all: import "context" instead of "golang.org/x/net/context"

There is no need to depend on the old context package now that the
minimum Go version is 1.7. The move to "context" eliminates our weird
vendoring setup. Some vendored code still uses golang.org/x/net/context
and it is now vendored in the normal way.

This change triggered new vet checks around context.WithTimeout which
didn't fire with golang.org/x/net/context.

69 files changed, 187 insertions, 437 deletions

diff --git a/accounts/abi/bind/backend.go b/accounts/abi/bind/backend.go
index 4509e222d..25b61928e 100644
--- a/accounts/abi/bind/backend.go
+++ b/accounts/abi/bind/backend.go
@@ -17,13 +17,13 @@
 package bind
 
 import (
+	"context"
 	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index 2e6796de6..2f5719c78 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -17,6 +17,7 @@
 package backends
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"math/big"
@@ -34,7 +35,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
-	"golang.org/x/net/context"
 )
 
 // Default chain configuration which sets homestead phase at block 0 (i.e. no frontier)
diff --git a/accounts/abi/bind/base.go b/accounts/abi/bind/base.go
index 93362d9e9..b40bd65e8 100644
--- a/accounts/abi/bind/base.go
+++ b/accounts/abi/bind/base.go
@@ -17,6 +17,7 @@
 package bind
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"math/big"
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 // SignerFn is a signer function callback when a contract requires a method to
diff --git a/accounts/abi/bind/util.go b/accounts/abi/bind/util.go
index 8348f6980..d129993ca 100644
--- a/accounts/abi/bind/util.go
+++ b/accounts/abi/bind/util.go
@@ -17,13 +17,13 @@
 package bind
 
 import (
+	"context"
 	"fmt"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/log"
-	"golang.org/x/net/context"
 )
 
 // WaitMined waits for tx to be mined on the blockchain.
diff --git a/accounts/abi/bind/util_test.go b/accounts/abi/bind/util_test.go
index f31dbfc29..b37a69cfc 100644
--- a/accounts/abi/bind/util_test.go
+++ b/accounts/abi/bind/util_test.go
@@ -17,6 +17,7 @@
 package bind_test
 
 import (
+	"context"
 	"math/big"
 	"testing"
 	"time"
@@ -27,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 var testKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
diff --git a/accounts/usbwallet/ledger_wallet.go b/accounts/usbwallet/ledger_wallet.go
index c3d0f0ac8..698e85f48 100644
--- a/accounts/usbwallet/ledger_wallet.go
+++ b/accounts/usbwallet/ledger_wallet.go
@@ -21,6 +21,7 @@
 package usbwallet
 
 import (
+	"context"
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
@@ -38,7 +39,6 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/karalabe/hid"
-	"golang.org/x/net/context"
 )
 
 // Maximum time between wallet health checks to detect USB unplugs.
diff --git a/build/_vendor/src/golang.org/x/net/LICENSE b/build/_vendor/src/golang.org/x/net/LICENSE
deleted file mode 100644
index 6a66aea5e..000000000
--- a/build/_vendor/src/golang.org/x/net/LICENSE
+++ /dev/null
@@ -1,27 +0,0 @@
-Copyright (c) 2009 The Go Authors. All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-   * Redistributions of source code must retain the above copyright
-notice, this list of conditions and the following disclaimer.
-   * Redistributions in binary form must reproduce the above
-copyright notice, this list of conditions and the following disclaimer
-in the documentation and/or other materials provided with the
-distribution.
-   * Neither the name of Google Inc. nor the names of its
-contributors may be used to endorse or promote products derived from
-this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/build/ci-notes.md b/build/ci-notes.md
index 92e7c54d0..cd2ba8bb2 100644
--- a/build/ci-notes.md
+++ b/build/ci-notes.md
@@ -1,18 +1,3 @@
-# Vendored Dependencies
-
-Dependencies are almost all vendored in at the standard Go `/vendor` path. This allows
-people to build go-ethereum using the standard toolchain without any particular package
-manager. It also plays nicely with `go get`, not requiring external code to be relied on.
-
-The one single dependent package missing from `vendor` is `golang.org/x/net/context`. As
-this is a package exposed via public library APIs, it must not be vendored as dependent
-code woulnd't be able to instantiate.
-
-To allow reproducible builds of go-ethereum nonetheless that don't need network access
-during build time to fetch `golang.org/x/net/context`, a version was copied into our repo
-at the very specific `/build/_vendor` path, which is added automatically by all CI build
-scripts and the makefile too.
-
 # Debian Packaging
 
 Tagged releases and develop branch commits are available as installable Debian packages
diff --git a/contracts/chequebook/cheque.go b/contracts/chequebook/cheque.go
index 945e56e86..7e0f7eafc 100644
--- a/contracts/chequebook/cheque.go
+++ b/contracts/chequebook/cheque.go
@@ -26,6 +26,7 @@ package chequebook
 
 import (
 	"bytes"
+	"context"
 	"crypto/ecdsa"
 	"encoding/json"
 	"fmt"
@@ -43,7 +44,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/swarm/services/swap/swap"
-	"golang.org/x/net/context"
 )
 
