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dhcpsvc: add constructor, validations, tests
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,11 @@ | ||
| package dhcpsvc | ||
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| import "github.com/AdguardTeam/golibs/errors" | ||
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| const ( | ||
| // errNilConfig is returned when a nil config met. | ||
| errNilConfig errors.Error = "config is nil" | ||
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| // errNoInterfaces is returned when no interfaces found in configuration. | ||
| errNoInterfaces errors.Error = "no interfaces specified" | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,124 @@ | ||
| package dhcpsvc | ||
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| import ( | ||
| "fmt" | ||
| "math" | ||
| "math/big" | ||
| "net" | ||
| "net/netip" | ||
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| "github.com/AdguardTeam/golibs/errors" | ||
| ) | ||
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| // ipRange is an inclusive range of IP addresses. A nil range is a range that | ||
| // doesn't contain any IP addresses. | ||
| // | ||
| // It is safe for concurrent use. | ||
| // | ||
| // TODO(a.garipov): Perhaps create an optimized version with uint32 for IPv4 | ||
| // ranges? Or use one of uint128 packages? | ||
| type ipRange struct { | ||
| start *big.Int | ||
| end *big.Int | ||
| } | ||
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| // maxRangeLen is the maximum IP range length. The bitsets used in servers only | ||
| // accept uints, which can have the size of 32 bit. | ||
| const maxRangeLen = math.MaxUint32 | ||
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| // newIPRange creates a new IP address range. start must be less than end. The | ||
| // resulting range must not be greater than maxRangeLen. | ||
| func newIPRange(start, end netip.Addr) (r *ipRange, err error) { | ||
| defer func() { err = errors.Annotate(err, "invalid ip range: %w") }() | ||
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| if !start.Less(end) { | ||
| return nil, fmt.Errorf("start is greater than or equal to end") | ||
| } | ||
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| // Make sure that both are 16 bytes long to simplify handling in | ||
| // methods. | ||
| startData, endData := start.As16(), end.As16() | ||
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| startInt := (&big.Int{}).SetBytes(startData[:]) | ||
| endInt := (&big.Int{}).SetBytes(endData[:]) | ||
| diff := (&big.Int{}).Sub(endInt, startInt) | ||
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| if !diff.IsUint64() || diff.Uint64() > maxRangeLen { | ||
| return nil, fmt.Errorf("range is too large") | ||
| } | ||
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| return &ipRange{ | ||
| start: startInt, | ||
| end: endInt, | ||
| }, nil | ||
| } | ||
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| // contains returns true if r contains ip. | ||
| func (r *ipRange) contains(ip netip.Addr) (ok bool) { | ||
| if r == nil { | ||
| return false | ||
| } | ||
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| ipData := ip.As16() | ||
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| return r.containsInt((&big.Int{}).SetBytes(ipData[:])) | ||
| } | ||
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| // containsInt returns true if r contains ipInt. For internal use only. | ||
| func (r *ipRange) containsInt(ipInt *big.Int) (ok bool) { | ||
| return ipInt.Cmp(r.start) >= 0 && ipInt.Cmp(r.end) <= 0 | ||
| } | ||
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| // ipPredicate is a function that is called on every IP address in | ||
| // (*ipRange).find. ip is given in the 16-byte form. | ||
| type ipPredicate func(ip netip.Addr) (ok bool) | ||
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| // find finds the first IP address in r for which p returns true. ip is in the | ||
| // 16-byte form. It returns an empty [netip.Addr] if no addresses satisfy p. | ||
| func (r *ipRange) find(p ipPredicate) (ip netip.Addr) { | ||
| if r == nil { | ||
| return netip.Addr{} | ||
| } | ||
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| _1 := big.NewInt(1) | ||
| var ipData [16]byte | ||
| for i := (&big.Int{}).Set(r.start); i.Cmp(r.end) <= 0; i.Add(i, _1) { | ||
| i.FillBytes(ipData[:]) | ||
| ip = netip.AddrFrom16(ipData) | ||
| if p(ip) { | ||
| return ip | ||
| } | ||
| } | ||
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| return netip.Addr{} | ||
| } | ||
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| // offset returns the offset of ip from the beginning of r. It returns 0 and | ||
| // false if ip is not in r. | ||
| func (r *ipRange) offset(ip netip.Addr) (offset uint64, ok bool) { | ||
| if r == nil { | ||
| return 0, false | ||
| } | ||
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| ipData := ip.As16() | ||
| ipInt := (&big.Int{}).SetBytes(ipData[:]) | ||
| if !r.containsInt(ipInt) { | ||
| return 0, false | ||
| } | ||
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| offsetInt := (&big.Int{}).Sub(ipInt, r.start) | ||
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| // Assume that the range was checked against maxRangeLen during | ||
| // construction. | ||
| return offsetInt.Uint64(), true | ||
| } | ||
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| // String implements the fmt.Stringer interface for *ipRange. | ||
| func (r *ipRange) String() (s string) { | ||
| start, end := [16]byte{}, [16]byte{} | ||
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| r.start.FillBytes(start[:]) | ||
| r.end.FillBytes(end[:]) | ||
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| return fmt.Sprintf("%s-%s", net.IP(start[:]), net.IP(end[:])) | ||
| } |
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