[dhcp_relay] sonic dhcp relay agent for IPv4

.gitignore

@@ -3,3 +3,8 @@ dhcp6relay/debian/*
 !dhcp6relay/debian/compat
 !dhcp6relay/debian/control
 !dhcp6relay/debian/rules
+dhcp4relay/debian/*
+!dhcp4relay/debian/changelog
+!dhcp4relay/debian/compat
+!dhcp4relay/debian/control
+!dhcp4relay/debian/rules

dhcp4relay/Makefile

@@ -0,0 +1,106 @@
+.ONESHELL:
+SHELL = /bin/bash
+
+RM := rm -rf
+WORKING_DIR := $(abspath .)
+BUILD_DIR := build
+BUILD_TEST_DIR := build-test
+DHCP4RELAY_TARGET := $(BUILD_DIR)/dhcp4relay
+DHCP4RELAY_TEST_TARGET := $(BUILD_TEST_DIR)/dhcp4relay-test
+CP := cp
+MKDIR := mkdir
+MV := mv
+FIND := find
+GCOVR := gcovr
+
+LD_PCAPPLUSPLUS_LIB := -lPcap++ -lPacket++ -lCommon++
+
+#pcap plus plus zip file pcappp_v24.09.zip
+PCAPPPVAR := 24.09
+PCAPPPZIP_FILE := pcappp_v${PCAPPPVAR}.zip
+PCAPPLUSPLUS_DIR := $(WORKING_DIR)/PcapPlusPlus-$(PCAPPPVAR)
+PCAPPP_DONE = $(WORKING_DIR)/pcappp.stamp
+INCLUDE_DIR = $(PCAPPLUSPLUS_DIR)/include
+LIB_DIR = $(PCAPPLUSPLUS_DIR)/lib
+
+override LDLIBS += -levent -lhiredis -lswsscommon -pthread -lboost_thread -lboost_system $(LD_PCAPPLUSPLUS_LIB) -lpcap
+override CPPFLAGS += -Wall -std=c++17 -fPIE -I/usr/include/swss -I$(INCLUDE_DIR)
+override CPPFLAGS += -MMD -MP -MF"$(@:%.o=%.d)" -MT"$(@)"
+override LDFLAGS += -L$(LIB_DIR) -Wl,-rpath=$(abspath $(LIB_DIR))
+CPPFLAGS_TEST := --coverage -fprofile-arcs -ftest-coverage -fprofile-generate -fsanitize=address -DUNIT_TEST
+LDLIBS_TEST := --coverage -lgtest -lgmock -pthread -lstdc++fs -fsanitize=address
+PWD := $(shell pwd)
+
+.PHONY: $(PCAPPP_DONE)
+$(PCAPPP_DONE):
+
+	# Remove stale files
+	rm -rf $(PCAPPLUSPLUS_DIR)
+
+	unzip ${PCAPPPZIP_FILE}
+	pushd $(PCAPPLUSPLUS_DIR)
+
+	# Create a git repository here for stg to apply patches
+	git init
+	git add -f *
+	git commit -qm "initial commit"
+
+	# Apply patches
+	stg init
+	stg import -s ../patch/series
+	popd
+
+	cd $(PCAPPLUSPLUS_DIR) && cmake -S . -B build && cmake --build build
+	cd build && make && sudo cmake --install .
+
+	touch $@
+
+all: $(DHCP4RELAY_TARGET) $(DHCP4RELAY_TEST_TARGET)
+
+-include src/subdir.mk
+-include test/subdir.mk
+
+# Use different build directories based on whether it's a regular build or a
+# test build. This is because in the test build, code coverage is enabled,
+# which means the object files that get built will be different
+OBJS = $(SRCS:%.cpp=$(BUILD_DIR)/%.o)
+TEST_OBJS = $(TEST_SRCS:%.cpp=$(BUILD_TEST_DIR)/%.o)
+
+ifneq ($(MAKECMDGOALS),clean)
+-include $(OBJS:%.o=%.d)
+-include $(TEST_OBJS:%.o=%.d)
+endif
+
+$(BUILD_DIR)/%.o: %.cpp
+	@mkdir -p $(@D)
+	$(CXX) $(CXXFLAGS) $(CPPFLAGS) -c -o $@ $<
+
+$(DHCP4RELAY_TARGET): $(PCAPPP_DONE) $(OBJS)
+	$(CXX) $(LDFLAGS) $^ $(LDLIBS) -o $@
+
+$(BUILD_TEST_DIR)/%.o: %.cpp
+	@mkdir -p $(@D)
+	$(CXX) $(CXXFLAGS) $(CPPFLAGS) $(CPPFLAGS_TEST) $(LDLIBS) -c -o $@ $<
+
+$(DHCP4RELAY_TEST_TARGET): $(TEST_OBJS)
+	$(CXX) $(LDFLAGS) $^ $(LDLIBS) $(LDLIBS_TEST) -o $@
+
+test: $(DHCP4RELAY_TEST_TARGET)
+	sudo ASAN_OPTIONS=detect_leaks=0 ./$(DHCP4RELAY_TEST_TARGET) --gtest_output=xml:$(DHCP4RELAY_TEST_TARGET)-test-result.xml || true
+	$(GCOVR) -r ./ --html --html-details -o $(DHCP4RELAY_TEST_TARGET)-code-coverage.html
+	$(GCOVR) -r ./ --xml-pretty -o $(DHCP4RELAY_TEST_TARGET)-code-coverage.xml
+
+install: $(DHCP4RELAY_TARGET)
+	install -D $(DHCP4RELAY_TARGET) $(DESTDIR)/usr/sbin/$(notdir $(DHCP4RELAY_TARGET))
+
+uninstall:
+	$(RM) $(DESTDIR)/usr/sbin/$(notdir $(DHCP4RELAY_TARGET))
+
+clean:
+	-$(RM) $(BUILD_DIR) $(BUILD_TEST_DIR) *.html *.xml
+	$(FIND) . -name *.gcda -exec rm -f {} \;
+	$(FIND) . -name *.gcno -exec rm -f {} \;
+	$(FIND) . -name *.gcov -exec rm -f {} \;
+	-@echo ' '
+
+.PHONY: all clean test install uninstall

