder = :id_folder and id_user = :id_user");
     query->bindValue(":id_folder", folderId);
-    query->bindValue(":id_user", userInfo->id());
+    query->bindValue(":id_user", userId);
     if (!sqlInterface->execSqlQuery(query)) {
         return false;
     }
 
     while (query->next()) {
+        const bool ownPublic = query->value(3).toBool();
+        if (publicOnly && !(inheritedPublic || ownPublic)) {
+            continue;
+        }
+
         ServerInfo_DeckStorage_TreeItem *newItem = folder->add_items();
         newItem->set_id(query->value(0).toInt());
         newItem->set_name(query->value(1).toString().toStdString());
 
         ServerInfo_DeckStorage_File *newFile = newItem->mutable_file();
         newFile->set_creation_time(query->value(2).toDateTime().toSecsSinceEpoch());
+        newFile->set_is_public(ownPublic);
+        newFile->set_banner_card_name(query->value(4).toString().toStdString());
+        newFile->set_banner_card_provider(query->value(5).toString().toStdString());
+        newFile->set_color_identity(query->value(6).toString().toStdString());
+        for (const QString &tag : deserializeDeckTags(query->value(7).toString())) {
+            newFile->add_tags(tag.toStdString());
+        }
     }
 
     return true;
@@ -626,7 +684,7 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckList(const Command_
     Response_DeckList *re = new Response_DeckList;
     ServerInfo_DeckStorage_Folder *root = re->mutable_root();
 
-    if (!deckListHelper(0, root)) {
+    if (!deckListHelper(0, root, userInfo->id(), false, false)) {
         return Response::RespContextError;
     }
 
@@ -634,6 +692,160 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckList(const Command_
     return Response::RespOk;
 }
 