 // TODO(zelig): watch peer solvency and notify of bouncing cheques
diff --git a/contracts/release/release.go b/contracts/release/release.go
index 613e62aa9..28a35381d 100644
--- a/contracts/release/release.go
+++ b/contracts/release/release.go
@@ -20,6 +20,7 @@ package release
 //go:generate abigen --sol ./contract.sol --pkg release --out ./contract.go
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"time"
@@ -33,7 +34,6 @@ import (
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // Interval to check for new releases
@@ -116,47 +116,49 @@ func (r *ReleaseService) checker() {
 
 	for {
 		select {
-		// If the time arrived, check for a new release
 		case <-timer.C:
 			// Rechedule the timer before continuing
 			timer.Reset(releaseRecheckInterval)
-
-			// Retrieve the current version, and handle missing contracts gracefully
-			ctx, _ := context.WithTimeout(context.Background(), time.Second*5)
-			opts := &bind.CallOpts{Context: ctx}
-			version, err := r.oracle.CurrentVersion(opts)
-			if err != nil {
-				if err == bind.ErrNoCode {
-					log.Debug("Release oracle not found", "contract", r.config.Oracle)
-					continue
-				}
-				log.Error("Failed to retrieve current release", "err", err)
-				continue
-			}
-			// Version was successfully retrieved, notify if newer than ours
-			if version.Major > r.config.Major ||
-				(version.Major == r.config.Major && version.Minor > r.config.Minor) ||
-				(version.Major == r.config.Major && version.Minor == r.config.Minor && version.Patch > r.config.Patch) {
-
-				warning := fmt.Sprintf("Client v%d.%d.%d-%x seems older than the latest upstream release v%d.%d.%d-%x",
-					r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4], version.Major, version.Minor, version.Patch, version.Commit[:4])
-				howtofix := fmt.Sprintf("Please check https://github.com/ethereum/go-ethereum/releases for new releases")
-				separator := strings.Repeat("-", len(warning))
-
-				log.Warn(separator)
-				log.Warn(warning)
-				log.Warn(howtofix)
-				log.Warn(separator)
-			} else {
-				log.Debug("Client seems up to date with upstream",
-					"local", fmt.Sprintf("v%d.%d.%d-%x", r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4]),
-					"upstream", fmt.Sprintf("v%d.%d.%d-%x", version.Major, version.Minor, version.Patch, version.Commit[:4]))
-			}
-
-		// If termination was requested, return
+			r.checkVersion()
 		case errc := <-r.quit:
 			errc <- nil
 			return
 		}
 	}
 }
+
+func (r *ReleaseService) checkVersion() {
+	// Retrieve the current version, and handle missing contracts gracefully
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	opts := &bind.CallOpts{Context: ctx}
+	defer cancel()
+
+	version, err := r.oracle.CurrentVersion(opts)
+	if err != nil {
+		if err == bind.ErrNoCode {
+			log.Debug("Release oracle not found", "contract", r.config.Oracle)
+		} else {
+			log.Error("Failed to retrieve current release", "err", err)
+		}
+		return
+	}
+	// Version was successfully retrieved, notify if newer than ours
+	if version.Major > r.config.Major ||
+		(version.Major == r.config.Major && version.Minor > r.config.Minor) ||
+		(version.Major == r.config.Major && version.Minor == r.config.Minor && version.Patch > r.config.Patch) {
+
+		warning := fmt.Sprintf("Client v%d.%d.%d-%x seems older than the latest upstream release v%d.%d.%d-%x",
+			r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4], version.Major, version.Minor, version.Patch, version.Commit[:4])
+		howtofix := fmt.Sprintf("Please check https://github.com/ethereum/go-ethereum/releases for new releases")
+		separator := strings.Repeat("-", len(warning))
+
+		log.Warn(separator)
+		log.Warn(warning)
+		log.Warn(howtofix)
+		log.Warn(separator)
+	} else {
+		log.Debug("Client seems up to date with upstream",
+			"local", fmt.Sprintf("v%d.%d.%d-%x", r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4]),
+			"upstream", fmt.Sprintf("v%d.%d.%d-%x", version.Major, version.Minor, version.Patch, version.Commit[:4]))
+	}
+}
diff --git a/eth/api.go b/eth/api.go
index b17968ebb..b64153fd7 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -19,6 +19,7 @@ package eth
 import (
 	"bytes"
 	"compress/gzip"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -39,7 +40,6 @@ import (
 	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 const defaultTraceTimeout = 5 * time.Second
diff --git a/eth/api_backend.go b/eth/api_backend.go
index bce772900..418a34435 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -33,7 +34,6 @@ import (
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // EthApiBackend implements ethapi.Backend for full nodes
diff --git a/eth/bind.go b/eth/bind.go
index 2ee9f2bf7..245934183 100644
--- a/eth/bind.go
+++ b/eth/bind.go
@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum"
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // ContractBackend implements bind.ContractBackend with direct calls to Ethereum
diff --git a/eth/downloader/api.go b/eth/downloader/api.go
index e41376810..d496fa6a4 100644
--- a/eth/downloader/api.go
+++ b/eth/downloader/api.go
@@ -17,12 +17,12 @@
 package downloader
 
 import (
+	"context"
 	"sync"
 
 	ethereum "github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // PublicDownloaderAPI provides an API which gives information about the current synchronisation status.
diff --git a/eth/filters/api.go b/eth/filters/api.go
index 02a544ce1..61647a5d0 100644
--- a/eth/filters/api.go
+++ b/eth/filters/api.go
@@ -17,6 +17,7 @@
 package filters
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -24,8 +25,6 @@ import (
 	"sync"
 	"time"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/types"
diff --git a/eth/filters/filter.go b/eth/filters/filter.go
index 9a8e2fd70..0a0b81224 100644
--- a/eth/filters/filter.go
+++ b/eth/filters/filter.go
@@ -17,10 +17,10 @@
 package filters
 
