/
ipv4.go
106 lines (97 loc) · 2.66 KB
/
ipv4.go
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package ipGeo
import (
"encoding/binary"
"errors"
"golang.org/x/text/encoding/simplifiedchinese"
"net"
"os"
)
func OpenIPv4DB(path string) (*IPv4DB, error) {
db := &IPv4DB{}
data, err := os.ReadFile(path)
if err != nil {
return nil, err
}
db.data = data
db.IndexStart = binary.LittleEndian.Uint32(data[0:4])
end := binary.LittleEndian.Uint32(data[4:8])
db.ipSize = 4
db.refSize = 3
db.indexSize = db.ipSize + db.refSize
db.RecordsCount = (end - db.IndexStart) / (db.ipSize + db.refSize)
return db, nil
}
func (db *IPv4DB) findIPRecord(ip uint32) uint32 {
var start uint32 = 0
var end uint32 = db.RecordsCount
for end-start > 1 {
mid := (start + end) / 2
midIndex := db.IndexStart + mid*db.indexSize
midIP := binary.LittleEndian.Uint32(db.data[midIndex : midIndex+db.ipSize])
if ip < midIP {
end = mid
} else {
start = mid
}
}
resIndex := db.IndexStart + start*db.indexSize
return bytesToUint32(db.data[resIndex+db.ipSize : resIndex+db.indexSize])
}
func (db *IPv4DB) readRecord(recordIndex uint32) *Result {
var nextArea uint32
head := db.data[recordIndex]
result := &Result{}
enc := simplifiedchinese.GBK.NewDecoder()
if head == 1 {
next := bytesToUint32(db.data[recordIndex+1 : recordIndex+1+db.refSize])
return db.readRecord(next)
} else {
result.Country = db.readIndirectString(recordIndex)
if head == 2 {
nextArea = recordIndex + 1 + db.refSize
} else {
nextArea = recordIndex + uint32(len(result.Country)) + 1
}
result.Area = db.readIndirectString(nextArea)
}
result.Country, _ = enc.String(result.Country)
result.Area, _ = enc.String(result.Area)
return result
}
func (db *IPv4DB) readIndirectString(current uint32) string {
flag := db.data[current]
if flag == 1 || flag == 2 {
next := bytesToUint32(db.data[current+1 : current+1+db.refSize])
return db.readString(next)
} else {
return db.readString(current)
}
}
func (db *IPv4DB) readString(stringIndex uint32) string {
endIndex := stringIndex
for db.data[endIndex] != 0 {
endIndex += 1
}
return string(db.data[stringIndex:endIndex])
}
func (db *IPv4DB) GetIPLocation(ip string) (*Result, error) {
var ipBytes []byte
if ipBytes = net.ParseIP(ip).To4(); ipBytes == nil {
return nil, errors.New("malformed ip address")
}
return db.GetIPNumLocation(ipBytes)
}
func (db *IPv4DB) GetIPNumLocation(ipBytes net.IP) (*Result, error) {
ipNum := binary.BigEndian.Uint32(ipBytes)
recordIndex := db.findIPRecord(ipNum)
res := db.readRecord(recordIndex + 4)
res.IP = ipBytes
return res, nil
}
func bytesToUint32(input []byte) uint32 {
var res = []byte{0, 0, 0, 0}
for i := 0; i < len(input); i++ {
res[i] = input[i]
}
return binary.LittleEndian.Uint32(res)
}