Add Roller: Dialer that cycles thru ClientHellos

u_roller.go

@@ -0,0 +1,106 @@
+package tls
+
+import (
+	"net"
+	"sync"
+	"time"
+)
+
+type Roller struct {
+	HelloIDs            []ClientHelloID
+	HelloIDMu           sync.Mutex
+	WorkingHelloID      *ClientHelloID
+	TcpDialTimeout      time.Duration
+	TlsHandshakeTimeout time.Duration
+}
+
+// NewRoller creates Roller object with default range of HelloIDs to cycle through until a
+// working/unblocked one is found.
+func NewRoller() (*Roller, error) {
+	tcpDialTimeoutInc, err := getRandInt(14)
+	if err != nil {
+		return nil, err
+	}
+	tcpDialTimeoutInc = 7 + tcpDialTimeoutInc
+
+	tlsHandshakeTimeoutInc, err := getRandInt(20)
+	if err != nil {
+		return nil, err
+	}
+	tlsHandshakeTimeoutInc = 11 + tlsHandshakeTimeoutInc
+
+	return &Roller{
+		HelloIDs: []ClientHelloID{
+			HelloChrome_Auto,
+			HelloFirefox_Auto,
+			HelloIOS_Auto,
+			HelloRandomized,
+		},
+		TcpDialTimeout:      time.Second * time.Duration(tcpDialTimeoutInc),
+		TlsHandshakeTimeout: time.Second * time.Duration(tlsHandshakeTimeoutInc),
+	}, nil
+}
+
+// Dial attempts to establish connection to given address using different HelloIDs.
+// If a working HelloID is found, it is used again for subsequent Dials.
+// If tcp connection fails or all HelloIDs are tried, returns with last error.
+//
+// Usage examples:
+//    Dial("tcp4", "google.com:443", "google.com")
+//    Dial("tcp", "10.23.144.22:443", "mywebserver.org")
+func (c *Roller) Dial(network, addr, serverName string) (*UConn, error) {
+	helloIDs, err := shuffleClientHelloIDs(c.HelloIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	c.HelloIDMu.Lock()
+	workingHelloId := c.WorkingHelloID // keep using same helloID, if it works
+	c.HelloIDMu.Unlock()
+	if workingHelloId != nil {
+		for i, ID := range helloIDs {
+			if ID == *workingHelloId {
+				helloIDs[i] = helloIDs[0]
+				helloIDs[0] = *workingHelloId // push working hello ID first
+				break
+			}
+		}
+	}
+
+	var tcpConn net.Conn
+	for _, helloID := range helloIDs {
+		tcpConn, err = net.DialTimeout(network, addr, c.TcpDialTimeout)
+		if err != nil {
+			return nil, err // on tcp Dial failure return with error right away
+		}
+
+		client := UClient(tcpConn, nil, helloID)
+		client.SetSNI(serverName)
+		client.SetDeadline(time.Now().Add(c.TlsHandshakeTimeout))
+		err = client.Handshake()
+		client.SetDeadline(time.Time{}) // unset timeout
+		if err != nil {
+			continue // on tls Dial error keep trying HelloIDs
+		}
+
+		c.HelloIDMu.Lock()
+		c.WorkingHelloID = &helloID
+		c.HelloIDMu.Unlock()
+		return client, err
+	}
+	return nil, err
+}
+
+// returns a shuffled copy of input
+func shuffleClientHelloIDs(helloIDs []ClientHelloID) ([]ClientHelloID, error) {
+	perm, err := getRandPerm(len(helloIDs))
+	if err != nil {
+		return nil, err
+	}
+
+	shuffled := make([]ClientHelloID, len(helloIDs))
+	for i, randI := range perm {
+		shuffled[i] = helloIDs[randI]
+	}
+	return shuffled, nil
+}