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package ice
import (
"net"
"strings"
)
func validateIPString(ipStr string) (net.IP, bool, error) {
ip := net.ParseIP(ipStr)
if ip == nil {
return nil, false, ErrInvalidNAT1To1IPMapping
}
return ip, (ip.To4() != nil), nil
}
// ipMapping holds the mapping of local and external IP address for a particular IP family
type ipMapping struct {
ipSole net.IP // when non-nil, this is the sole external IP for one local IP assumed
ipMap map[string]net.IP // local-to-external IP mapping (k: local, v: external)
valid bool // if not set any external IP, valid is false
}
func (m *ipMapping) setSoleIP(ip net.IP) error {
if m.ipSole != nil || len(m.ipMap) > 0 {
return ErrInvalidNAT1To1IPMapping
}
m.ipSole = ip
m.valid = true
return nil
}
func (m *ipMapping) addIPMapping(locIP, extIP net.IP) error {
if m.ipSole != nil {
return ErrInvalidNAT1To1IPMapping
}
locIPStr := locIP.String()
// check if dup of local IP
if _, ok := m.ipMap[locIPStr]; ok {
return ErrInvalidNAT1To1IPMapping
}
m.ipMap[locIPStr] = extIP
m.valid = true
return nil
}
func (m *ipMapping) findExternalIP(locIP net.IP) (net.IP, error) {
if !m.valid {
return locIP, nil
}
if m.ipSole != nil {
return m.ipSole, nil
}
extIP, ok := m.ipMap[locIP.String()]
if !ok {
return nil, ErrExternalMappedIPNotFound
}
return extIP, nil
}
type externalIPMapper struct {
ipv4Mapping ipMapping
ipv6Mapping ipMapping
candidateType CandidateType
}
func newExternalIPMapper(candidateType CandidateType, ips []string) (*externalIPMapper, error) { //nolint:gocognit
if len(ips) == 0 {
return nil, nil //nolint:nilnil
}
if candidateType == CandidateTypeUnspecified {
candidateType = CandidateTypeHost // defaults to host
} else if candidateType != CandidateTypeHost && candidateType != CandidateTypeServerReflexive {
return nil, ErrUnsupportedNAT1To1IPCandidateType
}
m := &externalIPMapper{
ipv4Mapping: ipMapping{ipMap: map[string]net.IP{}},
ipv6Mapping: ipMapping{ipMap: map[string]net.IP{}},
candidateType: candidateType,
}
for _, extIPStr := range ips {
ipPair := strings.Split(extIPStr, "/")
if len(ipPair) == 0 || len(ipPair) > 2 {
return nil, ErrInvalidNAT1To1IPMapping
}
extIP, isExtIPv4, err := validateIPString(ipPair[0])
if err != nil {
return nil, err
}
if len(ipPair) == 1 {
if isExtIPv4 {
if err := m.ipv4Mapping.setSoleIP(extIP); err != nil {
return nil, err
}
} else {
if err := m.ipv6Mapping.setSoleIP(extIP); err != nil {
return nil, err
}
}
} else {
locIP, isLocIPv4, err := validateIPString(ipPair[1])
if err != nil {
return nil, err
}
if isExtIPv4 {
if !isLocIPv4 {
return nil, ErrInvalidNAT1To1IPMapping
}
if err := m.ipv4Mapping.addIPMapping(locIP, extIP); err != nil {
return nil, err
}
} else {
if isLocIPv4 {
return nil, ErrInvalidNAT1To1IPMapping
}
if err := m.ipv6Mapping.addIPMapping(locIP, extIP); err != nil {
return nil, err
}
}
}
}
return m, nil
}
func (m *externalIPMapper) findExternalIP(localIPStr string) (net.IP, error) {
locIP, isLocIPv4, err := validateIPString(localIPStr)
if err != nil {
return nil, err
}
if isLocIPv4 {
return m.ipv4Mapping.findExternalIP(locIP)
}
return m.ipv6Mapping.findExternalIP(locIP)
}
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