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckListOtherUser(const Command_DeckListOtherUser &cmd,
+                                                                           ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    const QString userName = nameFromStdString(cmd.user_name());
+    const int userId = sqlInterface->getUserIdInDB(userName);
+    if (userId == -1) {
+        return Response::RespNameNotFound;
+    }
+
+    Response_DeckList *re = new Response_DeckList;
+    ServerInfo_DeckStorage_Folder *root = re->mutable_root();
+
+    if (!deckListHelper(0, root, userId, false, true)) {
+        return Response::RespContextError;
+    }
+
+    rc.setResponseExtension(re);
+    return Response::RespOk;
+}
+
+int AbstractServerSocketInterface::getDeckOwnerId(int deckId)
+{
+    QSqlQuery *query = sqlInterface->prepareQuery("select id_user from {prefix}_decklist_files where id = :id");
+    query->bindValue(":id", deckId);
+    if (!sqlInterface->execSqlQuery(query)) {
+        return -1;
+    }
+    if (!query->next()) {
+        return -1;
+    }
+    return query->value(0).toInt();
+}
+
+bool AbstractServerSocketInterface::isDeckEffectivelyPublic(int deckId)
+{
+    QSqlQuery *query =
+        sqlInterface->prepareQuery("select is_public, id_folder from {prefix}_decklist_files where id = :id");
+    query->bindValue(":id", deckId);
+    if (!sqlInterface->execSqlQuery(query)) {
+        return false;
+    }
+    if (!query->next()) {
+        return false;
+    }
+    if (query->value(0).toBool()) {
+        return true;
+    }
+
+    int folderId = query->value(1).toInt();
+    int guard = 0;
+    while (folderId != 0 && guard < 100) {
+        QSqlQuery *folderQuery =
+            sqlInterface->prepareQuery("select is_public, id_parent from {prefix}_decklist_folders where id = :id");
+        folderQuery->bindValue(":id", folderId);
+        if (!sqlInterface->execSqlQuery(folderQuery)) {
+            return false;
+        }
+        if (!folderQuery->next()) {
+            return false;
+        }
+        if (folderQuery->value(0).toBool()) {
+            return true;
+        }
+        folderId = folderQuery->value(1).toInt();
+        ++guard;
+    }
+    return false;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckSetVisibility(const Command_DeckSetVisibility &cmd,
+                                                                           ResponseContainer & /*rc*/)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    if (cmd.has_deck_id()) {
+        QSqlQuery *query =
+            sqlInterface->prepareQuery("select 1 from {prefix}_decklist_files where id = :id and id_user = :id_user");
+        query->bindValue(":id", cmd.deck_id());
+        query->bindValue(":id_user", userInfo->id());
+        sqlInterface->execSqlQuery(query);
+        if (!query->next()) {
+            return Response::RespNameNotFound;
+        }
+
+        query = sqlInterface->prepareQuery("update {prefix}_decklist_files set is_public = :is_public where id = :id "
+                                           "and id_user = :id_user");
+        query->bindValue(":is_public", cmd.is_public() ? 1 : 0);
+        query->bindValue(":id", cmd.deck_id());
+        query->bindValue(":id_user", userInfo->id());
+        if (!sqlInterface->execSqlQuery(query)) {
+            return Response::RespContextError;
+        }
+    } else if (cmd.has_folder_path()) {
+        const int folderId = getDeckPathId(nameFromStdString(cmd.folder_path()));
+        if (folderId == -1 || folderId == 0) {
+            return Response::RespNameNotFound;
+        }
+
+        QSqlQuery *query =
+            sqlInterface->prepareQuery("update {prefix}_decklist_folders set is_public = :is_public where id = :id "
+                                       "and id_user = :id_user");
+        query->bindValue(":is_public", cmd.is_public() ? 1 : 0);
+        query->bindValue(":id", folderId);
+        query->bindValue(":id_user", userInfo->id());
+        if (!sqlInterface->execSqlQuery(query)) {
+            return Response::RespContextError;
+        }
+    } else {
+        return Response::RespInvalidData;
+    }
+
+    return Response::RespOk;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckDownloadPublic(const Command_DeckDownloadPublic &cmd,
+                                                                            ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    const int deckId = cmd.deck_id();
+    const int ownerId = getDeckOwnerId(deckId);
+    if (ownerId == -1 || !isDeckEffectivelyPublic(deckId)) {
+        return Response::RespNameNotFound;
+    }
+
+    DeckList *deck;
+    try {
+        deck = sqlInterface->getDeckFromDatabase(deckId, ownerId);
+    } catch (Response::ResponseCode &r) {
+        return r;
+    }
+
+    Response_DeckDownload *re = new Response_DeckDownload;
+    re->set_deck(deck->writeToString_Native().toStdString());
+    rc.setResponseExtension(re);
+    delete deck;
+
+    return Response::RespOk;
+}
+
 Response::ResponseCode AbstractServerSocketInterface::cmdDeckNewDir(const Command_DeckNewDir &cmd,
                                                                     ResponseContainer & /*rc*/)
 {
@@ -742,6 +954,22 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckDel(const Command_D
     return Response::RespOk;
 }
 
+namespace
+{
+/** @brief Keeps only the WUBRG colors from a color identity string, deduplicated. */
+QString sanitizeColorIdentity(const QString &colorIdentity)
+{
+    QString sanitized;
+    for (const QChar &color : colorIdentity) {
+        const QChar upper = color.toUpper();
+        if (QStringLiteral("WUBRG").contains(upper) && !sanitized.contains(upper)) {
+            sanitized.append(upper);
+        }
+    }
+    return sanitized;
+}
+} // namespace
+
 Response::ResponseCode AbstractServerSocketInterface::cmdDeckUpload(const Command_DeckUpload &cmd,
                                                                     ResponseContainer &rc)
 {
@@ -766,6 +994,14 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckUpload(const Comman
         deckName = "Unnamed deck";
     }
 
+    // The server derives the banner card and tags from the deck itself. Only the
+    // color identity must come from the client, since the server has no card
+    // database to compute it. All values are bounded to the column sizes.
+    const QString bannerCardName = deck.getBannerCard().name.left(255);
+    const QString bannerCardProvider = deck.getBannerCard().providerId.left(32);
+    const QString tagsJson = serializeDeckTags(deck.getTags());
+    const QString colorIdentity = sanitizeColorIdentity(nameFromStdString(cmd.color_identity()));
+
     if (cmd.has_path()) {
         int folderId = getDeckPathId(nameFromStdString(cmd.path()));
         if (folderId == -1) {
@@ -774,38 +1010,74 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckUpload(const Comman
 
