Feature to add a topic remapping when in bridge mode

.clang-format

@@ -2,32 +2,7 @@
 Language:        Cpp
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+AlignAfterOpenBracket: Align
 AlignEscapedNewlines: Right
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@@ -68,7 +43,6 @@ BraceWrapping:
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@@ -80,59 +54,46 @@ BreakAfterJavaFieldAnnotations: false
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+BasedOnStyle: GNU
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 ForEachMacros:
   - foreach
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-    CaseSensitive:   false
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 IncludeIsMainRegex: '(Test)?$'
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+SortIncludes:    false
 SortJavaStaticImport: Before
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.gitignore

@@ -4,3 +4,9 @@ FlashMQBuild*
 *.swp
 compile_commands.json
 .clangd/
+/cmake-build-debug/
+/.idea/
+/cmake-build-debug-remote/
+/cmake-build-release/
+/cmake-build-release-remote/
+.*

bridgeconfig.cpp

@@ -182,17 +182,16 @@ void BridgeConfig::isValid()
     setClientId();
 }
 
-bool BridgeConfig::operator ==(const BridgeConfig &other) const
+bool BridgeConfig::operator==(const BridgeConfig &other) const
 {
-    return this->address == other.address && this->port == other.port && this->inet_protocol == other.inet_protocol && this->tlsMode == other.tlsMode
-           && this->caFile == other.caFile && this->caDir == other.caDir && this->protocolVersion == other.protocolVersion
-           && this->bridgeProtocolBit == other.bridgeProtocolBit && this->keepalive == other.keepalive && this->clientidPrefix == other.clientidPrefix
-           && this->publishes == other.publishes && this->subscribes == other.subscribes && this->local_username == other.local_username
-           && this->remote_username == other.remote_username && this->remote_password == other.remote_password && this->remoteCleanStart == other.remoteCleanStart
-           && this->localCleanStart == other.localCleanStart && this->remoteSessionExpiryInterval == other.remoteSessionExpiryInterval
-           && this->localSessionExpiryInterval == other.localSessionExpiryInterval && this->remoteRetainAvailable == other.remoteRetainAvailable
-           && this->useSavedClientId == other.useSavedClientId && this->maxOutgoingTopicAliases == other.maxOutgoingTopicAliases
-           && this->maxIncomingTopicAliases == other.maxIncomingTopicAliases && this->tcpNoDelay == other.tcpNoDelay;
+    return this->address == other.address && this->port == other.port && this->inet_protocol == other.inet_protocol && this->tlsMode == other.tlsMode &&
+           this->caFile == other.caFile && this->caDir == other.caDir && this->protocolVersion == other.protocolVersion && this->bridgeProtocolBit == other.bridgeProtocolBit &&
+           this->keepalive == other.keepalive && this->clientidPrefix == other.clientidPrefix && this->topicPrefix == other.topicPrefix && this->publishes == other.publishes &&
+           this->subscribes == other.subscribes && this->local_username == other.local_username && this->remote_username == other.remote_username &&
+           this->remote_password == other.remote_password && this->remoteCleanStart == other.remoteCleanStart && this->localCleanStart == other.localCleanStart &&
+           this->remoteSessionExpiryInterval == other.remoteSessionExpiryInterval && this->localSessionExpiryInterval == other.localSessionExpiryInterval &&
+           this->remoteRetainAvailable == other.remoteRetainAvailable && this->useSavedClientId == other.useSavedClientId &&
+           this->maxOutgoingTopicAliases == other.maxOutgoingTopicAliases && this->maxIncomingTopicAliases == other.maxIncomingTopicAliases && this->tcpNoDelay == other.tcpNoDelay;
 }
 
 bool BridgeConfig::operator !=(const BridgeConfig &other) const

bridgeconfig.h

@@ -54,6 +54,7 @@ class BridgeConfig
     uint16_t maxOutgoingTopicAliases = 0;
     bool useSavedClientId = false;
     bool remoteRetainAvailable = true;
+    std::optional<std::string> topicPrefix;
     std::vector<BridgeTopicPath> subscribes;
     std::vector<BridgeTopicPath> publishes;
     std::weak_ptr<ThreadData> owner;

client.cpp

@@ -366,6 +366,14 @@ PacketDropReason Client::writeMqttPacketAndBlameThisClient(
 
     MqttPacket *p = copyFactory.getOptimumPacket(max_qos, this->protocolVersion, topic_alias, skip_topic, subscriptionIdentifier);
 
