diff options
Diffstat (limited to 'libgo/go/net/addrselect.go')
| -rw-r--r-- | libgo/go/net/addrselect.go | 51 |
1 files changed, 5 insertions, 46 deletions
diff --git a/libgo/go/net/addrselect.go b/libgo/go/net/addrselect.go index 0b9d160fd43..1ab9fc53261 100644 --- a/libgo/go/net/addrselect.go +++ b/libgo/go/net/addrselect.go @@ -188,33 +188,17 @@ func (s *byRFC6724) Less(i, j int) bool { // Rule 9: Use longest matching prefix. // When DA and DB belong to the same address family (both are IPv6 or - // both are IPv4): If CommonPrefixLen(Source(DA), DA) > + // both are IPv4 [but see below]): If CommonPrefixLen(Source(DA), DA) > // CommonPrefixLen(Source(DB), DB), then prefer DA. Similarly, if // CommonPrefixLen(Source(DA), DA) < CommonPrefixLen(Source(DB), DB), // then prefer DB. - da4 := DA.To4() != nil - db4 := DB.To4() != nil - if da4 == db4 { + // + // However, applying this rule to IPv4 addresses causes + // problems (see issues 13283 and 18518), so limit to IPv6. + if DA.To4() == nil && DB.To4() == nil { commonA := commonPrefixLen(SourceDA, DA) commonB := commonPrefixLen(SourceDB, DB) - // CommonPrefixLen doesn't really make sense for IPv4, and even - // causes problems for common load balancing practices - // (e.g., https://golang.org/issue/13283). Glibc instead only - // uses CommonPrefixLen for IPv4 when the source and destination - // addresses are on the same subnet, but that requires extra - // work to find the netmask for our source addresses. As a - // simpler heuristic, we limit its use to when the source and - // destination belong to the same special purpose block. - if da4 { - if !sameIPv4SpecialPurposeBlock(SourceDA, DA) { - commonA = 0 - } - if !sameIPv4SpecialPurposeBlock(SourceDB, DB) { - commonB = 0 - } - } - if commonA > commonB { return preferDA } @@ -404,28 +388,3 @@ func commonPrefixLen(a, b IP) (cpl int) { } return } - -// sameIPv4SpecialPurposeBlock reports whether a and b belong to the same -// address block reserved by the IANA IPv4 Special-Purpose Address Registry: -// http://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml -func sameIPv4SpecialPurposeBlock(a, b IP) bool { - a, b = a.To4(), b.To4() - if a == nil || b == nil || a[0] != b[0] { - return false - } - // IANA defines more special-purpose blocks, but these are the only - // ones likely to be relevant to typical Go systems. - switch a[0] { - case 10: // 10.0.0.0/8: Private-Use - return true - case 127: // 127.0.0.0/8: Loopback - return true - case 169: // 169.254.0.0/16: Link Local - return a[1] == 254 && b[1] == 254 - case 172: // 172.16.0.0/12: Private-Use - return a[1]&0xf0 == 16 && b[1]&0xf0 == 16 - case 192: // 192.168.0.0/16: Private-Use - return a[1] == 168 && b[1] == 168 - } - return false -} |