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Truncated #5

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merged 3 commits into from
Aug 17, 2016
Merged

Truncated #5

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8e0a2ec
fix feature: about dns msg Truncated in q/q.go
FreeRegin Aug 17, 2016
9dfbcc9
fix feature: about dns msg Truncated in q/q.go
FreeRegin Aug 17, 2016
75d2564
fix: tcp msg truncated
FreeRegin Aug 17, 2016
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50 changes: 27 additions & 23 deletions q/q.go
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Original file line number Diff line number Diff line change
Expand Up @@ -348,36 +348,40 @@ Query:
}
r, rtt, e := c.Exchange(m, nameserver)
Redo:
if e != nil {
switch e {
case nil:
//do nothing
case dns.ErrTruncated:
if *fallback {
if !*dnssec {
fmt.Printf(";; Truncated, trying %d bytes bufsize\n", dns.DefaultMsgSize)
o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
o.SetUDPSize(dns.DefaultMsgSize)
m.Extra = append(m.Extra, o)
r, rtt, e = c.Exchange(m, nameserver)
*dnssec = true
goto Redo
} else {
// First EDNS, then TCP
fmt.Printf(";; Truncated, trying TCP\n")
c.Net = "tcp"
r, rtt, e = c.Exchange(m, nameserver)
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hmmm, we should also quit if the tcp query also comes back truncated? If not we enter an infinite loop

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hmm, by tcp, the msg will cut into slices, so do we should consider about this case? Maybe I am wrong, if so, I am really sorry~

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No, when you get a truncated TCP message there is no follow up, the client should then just give up.

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hmm, you mean the server may truncate the tcp msg, I will change the code

*fallback = false
goto Redo
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set *fallback false and output "Truncated", this is OK~

}
}
fmt.Printf(";; Truncated\n")
default:
fmt.Printf(";; %s\n", e.Error())
continue
}
if r.Id != m.Id {
fmt.Fprintf(os.Stderr, "Id mismatch\n")
return
}
if r.MsgHdr.Truncated && *fallback {
if !*dnssec {
fmt.Printf(";; Truncated, trying %d bytes bufsize\n", dns.DefaultMsgSize)
o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
o.SetUDPSize(dns.DefaultMsgSize)
m.Extra = append(m.Extra, o)
r, rtt, e = c.Exchange(m, nameserver)
*dnssec = true
goto Redo
} else {
// First EDNS, then TCP
fmt.Printf(";; Truncated, trying TCP\n")
c.Net = "tcp"
r, rtt, e = c.Exchange(m, nameserver)
goto Redo
}
}
if r.MsgHdr.Truncated && !*fallback {
fmt.Printf(";; Truncated\n")
}

if *check {
sigCheck(r, nameserver, *tcp)
denialCheck(r)
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