src/net/http/httptrace/trace.go - go - Git at Google

 // 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 httptrace provides mechanisms to trace the events within
 // HTTP client requests.
 package httptrace

 import (
 	"context"
 	"crypto/tls"
 	"internal/nettrace"
 	"net"
 	"net/textproto"
 	"reflect"
 	"time"
 )

 // unique type to prevent assignment.
 type clientEventContextKey struct{}

 // ContextClientTrace returns the ClientTrace associated with the
 // provided context. If none, it returns nil.
 func ContextClientTrace(ctx context.Context) *ClientTrace {
 	trace, _ := ctx.Value(clientEventContextKey{}).(*ClientTrace)
 	return trace
 }

 // WithClientTrace returns a new context based on the provided parent
 // ctx. HTTP client requests made with the returned context will use
 // the provided trace hooks, in addition to any previous hooks
 // registered with ctx. Any hooks defined in the provided trace will
 // be called first.
 func WithClientTrace(ctx context.Context, trace *ClientTrace) context.Context {
 	if trace == nil {
 		panic("nil trace")
 	}
 	old := ContextClientTrace(ctx)
 	trace.compose(old)

 	ctx = context.WithValue(ctx, clientEventContextKey{}, trace)
 	if trace.hasNetHooks() {
 		nt := &nettrace.Trace{
 			ConnectStart: trace.ConnectStart,
 			ConnectDone:  trace.ConnectDone,
 		}
 		if trace.DNSStart != nil {
 			nt.DNSStart = func(name string) {
 				trace.DNSStart(DNSStartInfo{Host: name})
 			}
 		}
 		if trace.DNSDone != nil {
 			nt.DNSDone = func(netIPs []interface{}, coalesced bool, err error) {
 				addrs := make([]net.IPAddr, len(netIPs))
 				for i, ip := range netIPs {
 					addrs[i] = ip.(net.IPAddr)
 				}
 				trace.DNSDone(DNSDoneInfo{
 					Addrs:     addrs,
 					Coalesced: coalesced,
 					Err:       err,
 				})
 			}
 		}
 		ctx = context.WithValue(ctx, nettrace.TraceKey{}, nt)
 	}
 	return ctx
 }

 // ClientTrace is a set of hooks to run at various stages of an outgoing
 // HTTP request. Any particular hook may be nil. Functions may be
 // called concurrently from different goroutines and some may be called
 // after the request has completed or failed.
 //
 // ClientTrace currently traces a single HTTP request & response
 // during a single round trip and has no hooks that span a series
 // of redirected requests.
 //
 // See https://blog.golang.org/http-tracing for more.
 type ClientTrace struct {
 	// GetConn is called before a connection is created or
 	// retrieved from an idle pool. The hostPort is the
 	// "host:port" of the target or proxy. GetConn is called even
 	// if there's already an idle cached connection available.
 	GetConn func(hostPort string)

 	// GotConn is called after a successful connection is
 	// obtained. There is no hook for failure to obtain a
 	// connection; instead, use the error from
 	// Transport.RoundTrip.
 	GotConn func(GotConnInfo)

 	// PutIdleConn is called when the connection is returned to
 	// the idle pool. If err is nil, the connection was
 	// successfully returned to the idle pool. If err is non-nil,
 	// it describes why not. PutIdleConn is not called if
 	// connection reuse is disabled via Transport.DisableKeepAlives.
 	// PutIdleConn is called before the caller's Response.Body.Close
 	// call returns.
 	// For HTTP/2, this hook is not currently used.
 	PutIdleConn func(err error)

 	// GotFirstResponseByte is called when the first byte of the response
 	// headers is available.
 	GotFirstResponseByte func()

 	// Got100Continue is called if the server replies with a "100
 	// Continue" response.
 	Got100Continue func()

 	// Got1xxResponse is called for each 1xx informational response header
 	// returned before the final non-1xx response. Got1xxResponse is called
 	// for "100 Continue" responses, even if Got100Continue is also defined.
 	// If it returns an error, the client request is aborted with that error value.
 	Got1xxResponse func(code int, header textproto.MIMEHeader) error

 	// DNSStart is called when a DNS lookup begins.
 	DNSStart func(DNSStartInfo)

 	// DNSDone is called when a DNS lookup ends.
 	DNSDone func(DNSDoneInfo)