         QSqlQuery *query =
             sqlInterface->prepareQuery("insert into {prefix}_decklist_files (id_folder, id_user, name, upload_time, "
-                                       "content) values(:id_folder, :id_user, :name, NOW(), :content)");
+                                       "content, is_public, banner_card_name, banner_card_provider, color_identity, "
+                                       "tags) values(:id_folder, :id_user, :name, NOW(), :content, :is_public, "
+                                       ":banner_card_name, :banner_card_provider, :color_identity, :tags)");
         query->bindValue(":id_folder", folderId);
         query->bindValue(":id_user", userInfo->id());
         query->bindValue(":name", deckName);
         query->bindValue(":content", deckStr);
-        sqlInterface->execSqlQuery(query);
+        query->bindValue(":is_public", cmd.has_is_public() && cmd.is_public() ? 1 : 0);
+        query->bindValue(":banner_card_name", bannerCardName);
+        query->bindValue(":banner_card_provider", bannerCardProvider);
+        query->bindValue(":color_identity", colorIdentity);
+        query->bindValue(":tags", tagsJson);
+        if (!sqlInterface->execSqlQuery(query)) {
+            return Response::RespContextError;
+        }
 
         Response_DeckUpload *re = new Response_DeckUpload;
         ServerInfo_DeckStorage_TreeItem *fileInfo = re->mutable_new_file();
         fileInfo->set_id(query->lastInsertId().toInt());
         fileInfo->set_name(deckName.toStdString());
         fileInfo->mutable_file()->set_creation_time(QDateTime::currentDateTime().toSecsSinceEpoch());
+        fileInfo->mutable_file()->set_is_public(cmd.has_is_public() && cmd.is_public());
         rc.setResponseExtension(re);
     } else if (cmd.has_deck_id()) {
-        QSqlQuery *query =
-            sqlInterface->prepareQuery("update {prefix}_decklist_files set name=:name, upload_time=NOW(), "
-                                       "content=:content where id = :id_deck and id_user = :id_user");
+        QString updateQuery = "update {prefix}_decklist_files set name=:name, upload_time=NOW(), content=:content, "
+                              "banner_card_name=:banner_card_name, banner_card_provider=:banner_card_provider, "
+                              "color_identity=:color_identity, tags=:tags";
+        if (cmd.has_is_public()) {
+            updateQuery += ", is_public=:is_public";
+        }
+        updateQuery += " where id = :id_deck and id_user = :id_user";
+
+        QSqlQuery *query = sqlInterface->prepareQuery(updateQuery);
         query->bindValue(":id_deck", cmd.deck_id());
         query->bindValue(":id_user", userInfo->id());
         query->bindValue(":name", deckName);
         query->bindValue(":content", deckStr);
-        sqlInterface->execSqlQuery(query);
+        query->bindValue(":banner_card_name", bannerCardName);
+        query->bindValue(":banner_card_provider", bannerCardProvider);
+        query->bindValue(":color_identity", colorIdentity);
+        query->bindValue(":tags", tagsJson);
+        if (cmd.has_is_public()) {
+            query->bindValue(":is_public", cmd.is_public() ? 1 : 0);
+        }
+        if (!sqlInterface->execSqlQuery(query)) {
+            return Response::RespContextError;
+        }
 
         if (query->numRowsAffected() == 0) {
             return Response::RespNameNotFound;
         }
 
+        QSqlQuery *visibilityQuery =
+            sqlInterface->prepareQuery("select is_public from {prefix}_decklist_files where id = :id and "
+                                       "id_user = :id_user");
+        visibilityQuery->bindValue(":id", cmd.deck_id());
+        visibilityQuery->bindValue(":id_user", userInfo->id());
+        if (!sqlInterface->execSqlQuery(visibilityQuery)) {
+            return Response::RespContextError;
+        }
+        const bool isPublic = visibilityQuery->next() && visibilityQuery->value(0).toBool();
+
         Response_DeckUpload *re = new Response_DeckUpload;
         ServerInfo_DeckStorage_TreeItem *fileInfo = re->mutable_new_file();
         fileInfo->set_id(cmd.deck_id());
         fileInfo->set_name(deckName.toStdString());
         fileInfo->mutable_file()->set_creation_time(QDateTime::currentDateTime().toSecsSinceEpoch());
+        fileInfo->mutable_file()->set_is_public(isPublic);
         rc.setResponseExtension(re);
     } else {
         return Response::RespInvalidData;
@@ -836,6 +1108,248 @@ Response::ResponseCode AbstractServerSocketInterface::cmdDeckDownload(const Comm
     return Response::RespOk;
 }
 