+    // If client is a bridge, add the topic prefix, if set.
+    if (getBridgeState() && getBridgeState()->c.topicPrefix)
+        p->addTopicPrefix(getBridgeState()->c.topicPrefix.value());
+    else
+        p->removeTopicPrefix();
+
+    logger->log(LOG_DEBUG) << "writeMqttPacketAndBlameThisClient(): " << p->getTopic();
+
     assert(static_cast<bool>(p->getQos()) == static_cast<bool>(max_qos));
     assert(PublishCopyFactory::getPublishLayoutCompareKey(this->protocolVersion, p->getQos()) ==
            PublishCopyFactory::getPublishLayoutCompareKey(p->getProtocolVersion(), p->getQos()));

configfileparser.cpp

@@ -256,6 +256,7 @@ ConfigFileParser::ConfigFileParser(const std::string &path) :
     validBridgeKeys.insert("remote_retain_available");
     validBridgeKeys.insert("local_clean_start");
     validBridgeKeys.insert("local_session_expiry_interval");
+    validBridgeKeys.insert("topic_prefix");
     validBridgeKeys.insert("subscribe");
     validBridgeKeys.insert("publish");
     validBridgeKeys.insert("clientid_prefix");
@@ -582,6 +583,13 @@ void ConfigFileParser::loadFile(bool test)
                     }
                     curBridge->localSessionExpiryInterval = newVal;
                 }
+                if (testKeyValidity(key, "topic_prefix", validBridgeKeys))
+                {
+                    if (!isValidUtf8(value) || !isValidSubscribePath(value))
+                        throw ConfigFileException(formatString("Path '%s' is not a valid subscribe match", value.c_str()));
+
+                    curBridge->topicPrefix = value;
+                }
                 if (testKeyValidity(key, "subscribe", validBridgeKeys))
                 {
                     if (!isValidUtf8(value) || !isValidSubscribePath(value))

man/flashmq.conf.5

@@ -5,7 +5,7 @@
 \\$2 \(la\\$1\(ra\\$3
 ..
 .if \n(.g .mso www.tmac
-.TH flashmq.conf 5 "Dec 23 2024" "" ""
+.TH flashmq.conf 5 "Jan 07 2025" "" ""
 .SH NAME
 flashmq.conf \- FlashMQ configuration file format
 .SH SYNOPSIS
@@ -518,6 +518,31 @@ The QoS value is like any subscription at a server. Messages received by the oth
 
 Default: \fI0\fR
 .TP
+\*(T<\fB\m[green]topic_prefix\m[] \fI\m[cyan]prefix\m[]\fR\fR\*(T>
+When sending messages to a remote server, the topic defined in \fB\m[green]subscribe\fR\m[] or \fB\m[green]publish\fR\m[] will be prepended with \fI\m[cyan]prefix\m[]\fR. This gives the ability to publish all topics from this broker under a common topic on the remote site.
+
+The difference in using \fB\m[green]topic_prefix\fR\m[] instead of adding it manually to \fB\m[green]subscribe\fR\m[] or \fB\m[green]publish\fR\m[] is, that the \fI\m[cyan]prefix\m[]\fR is being dynamically added or removed when messages are sent or received to/from the broker. This applies to all \fB\m[green]subscribe\fR\m[] or \fB\m[green]publish\fR\m[] options at once.
+
+Always add a trailing slash (/) to the prefix! Otherwise something like \fItopic1/\fR on the local site becomes \fIprefixtopic1/\fR on the remote site and this is probably not intended.
+
+Example 1: Publish all messages in all local topics to the remote system under topic \fIbridge1/\fR and receive all messages from the remote system in topic \fIbridge1/\fR in local. For instance, the local topic \fIhome/sensor1/temp\fR becomes \fIbridge1/home/sensor1/temp\fR on the remote site and vice versa.
+
+Example 2: Publish all messages from local \fItopic1/\fR to the remote system under \fIbridge1/topic1/\fR and receive all messages from the remote system under \fIbridge1/topic2/\fR to local \fItopic2/\fR.
+.PP
+.nf
+.in +7
+\m[blue]# Example 1:\m[]
+\m[green]topic_prefix \m[]\m[cyan]bridge1/\m[]
+\m[green]publish \m[]\m[cyan]#\m[]
+\m[green]subscribe \m[]\m[cyan]#\m[]
+\m[blue]# Example 2:\m[]
+\m[green]topic_prefix \m[]\m[cyan]bridge1/\m[]
+\m[green]publish \m[]\m[cyan]topic1/#\m[]
+\m[green]subscribe \m[]\m[cyan]topic2/#\m[]
+
+.in
+.fi
+.TP
 \*(T<\fB\m[green]local_username\m[] \fI\m[cyan]username\m[]\fR\fR\*(T>
 Username as seen by the local FlashMQ's plugin or ACL checks. This is not always necessary.
 .TP

