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net: Interfaces() fails on Plan 9 if there is a packet interface #39908

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fhs opened this issue Jun 29, 2020 · 2 comments
Closed

net: Interfaces() fails on Plan 9 if there is a packet interface #39908

fhs opened this issue Jun 29, 2020 · 2 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. OS-Plan9

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@fhs
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fhs commented Jun 29, 2020

What version of Go are you using (go version)?

$ go version
go version devel +master Thu Jun 25 19:13:01 EDT 2020 plan9/amd64

What did you do?

  • Create a packet interface. For example, 6in4(8) and tinc(8) creates them by writing bind pkt to the interface control file.
    Note that the device name in the interface status file is pkt2:
cpu% cat /net/ipifc/2/status | sed 1q
device pkt2 maxtu 1472 sendra 0 recvra 0 mflag 0 oflag 0 maxraint 600000 minraint 200000 linkmtu 0 reachtime 0 rxmitra 0 ttl 255 routerlt 1800 pktin 0 pktout 0 errin 0 errout 0 speed 0 delay 40
  • Call net.Interfaces() in a Go program.

What did you expect to see?

nil error

What did you see instead?

Error returned:

route ip+net: open pkt2/addr: 'pkt2' file not found

The code is assuming pkt2 is a path to a network device (e.g. /net/ether0) and tries to open pkt2/addr to read in the Interface.HardwareAddr:

go/src/net/interface_plan9.go

Lines 71 to 76 in c875503

// Not a loopback device
if device != "/dev/null" {
deviceaddrf, err := open(device + "/addr")
if err != nil {
return nil, err
}

It does skip this for the loopback interface (/dev/null device), but it should also skip for packet interfaces. Maybe it should just skip anything without a /net/ prefix.

@gopherbot add labels OS-Plan9, NeedsFix
@gopherbot gopherbot added NeedsFix The path to resolution is known, but the work has not been done. OS-Plan9 labels Jun 29, 2020
@fhs fhs changed the title net: net.Interfaces() fails on Plan 9 if there is a packet interface net: Interfaces() fails on Plan 9 if there is a packet interface Jun 29, 2020
@fhs
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fhs commented Jun 29, 2020

Tests are also failing:

cpu% cd src/net
cpu% go test -short
--- FAIL: TestInterfaces (0.00s)
    interface_test.go:56: route ip+net: open pkt2/addr: 'pkt2' './home/big/go/src/net/pkt2' does not exist
--- FAIL: TestInterfaceAddrs (0.00s)
    interface_test.go:87: route ip+net: open pkt2/addr: 'pkt2' './home/big/go/src/net/pkt2' does not exist
--- FAIL: TestInterfaceUnicastAddrs (0.00s)
    interface_test.go:106: route ip+net: open pkt2/addr: 'pkt2' './home/big/go/src/net/pkt2' does not exist
--- FAIL: TestInterfaceMulticastAddrs (0.00s)
    interface_test.go:133: route ip+net: open pkt2/addr: 'pkt2' './home/big/go/src/net/pkt2' does not exist
FAIL
exit status: 'net.test 11992: 1'
FAIL	net	40.497s

@gopherbot
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Change https://golang.org/cl/240259 mentions this issue: net: handle more interface types without a hardware address on Plan 9

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