dhcp4relay/debian/changelog

@@ -0,0 +1,5 @@
+sonic-dhcp4relay (1.0.0-0) UNRELEASED; urgency=medium
+
+  * Initial release.
+
+ -- Ashutosh Agrawal <ashu@cisco.com>  Thu, 16 Jan 2025 09:11:40 -0700 

dhcp4relay/debian/compat

@@ -0,0 +1 @@
+12

dhcp4relay/debian/control

@@ -0,0 +1,14 @@
+Source: sonic-dhcp4relay
+Section: devel
+Priority: optional
+Maintainer: Ashutosh Agrawal <ashu@cisco.com>
+Build-Depends: debhelper (>= 12.0.0), libevent-dev, libboost-thread-dev, libboost-system-dev, libswsscommon-dev
+Standards-Version: 3.9.3
+Homepage: https://github.com/Azure/sonic-buildimage
+XS-Go-Import-Path: github.com/Azure/sonic-buildimage
+
+Package: sonic-dhcp4relay
+Architecture: any
+Built-Using: ${misc:Built-Using}
+Depends: ${shlibs:Depends}
+Description: SONiC DHCPv4 Relay

dhcp4relay/debian/rules

@@ -0,0 +1,6 @@
+#!/usr/bin/make -f
+
+export DEB_BUILD_MAINT_OPTIONS=hardening=+all
+
+%:
+	dh $@ --parallel