+namespace
+{
+/** @brief Builds a cryptographically random, URL-safe share token. */
+QString generateShareToken()
+{
+    QByteArray bytes(32, Qt::Uninitialized);
+    QRandomGenerator::system()->fillRange(reinterpret_cast<quint32 *>(bytes.data()), bytes.size() / sizeof(quint32));
+    return QString::fromLatin1(bytes.toBase64(QByteArray::Base64UrlEncoding | QByteArray::OmitTrailingEquals));
+}
+
+/** @brief Extracts the share metadata for a deck, materializing its content. */
+DeckShareItemRecord makeShareItemFromDeck(const DeckList &deck, const QString &colorIdentity)
+{
+    DeckShareItemRecord item;
+    item.name = deck.getName();
+    if (item.name.isEmpty()) {
+        item.name = "Unnamed deck";
+    }
+    item.tags = deck.getTags();
+    item.bannerCard = deck.getBannerCard().name;
+    item.gameFormat = deck.getGameFormat();
+    item.colorIdentity = sanitizeColorIdentity(colorIdentity);
+    item.content = deck.writeToString_Native();
+    return item;
+}
+} // namespace
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckShareCreate(const Command_DeckShareCreate &cmd,
+                                                                         ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    const int maxItems = servatrice->getDeckShareMaxDecksPerShare();
+    if (maxItems > 0 && cmd.items_size() > maxItems) {
+        return Response::RespInvalidData;
+    }
+
+    // Per-user rate limit so share links cannot be used to build an unbounded
+    // word-of-mouth leak of public decks.
+    const int maxSharesPerDay = servatrice->getDeckShareMaxSharesPerDay();
+    if (maxSharesPerDay > 0) {
+        QSqlQuery *countQuery = sqlInterface->prepareQuery("select count(*) from {prefix}_deck_share where "
+                                                           "created_by = :created_by and created_at >= "
+                                                           "DATE_SUB(NOW(), INTERVAL 1 DAY)");
+        countQuery->bindValue(":created_by", userInfo->id());
+        if (!sqlInterface->execSqlQuery(countQuery) || !countQuery->next()) {
+            return Response::RespContextError;
+        }
+        if (countQuery->value(0).toInt() >= maxSharesPerDay) {
+            return Response::RespTooManyRequests;
+        }
+    }
+
+    QList<DeckShareItemRecord> items;
+    if (cmd.items_size() > 0) {
+        for (const DeckShareItem &shareItem : cmd.items()) {
+            if (shareItem.has_deck_list()) {
+                DeckList deck;
+                if (!deck.loadFromString_Native(fileFromStdString(shareItem.deck_list()))) {
+                    return Response::RespContextError;
+                }
+                items.append(makeShareItemFromDeck(deck, nameFromStdString(shareItem.color_identity())));
+            } else if (shareItem.has_deck_id()) {
+                DeckList *deck;
+                try {
+                    deck = sqlInterface->getDeckFromDatabase(shareItem.deck_id(), userInfo->id());
+                } catch (Response::ResponseCode &r) {
+                    return r;
+                }
+                items.append(makeShareItemFromDeck(*deck, nameFromStdString(shareItem.color_identity())));
+                delete deck;
+            } else {
+                return Response::RespInvalidData;
+            }
+        }
+    } else if (cmd.has_folder_path()) {
+        const int folderId = getDeckPathId(nameFromStdString(cmd.folder_path()));
+        if (folderId == -1) {
+            return Response::RespNameNotFound;
+        }
+
+        // Drain the deck list before resolving each deck: getDeckFromDatabase
+        // issues its own query on the same cached statement set.
+        QSqlQuery *query =
+            sqlInterface->prepareQuery("select id, color_identity from {prefix}_decklist_files where id_folder = "
+                                       ":id_folder and id_user = :id_user");
+        query->bindValue(":id_folder", folderId);
+        query->bindValue(":id_user", userInfo->id());
+        if (!sqlInterface->execSqlQuery(query)) {
+            return Response::RespContextError;
+        }
+        QList<std::pair<int, QString>> deckRows;
+        while (query->next()) {
+            deckRows.append({query->value(0).toInt(), query->value(1).toString()});
+        }
+        for (const auto &[deckId, colorIdentity] : deckRows) {
+            DeckList *deck;
+            try {
+                deck = sqlInterface->getDeckFromDatabase(deckId, userInfo->id());
+            } catch (Response::ResponseCode &r) {
+                return r;