 import (
+	"context"
 	"math"
-	"time"
-
 	"math/big"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
@@ -28,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 type Backend interface {
diff --git a/eth/filters/filter_system.go b/eth/filters/filter_system.go
index 3adf8111a..7abace1e6 100644
--- a/eth/filters/filter_system.go
+++ b/eth/filters/filter_system.go
@@ -19,6 +19,7 @@
 package filters
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"sync"
@@ -29,7 +30,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // Type determines the kind of filter and is used to put the filter in to
@@ -372,7 +372,8 @@ func (es *EventSystem) lightFilterNewHead(newHeader *types.Header, callBack func
 func (es *EventSystem) lightFilterLogs(header *types.Header, addresses []common.Address, topics [][]common.Hash, remove bool) []*types.Log {
 	if bloomFilter(header.Bloom, addresses, topics) {
 		// Get the logs of the block
-		ctx, _ := context.WithTimeout(context.Background(), time.Second*5)
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+		defer cancel()
 		receipts, err := es.backend.GetReceipts(ctx, header.Hash())
 		if err != nil {
 			return nil
diff --git a/eth/filters/filter_system_test.go b/eth/filters/filter_system_test.go
index 1cfced7e4..d9c245a85 100644
--- a/eth/filters/filter_system_test.go
+++ b/eth/filters/filter_system_test.go
@@ -17,13 +17,12 @@
 package filters
 
 import (
+	"context"
 	"math/big"
 	"reflect"
 	"testing"
 	"time"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
diff --git a/eth/filters/filter_test.go b/eth/filters/filter_test.go
index 83ff3e9ce..c2dc2b842 100644
--- a/eth/filters/filter_test.go
+++ b/eth/filters/filter_test.go
@@ -17,13 +17,12 @@
 package filters
 
 import (
+	"context"
 	"io/ioutil"
 	"math/big"
 	"os"
 	"testing"
 
-	"golang.org/x/net/context"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
diff --git a/eth/gasprice/lightprice.go b/eth/gasprice/lightprice.go
index 8886d32d7..562c7dd97 100644
--- a/eth/gasprice/lightprice.go
+++ b/eth/gasprice/lightprice.go
@@ -17,6 +17,7 @@
 package gasprice
 
 import (
+	"context"
 	"math/big"
 	"sort"
 	"sync"
@@ -24,7 +25,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 const (
diff --git a/ethclient/ethclient.go b/ethclient/ethclient.go
index 1d04d9e03..59f60d659 100644
--- a/ethclient/ethclient.go
+++ b/ethclient/ethclient.go
@@ -18,6 +18,7 @@
 package ethclient
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"math/big"
@@ -28,7 +29,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // Client defines typed wrappers for the Ethereum RPC API.
diff --git a/event/subscription.go b/event/subscription.go
index 83bd21213..02d7b9d7d 100644
--- a/event/subscription.go
+++ b/event/subscription.go
@@ -17,11 +17,11 @@
 package event
 
 import (
+	"context"
 	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
-	"golang.org/x/net/context"
 )
 
 // Subscription represents a stream of events. The carrier of the events is typically a
diff --git a/event/subscription_test.go b/event/subscription_test.go
index a4fe30298..aa6d98984 100644
--- a/event/subscription_test.go
+++ b/event/subscription_test.go
@@ -17,11 +17,10 @@
 package event
 
 import (
+	"context"
 	"errors"
 	"testing"
 	"time"
-
-	"golang.org/x/net/context"
 )
 
 var errInts = errors.New("error in subscribeInts")
diff --git a/interfaces.go b/interfaces.go
index f7e71a317..744f07b95 100644
--- a/interfaces.go
+++ b/interfaces.go
@@ -18,12 +18,12 @@
 package ethereum
 
 import (
+	"context"
 	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
-	"golang.org/x/net/context"
 )
 
 // NotFound is returned by API methods if the requested item does not exist.
diff --git a/internal/build/util.go b/internal/build/util.go
index 1523a067b..4df7b9138 100644
--- a/internal/build/util.go
+++ b/internal/build/util.go
@@ -52,19 +52,10 @@ func MustRunCommand(cmd string, args ...string) {
 // GOPATH returns the value that the GOPATH environment
 // variable should be set to.
 func GOPATH() string {
-	path := filepath.SplitList(os.Getenv("GOPATH"))
-	if len(path) == 0 {
+	if os.Getenv("GOPATH") == "" {
 		log.Fatal("GOPATH is not set")
 	}
-	// Ensure that our internal vendor folder is on GOPATH
-	vendor, _ := filepath.Abs(filepath.Join("build", "_vendor"))
-	for _, dir := range path {
-		if dir == vendor {
-			return strings.Join(path, string(filepath.ListSeparator))
-		}
-	}
-	newpath := append(path[:1], append([]string{vendor}, path[1:]...)...)
-	return strings.Join(newpath, string(filepath.ListSeparator))
+	return os.Getenv("GOPATH")
 }
 
