traefik/pkg/ip/strategy.go
2024-09-24 18:04:05 +02:00

112 lines
2.4 KiB
Go

package ip
import (
"net"
"net/http"
"net/netip"
"strings"
)
const (
xForwardedFor = "X-Forwarded-For"
)
// Strategy a strategy for IP selection.
type Strategy interface {
GetIP(req *http.Request) string
}
// RemoteAddrStrategy a strategy that always return the remote address.
type RemoteAddrStrategy struct {
// IPv6Subnet instructs the strategy to return the first IP of the subnet where IP belongs.
IPv6Subnet *int
}
// GetIP returns the selected IP.
func (s *RemoteAddrStrategy) GetIP(req *http.Request) string {
ip, _, err := net.SplitHostPort(req.RemoteAddr)
if err != nil {
return req.RemoteAddr
}
if s.IPv6Subnet != nil {
return getIPv6SubnetIP(ip, *s.IPv6Subnet)
}
return ip
}
// DepthStrategy a strategy based on the depth inside the X-Forwarded-For from right to left.
type DepthStrategy struct {
Depth int
// IPv6Subnet instructs the strategy to return the first IP of the subnet where IP belongs.
IPv6Subnet *int
}
// GetIP returns the selected IP.
func (s *DepthStrategy) GetIP(req *http.Request) string {
xff := req.Header.Get(xForwardedFor)
xffs := strings.Split(xff, ",")
if len(xffs) < s.Depth {
return ""
}
ip := strings.TrimSpace(xffs[len(xffs)-s.Depth])
if s.IPv6Subnet != nil {
return getIPv6SubnetIP(ip, *s.IPv6Subnet)
}
return ip
}
// PoolStrategy is a strategy based on an IP Checker.
// It allows to check whether addresses are in a given pool of IPs.
type PoolStrategy struct {
Checker *Checker
}
// GetIP checks the list of Forwarded IPs (most recent first) against the
// Checker pool of IPs. It returns the first IP that is not in the pool, or the
// empty string otherwise.
func (s *PoolStrategy) GetIP(req *http.Request) string {
if s.Checker == nil {
return ""
}
xff := req.Header.Get(xForwardedFor)
xffs := strings.Split(xff, ",")
for i := len(xffs) - 1; i >= 0; i-- {
xffTrimmed := strings.TrimSpace(xffs[i])
if len(xffTrimmed) == 0 {
continue
}
if contain, _ := s.Checker.Contains(xffTrimmed); !contain {
return xffTrimmed
}
}
return ""
}
// getIPv6SubnetIP returns the IPv6 subnet IP.
// It returns the original IP when it is not an IPv6, or if parsing the IP has failed with an error.
func getIPv6SubnetIP(ip string, ipv6Subnet int) string {
addr, err := netip.ParseAddr(ip)
if err != nil {
return ip
}
if !addr.Is6() {
return ip
}
prefix, err := addr.Prefix(ipv6Subnet)
if err != nil {
return ip
}
return prefix.Addr().String()
}