Add DHCPv6 Relay Agent

src/dhcp6relay/.gitignore

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+debian/*
+!debian/changelog
+!debian/compat
+!debian/control
+!debian/rules

src/dhcp6relay/Makefile

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+RM := rm -rf
+DHCP6RELAY_TARGET := dhcp6relay
+CP := cp
+MKDIR := mkdir
+CC := g++
+MV := mv
+LIBS := -levent -lhiredis -lswsscommon -pthread -lboost_thread -lboost_system -I $(PWD)/../sonic-swss-common/common
+CFLAGS  = -g -Wall
+PWD := $(shell pwd)
+
+ifneq ($(MAKECMDGOALS),clean)
+ifneq ($(strip $(C_DEPS)),)
+-include $(C_DEPS) $(OBJS)
+endif
+endif
+
+-include src/subdir.mk
+
+all: sonic-dhcp6relay
+
+sonic-dhcp6relay: $(OBJS)
+	@echo 'Building target: $@'
+	@echo 'Invoking: G++ Linker'
+	$(CC) -o $(DHCP6RELAY_TARGET) $(OBJS) $(LIBS) 
+	@echo 'Finished building target: $@'
+	@echo ' '
+
+install:
+	$(MKDIR) -p $(DESTDIR)/usr/sbin
+	$(MV) $(DHCP6RELAY_TARGET) $(DESTDIR)/usr/sbin
+
+deinstall:
+	$(RM) $(DESTDIR)/usr/sbin/$(DHCP6RELAY_TARGET)
+	$(RM) -rf $(DESTDIR)/usr/sbin
+
+clean:
+	-$(RM) $(EXECUTABLES) $(C_DEPS) $(OBJS) $(DHCP6RELAY_TARGET)
+	-@echo ' '
+
+.PHONY: all clean dependents
+
+

src/dhcp6relay/debian/changelog

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+sonic-dhcp6relay (1.0.0-0) UNRELEASED; urgency=medium
+
+  * Initial release.
+
+ -- Kelly Yeh <kellyyeh@microsoft.com>  

src/dhcp6relay/debian/compat

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+9

src/dhcp6relay/debian/control

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+Source: sonic-dhcp6relay
+Section: devel
+Priority: optional
+Maintainer: Kelly Yeh <kellyyeh@microsoft.com>
+Build-Depends: debhelper (>= 8.0.0),
+               dh-systemd
+Standards-Version: 3.9.3
+Homepage: https://github.com/Azure/sonic-buildimage
+XS-Go-Import-Path: github.com/Azure/sonic-buildimage
+
+Package: sonic-dhcp6relay
+Architecture: any
+Built-Using: ${misc:Built-Using}
+Depends: libevent-2.1-6,
+        libboost-thread1.71.0.
+        libboost-system1.71.0
+Description: SONiC DHCPv6 Relay

src/dhcp6relay/debian/rules

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+#!/usr/bin/make -f
+
+DEB_CFLAGS_APPEND=-std=gnu11
+export DEB_CFLAGS_APPEND
+
+%:
+	dh $@ --parallel

