Optimize Linux process finder

common/process/searcher_linux_shared_test.go

@@ -0,0 +1,60 @@
+//go:build linux
+
+package process
+
+import (
+	"net"
+	"net/netip"
+	"os"
+	"syscall"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestQuerySocketDiagUDPExact(t *testing.T) {
+	t.Parallel()
+	server, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0})
+	require.NoError(t, err)
+	defer server.Close()
+
+	client, err := net.DialUDP("udp4", nil, server.LocalAddr().(*net.UDPAddr))
+	require.NoError(t, err)
+	defer client.Close()
+
+	err = client.SetDeadline(time.Now().Add(time.Second))
+	require.NoError(t, err)
+	_, err = client.Write([]byte{0})
+	require.NoError(t, err)
+
+	err = server.SetReadDeadline(time.Now().Add(time.Second))
+	require.NoError(t, err)
+	buffer := make([]byte, 1)
+	_, _, err = server.ReadFromUDP(buffer)
+	require.NoError(t, err)
+
+	source := addrPortFromUDPAddr(t, client.LocalAddr())
+	destination := addrPortFromUDPAddr(t, client.RemoteAddr())
+
+	fd, err := openSocketDiag()
+	require.NoError(t, err)
+	defer syscall.Close(fd)
+
+	inode, uid, err := querySocketDiag(fd, packSocketDiagRequest(syscall.AF_INET, syscall.IPPROTO_UDP, source, destination, false))
+	require.NoError(t, err)
+	require.NotZero(t, inode)
+	require.EqualValues(t, os.Getuid(), uid)
+}
+
+func addrPortFromUDPAddr(t *testing.T, addr net.Addr) netip.AddrPort {
+	t.Helper()
+
+	udpAddr, ok := addr.(*net.UDPAddr)
+	require.True(t, ok)
+
+	ip, ok := netip.AddrFromSlice(udpAddr.IP)
+	require.True(t, ok)
+
+	return netip.AddrPortFrom(ip.Unmap(), uint16(udpAddr.Port))
+}