 // VERSION returns the content of the VERSION file.
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 0928c973f..ccb7ec80b 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -18,6 +18,7 @@ package ethapi
 
 import (
 	"bytes"
+	"context"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -43,7 +44,6 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/util"
-	"golang.org/x/net/context"
 )
 
 const (
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index e10fb14ff..50cd3801b 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -18,6 +18,7 @@
 package ethapi
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -30,7 +31,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // Backend interface provides the common API services (that are provided by
diff --git a/les/api_backend.go b/les/api_backend.go
index 006240369..df2782f78 100644
--- a/les/api_backend.go
+++ b/les/api_backend.go
@@ -17,6 +17,7 @@
 package les
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -33,7 +34,6 @@ import (
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 type LesApiBackend struct {
diff --git a/les/odr.go b/les/odr.go
index 06b44d318..684f36c76 100644
--- a/les/odr.go
+++ b/les/odr.go
@@ -17,6 +17,7 @@
 package les
 
 import (
+	"context"
 	"crypto/rand"
 	"encoding/binary"
 	"sync"
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/les/odr_test.go b/les/odr_test.go
index 1b436b8e6..6b074f1a2 100644
--- a/les/odr_test.go
+++ b/les/odr_test.go
@@ -18,6 +18,7 @@ package les
 
 import (
 	"bytes"
+	"context"
 	"math/big"
 	"testing"
 	"time"
@@ -32,7 +33,6 @@ import (
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 type odrTestFn func(ctx context.Context, db ethdb.Database, config *params.ChainConfig, bc *core.BlockChain, lc *light.LightChain, bhash common.Hash) []byte
@@ -181,8 +181,11 @@ func testOdr(t *testing.T, protocol int, expFail uint64, fn odrTestFn) {
 		for i := uint64(0); i <= pm.blockchain.CurrentHeader().Number.Uint64(); i++ {
 			bhash := core.GetCanonicalHash(db, i)
 			b1 := fn(light.NoOdr, db, pm.chainConfig, pm.blockchain.(*core.BlockChain), nil, bhash)
-			ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
+			defer cancel()
 			b2 := fn(ctx, ldb, lpm.chainConfig, nil, lpm.blockchain.(*light.LightChain), bhash)
+
 			eq := bytes.Equal(b1, b2)
 			exp := i < expFail
 			if exp && !eq {
diff --git a/les/request_test.go b/les/request_test.go
index bec6bf1bc..ba1fc15bd 100644
--- a/les/request_test.go
+++ b/les/request_test.go
@@ -17,6 +17,7 @@
 package les
 
 import (
+	"context"
 	"testing"
 	"time"
 
@@ -25,7 +26,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/light"
-	"golang.org/x/net/context"
 )
 
 var testBankSecureTrieKey = secAddr(testBankAddress)
@@ -91,7 +91,9 @@ func testAccess(t *testing.T, protocol int, fn accessTestFn) {
 		for i := uint64(0); i <= pm.blockchain.CurrentHeader().Number.Uint64(); i++ {
 			bhash := core.GetCanonicalHash(db, i)
 			if req := fn(ldb, bhash, i); req != nil {
-				ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
+				ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
+				defer cancel()
+
 				err := odr.Retrieve(ctx, req)
 				got := err == nil
 				exp := i < expFail
diff --git a/les/sync.go b/les/sync.go
index c143cb145..c0e17f97d 100644
--- a/les/sync.go
+++ b/les/sync.go
@@ -17,12 +17,12 @@
 package les
 
 import (
+	"context"
 	"time"
 
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/light"
-	"golang.org/x/net/context"
 )
 
 const (
@@ -77,8 +77,8 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
 		return
 	}
 
-	ctx, _ := context.WithTimeout(context.Background(), time.Second*5)
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
 	pm.blockchain.(*light.LightChain).SyncCht(ctx)
-
 	pm.downloader.Synchronise(peer.id, peer.Head(), peer.Td(), downloader.LightSync)
 }
diff --git a/light/lightchain.go b/light/lightchain.go
index 4715d47ab..82b7a5866 100644
--- a/light/lightchain.go
+++ b/light/lightchain.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"math/big"
 	"sync"
 	"sync/atomic"
@@ -32,7 +33,6 @@ import (
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/hashicorp/golang-lru"
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/light/lightchain_test.go b/light/lightchain_test.go
index 8a99c69f1..7460fd1a3 100644
--- a/light/lightchain_test.go
+++ b/light/lightchain_test.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"fmt"
 	"math/big"
 	"runtime"
@@ -30,7 +31,6 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/hashicorp/golang-lru"
-	"golang.org/x/net/context"
 )
 
 // So we can deterministically seed different blockchains
diff --git a/light/odr.go b/light/odr.go
index 4f6ef6b9e..ca6364f28 100644
--- a/light/odr.go
+++ b/light/odr.go
@@ -19,6 +19,7 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -27,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 // NoOdr is the default context passed to an ODR capable function when the ODR
diff --git a/light/odr_test.go b/light/odr_test.go
index e2eced346..ba82ec04f 100644
--- a/light/odr_test.go
+++ b/light/odr_test.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"math/big"
 	"testing"
@@ -36,7 +37,6 @@ import (
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
-	"golang.org/x/net/context"
 )
 
 var (
@@ -277,8 +277,11 @@ func testChainOdr(t *testing.T, protocol int, expFail uint64, fn odrTestFn) {
 		for i := uint64(0); i <= blockchain.CurrentHeader().Number.Uint64(); i++ {
 			bhash := core.GetCanonicalHash(sdb, i)
 			b1 := fn(NoOdr, sdb, blockchain, nil, bhash)
-			ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
+			defer cancel()
 			b2 := fn(ctx, ldb, nil, lightchain, bhash)
+
 			eq := bytes.Equal(b1, b2)
 			exp := i < expFail
 			if exp && !eq {
diff --git a/light/odr_util.go b/light/odr_util.go
index 17e9aadcb..d7f8458f1 100644
--- a/light/odr_util.go
+++ b/light/odr_util.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"math/big"
 