man/flashmq.conf.5.dbk5

@@ -1057,6 +1057,36 @@ listen {
         </listitem>
       </varlistentry>
 
+      <varlistentry xml:id="bridge__topic_prefix" condition="flashmq ≥ 1.7.0">
+      <term><option>topic_prefix</option> <replaceable>prefix</replaceable></term>
+      <listitem>
+        <para>
+          When sending messages to a remote server, the topic defined in <option>subscribe</option> or <option>publish</option> will be prepended with <replaceable>prefix</replaceable>. This gives the ability to publish all topics from this broker under a common topic on the remote site.
+        </para>
+        <para>
+          The difference in using <option>topic_prefix</option> instead of adding it manually to <option>subscribe</option> or <option>publish</option> is, that the <replaceable>prefix</replaceable> is being dynamically added or removed when messages are sent or received to/from the broker. This applies to all <option>subscribe</option> or <option>publish</option> options at once.
+        </para>
+        <para>
+          Always add a trailing slash (/) to the prefix! Otherwise something like <literal>topic1/</literal> on the local site becomes <literal>prefixtopic1/</literal> on the remote site and this is probably not intended.
+        </para>
+        <para>
+          Example 1: Publish all messages in all local topics to the remote system under topic <literal>bridge1/</literal> and receive all messages from the remote system in topic <literal>bridge1/</literal> in local. For instance, the local topic <literal>home/sensor1/temp</literal> becomes <literal>bridge1/home/sensor1/temp</literal> on the remote site and vice versa.
+        </para>
+        <para>
+          Example 2: Publish all messages from local <literal>topic1/</literal> to the remote system under <literal>bridge1/topic1/</literal> and receive all messages from the remote system under <literal>bridge1/topic2/</literal> to local <literal>topic2/</literal>.
+        </para>
+        <literallayout language="flashmq.conf" class="monospaced"><![CDATA[# Example 1:
+topic_prefix bridge1/
+publish #
+subscribe #
+
+# Example 2:
+topic_prefix bridge1/
+publish topic1/#
+subscribe topic2/#]]></literallayout>
+      </listitem>
+    </varlistentry>
+
       <varlistentry xml:id="bridge__local_username" condition="flashmq ≥ 1.7.0">
         <term><option>local_username</option> <replaceable>username</replaceable></term>
         <listitem>

man/flashmq.conf.5.html

@@ -1267,6 +1267,36 @@
 
 
 
+      <dt id="bridge__topic_prefix"><div xmlns="http://docbook.org/ns/docbook" class="flashmq_version_requirement" data-since-flashmq-version="1.7.0">≥ v1.7.0</div><code class="option">topic_prefix</code> <code class="replaceable">prefix</code><a class="hash-anchor" href="#bridge__topic_prefix">#</a></dt>
+      <dd>
+        <p>
+          When sending messages to a remote server, the topic defined in <code class="option">subscribe</code> or <code class="option">publish</code> will be prepended with <code class="replaceable">prefix</code>. This gives the ability to publish all topics from this broker under a common topic on the remote site.
+        </p>
+        <p>
+          The difference in using <code class="option">topic_prefix</code> instead of adding it manually to <code class="option">subscribe</code> or <code class="option">publish</code> is, that the <code class="replaceable">prefix</code> is being dynamically added or removed when messages are sent or received to/from the broker. This applies to all <code class="option">subscribe</code> or <code class="option">publish</code> options at once.
+        </p>
+        <p>
+          Always add a trailing slash (/) to the prefix! Otherwise something like <code class="literal">topic1/</code> on the local site becomes <code class="literal">prefixtopic1/</code> on the remote site and this is probably not intended.
+        </p>
+        <p>
+          Example 1: Publish all messages in all local topics to the remote system under topic <code class="literal">bridge1/</code> and receive all messages from the remote system in topic <code class="literal">bridge1/</code> in local. For instance, the local topic <code class="literal">home/sensor1/temp</code> becomes <code class="literal">bridge1/home/sensor1/temp</code> on the remote site and vice versa.
+        </p>
+        <p>
+          Example 2: Publish all messages from local <code class="literal">topic1/</code> to the remote system under <code class="literal">bridge1/topic1/</code> and receive all messages from the remote system under <code class="literal">bridge1/topic2/</code> to local <code class="literal">topic2/</code>.
+        </p>
+        <pre class="literallayout monospaced"># Example 1:
+topic_prefix bridge1/
+publish #
+subscribe #
+
+# Example 2:
+topic_prefix bridge1/
+publish topic1/#
+subscribe topic2/#</pre>
+      </dd>
+
+
+
         <dt id="bridge__local_username"><div xmlns="http://docbook.org/ns/docbook" class="flashmq_version_requirement" data-since-flashmq-version="1.7.0">≥ v1.7.0</div><code class="option">local_username</code> <code class="replaceable">username</code><a class="hash-anchor" href="#bridge__local_username">#</a></dt>
         <dd>
           <p>