 	// ConnectStart is called when a new connection's Dial begins.
 	// If net.Dialer.DualStack (IPv6 "Happy Eyeballs") support is
 	// enabled, this may be called multiple times.
 	ConnectStart func(network, addr string)

 	// ConnectDone is called when a new connection's Dial
 	// completes. The provided err indicates whether the
 	// connection completed successfully.
 	// If net.Dialer.DualStack ("Happy Eyeballs") support is
 	// enabled, this may be called multiple times.
 	ConnectDone func(network, addr string, err error)

 	// TLSHandshakeStart is called when the TLS handshake is started. When
 	// connecting to an HTTPS site via an HTTP proxy, the handshake happens
 	// after the CONNECT request is processed by the proxy.
 	TLSHandshakeStart func()

 	// TLSHandshakeDone is called after the TLS handshake with either the
 	// successful handshake's connection state, or a non-nil error on handshake
 	// failure.
 	TLSHandshakeDone func(tls.ConnectionState, error)

 	// WroteHeaderField is called after the Transport has written
 	// each request header. At the time of this call the values
 	// might be buffered and not yet written to the network.
 	WroteHeaderField func(key string, value []string)

 	// WroteHeaders is called after the Transport has written
 	// all request headers.
 	WroteHeaders func()

 	// Wait100Continue is called if the Request specified
 	// "Expect: 100-continue" and the Transport has written the
 	// request headers but is waiting for "100 Continue" from the
 	// server before writing the request body.
 	Wait100Continue func()

 	// WroteRequest is called with the result of writing the
 	// request and any body. It may be called multiple times
 	// in the case of retried requests.
 	WroteRequest func(WroteRequestInfo)
 }

 // WroteRequestInfo contains information provided to the WroteRequest
 // hook.
 type WroteRequestInfo struct {
 	// Err is any error encountered while writing the Request.
 	Err error
 }

 // compose modifies t such that it respects the previously-registered hooks in old,
 // subject to the composition policy requested in t.Compose.
 func (t *ClientTrace) compose(old *ClientTrace) {
 	if old == nil {
 		return
 	}
 	tv := reflect.ValueOf(t).Elem()
 	ov := reflect.ValueOf(old).Elem()
 	structType := tv.Type()
 	for i := 0; i < structType.NumField(); i++ {
 		tf := tv.Field(i)
 		hookType := tf.Type()
 		if hookType.Kind() != reflect.Func {
 			continue
 		}
 		of := ov.Field(i)
 		if of.IsNil() {
 			continue
 		}
 		if tf.IsNil() {
 			tf.Set(of)
 			continue
 		}

 		// Make a copy of tf for tf to call. (Otherwise it
 		// creates a recursive call cycle and stack overflows)
 		tfCopy := reflect.ValueOf(tf.Interface())

 		// We need to call both tf and of in some order.
 		newFunc := reflect.MakeFunc(hookType, func(args []reflect.Value) []reflect.Value {
 			tfCopy.Call(args)
 			return of.Call(args)
 		})
 		tv.Field(i).Set(newFunc)
 	}
 }

 // DNSStartInfo contains information about a DNS request.
 type DNSStartInfo struct {
 	Host string
 }

 // DNSDoneInfo contains information about the results of a DNS lookup.
 type DNSDoneInfo struct {
 	// Addrs are the IPv4 and/or IPv6 addresses found in the DNS
 	// lookup. The contents of the slice should not be mutated.
 	Addrs []net.IPAddr

 	// Err is any error that occurred during the DNS lookup.
 	Err error

 	// Coalesced is whether the Addrs were shared with another
 	// caller who was doing the same DNS lookup concurrently.
 	Coalesced bool
 }

 func (t *ClientTrace) hasNetHooks() bool {
 	if t == nil {
 		return false
 	}
 	return t.DNSStart != nil || t.DNSDone != nil || t.ConnectStart != nil || t.ConnectDone != nil
 }

 // GotConnInfo is the argument to the ClientTrace.GotConn function and
 // contains information about the obtained connection.
 type GotConnInfo struct {
 	// Conn is the connection that was obtained. It is owned by
 	// the http.Transport and should not be read, written or
 	// closed by users of ClientTrace.
 	Conn net.Conn

 	// Reused is whether this connection has been previously
 	// used for another HTTP request.
 	Reused bool