@@ -27,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 var sha3_nil = crypto.Keccak256Hash(nil)
diff --git a/light/state.go b/light/state.go
index d3e047ef4..b184dc3a5 100644
--- a/light/state.go
+++ b/light/state.go
@@ -17,11 +17,11 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 // LightState is a memory representation of a state.
diff --git a/light/state_object.go b/light/state_object.go
index f33ba217e..a54ea1d9f 100644
--- a/light/state_object.go
+++ b/light/state_object.go
@@ -18,13 +18,13 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 var emptyCodeHash = crypto.Keccak256(nil)
diff --git a/light/state_test.go b/light/state_test.go
index d594ab9ff..e776efec8 100644
--- a/light/state_test.go
+++ b/light/state_test.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"math/big"
 	"testing"
 
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
-	"golang.org/x/net/context"
 )
 
 func makeTestState() (common.Hash, ethdb.Database) {
diff --git a/light/trie.go b/light/trie.go
index c5525358a..1440f2fbf 100644
--- a/light/trie.go
+++ b/light/trie.go
@@ -17,9 +17,10 @@
 package light
 
 import (
+	"context"
+
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/trie"
-	"golang.org/x/net/context"
 )
 
 // LightTrie is an ODR-capable wrapper around trie.SecureTrie
diff --git a/light/txpool.go b/light/txpool.go
index 5eb1ba801..446195806 100644
--- a/light/txpool.go
+++ b/light/txpool.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"fmt"
 	"sync"
 	"time"
@@ -29,7 +30,6 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 // txPermanent is the number of mined blocks after a mined transaction is
@@ -230,13 +230,13 @@ func (pool *TxPool) rollbackTxs(hash common.Hash, txc txStateChanges) {
 	}
 }
 
-// setNewHead sets a new head header, processing (and rolling back if necessary)
+// reorgOnNewHead sets a new head header, processing (and rolling back if necessary)
 // the blocks since the last known head and returns a txStateChanges map containing
 // the recently mined and rolled back transaction hashes. If an error (context
 // timeout) occurs during checking new blocks, it leaves the locally known head
 // at the latest checked block and still returns a valid txStateChanges, making it
 // possible to continue checking the missing blocks at the next chain head event
-func (pool *TxPool) setNewHead(ctx context.Context, newHeader *types.Header) (txStateChanges, error) {
+func (pool *TxPool) reorgOnNewHead(ctx context.Context, newHeader *types.Header) (txStateChanges, error) {
 	txc := make(txStateChanges)
 	oldh := pool.chain.GetHeaderByHash(pool.head)
 	newh := newHeader
@@ -305,20 +305,28 @@ func (pool *TxPool) eventLoop() {
 	for ev := range pool.events.Chan() {
 		switch ev.Data.(type) {
 		case core.ChainHeadEvent:
-			head := pool.chain.CurrentHeader()
-			pool.mu.Lock()
-			ctx, _ := context.WithTimeout(context.Background(), blockCheckTimeout)
-			txc, _ := pool.setNewHead(ctx, head)
-			m, r := txc.getLists()
-			pool.relay.NewHead(pool.head, m, r)
-			pool.homestead = pool.config.IsHomestead(head.Number)
-			pool.signer = types.MakeSigner(pool.config, head.Number)
-			pool.mu.Unlock()
-			time.Sleep(time.Millisecond) // hack in order to avoid hogging the lock; this part will be replaced by a subsequent PR
+			pool.setNewHead(ev.Data.(core.ChainHeadEvent).Block.Header())
+			// hack in order to avoid hogging the lock; this part will
+			// be replaced by a subsequent PR.
+			time.Sleep(time.Millisecond)
 		}
 	}
 }
 
+func (pool *TxPool) setNewHead(head *types.Header) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
+
+	ctx, cancel := context.WithTimeout(context.Background(), blockCheckTimeout)
+	defer cancel()
+
+	txc, _ := pool.reorgOnNewHead(ctx, head)
+	m, r := txc.getLists()
+	pool.relay.NewHead(pool.head, m, r)
+	pool.homestead = pool.config.IsHomestead(head.Number)
+	pool.signer = types.MakeSigner(pool.config, head.Number)
+}
+
 // Stop stops the light transaction pool
 func (pool *TxPool) Stop() {
 	close(pool.quit)
diff --git a/light/txpool_test.go b/light/txpool_test.go
index 980c7c898..e93955511 100644
--- a/light/txpool_test.go
+++ b/light/txpool_test.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"math"
 	"math/big"
 	"testing"
@@ -30,7 +31,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
-	"golang.org/x/net/context"
 )
 
 type testTxRelay struct {
@@ -107,10 +107,11 @@ func TestTxPool(t *testing.T) {
 	lightchain.SetValidator(bproc{})
 	txPermanent = 50
 	pool := NewTxPool(testChainConfig(), evmux, lightchain, relay)
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
 
 	for ii, block := range gchain {
 		i := ii + 1
-		ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
 		s := sentTx(i - 1)
 		e := sentTx(i)
 		for i := s; i < e; i++ {
diff --git a/light/vm_env.go b/light/vm_env.go
index ebd229de8..54aa12875 100644
--- a/light/vm_env.go
+++ b/light/vm_env.go
@@ -17,12 +17,12 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 // VMState is a wrapper for the light state that holds the actual context and
diff --git a/mobile/context.go b/mobile/context.go
index 9df94b689..f1fff9011 100644
--- a/mobile/context.go
+++ b/mobile/context.go
@@ -20,9 +20,8 @@
 package geth
 
 import (
+	"context"
 	"time"
-
-	"golang.org/x/net/context"
 )
 
