fix hd-rum-transcode crash

crashes since the commit ab5d2a5 (2025-06-17)

That commit started to enforce existence of control socket, which is
not true in case of the reflector.

fixes ab5d2a5

closes GH-461

Author: MartinPulec

src/audio/filter/controlport_stats.cpp

@@ -53,11 +53,9 @@
 #include "lib_common.h"
 
 struct state_controlport_stats{
-        state_controlport_stats(struct module *mod) : mod(MODULE_CLASS_DATA, mod, this)
+        explicit state_controlport_stats(struct module *mod)
+            : mod(MODULE_CLASS_DATA, mod, this), control(get_control_state(mod))
         {
-                control = (control_state *) (get_module(get_root_module(mod),
-                                                        "control"))
-                              ->priv_data;
         }
 
         module_raii mod;

src/control_socket.cpp

@@ -1043,6 +1043,26 @@ int control_audio_ch_report_count(struct control_state *state){
         return state ? state->audio_channel_report_count : 0;
 }
 
+/**
+ * finds control socket state from module hierarchy
+ *
+ * @param mod module in the tree (doesn't need to be root), may be nullptr (nullptr is returned then)
+ * @returns found state; nullptr if state not found (or mod=0)
+ */
+struct control_state *
+get_control_state(struct module *mod)
+{
+        if (mod == nullptr) {
+                return nullptr;
+        }
+        struct module *control_mod =
+            get_module(get_root_module(mod), "control");
+        if (control_mod == nullptr) {
+                return nullptr;
+        }
+        return (struct control_state *) control_mod->priv_data;
+}
+
 static void print_control_help() {
         color_printf("Control internal commands:\n"
                         TBOLD("\texit") "\n"

src/control_socket.h

@@ -3,7 +3,7 @@
  * @author Martin Pulec     <martin.pulec@cesnet.cz>
  */
 /*
- * Copyright (c) 2013-2021 CESNET, z. s. p. o.
+ * Copyright (c) 2013-2025 CESNET
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,13 +51,13 @@ struct module;
  * @retval 0 if success
  */
 int control_init(int port, int connection_type, struct control_state **state, struct module *root_module, int force_ip_version);
+struct control_state *get_control_state(struct module *mod);
 void control_start(struct control_state *state);
 void control_done(struct control_state *s);
 void control_report_stats(struct control_state *state, const std::string & stat_line);
 void control_report_event(struct control_state *state, const std::string & event_line);
 bool control_stats_enabled(struct control_state *state);
 int control_audio_ch_report_count(struct control_state *state);
 
-
 #endif // control_socket_h_
 

src/rtp/audio_decoders.cpp

@@ -271,10 +271,7 @@ void *audio_decoder_init(char *audio_channel_map, const char *audio_scale, const
         s->packet_counter = packet_counter_init(0);
 
         s->audio_decompress = NULL;
-
-        s->control = (struct control_state *) get_module(
-                         get_root_module(parent), "control")
-                         ->priv_data;
+        s->control = get_control_state(parent);
 
         if (strlen(encryption) > 0) {
                 s->dec_funcs = static_cast<const struct openssl_decrypt_info *>(load_library("openssl_decrypt",

src/rtp/video_decoders.cpp

@@ -335,21 +335,20 @@ struct main_msg_reconfigure {
  */
 struct state_video_decoder
 {
-        state_video_decoder(struct module *parent) {
+        explicit state_video_decoder(struct module *parent)
+            : control(get_control_state(parent))
+        {
                 module_init_default(&mod);
                 mod.cls = MODULE_CLASS_DECODER;
                 mod.priv_data = this;
                 mod.new_message = decoder_process_message;
                 module_register(&mod, parent);
-                control = (struct control_state *) get_module(
-                              get_root_module(parent), "control")
-                              ->priv_data;
         }
         ~state_video_decoder() {
                 module_done(&mod);
         }
         struct module mod;
-        struct control_state *control = {};
+        struct control_state *control;
 
         thread decompress_thread_id,
                   fec_thread_id;

src/transmit.cpp

@@ -263,11 +263,7 @@ struct tx *tx_init(struct module *parent, unsigned mtu, enum tx_media_type media
         }
 
         tx->bitrate = bitrate;
-
-        if (parent) {
-                tx->control = (struct control_state *) get_module(
-                    get_root_module(parent), "control")->priv_data;
-        }
+        tx->control = get_control_state(parent);
 
         return tx;
 }

src/video_rxtx/ultragrid_rtp.cpp

@@ -92,8 +92,7 @@ ultragrid_rtp_video_rxtx::ultragrid_rtp_video_rxtx(const map<string, param_u> &p
                 throw ug_no_error();
         }
 
-        m_control = (struct control_state *) get_module(
-            get_root_module(m_common.parent), "control")->priv_data;
+        m_control = get_control_state(m_common.parent);
 }
 
 ultragrid_rtp_video_rxtx::~ultragrid_rtp_video_rxtx()