Adds function ExchangeWithConn (#1110)
* Implements ExchangeWithConn, a function that allows callers to pass in a connection instead of having the library create a new one for them. Exchange now wraps around this, implementing the existing behavior by creating a new connection and passing it to ExchangeWithConn. c.exchange has been updated to support this behavior as well. * adding tab * formatting problem * adds test case for ExchangeWithConn
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parent
d128d10d17
commit
1fc9fa1db0
37
client.go
37
client.go
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@ -124,15 +124,38 @@ func (c *Client) Dial(address string) (conn *Conn, err error) {
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// of 512 bytes
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// To specify a local address or a timeout, the caller has to set the `Client.Dialer`
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// attribute appropriately
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func (c *Client) Exchange(m *Msg, address string) (r *Msg, rtt time.Duration, err error) {
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co, err := c.Dial(address)
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if err != nil {
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return nil, 0, err
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}
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defer co.Close()
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return c.ExchangeWithConn(m, co)
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}
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// ExchangeWithConn has the same behavior as Exchange, just with a predetermined connection
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// that will be used instead of creating a new one.
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// Usage pattern with a *dns.Client:
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// c := new(dns.Client)
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// // connection management logic goes here
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//
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// conn := c.Dial(address)
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// in, rtt, err := c.ExchangeWithConn(message, conn)
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//
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// This allows users of the library to implement their own connection management,
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// as opposed to Exchange, which will always use new connections and incur the added overhead
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// that entails when using "tcp" and especially "tcp-tls" clients.
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func (c *Client) ExchangeWithConn(m *Msg, conn *Conn) (r *Msg, rtt time.Duration, err error) {
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if !c.SingleInflight {
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return c.exchange(m, address)
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return c.exchange(m, conn)
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}
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q := m.Question[0]
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key := fmt.Sprintf("%s:%d:%d", q.Name, q.Qtype, q.Qclass)
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r, rtt, err, shared := c.group.Do(key, func() (*Msg, time.Duration, error) {
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return c.exchange(m, address)
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return c.exchange(m, conn)
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})
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if r != nil && shared {
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r = r.Copy()
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@ -141,15 +164,7 @@ func (c *Client) Exchange(m *Msg, address string) (r *Msg, rtt time.Duration, er
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return r, rtt, err
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}
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func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
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var co *Conn
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co, err = c.Dial(a)
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if err != nil {
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return nil, 0, err
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}
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defer co.Close()
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func (c *Client) exchange(m *Msg, co *Conn) (r *Msg, rtt time.Duration, err error) {
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opt := m.IsEdns0()
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// If EDNS0 is used use that for size.
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@ -565,3 +565,34 @@ func TestConcurrentExchanges(t *testing.T) {
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}
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}
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}
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func TestExchangeWithConn(t *testing.T) {
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HandleFunc("miek.nl.", HelloServer)
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defer HandleRemove("miek.nl.")
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s, addrstr, err := RunLocalUDPServer(":0")
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if err != nil {
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t.Fatalf("unable to run test server: %v", err)
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}
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defer s.Shutdown()
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m := new(Msg)
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m.SetQuestion("miek.nl.", TypeSOA)
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c := new(Client)
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conn, err := c.Dial(addrstr)
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if err != nil {
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t.Fatalf("failed to dial: %v", err)
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}
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r, _, err := c.ExchangeWithConn(m, conn)
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if err != nil {
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t.Fatalf("failed to exchange: %v", err)
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}
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if r == nil {
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t.Fatal("response is nil")
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}
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if r.Rcode != RcodeSuccess {
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t.Errorf("failed to get an valid answer\n%v", r)
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}
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}
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