 // Context carries a deadline, a cancelation signal, and other values across API
diff --git a/rpc/client.go b/rpc/client.go
index 78a6fe789..2c35ba54a 100644
--- a/rpc/client.go
+++ b/rpc/client.go
@@ -19,6 +19,7 @@ package rpc
 import (
 	"bytes"
 	"container/list"
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -31,7 +32,6 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/log"
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/rpc/client_context_go1.4.go b/rpc/client_context_go1.4.go
deleted file mode 100644
index ac956a17d..000000000
--- a/rpc/client_context_go1.4.go
+++ /dev/null
@@ -1,60 +0,0 @@
-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-// +build !go1.5
-
-package rpc
-
-import (
-	"net"
-	"net/http"
-	"time"
-
-	"golang.org/x/net/context"
-)
-
-// In older versions of Go (below 1.5), dials cannot be canceled
-// via a channel or context. The context deadline can still applied.
-
-// contextDialer returns a dialer that applies the deadline value from the given context.
-func contextDialer(ctx context.Context) *net.Dialer {
-	dialer := &net.Dialer{KeepAlive: tcpKeepAliveInterval}
-	if deadline, ok := ctx.Deadline(); ok {
-		dialer.Deadline = deadline
-	} else {
-		dialer.Deadline = time.Now().Add(defaultDialTimeout)
-	}
-	return dialer
-}
-
-// dialContext connects to the given address, aborting the dial if ctx is canceled.
-func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	return contextDialer(ctx).Dial(network, addr)
-}
-
-// requestWithContext copies req, adding the cancelation channel and deadline from ctx.
-func requestWithContext(c *http.Client, req *http.Request, ctx context.Context) (*http.Client, *http.Request) {
-	// Set Timeout on the client if the context has a deadline.
-	// Note that there is no default timeout (unlike in contextDialer) because
-	// the timeout applies to the entire request, including reads from body.
-	if deadline, ok := ctx.Deadline(); ok {
-		c2 := *c
-		c2.Timeout = deadline.Sub(time.Now())
-		c = &c2
-	}
-	req2 := *req
-	return c, &req2
-}
diff --git a/rpc/client_context_go1.5.go b/rpc/client_context_go1.5.go
deleted file mode 100644
index 4a007d9f8..000000000
--- a/rpc/client_context_go1.5.go
+++ /dev/null
@@ -1,61 +0,0 @@
-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-// +build go1.5,!go1.6
-
-package rpc
-
-import (
-	"net"
-	"net/http"
-	"time"
-
-	"golang.org/x/net/context"
-)
-
-// In Go 1.5, dials cannot be canceled via a channel or context. The context deadline can
-// still be applied. Go 1.5 adds the ability to cancel HTTP requests via a channel.
-
-// contextDialer returns a dialer that applies the deadline value from the given context.
-func contextDialer(ctx context.Context) *net.Dialer {
-	dialer := &net.Dialer{KeepAlive: tcpKeepAliveInterval}
-	if deadline, ok := ctx.Deadline(); ok {
-		dialer.Deadline = deadline
-	} else {
-		dialer.Deadline = time.Now().Add(defaultDialTimeout)
-	}
-	return dialer
-}
-
-// dialContext connects to the given address, aborting the dial if ctx is canceled.
-func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	return contextDialer(ctx).Dial(network, addr)
-}
-
-// requestWithContext copies req, adding the cancelation channel and deadline from ctx.
-func requestWithContext(c *http.Client, req *http.Request, ctx context.Context) (*http.Client, *http.Request) {
-	// Set Timeout on the client if the context has a deadline.
-	// Note that there is no default timeout (unlike in contextDialer) because
-	// the timeout applies to the entire request, including reads from body.
-	if deadline, ok := ctx.Deadline(); ok {
-		c2 := *c
-		c2.Timeout = deadline.Sub(time.Now())
-		c = &c2
-	}
-	req2 := *req
-	req2.Cancel = ctx.Done()
-	return c, &req2
-}
diff --git a/rpc/client_context_go1.6.go b/rpc/client_context_go1.6.go
deleted file mode 100644
index 67777ddc6..000000000
--- a/rpc/client_context_go1.6.go
+++ /dev/null
@@ -1,55 +0,0 @@
-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-// +build go1.6,!go1.7
-
-package rpc
-
-import (
-	"net"
-	"net/http"
-	"time"
-
-	"golang.org/x/net/context"
-)
-
-// In Go 1.6, net.Dialer gained the ability to cancel via a channel.
-
-// contextDialer returns a dialer that applies the deadline value from the given context.
-func contextDialer(ctx context.Context) *net.Dialer {
-	dialer := &net.Dialer{Cancel: ctx.Done(), KeepAlive: tcpKeepAliveInterval}
-	if deadline, ok := ctx.Deadline(); ok {
-		dialer.Deadline = deadline
-	} else {
-		dialer.Deadline = time.Now().Add(defaultDialTimeout)
-	}
-	return dialer
-}
-
-// dialContext connects to the given address, aborting the dial if ctx is canceled.
-func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	return contextDialer(ctx).Dial(network, addr)
-}
-
-// requestWithContext copies req, adding the cancelation channel and deadline from ctx.
-func requestWithContext(c *http.Client, req *http.Request, ctx context.Context) (*http.Client, *http.Request) {
-	// We set Timeout on the client for Go <= 1.5. There
-	// is no need to do that here because the dial will be canceled
-	// by package http.
-	req2 := *req
-	req2.Cancel = ctx.Done()
-	return c, &req2
-}
diff --git a/rpc/client_context_go1.7.go b/rpc/client_context_go1.7.go
deleted file mode 100644
index 56ce12ab8..000000000
--- a/rpc/client_context_go1.7.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2016 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-// +build go1.7
-
-package rpc
-
-import (
-	"context"
-	"net"
-	"net/http"
-	"time"
-)
-
-// In Go 1.7, context moved into the standard library and support
-// for cancelation via context was added to net.Dialer and http.Request.
-
-// contextDialer returns a dialer that applies the deadline value from the given context.
-func contextDialer(ctx context.Context) *net.Dialer {
-	dialer := &net.Dialer{Cancel: ctx.Done(), KeepAlive: tcpKeepAliveInterval}
-	if deadline, ok := ctx.Deadline(); ok {
-		dialer.Deadline = deadline
-	} else {
-		dialer.Deadline = time.Now().Add(defaultDialTimeout)
-	}
-	return dialer
-}
-
-// dialContext connects to the given address, aborting the dial if ctx is canceled.
-func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	d := &net.Dialer{KeepAlive: tcpKeepAliveInterval}
-	return d.DialContext(ctx, network, addr)
-}
-
-// requestWithContext copies req, adding the cancelation channel and deadline from ctx.
-func requestWithContext(c *http.Client, req *http.Request, ctx context.Context) (*http.Client, *http.Request) {
-	return c, req.WithContext(ctx)
-}
diff --git a/rpc/client_example_test.go b/rpc/client_example_test.go
index 3462b3685..8276a9ead 100644
--- a/rpc/client_example_test.go
+++ b/rpc/client_example_test.go
@@ -17,12 +17,12 @@
 package rpc_test
 