 	// WasIdle is whether this connection was obtained from an
 	// idle pool.
 	WasIdle bool

 	// IdleTime reports how long the connection was previously
 	// idle, if WasIdle is true.
 	IdleTime time.Duration
 }
	// 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 httptrace provides mechanisms to trace the events within
	// HTTP client requests.
	package httptrace

	import (
	"context"
	"crypto/tls"
	"internal/nettrace"
	"net"
	"net/textproto"
	"reflect"
	"time"
	)

	// unique type to prevent assignment.
	type clientEventContextKey struct{}

	// ContextClientTrace returns the ClientTrace associated with the
	// provided context. If none, it returns nil.
	func ContextClientTrace(ctx context.Context) *ClientTrace {
	trace, _ := ctx.Value(clientEventContextKey{}).(*ClientTrace)
	return trace
	}

	// WithClientTrace returns a new context based on the provided parent
	// ctx. HTTP client requests made with the returned context will use
	// the provided trace hooks, in addition to any previous hooks
	// registered with ctx. Any hooks defined in the provided trace will
	// be called first.
	func WithClientTrace(ctx context.Context, trace *ClientTrace) context.Context {
	if trace == nil {
	panic("nil trace")
	}
	old := ContextClientTrace(ctx)
	trace.compose(old)

	ctx = context.WithValue(ctx, clientEventContextKey{}, trace)
	if trace.hasNetHooks() {
	nt := &nettrace.Trace{
	ConnectStart: trace.ConnectStart,
	ConnectDone: trace.ConnectDone,
	}
	if trace.DNSStart != nil {
	nt.DNSStart = func(name string) {
	trace.DNSStart(DNSStartInfo{Host: name})
	}
	}
	if trace.DNSDone != nil {
	nt.DNSDone = func(netIPs []interface{}, coalesced bool, err error) {
	addrs := make([]net.IPAddr, len(netIPs))
	for i, ip := range netIPs {
	addrs[i] = ip.(net.IPAddr)
	}
	trace.DNSDone(DNSDoneInfo{
	Addrs: addrs,
	Coalesced: coalesced,
	Err: err,
	})
	}
	}
	ctx = context.WithValue(ctx, nettrace.TraceKey{}, nt)
	}
	return ctx
	}

	// ClientTrace is a set of hooks to run at various stages of an outgoing
	// HTTP request. Any particular hook may be nil. Functions may be
	// called concurrently from different goroutines and some may be called
	// after the request has completed or failed.
	//
	// ClientTrace currently traces a single HTTP request & response
	// during a single round trip and has no hooks that span a series
	// of redirected requests.
	//
	// See https://blog.golang.org/http-tracing for more.
	type ClientTrace struct {
	// GetConn is called before a connection is created or
	// retrieved from an idle pool. The hostPort is the
	// "host:port" of the target or proxy. GetConn is called even
	// if there's already an idle cached connection available.
	GetConn func(hostPort string)

	// GotConn is called after a successful connection is
	// obtained. There is no hook for failure to obtain a
	// connection; instead, use the error from
	// Transport.RoundTrip.
	GotConn func(GotConnInfo)

	// PutIdleConn is called when the connection is returned to
	// the idle pool. If err is nil, the connection was
	// successfully returned to the idle pool. If err is non-nil,
	// it describes why not. PutIdleConn is not called if
	// connection reuse is disabled via Transport.DisableKeepAlives.
	// PutIdleConn is called before the caller's Response.Body.Close
	// call returns.
	// For HTTP/2, this hook is not currently used.
	PutIdleConn func(err error)

	// GotFirstResponseByte is called when the first byte of the response
	// headers is available.
	GotFirstResponseByte func()

	// Got100Continue is called if the server replies with a "100
	// Continue" response.
	Got100Continue func()

	// Got1xxResponse is called for each 1xx informational response header
	// returned before the final non-1xx response. Got1xxResponse is called
	// for "100 Continue" responses, even if Got100Continue is also defined.
	// If it returns an error, the client request is aborted with that error value.
	Got1xxResponse func(code int, header textproto.MIMEHeader) error

	// DNSStart is called when a DNS lookup begins.
	DNSStart func(DNSStartInfo)

	// DNSDone is called when a DNS lookup ends.
	DNSDone func(DNSDoneInfo)

