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Fixed port overwrite issue on kernels without ipv6

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Fixed an issue in CreateBind for Linux:
If ipv6 was not supported the error code would be
correctly identified as EAFNOSUPPORT and ipv4 binding attempted.
However the port would be set to 0,
which results in the subsequent create4 call requesting
a random port rather than the one provided to CreateBind.

This issue was identified by:
Kent Friis <leeloored@gmx.com>
This commit is contained in:
Mathias Hall-Andersen 2018-09-16 15:05:08 +02:00 committed by Jason A. Donenfeld
parent 5be541d147
commit 32d2148835
1 changed files with 35 additions and 13 deletions
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48
conn_linux.go
View file

@ -27,6 +27,10 @@ import (
"unsafe"
)
const (
FD_ERR = -1
)
type IPv4Source struct {
src [4]byte
ifindex int32
@ -126,6 +130,7 @@ func createNetlinkRouteSocket() (int, error) {
func CreateBind(port uint16, device *Device) (*NativeBind, uint16, error) {
var err error
var bind NativeBind
var newPort uint16
bind.netlinkSock, err = createNetlinkRouteSocket()
if err != nil {
@ -139,18 +144,35 @@ func CreateBind(port uint16, device *Device) (*NativeBind, uint16, error) {
go bind.routineRouteListener(device)
bind.sock6, port, err = create6(port)
if err != nil && err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
return nil, 0, err
// attempt ipv6 bind, update port if succesful
bind.sock6, newPort, err = create6(port)
if err != nil {
if err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
return nil, 0, err
}
} else {
port = newPort
}
bind.sock4, port, err = create4(port)
if err != nil && err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
unix.Close(bind.sock6)
return nil, 0, err
// attempt ipv4 bind, update port if succesful
bind.sock4, newPort, err = create4(port)
if err != nil {
if err != syscall.EAFNOSUPPORT {
bind.netlinkCancel.Cancel()
unix.Close(bind.sock6)
return nil, 0, err
}
} else {
port = newPort
}
if bind.sock4 == FD_ERR && bind.sock6 == FD_ERR {
return nil, 0, errors.New("ipv4 and ipv6 not supported")
}
return &bind, port, nil
}
@ -334,7 +356,7 @@ func create4(port uint16) (int, uint16, error) {
)
if err != nil {
return -1, 0, err
return FD_ERR, 0, err
}
addr := unix.SockaddrInet4{
@ -365,7 +387,7 @@ func create4(port uint16) (int, uint16, error) {
return unix.Bind(fd, &addr)
}(); err != nil {
unix.Close(fd)
return -1, 0, err
return FD_ERR, 0, err
}
return fd, uint16(addr.Port), err
@ -382,7 +404,7 @@ func create6(port uint16) (int, uint16, error) {
)
if err != nil {
return -1, 0, err
return FD_ERR, 0, err
}
// set sockopts and bind
@ -424,7 +446,7 @@ func create6(port uint16) (int, uint16, error) {
}(); err != nil {
unix.Close(fd)
return -1, 0, err
return FD_ERR, 0, err
}
return fd, uint16(addr.Port), err