hdx/ip.go

79 lines
1.8 KiB
Go

// https://github.com/tomasen/realip
package hdx
import (
"errors"
"net"
"net/http"
"strings"
)
var cidrs []*net.IPNet
func init() {
maxCidrBlocks := []string{
"127.0.0.1/8", // localhost
"10.0.0.0/8", // 24-bit block
"172.16.0.0/12", // 20-bit block
"192.168.0.0/16", // 16-bit block
"169.254.0.0/16", // link local address
"::1/128", // localhost IPv6
"fc00::/7", // unique local address IPv6
"fe80::/10", // link local address IPv6
}
cidrs = make([]*net.IPNet, len(maxCidrBlocks))
for i, maxCidrBlock := range maxCidrBlocks {
_, cidr, _ := net.ParseCIDR(maxCidrBlock)
cidrs[i] = cidr
}
}
func getIP(r *http.Request) string {
// Fetch header value
xRealIP := r.Header.Get("X-Real-Ip")
xForwardedFor := r.Header.Get("X-Forwarded-For")
// If both empty, return IP from remote address
if xRealIP == "" && xForwardedFor == "" {
var remoteIP string
// If there are colon in remote address, remove the port number
// otherwise, return remote address as is
if strings.ContainsRune(r.RemoteAddr, ':') {
remoteIP, _, _ = net.SplitHostPort(r.RemoteAddr)
} else {
remoteIP = r.RemoteAddr
}
return remoteIP
}
// Check list of IP in X-Forwarded-For and return the first global address
for _, address := range strings.Split(xForwardedFor, ",") {
address = strings.TrimSpace(address)
isPrivate, err := isPrivateAddress(address)
if !isPrivate && err == nil {
return address
}
}
// If nothing succeed, return X-Real-IP
return xRealIP
}
func isPrivateAddress(address string) (bool, error) {
ipAddress := net.ParseIP(address)
if ipAddress == nil {
return false, errors.New("address is not valid")
}
for i := range cidrs {
if cidrs[i].Contains(ipAddress) {
return true, nil
}
}
return false, nil
}