dhcp4relay/src/dhcp4_sender.cpp

@@ -0,0 +1,78 @@
+#include "dhcp4_sender.h"
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <syslog.h>
+
+#include <cstring>
+
+/**
+ * @code                            bool send_udp(int sock, uint8_t *buffer, struct sockaddr_in target, uint32_t len, const char* src_ip, bool use_src_ip);
+ *
+ * @brief                           send udp packet and return true if successful
+ *
+ * @param *buffer                   message buffer
+ * @param sockaddr_in  target       target socket
+ * @param len                       length of message
+ * @param src_ip                    source IP address as string (optional)
+ * @param use_src_ip                if true, use src_ip as source address
+ *
+ * @return boolean   True if packet successfully sent
+ */
+#ifndef UNIT_TEST
+bool send_udp(int sock, uint8_t *buffer, struct sockaddr_in target, uint32_t len, in_addr src_ip, bool use_src_ip) {
+   /* Pad additional bytes if length is lesser than 300
+    * to make DHCP packet length to minimum of 300 bytes */
+   if (len < BOOTP_MIN_LEN) {
+      auto pad_len = BOOTP_MIN_LEN - len;
+      memset(buffer+len, 0, pad_len);
+      len = BOOTP_MIN_LEN;
+   }
+
+   if (use_src_ip && src_ip.s_addr != 0) {
+        // Enable IP_PKTINFO on the socket
+        int on = 1;
+        setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
+
+        struct msghdr msg = {};
+        struct iovec iov = {};
+        char cmsgbuf[CMSG_SPACE(sizeof(struct in_pktinfo))];
+
+        iov.iov_base = buffer;
+        iov.iov_len = len;
+
+        msg.msg_name = &target;
+        msg.msg_namelen = sizeof(target);
+        msg.msg_iov = &iov;
+        msg.msg_iovlen = 1;
+        msg.msg_control = cmsgbuf;
+        msg.msg_controllen = sizeof(cmsgbuf);
+
+        struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_level = IPPROTO_IP;
+        cmsg->cmsg_type = IP_PKTINFO;
+        cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+
+        struct in_pktinfo *pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsg);
+        memset(pktinfo, 0, sizeof(struct in_pktinfo));
+        pktinfo->ipi_spec_dst = src_ip;
+
+        msg.msg_controllen = cmsg->cmsg_len;
+
+        if (sendmsg(sock, &msg, 0) == -1) {
+            char server_addr[INET_ADDRSTRLEN];
+            inet_ntop(AF_INET, &(target.sin_addr), server_addr, INET_ADDRSTRLEN);
+            syslog(LOG_ERR, "sendmsg: Failed to send to target address: %s, error: %s\n", server_addr, strerror(errno));
+            return false;
+        }
+    } else {
+        if (sendto(sock, buffer, len, 0, (const struct sockaddr *)&target, sizeof(target)) == -1) {
+            char server_addr[INET_ADDRSTRLEN];
+            inet_ntop(AF_INET, &(target.sin_addr), server_addr, INET_ADDRSTRLEN);
+            syslog(LOG_ERR, "sendto: Failed to send to target address: %s, error: %s\n", server_addr, strerror(errno));
+            return false;
+        }
+    }
+    return true;
+}
+#endif

dhcp4relay/src/dhcp4_sender.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include <string>
+
+#define BOOTP_MIN_LEN 300
+/**
+ * @code                            bool send_udp(int sock, uint8_t *buffer, struct sockaddr_in target, uint32_t len, const char* src_ip, bool use_src_ip);
+ *
+ * @brief                           send udp packet and return true if successful
+ *
+ * @param *buffer                   message buffer
+ * @param sockaddr_in  target       target socket
+ * @param len                         length of message
+ * @param src_ip                    source IP address as string (optional)
+ * @param use_src_ip                if true, use src_ip as source address
+ *
+ * @return boolean   True if packet successfully sent
+ */
+bool send_udp(int sock, uint8_t *buffer, struct sockaddr_in target, uint32_t len, in_addr src_ip, bool use_src_ip);