From 6834e9f49a00449d947ceb80b4bf1345a6b032c8 Mon Sep 17 00:00:00 2001
From: Bryan Biedenkapp <gatekeep@gmail.com>
Date: Tue, 11 Oct 2022 09:48:35 -0400
Subject: [PATCH] add "emergDisabled" flag to p25 protocol stanza to
 selectively disable emergency support (emergency support is disabled by
 default);

---
 config.example.yml   |  1 +
 p25/Control.cpp      |  4 ++++
 p25/Control.h        |  1 +
 p25/packet/Trunk.cpp | 37 +++++++++++++++++++++++++------------
 4 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/config.example.yml b/config.example.yml
index 55f31563..dd91c045 100644
--- a/config.example.yml
+++ b/config.example.yml
@@ -77,6 +77,7 @@ protocols:
         sndcpGrant: false
         silenceThreshold: 124
         disableNetworkHDU: false
+        emergDisabled: true
         queueSize: 12
         verbose: true
         debug: false
diff --git a/p25/Control.cpp b/p25/Control.cpp
index 83f8e8f4..f1cb311e 100644
--- a/p25/Control.cpp
+++ b/p25/Control.cpp
@@ -102,6 +102,7 @@ Control::Control(uint32_t nac, uint32_t callHang, uint32_t queueSize, modem::Mod
     m_voiceOnControl(false),
     m_ackTSBKRequests(true),
     m_disableNetworkHDU(false),
+    m_emergDisabled(true),
     m_idenTable(idenTable),
     m_ridLookup(ridLookup),
     m_tidLookup(tidLookup),
@@ -303,6 +304,8 @@ void Control::setOptions(yaml::Node& conf, const std::string cwCallsign, const s
     uint32_t ccBcstInterval = p25Protocol["control"]["interval"].as<uint32_t>(300U);
     m_trunk->m_adjSiteUpdateInterval += ccBcstInterval;
 
+    m_emergDisabled = p25Protocol["emergDisabled"].as<bool>(true);
+
     if (printOptions) {
         LogInfo("    Silence Threshold: %u (%.1f%%)", m_voice->m_silenceThreshold, float(m_voice->m_silenceThreshold) / 12.33F);
 
@@ -315,6 +318,7 @@ void Control::setOptions(yaml::Node& conf, const std::string cwCallsign, const s
         if (!m_trunk->m_ctrlTSDUMBF) {
             LogInfo("    Disable Multi-Block TSDUs: yes");
         }
+        LogInfo("    Emergency Support Disabled: %s", m_emergDisabled ? "yes" : "no");
 
         LogInfo("    Inhibit Illegal: %s", m_inhibitIllegal ? "yes" : "no");
         LogInfo("    Legacy Group Grant: %s", m_legacyGroupGrnt ? "yes" : "no");
diff --git a/p25/Control.h b/p25/Control.h
index 667e59ae..a5d4f8b3 100644
--- a/p25/Control.h
+++ b/p25/Control.h
@@ -155,6 +155,7 @@ namespace p25
         bool m_voiceOnControl;
         bool m_ackTSBKRequests;
         bool m_disableNetworkHDU;
+        bool m_emergDisabled;
 
         ::lookups::IdenTableLookup* m_idenTable;
         ::lookups::RadioIdLookup* m_ridLookup;
diff --git a/p25/packet/Trunk.cpp b/p25/packet/Trunk.cpp
index 9ca8c35c..452c7232 100644
--- a/p25/packet/Trunk.cpp
+++ b/p25/packet/Trunk.cpp
@@ -425,18 +425,22 @@ bool Trunk::process(uint8_t* data, uint32_t len, bool preDecoded)
                 writeRF_TSDU_SBF(true);
                 break;
             case TSBK_ISP_EMERG_ALRM_REQ:
-                if (m_rfTSBK.getEmergency()) {
-                    if (m_verbose) {
-                        LogMessage(LOG_RF, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request), srcId = %u, dstId = %u",
-                            srcId, dstId);
-                    }
+                if (!m_p25->m_emergDisabled) {
+                    if (m_rfTSBK.getEmergency()) {
+                        if (m_verbose) {
+                            LogMessage(LOG_RF, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request), srcId = %u, dstId = %u",
+                                srcId, dstId);
+                        }
 
-                    ::ActivityLog("P25", true, "emergency alarm request request from %u", srcId);
+                        ::ActivityLog("P25", true, "emergency alarm request request from %u", srcId);
 
-                    writeRF_TSDU_ACK_FNE(srcId, TSBK_ISP_EMERG_ALRM_REQ, false, true);
-                    if (m_localEmergAlarm) {
-                        writeRF_TSDU_Emerg_Alrm(srcId, dstId);
+                        writeRF_TSDU_ACK_FNE(srcId, TSBK_ISP_EMERG_ALRM_REQ, false, true);
+                        if (m_localEmergAlarm) {
+                            writeRF_TSDU_Emerg_Alrm(srcId, dstId);
+                        }
                     }
+                } else {
+                    LogWarning(LOG_RF, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request) denial, emergency while emergency disabled, srcId = %u", srcId);
                 }
                 break;
             case TSBK_IOSP_GRP_AFF:
@@ -777,9 +781,14 @@ bool Trunk::processNetwork(uint8_t* data, uint32_t len, lc::LC& control, data::L
                                     m_netTSBK.getAIV(), m_netTSBK.getResponse(), m_netTSBK.getSrcId(), m_netTSBK.getDstId());
                             }
                         } else {
-                            if (m_verbose) {
-                                LogMessage(LOG_NET, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request), srcId = %u, dstId = %u",
-                                    srcId, dstId);
+                            if (!m_p25->m_emergDisabled) {
+                                if (m_verbose) {
+                                    LogMessage(LOG_NET, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request), srcId = %u, dstId = %u",
+                                        srcId, dstId);
+                                }
+                            } else {
+                                LogWarning(LOG_NET, P25_TSDU_STR ", TSBK_ISP_EMERG_ALRM_REQ (Emergency Alarm Request) denial, emergency while emergency disabled, srcId = %u", srcId);
+                                return true; // don't allow this to write to the air
                             }
                         }
                         break;
@@ -1079,6 +1088,10 @@ void Trunk::writeRF_TSDU_U_Reg_Cmd(uint32_t dstId)
 /// <param name="dstId"></param>
 void Trunk::writeRF_TSDU_Emerg_Alrm(uint32_t srcId, uint32_t dstId)
 {
+    if (m_p25->m_emergDisabled) {
+        return;
+    }
+
     uint8_t lco = m_rfTSBK.getLCO();
     uint32_t _srcId = m_rfTSBK.getSrcId();