	// ConnectStart is called when a new connection's Dial begins.
	// If net.Dialer.DualStack (IPv6 "Happy Eyeballs") support is
	// enabled, this may be called multiple times.
	ConnectStart func(network, addr string)

	// ConnectDone is called when a new connection's Dial
	// completes. The provided err indicates whether the
	// connection completed successfully.
	// If net.Dialer.DualStack ("Happy Eyeballs") support is
	// enabled, this may be called multiple times.
	ConnectDone func(network, addr string, err error)

	// TLSHandshakeStart is called when the TLS handshake is started. When
	// connecting to an HTTPS site via an HTTP proxy, the handshake happens
	// after the CONNECT request is processed by the proxy.
	TLSHandshakeStart func()

	// TLSHandshakeDone is called after the TLS handshake with either the
	// successful handshake's connection state, or a non-nil error on handshake
	// failure.
	TLSHandshakeDone func(tls.ConnectionState, error)

	// WroteHeaderField is called after the Transport has written
	// each request header. At the time of this call the values
	// might be buffered and not yet written to the network.
	WroteHeaderField func(key string, value []string)

	// WroteHeaders is called after the Transport has written
	// all request headers.
	WroteHeaders func()

	// Wait100Continue is called if the Request specified
	// "Expect: 100-continue" and the Transport has written the
	// request headers but is waiting for "100 Continue" from the
	// server before writing the request body.
	Wait100Continue func()

	// WroteRequest is called with the result of writing the
	// request and any body. It may be called multiple times
	// in the case of retried requests.
	WroteRequest func(WroteRequestInfo)
	}

	// WroteRequestInfo contains information provided to the WroteRequest
	// hook.
	type WroteRequestInfo struct {
	// Err is any error encountered while writing the Request.
	Err error
	}

	// compose modifies t such that it respects the previously-registered hooks in old,
	// subject to the composition policy requested in t.Compose.
	func (t ClientTrace) compose(old ClientTrace) {
	if old == nil {
	return
	}
	tv := reflect.ValueOf(t).Elem()
	ov := reflect.ValueOf(old).Elem()
	structType := tv.Type()
	for i := 0; i < structType.NumField(); i++ {
	tf := tv.Field(i)
	hookType := tf.Type()
	if hookType.Kind() != reflect.Func {
	continue
	}
	of := ov.Field(i)
	if of.IsNil() {
	continue
	}
	if tf.IsNil() {
	tf.Set(of)
	continue
	}

	// Make a copy of tf for tf to call. (Otherwise it
	// creates a recursive call cycle and stack overflows)
	tfCopy := reflect.ValueOf(tf.Interface())

	// We need to call both tf and of in some order.
	newFunc := reflect.MakeFunc(hookType, func(args []reflect.Value) []reflect.Value {
	tfCopy.Call(args)
	return of.Call(args)
	})
	tv.Field(i).Set(newFunc)
	}
	}

	// DNSStartInfo contains information about a DNS request.
	type DNSStartInfo struct {
	Host string
	}

	// DNSDoneInfo contains information about the results of a DNS lookup.
	type DNSDoneInfo struct {
	// Addrs are the IPv4 and/or IPv6 addresses found in the DNS
	// lookup. The contents of the slice should not be mutated.
	Addrs []net.IPAddr

	// Err is any error that occurred during the DNS lookup.
	Err error

	// Coalesced is whether the Addrs were shared with another
	// caller who was doing the same DNS lookup concurrently.
	Coalesced bool
	}

	func (t *ClientTrace) hasNetHooks() bool {
	if t == nil {
	return false
	}
	return t.DNSStart != nil \|\| t.DNSDone != nil \|\| t.ConnectStart != nil \|\| t.ConnectDone != nil
	}

	// GotConnInfo is the argument to the ClientTrace.GotConn function and
	// contains information about the obtained connection.
	type GotConnInfo struct {
	// Conn is the connection that was obtained. It is owned by
	// the http.Transport and should not be read, written or
	// closed by users of ClientTrace.
	Conn net.Conn

	// Reused is whether this connection has been previously
	// used for another HTTP request.
	Reused bool

	// WasIdle is whether this connection was obtained from an
	// idle pool.
	WasIdle bool

	// IdleTime reports how long the connection was previously
	// idle, if WasIdle is true.
	IdleTime time.Duration
	}