Add support for hostkey certificates

While they're not exactly certificates, they belong in the same
category.

remote.go

@@ -2,6 +2,7 @@ package git
 
 /*
 #include <git2.h>
+#include <strings.h>
 
 extern void _go_git_setup_callbacks(git_remote_callbacks *callbacks);
 
@@ -45,7 +46,7 @@ type CompletionCallback func(RemoteCompletion) int
 type CredentialsCallback func(url string, username_from_url string, allowed_types CredType) (int, *Cred)
 type TransferProgressCallback func(stats TransferProgress) int
 type UpdateTipsCallback func(refname string, a *Oid, b *Oid) int
-type CertificateCheckCallback func(cert *x509.Certificate, valid bool, hostname string) int
+type CertificateCheckCallback func(cert *Certificate, valid bool, hostname string) int
 
 type RemoteCallbacks struct {
 	SidebandProgressCallback TransportMessageCallback
@@ -61,6 +62,39 @@ type Remote struct {
 	callbacks RemoteCallbacks
 }
 
+type CertificateKind uint
+
+const (
+	CertificateX509    CertificateKind = C.GIT_CERT_X509
+	CertificateHostkey                 = C.GIT_CERT_HOSTKEY_LIBSSH2
+)
+
+// Certificate represents the two possible certificates which libgit2
+// knows it might find. If Kind is CertficateX509 then the X509 field
+// will be filled. If Kind is CertificateHostkey then the Hostkey
+// field will be fille.d
+type Certificate struct {
+	Kind    CertificateKind
+	X509    *x509.Certificate
+	Hostkey HostkeyCertificate
+}
+
+type HostkeyKind uint
+
+const (
+	HostkeyMD5  HostkeyKind = C.GIT_CERT_SSH_MD5
+	HostkeySHA1             = C.GIT_CERT_SSH_SHA1
+)
+
+// Server host key information. If Kind is HostkeyMD5 the MD5 field
+// will be filled. If Kind is HostkeySHA1, then HashSHA1 will be
+// filled.
+type HostkeyCertificate struct {
+	Kind     HostkeyKind
+	HashMD5  [16]byte
+	HashSHA1 [20]byte
+}
+
 func populateRemoteCallbacks(ptr *C.git_remote_callbacks, callbacks *RemoteCallbacks) {
 	C.git_remote_init_callbacks(ptr, C.GIT_REMOTE_CALLBACKS_VERSION)
 	if callbacks == nil {
@@ -132,21 +166,32 @@ func certificateCheckCallback(_cert *C.git_cert,  _valid C.int, _host *C.char, d
 	host := C.GoString(_host)
 	valid := _valid != 0
 
+	var cert Certificate
 	if _cert.cert_type == C.GIT_CERT_X509 {
+		cert.Kind = CertificateX509
 		ccert := (*C.git_cert_x509)(unsafe.Pointer(_cert))
 		x509_certs, err := x509.ParseCertificates(C.GoBytes(ccert.data, C.int(ccert.len)))
 		if err != nil {
-			return C.GIT_EUSER;
+			return C.GIT_EUSER
 		}
 
 		// we assume there's only one, which should hold true for any web server we want to talk to
-		return callbacks.CertificateCheckCallback(x509_certs[0], valid, host)
+		cert.X509 = x509_certs[0]
-	}
+	} else if _cert.cert_type == C.GIT_CERT_HOSTKEY_LIBSSH2 {
-
+		cert.Kind = CertificateHostkey
+		ccert := (*C.git_cert_hostkey)(unsafe.Pointer(_cert))
+		cert.Hostkey.Kind = HostkeyKind(ccert._type)
+		C.memcpy(unsafe.Pointer(&cert.Hostkey.HashMD5[0]), unsafe.Pointer(&ccert.hash_md5[0]), C.size_t(len(cert.Hostkey.HashMD5)))
+		C.memcpy(unsafe.Pointer(&cert.Hostkey.HashSHA1[0]), unsafe.Pointer(&ccert.hash_sha1[0]), C.size_t(len(cert.Hostkey.HashSHA1)))
+	} else {
 		cstr := C.CString("Unsupported certificate type")
 		C.giterr_set_str(C.GITERR_NET, cstr)
 		C.free(unsafe.Pointer(cstr))
-	return ErrUser // we don't support anything else atm
+		return -1 // we don't support anything else atm
+	}
+
+
+	return callbacks.CertificateCheckCallback(&cert, valid, host)
 }
 
 func RemoteIsValidName(name string) bool {

remote_test.go

@@ -1,8 +1,6 @@
 package git
 
 import (
-	"fmt"
-	"crypto/x509"
 	"os"
 	"testing"
 )
@@ -49,8 +47,7 @@ func TestListRemotes(t *testing.T) {
 }
 
 
-func assertHostname(cert *x509.Certificate, valid bool, hostname string, t *testing.T) int {
+func assertHostname(cert *Certificate, valid bool, hostname string, t *testing.T) int {
-	fmt.Println("hostname", hostname)
 	if hostname != "github.com" {
 		t.Fatal("Hostname does not match")
 		return ErrUser
@@ -68,7 +65,7 @@ func TestCertificateCheck(t *testing.T) {
 	checkFatal(t, err)
 
 	callbacks := RemoteCallbacks{
-		CertificateCheckCallback: func (cert *x509.Certificate, valid bool, hostname string) int {
+		CertificateCheckCallback: func (cert *Certificate, valid bool, hostname string) int {
 			return assertHostname(cert, valid, hostname, t)
 		},
 	}
@@ -77,5 +74,4 @@ func TestCertificateCheck(t *testing.T) {
 	checkFatal(t, err)
 	err = remote.Fetch([]string{}, nil, "")
 	checkFatal(t, err)
-	fmt.Println("after Fetch()")
 }