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Updates AdguardTeam#2541. Squashed commit of the following: commit c812999 Author: Ainar Garipov <[email protected]> Date: Tue Mar 16 18:10:07 2021 +0300 agherr: imp docs commit f43a5f5 Author: Ainar Garipov <[email protected]> Date: Tue Mar 16 17:35:59 2021 +0300 all: imp err handling, fix code commit ed26ad0 Author: Ainar Garipov <[email protected]> Date: Tue Mar 16 12:24:17 2021 +0300 dhcpd: fix ip ranges
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| package dhcpd | ||
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| import ( | ||
| "fmt" | ||
| "math" | ||
| "math/big" | ||
| "net" | ||
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| "github.com/AdguardTeam/AdGuardHome/internal/agherr" | ||
| ) | ||
|
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| // ipRange is an inclusive range of IP addresses. | ||
| // | ||
| // It is safe for concurrent use. | ||
| // | ||
| // TODO(a.garipov): Perhaps create an optimised 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 net.IP) (r *ipRange, err error) { | ||
| defer agherr.Annotate("invalid ip range: %w", &err) | ||
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| // Make sure that both are 16 bytes long to simplify handling in | ||
| // methods. | ||
| start, end = start.To16(), end.To16() | ||
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| startInt := (&big.Int{}).SetBytes(start) | ||
| endInt := (&big.Int{}).SetBytes(end) | ||
| diff := (&big.Int{}).Sub(endInt, startInt) | ||
|
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| if diff.Sign() <= 0 { | ||
| return nil, fmt.Errorf("start is greater than or equal to end") | ||
| } else if !diff.IsUint64() || diff.Uint64() > maxRangeLen { | ||
| return nil, fmt.Errorf("range is too large") | ||
| } | ||
|
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| r = &ipRange{ | ||
| start: startInt, | ||
| end: endInt, | ||
| } | ||
|
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| return r, nil | ||
| } | ||
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| // contains returns true if r contains ip. | ||
| func (r *ipRange) contains(ip net.IP) (ok bool) { | ||
| ipInt := (&big.Int{}).SetBytes(ip.To16()) | ||
|
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| return r.containsInt(ipInt) | ||
| } | ||
|
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| // containsInt returns true if r contains ipInt. | ||
| 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 net.IP) (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. | ||
| func (r *ipRange) find(p ipPredicate) (ip net.IP) { | ||
| ip = make(net.IP, net.IPv6len) | ||
| _1 := big.NewInt(1) | ||
| for i := (&big.Int{}).Set(r.start); i.Cmp(r.end) <= 0; i.Add(i, _1) { | ||
| i.FillBytes(ip) | ||
| if p(ip) { | ||
| return ip | ||
| } | ||
| } | ||
|
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| return nil | ||
| } | ||
|
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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 net.IP) (offset uint, ok bool) { | ||
| ip = ip.To16() | ||
| ipInt := (&big.Int{}).SetBytes(ip) | ||
| 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 uint(offsetInt.Uint64()), true | ||
| } |
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