move udpproxy files into repo root

udpproxy.go

@@ -0,0 +1,102 @@
+package udpproxy
+
+import (
+	"net"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// Option is a functional option type that allows us to configure the Client.
+type Option func(*Client)
+
+// WithSessionTimeout is a functional option to set the session timeout
+func WithSessionTimeout(timeout time.Duration) Option {
+	return func(c *Client) {
+		if timeout < time.Minute {
+			log.Warnf("cannot set stale session timeout to less than 1 minute.. defaulting to 20 minutes")
+			return
+		}
+
+		c.sessionTimeout = timeout
+	}
+}
+
+type Client struct {
+	laddr *net.UDPAddr
+	raddr *net.UDPAddr
+
+	proxyConn *net.UDPConn
+
+	sessionCache   sessionCache
+	sessionTimeout time.Duration
+}
+
+func New(proxy, target string, options ...Option) (*Client, error) {
+	laddr, err := net.ResolveUDPAddr("udp", proxy)
+	if err != nil {
+		return nil, err
+	}
+
+	raddr, err := net.ResolveUDPAddr("udp", target)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &Client{
+		laddr:          laddr,
+		raddr:          raddr,
+		sessionCache:   newSessionCache(),
+		sessionTimeout: 20 * time.Minute,
+	}
+
+	for _, o := range options {
+		o(c)
+	}
+
+	return c, nil
+}
+
+func (c *Client) ListenAndServe() error {
+	var err error
+	c.proxyConn, err = net.ListenUDP("udp", c.laddr)
+	if err != nil {
+		return err
+	}
+
+	go c.pruneSessions()
+
+	buf := make([]byte, 2048)
+	for {
+		n, caddr, err := c.proxyConn.ReadFromUDP(buf)
+		if err != nil {
+			log.Error(err)
+		}
+
+		session, ok := c.sessionCache.read(caddr.String())
+		if !ok {
+			session, err = newSession(caddr, c.raddr, c.proxyConn)
+			if err != nil {
+				log.Error(err)
+				continue
+			}
+
+			c.sessionCache.insert(caddr.String(), session)
+		}
+
+		go session.proxyTo(buf[:n])
+	}
+}
+
+func (c *Client) pruneSessions() {
+	ticker := time.NewTicker(1 * time.Minute)
+
+	for range ticker.C {
+		for _, session := range c.sessionCache.data {
+			if time.Since(session.updateTime) > c.sessionTimeout {
+				c.sessionCache.delete(session.caddr.String())
+				log.Tracef("session for %s deleted", session.caddr)
+			}
+		}
+	}
+}