panic using examples/pcapdump/main.go

[cleesmith]

go version go1.6 darwin/amd64

go get -u github.com/google/gopacket
go get -u github.com/google/gopacket/layers
go get -u github.com/google/gopacket/tcpassembly

using gopacket/examples/pcapdump/main.go:
go run pcapdump.go -r test_ethernet.pcap ... tried with many pcap files
... output is lots of these:
%!v(PANIC=reflect.Value.Interface: cannot return value obtained from unexported field or method)
.layerString() ?
... maybe it's related to this:
https://groups.google.com/forum/#!topic/golang-nuts/iHJcOWmWAag
http://tip.golang.org/doc/go1.6#reflect

other programs work fine ... like: httpassembly.go and bidirectional.go

[cleesmith]

After trying a bunch more pcap files, the following lame fix to packet.go seems to work:

func layerString(...)
   . . .
   case reflect.Struct:
   . . .
     if ftype.Anonymous {
       // the old line that panics:
       // anonStr := layerString(f.Interface(), true, writeSpace)
       . . .
       // this seems to only affect output like:
       //   "Contents=[..20..] Payload=[..1389..]"
       // which appears to be "type BaseLayer struct", so
       // just using an empty string when it's anonymous seems
       // to work ... and that's not a lot of info to lose
       anonStr := layerString("", true, writeSpace)
       . . .

... back to more testing with Go 1.6

[gconnell]

Fixed by 4457463, thanks for the heads up. You were 100% right, http://tip.golang.org/doc/go1.6#reflect was the cause.