 import (
+	"context"
 	"fmt"
 	"math/big"
 	"time"
 
 	"github.com/ethereum/go-ethereum/rpc"
-	"golang.org/x/net/context"
 )
 
 // In this example, our client whishes to track the latest 'block number'
diff --git a/rpc/client_test.go b/rpc/client_test.go
index 407ed9c06..41471dcea 100644
--- a/rpc/client_test.go
+++ b/rpc/client_test.go
@@ -17,6 +17,7 @@
 package rpc
 
 import (
+	"context"
 	"fmt"
 	"math/rand"
 	"net"
@@ -31,7 +32,6 @@ import (
 
 	"github.com/davecgh/go-spew/spew"
 	"github.com/ethereum/go-ethereum/log"
-	"golang.org/x/net/context"
 )
 
 func TestClientRequest(t *testing.T) {
diff --git a/rpc/http.go b/rpc/http.go
index 5a0770231..89175b149 100644
--- a/rpc/http.go
+++ b/rpc/http.go
@@ -18,6 +18,7 @@ package rpc
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -29,7 +30,6 @@ import (
 	"time"
 
 	"github.com/rs/cors"
-	"golang.org/x/net/context"
 )
 
 const (
@@ -115,11 +115,11 @@ func (hc *httpConn) doRequest(ctx context.Context, msg interface{}) (io.ReadClos
 	if err != nil {
 		return nil, err
 	}
-	client, req := requestWithContext(hc.client, hc.req, ctx)
+	req := hc.req.WithContext(ctx)
 	req.Body = ioutil.NopCloser(bytes.NewReader(body))
 	req.ContentLength = int64(len(body))
 
-	resp, err := client.Do(req)
+	resp, err := hc.client.Do(req)
 	if err != nil {
 		return nil, err
 	}
diff --git a/rpc/inproc.go b/rpc/inproc.go
index f72b97497..595a7ca65 100644
--- a/rpc/inproc.go
+++ b/rpc/inproc.go
@@ -17,9 +17,8 @@
 package rpc
 
 import (
+	"context"
 	"net"
-
-	"golang.org/x/net/context"
 )
 
 // NewInProcClient attaches an in-process connection to the given RPC server.
diff --git a/rpc/ipc.go b/rpc/ipc.go
index 3c86d711c..8de18a56f 100644
--- a/rpc/ipc.go
+++ b/rpc/ipc.go
@@ -17,12 +17,11 @@
 package rpc
 
 import (
+	"context"
 	"fmt"
 	"net"
 
 	"github.com/ethereum/go-ethereum/log"
-
-	"golang.org/x/net/context"
 )
 
 // CreateIPCListener creates an listener, on Unix platforms this is a unix socket, on
diff --git a/rpc/ipc_unix.go b/rpc/ipc_unix.go
index a25b21627..0851ea61e 100644
--- a/rpc/ipc_unix.go
+++ b/rpc/ipc_unix.go
@@ -19,11 +19,10 @@
 package rpc
 
 import (
+	"context"
 	"net"
 	"os"
 	"path/filepath"
-
-	"golang.org/x/net/context"
 )
 
 // ipcListen will create a Unix socket on the given endpoint.
diff --git a/rpc/ipc_windows.go b/rpc/ipc_windows.go
index 68234d215..ca56a3ce4 100644
--- a/rpc/ipc_windows.go
+++ b/rpc/ipc_windows.go
@@ -19,10 +19,10 @@
 package rpc
 
 import (
+	"context"
 	"net"
 	"time"
 