+            }
+            items.append(makeShareItemFromDeck(*deck, colorIdentity));
+            delete deck;
+        }
+    } else {
+        return Response::RespInvalidData;
+    }
+
+    if (items.isEmpty() || (maxItems > 0 && items.size() > maxItems)) {
+        return Response::RespInvalidData;
+    }
+
+    QString shareName = nameFromStdString(cmd.name());
+    if (shareName.isEmpty()) {
+        shareName = "Shared decks";
+    }
+
+    const QString token = generateShareToken();
+    qint64 expiresAt = 0;
+    if (!sqlInterface->createDeckShare(token, shareName, userInfo->id(), items, servatrice->getDeckShareExpiryDays(),
+                                       expiresAt)) {
+        return Response::RespInvalidData;
+    }
+
+    Response_DeckShareCreate *re = new Response_DeckShareCreate;
+    re->set_token(token.toStdString());
+    re->set_expires_at(expiresAt);
+    re->set_item_count(items.size());
+    rc.setResponseExtension(re);
+
+    return Response::RespOk;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckShareListMine(const Command_DeckShareListMine & /*cmd*/,
+                                                                           ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    QList<DeckShareSummaryRecord> shares;
+    if (!sqlInterface->getDeckSharesForUser(userInfo->id(), shares)) {
+        return Response::RespContextError;
+    }
+
+    Response_DeckShareListMine *re = new Response_DeckShareListMine;
+    for (const DeckShareSummaryRecord &share : shares) {
+        ServerInfo_DeckShareSummary *summary = re->add_shares();
+        summary->set_id(share.id);
+        summary->set_name(share.name.toStdString());
+        summary->set_creation_time(share.creationTime);
+        summary->set_expires_at(share.expiresAt);
+        summary->set_item_count(share.itemCount);
+    }
+    rc.setResponseExtension(re);
+
+    return Response::RespOk;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckShareRemove(const Command_DeckShareRemove &cmd,
+                                                                         ResponseContainer & /*rc*/)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    if (!cmd.has_share_id()) {
+        return Response::RespInvalidData;
+    }
+
+    sqlInterface->checkSql();
+
+    if (!sqlInterface->deleteDeckShare(cmd.share_id(), userInfo->id())) {
+        return Response::RespNameNotFound;
+    }
+
+    return Response::RespOk;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckShareList(const Command_DeckShareList &cmd,
+                                                                       ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    QString name;
+    qint64 expiresAt = 0;
+    QList<DeckShareItemRecord> items;
+    if (!sqlInterface->getDeckShareList(nameFromStdString(cmd.token()), name, expiresAt, items)) {
+        return Response::RespNameNotFound;
+    }
+
+    Response_DeckShareList *re = new Response_DeckShareList;
+    re->set_name(name.toStdString());
+    re->set_expires_at(expiresAt);
+    for (const DeckShareItemRecord &item : items) {
+        ServerInfo_DeckShareItem *itemInfo = re->add_items();
+        itemInfo->set_id(item.id);
+        itemInfo->set_name(item.name.toStdString());
+        for (const QString &tag : item.tags) {
+            itemInfo->add_tags(tag.toStdString());
+        }
+        itemInfo->set_banner_card(item.bannerCard.toStdString());
+        itemInfo->set_game_format(item.gameFormat.toStdString());
+        itemInfo->set_color_identity(item.colorIdentity.toStdString());
+    }
+    rc.setResponseExtension(re);
+
+    return Response::RespOk;
+}
+
+Response::ResponseCode AbstractServerSocketInterface::cmdDeckShareDownload(const Command_DeckShareDownload &cmd,
+                                                                           ResponseContainer &rc)
+{
+    if (authState != PasswordRight) {
+        return Response::RespFunctionNotAllowed;
+    }
+
+    sqlInterface->checkSql();
+
+    QString content;
+    if (!sqlInterface->getDeckShareItem(nameFromStdString(cmd.token()), cmd.item_id(), content)) {
+        return Response::RespNameNotFound;
+    }
+
+    Response_DeckShareDownload *re = new Response_DeckShareDownload;
+    re->set_deck(content.toStdString());
+    rc.setResponseExtension(re);
+
+    return Response::RespOk;
+}
+
 Response::ResponseCode AbstractServerSocketInterface::cmdReplayList(const Command_ReplayList & /*cmd*/,
                                                                     ResponseContainer &rc)
 {

