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handshake.go
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handshake.go
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package tlsaudit
import (
"net"
"net/textproto"
"strings"
"time"
gotls "github.com/adedayo/tlsaudit/pkg/golang"
tlsmodel "github.com/adedayo/tlsaudit/pkg/model"
)
// HandShakeUpToKeyExchange starts the handshake up till the acquisition of server key exchanges
func HandShakeUpToKeyExchange(hostname string, config *gotls.Config, startTLS bool, timeout time.Duration) (tlsmodel.HelloAndKey, error) {
hk := tlsmodel.HelloAndKey{}
serverHello := tlsmodel.ServerHelloMessage{}
c := &gotls.Conn{}
if startTLS {
rawConn2, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
return hk, err
}
defer rawConn2.Close()
rawConn2.SetDeadline(time.Now().Add(timeout))
err = checkAndSetupForStartTLS(rawConn2)
if err != nil {
return hk, err
}
c = gotls.MakeClientConnection(rawConn2, config)
} else {
rawConn, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
return hk, err
}
defer rawConn.Close()
rawConn.SetDeadline(time.Now().Add(timeout))
c = gotls.MakeClientConnection(rawConn, config)
}
hello, ecdheParameters, err := gotls.MakeClientHello(config)
if err != nil {
return hk, err
}
// send ClientHello
if _, err := c.WriteRecord(gotls.RecordTypeHandshake, hello.Marshal()); err != nil {
return hk, err
}
serverHello, rawHello, err := c.ReadServerHello()
if err != nil {
return hk, err
}
k, err := c.ReadServerKeyExchange(hello, &serverHello, rawHello, ecdheParameters)
if err != nil {
return tlsmodel.HelloAndKey{Hello: serverHello, Key: k, HasKey: false}, err
}
return tlsmodel.HelloAndKey{Hello: serverHello, Key: k, HasKey: true}, nil
}
// HandShakeClientHello sends client hello and gets Server Hello and Certificates
func HandShakeClientHello(hostname string, config *gotls.Config, startTLS bool, timeout time.Duration) (tlsmodel.ServerHelloMessage, error) {
serverHello := tlsmodel.ServerHelloMessage{}
// dialer := new(net.Dialer)
c := &gotls.Conn{}
if startTLS {
// dialer := new(net.Dialer)
rawConn2, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
return serverHello, err
}
defer rawConn2.Close()
rawConn2.SetDeadline(time.Now().Add(timeout))
err = checkAndSetupForStartTLS(rawConn2)
if err != nil {
return serverHello, err
}
c = gotls.MakeClientConnection(rawConn2, config)
} else {
rawConn, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
return serverHello, err
}
defer rawConn.Close()
rawConn.SetDeadline(time.Now().Add(timeout))
c = gotls.MakeClientConnection(rawConn, config)
}
hello, _, err := gotls.MakeClientHello(config)
if err != nil {
return serverHello, err
}
// send ClientHello
if _, err := c.WriteRecord(gotls.RecordTypeHandshake, hello.Marshal()); err != nil {
return serverHello, err
}
serverHello, _, err = c.ReadServerHello()
return serverHello, err
}
// HandShakeClientHelloGetServerCert sends client hello and gets Server Hello and Certificates
func HandShakeClientHelloGetServerCert(hostname string, config *gotls.Config, timeout time.Duration) <-chan ServerHelloAndCert {
hs := make(chan ServerHelloAndCert)
go func() {
defer close(hs)
serverHello := tlsmodel.ServerHelloMessage{}
certs := tlsmodel.CertificateMessage{}
rawConn, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
defer rawConn.Close()
rawConn.SetDeadline(time.Now().Add(timeout))
c := gotls.MakeClientConnection(rawConn, config)
clientHello, ecdheParameters, err := gotls.MakeClientHello(config)
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
// send ClientHello
if _, err := c.WriteRecord(gotls.RecordTypeHandshake, clientHello.Marshal()); err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
var rawHello interface{}
serverHello, rawHello, err = c.ReadServerHello()
startTLS := false
if err != nil {
//If ServerHello fails, check STARTTLS
rawConn2, err := net.DialTimeout("tcp", hostname, timeout)
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
defer rawConn2.Close()
rawConn2.SetDeadline(time.Now().Add(timeout))
err = checkAndSetupForStartTLS(rawConn2)
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
}
c = gotls.MakeClientConnection(rawConn2, config)
clientHello, ecdheParameters, err = gotls.MakeClientHello(config)
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
// send ClientHello
if _, err := c.WriteRecord(gotls.RecordTypeHandshake, clientHello.Marshal()); err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
serverHello, rawHello, err = c.ReadServerHello()
if err != nil {
hs <- ServerHelloAndCert{ServerHello: serverHello, Cert: certs, Err: err}
return
}
startTLS = true
}
certs, err = c.ReadServerCertificate(clientHello, &serverHello, rawHello, ecdheParameters)
hs <- ServerHelloAndCert{ServerHello: serverHello, StartTLS: startTLS, Cert: certs, Err: err}
return
}()
return hs
}
//Test whether connection is STARTTLS
func checkAndSetupForStartTLS(rawConn net.Conn) error {
smtp := textproto.NewConn(rawConn)
_, _, err := smtp.ReadResponse(220)
if err != nil {
//Not SMTP
smtp.Close()
return err
}
id, err := smtp.Cmd("EHLO %s", "localhost")
if err != nil {
return err
}
smtp.StartResponse(id)
_, m, err := smtp.ReadResponse(250)
smtp.EndResponse(id)
if err != nil {
return err
}
if !strings.Contains(m, "STARTTLS") {
return err
}
id, err = smtp.Cmd("STARTTLS")
if err != nil {
return err
}
smtp.StartResponse(id)
_, m, err = smtp.ReadResponse(220)
smtp.EndResponse(id)
if err != nil {
return err
}
return nil
}