// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nettrace contains internal hooks for tracing activity in // the net package. This package is purely internal for use by the // net/http/httptrace package and has no stable API exposed to end // users.
package nettrace // TraceKey is a context.Context Value key. Its associated value should // be a *Trace struct. type TraceKey struct{} // LookupIPAltResolverKey is a context.Context Value key used by tests to // specify an alternate resolver func. // It is not exposed to outsider users. (But see issue 12503) // The value should be the same type as lookupIP: // // func lookupIP(ctx context.Context, host string) ([]IPAddr, error) type LookupIPAltResolverKey struct{} // Trace contains a set of hooks for tracing events within // the net package. Any specific hook may be nil. type Trace struct { // DNSStart is called with the hostname of a DNS lookup // before it begins. DNSStart func(name string) // DNSDone is called after a DNS lookup completes (or fails). // The coalesced parameter is whether singleflight de-duped // the call. The addrs are of type net.IPAddr but can't // actually be for circular dependency reasons. DNSDone func(netIPs []any, coalesced bool, err error) // ConnectStart is called before a Dial, excluding Dials made // during DNS lookups. In the case of DualStack (Happy Eyeballs) // dialing, this may be called multiple times, from multiple // goroutines. ConnectStart func(network, addr string) // ConnectStart is called after a Dial with the results, excluding // Dials made during DNS lookups. It may also be called multiple // times, like ConnectStart. ConnectDone func(network, addr string, err error) }