ooni-probe-cli/internal/netxlite/tproxy.go
Simone Basso cf6dbe48e0
netxlite: call getaddrinfo and handle platform-specific oddities (#764)
This commit changes our system resolver to call getaddrinfo directly when CGO is enabled. This change allows us to:

1. obtain the CNAME easily

2. obtain the real getaddrinfo retval

3. handle platform specific oddities such as `EAI_NODATA`
returned on Android devices

See https://github.com/ooni/probe/issues/2029 and https://github.com/ooni/probe/issues/2029#issuecomment-1140258729 in particular.

See https://github.com/ooni/probe/issues/2033 for documentation regarding the desire to see `getaddrinfo`'s retval.

See https://github.com/ooni/probe/issues/2118 for possible follow-up changes.
2022-05-28 15:10:30 +02:00

45 lines
1.6 KiB
Go

package netxlite
//
// Transparent proxy (for integration testing)
//
import (
"context"
"net"
"time"
"github.com/ooni/probe-cli/v3/internal/model"
)
// TProxy is the fundamental variable controlling how netxlite creates
// net.Conn and model.UDPLikeConn, as well as how it uses the stdlib
// resolver. By modifying this variable, you can effectively transparently
// proxy netxlite (and hence OONI) activities to other services. This is
// quite convenient when performing quality assurance tests.
var TProxy model.UnderlyingNetworkLibrary = &TProxyStdlib{}
// TProxyStdlib is the default model.UnderlyingNetworkLibrary using
// the stdlib in the most obvious way for every functionality.
type TProxyStdlib struct{}
// ListenUDP calls net.ListenUDP.
func (*TProxyStdlib) ListenUDP(network string, laddr *net.UDPAddr) (model.UDPLikeConn, error) {
return net.ListenUDP(network, laddr)
}
// LookupHost calls net.DefaultResolver.LookupHost.
func (*TProxyStdlib) LookupHost(ctx context.Context, domain string) ([]string, error) {
// Implementation note: if possible, we try to call getaddrinfo
// directly, which allows us to gather the underlying error. The
// specifics of whether "it's possible" depend on whether we've
// been compiled linking to libc as well as whether we think that
// a platform is ready for using getaddrinfo directly.
return getaddrinfoLookupHost(ctx, domain)
}
// NewSimpleDialer returns a &net.Dialer{Timeout: timeout} instance.
func (*TProxyStdlib) NewSimpleDialer(timeout time.Duration) model.SimpleDialer {
return &net.Dialer{Timeout: timeout}
}