servatrice/src/serversocketinterface.h

@@ -45,11 +45,19 @@ class ServerInfo_DeckStorage_Folder;
 class Command_AddToList;
 class Command_RemoveFromList;
 class Command_DeckList;
+class Command_DeckListOtherUser;
 class Command_DeckNewDir;
 class Command_DeckDelDir;
 class Command_DeckDel;
 class Command_DeckDownload;
+class Command_DeckDownloadPublic;
 class Command_DeckUpload;
+class Command_DeckSetVisibility;
+class Command_DeckShareCreate;
+class Command_DeckShareList;
+class Command_DeckShareListMine;
+class Command_DeckShareRemove;
+class Command_DeckShareDownload;
 class Command_ReplayList;
 class Command_ReplayDownload;
 class Command_ReplayModifyMatch;
@@ -97,8 +105,16 @@ private:
     Response::ResponseCode cmdRemoveFromList(const Command_RemoveFromList &cmd, ResponseContainer &rc);
     int getDeckPathId(int basePathId, QStringList path);
     int getDeckPathId(const QString &path);
-    bool deckListHelper(int folderId, ServerInfo_DeckStorage_Folder *folder);
+    bool deckListHelper(int folderId,
+                        ServerInfo_DeckStorage_Folder *folder,
+                        int userId,
+                        bool inheritedPublic,
+                        bool publicOnly);
+    int getDeckOwnerId(int deckId);
+    bool isDeckEffectivelyPublic(int deckId);
     Response::ResponseCode cmdDeckList(const Command_DeckList &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckListOtherUser(const Command_DeckListOtherUser &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckSetVisibility(const Command_DeckSetVisibility &cmd, ResponseContainer &rc);
     Response::ResponseCode cmdDeckNewDir(const Command_DeckNewDir &cmd, ResponseContainer &rc);
     void deckDelDirHelper(int basePathId);
     void sendServerMessage(const QString userName, const QString message);
@@ -107,6 +123,12 @@ private:
     Response::ResponseCode cmdDeckUpload(const Command_DeckUpload &cmd, ResponseContainer &rc);
     DeckList *getDeckFromDatabase(int deckId);
     Response::ResponseCode cmdDeckDownload(const Command_DeckDownload &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckDownloadPublic(const Command_DeckDownloadPublic &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckShareCreate(const Command_DeckShareCreate &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckShareList(const Command_DeckShareList &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckShareListMine(const Command_DeckShareListMine &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckShareRemove(const Command_DeckShareRemove &cmd, ResponseContainer &rc);
+    Response::ResponseCode cmdDeckShareDownload(const Command_DeckShareDownload &cmd, ResponseContainer &rc);
     Response::ResponseCode cmdReplayList(const Command_ReplayList &cmd, ResponseContainer &rc);
     Response::ResponseCode cmdReplayDownload(const Command_ReplayDownload &cmd, ResponseContainer &rc);
     Response::ResponseCode cmdReplayModifyMatch(const Command_ReplayModifyMatch &cmd, ResponseContainer &rc);