src/dhcp6relay/src/configInterface.cpp

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+#include <sstream>
+#include <syslog.h>
+#include <algorithm>
+#include "configInterface.h"
+
+constexpr auto DEFAULT_TIMEOUT_MSEC = 1000;
+
+bool mPollSwssNotifcation = true;
+std::shared_ptr<boost::thread> mSwssThreadPtr;
+
+//
+// ---> initialize();
+//
+// initialize DB tables and start SWSS listening thread
+//
+void initialize_swss(arg_config *context)
+{
+    try {
+        mSwssThreadPtr = std::make_shared<boost::thread> (&handleSwssNotification, context);
+    }
+    catch (const std::bad_alloc &e) {
+        syslog(LOG_ERR, "Failed allocate memory. Exception details: %s", e.what());
+    }
+}
+
+//
+// ---> deinitialize();
+//
+// deinitialize DB interface and join SWSS listening thread
+//
+void deinitialize_swss()
+{
+    stopSwssNotificationPoll();
+    mSwssThreadPtr->interrupt();
+}
+
+/**
+ * @code                void handleSwssNotification(arg_config *context)
+ * 
+ * @brief               main thread for handling SWSS notification
+ *
+ * @param context       argument config that contains strings of server and option
+ *
+ * @return              none
+ */
+void handleSwssNotification(arg_config *context)
+{
+    std::shared_ptr<swss::DBConnector> configDbPtr = std::make_shared<swss::DBConnector> ("CONFIG_DB", 0);
+    swss::SubscriberStateTable ipHelpersTable(configDbPtr.get(), "DHCP");
+
+    swss::Select swssSelect;
+    swssSelect.addSelectable(&ipHelpersTable);
+    while (mPollSwssNotifcation) {
+        swss::Selectable *selectable;
+        int ret = swssSelect.select(&selectable, DEFAULT_TIMEOUT_MSEC);
+        if (ret == swss::Select::ERROR) {
+            syslog(LOG_WARNING, "Select: returned ERROR");
+            continue;
+        } else if (ret == swss::Select::TIMEOUT) {
+            continue;
+        } 
+        if (selectable == static_cast<swss::Selectable *> (&ipHelpersTable)) {
+            handleRelayNotification(ipHelpersTable, context);
+        }
+    } 
+}
+
+/**
+ * @code                    void handleRelayNotification(swss::SubscriberStateTable &ipHelpersTable, arg_config context)
+ * 
+ * @brief                   handles DHCPv6 relay configuration change notification
+ *
+ * @param ipHelpersTable    DHCP table
+ * @param context           argument config that contains strings of server and option
+ *
+ * @return                  none
+ */
+void handleRelayNotification(swss::SubscriberStateTable &ipHelpersTable, arg_config *context)
+{
+    std::deque<swss::KeyOpFieldsValuesTuple> entries;
+
+    ipHelpersTable.pops(entries);
+    processRelayNotification(entries, context);
+}
+
+/**
+ * @code                    void processRelayNotification(std::deque<swss::KeyOpFieldsValuesTuple> &entries, arg_config context)
+ * 
+ * @brief                   process DHCPv6 relay servers and options configuration change notification
+ *
+ * @param entries           queue of std::tuple<std::string, std::string, std::vector<FieldValueTuple>> entries in DHCP table
+ * @param context           argument config that contains strings of server and option
+ *
+ * @return                  none
+ */
+void processRelayNotification(std::deque<swss::KeyOpFieldsValuesTuple> &entries, arg_config *context)
+{
+    std::vector<std::string> servers;
+
+    for (auto &entry: entries) {
+        std::string vlan = kfvKey(entry);
+        std::vector<swss::FieldValueTuple> fieldValues = kfvFieldsValues(entry);
+
+        for (auto &fieldValue: fieldValues) {
+            std::string f = fvField(fieldValue);
+            std::string v = fvValue(fieldValue);
+            if(f == "dhcpv6_servers") {
+                std::stringstream ss(v);
+                while (ss.good()) {
+                    std::string substr;
+                    getline(ss, substr, ',');
+                    context->servers.push_back(substr);
+                }
+            }
+            if(f == "options") {
+                std::stringstream ss(v);
+                while (ss.good()) {
+                    std::string substr;
+                    getline(ss, substr, ',');
+                    if(substr == "79")
+                        context->is_option_79 = true;
+                }
+            }
+        }
+    }
+}
+
+/**
+*@code      stopSwssNotificationPoll
+*
+*@brief     stop SWSS listening thread
+*
+*@return    none
+*/
+void stopSwssNotificationPoll() {
+    mPollSwssNotifcation = false;
+};

src/dhcp6relay/src/configInterface.h

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+#include <boost/thread.hpp>
+#include "subscriberstatetable.h"
+#include "select.h"
+#include "relay.h"
+
+void initialize_swss(arg_config *context);
+
+void deinitialize_swss();
+
+void handleSwssNotification(arg_config *context);
+
+void handleRelayNotification(swss::SubscriberStateTable &configMuxTable, arg_config *context);
+
+void processRelayNotification(std::deque<swss::KeyOpFieldsValuesTuple> &entries, arg_config *context);
+
+void stopSwssNotificationPoll();

src/dhcp6relay/src/main.cpp

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+#include <stdlib.h>
+#include "configInterface.h"
+
+int main(int argc, char *argv[]) {
+    try {
+        auto parser = ArgumentParser();
+        parser.parse_args(argc, argv);
+        auto context = parser.get_arg();
+        initialize_swss(&context);
+        loop_relay(&context);
+    }
+    catch (std::exception &e)
+    {
+        printf("Usage: -i <interface> -o <option>\n");
+        return 1;
+    }
+    return 0;
+}