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client: SetReadDeadline after write, before read 

The current code sets the read deadline at the same time as the write
deadline. If the write nearly times out but doesn't, the read timeout
can fire before the read happens within the specified deadline.
This commit is contained in:
Tomás Senart 2015-10-06 13:30:01 +02:00
parent 373b848617
commit 56b3ff5401
1 changed files with 6 additions and 5 deletions
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11
client.go
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@ -53,8 +53,6 @@ func Exchange(m *Msg, a string) (r *Msg, err error) {
}
defer co.Close()
co.SetReadDeadline(time.Now().Add(dnsTimeout))
co.SetWriteDeadline(time.Now().Add(dnsTimeout))
opt := m.IsEdns0()
// If EDNS0 is used use that for size.
@ -62,9 +60,12 @@ func Exchange(m *Msg, a string) (r *Msg, err error) {
co.UDPSize = opt.UDPSize()
}
co.SetWriteDeadline(time.Now().Add(dnsTimeout))
if err = co.WriteMsg(m); err != nil {
return nil, err
}
co.SetReadDeadline(time.Now().Add(dnsTimeout))
r, err = co.ReadMsg()
if err == nil && r.Id != m.Id {
err = ErrId
@ -171,13 +172,13 @@ func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err erro
co.UDPSize = c.UDPSize
}
co.SetReadDeadline(time.Now().Add(c.readTimeout()))
co.SetWriteDeadline(time.Now().Add(c.writeTimeout()))
co.TsigSecret = c.TsigSecret
co.SetWriteDeadline(time.Now().Add(c.writeTimeout()))
if err = co.WriteMsg(m); err != nil {
return nil, 0, err
}
co.SetReadDeadline(time.Now().Add(c.readTimeout()))
r, err = co.ReadMsg()
if err == nil && r.Id != m.Id {
err = ErrId