-	"golang.org/x/net/context"
 	"gopkg.in/natefinch/npipe.v2"
 )
 
diff --git a/rpc/server.go b/rpc/server.go
index 4f9ce541e..ca7e3c01a 100644
--- a/rpc/server.go
+++ b/rpc/server.go
@@ -17,14 +17,13 @@
 package rpc
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 	"runtime"
 	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/log"
-
-	"golang.org/x/net/context"
 	"gopkg.in/fatih/set.v0"
 )
 
diff --git a/rpc/server_test.go b/rpc/server_test.go
index c3c88fab7..90d62f26d 100644
--- a/rpc/server_test.go
+++ b/rpc/server_test.go
@@ -17,13 +17,12 @@
 package rpc
 
 import (
+	"context"
 	"encoding/json"
 	"net"
 	"reflect"
 	"testing"
 	"time"
-
-	"golang.org/x/net/context"
 )
 
 type Service struct{}
diff --git a/rpc/subscription.go b/rpc/subscription.go
index bcdc3cdfc..9ab6af9e1 100644
--- a/rpc/subscription.go
+++ b/rpc/subscription.go
@@ -17,10 +17,9 @@
 package rpc
 
 import (
+	"context"
 	"errors"
 	"sync"
-
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/rpc/subscription_test.go b/rpc/subscription_test.go
index 00c4e0e35..345b4e5f2 100644
--- a/rpc/subscription_test.go
+++ b/rpc/subscription_test.go
@@ -17,13 +17,12 @@
 package rpc
 
 import (
+	"context"
 	"encoding/json"
 	"net"
 	"sync"
 	"testing"
 	"time"
-
-	"golang.org/x/net/context"
 )
 
 type NotificationTestService struct {
diff --git a/rpc/utils.go b/rpc/utils.go
index c249e9b4a..2506c4833 100644
--- a/rpc/utils.go
+++ b/rpc/utils.go
@@ -18,6 +18,7 @@ package rpc
 
 import (
 	"bufio"
+	"context"
 	crand "crypto/rand"
 	"encoding/binary"
 	"encoding/hex"
@@ -29,8 +30,6 @@ import (
 	"time"
 	"unicode"
 	"unicode/utf8"
-
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/rpc/websocket.go b/rpc/websocket.go
index f4271fda8..587010820 100644
--- a/rpc/websocket.go
+++ b/rpc/websocket.go
@@ -17,6 +17,7 @@
 package rpc
 
 import (
+	"context"
 	"crypto/tls"
 	"fmt"
 	"net"
@@ -24,10 +25,9 @@ import (
 	"net/url"
 	"os"
 	"strings"
+	"time"
 
 	"github.com/ethereum/go-ethereum/log"
-
-	"golang.org/x/net/context"
 	"golang.org/x/net/websocket"
 	"gopkg.in/fatih/set.v0"
 )
@@ -150,3 +150,18 @@ func wsDialAddress(location *url.URL) string {
 	}
 	return location.Host
 }
+
+func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	d := &net.Dialer{KeepAlive: tcpKeepAliveInterval}
+	return d.DialContext(ctx, network, addr)
+}
+
+func contextDialer(ctx context.Context) *net.Dialer {
+	dialer := &net.Dialer{Cancel: ctx.Done(), KeepAlive: tcpKeepAliveInterval}
+	if deadline, ok := ctx.Deadline(); ok {
+		dialer.Deadline = deadline
+	} else {
+		dialer.Deadline = time.Now().Add(defaultDialTimeout)
+	}
+	return dialer
+}
diff --git a/swarm/services/swap/swap.go b/swarm/services/swap/swap.go
index eb21a598d..093892e8d 100644
--- a/swarm/services/swap/swap.go
+++ b/swarm/services/swap/swap.go
@@ -17,6 +17,7 @@
 package swap
 
 import (
+	"context"
 	"crypto/ecdsa"
 	"fmt"
 	"math/big"
@@ -33,7 +34,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/swarm/services/swap/swap"
-	"golang.org/x/net/context"
 )
 
 // SwAP       Swarm Accounting Protocol with
diff --git a/swarm/swarm.go b/swarm/swarm.go
index 44564a71d..bd256edaa 100644
--- a/swarm/swarm.go
+++ b/swarm/swarm.go
@@ -18,6 +18,7 @@ package swarm
 
 import (
 	"bytes"
+	"context"
 	"crypto/ecdsa"
 	"fmt"
 
@@ -35,7 +36,6 @@ import (
 	httpapi "github.com/ethereum/go-ethereum/swarm/api/http"
 	"github.com/ethereum/go-ethereum/swarm/network"
 	"github.com/ethereum/go-ethereum/swarm/storage"
-	"golang.org/x/net/context"
 )
 
 // the swarm stack
diff --git a/build/_vendor/src/golang.org/x/net/context/context.go b/vendor/golang.org/x/net/context/context.go
index 134654cf7..f143ed6a1 100644
--- a/build/_vendor/src/golang.org/x/net/context/context.go
+++ b/vendor/golang.org/x/net/context/context.go
@@ -7,7 +7,7 @@
 // and between processes.
 //
 // Incoming requests to a server should create a Context, and outgoing calls to
-// servers should accept a Context.  The chain of function calls between must
+// servers should accept a Context. The chain of function calls between must
 // propagate the Context, optionally replacing it with a modified copy created
 // using WithDeadline, WithTimeout, WithCancel, or WithValue.
 //
@@ -16,14 +16,14 @@
 // propagation:
 //
 // Do not store Contexts inside a struct type; instead, pass a Context
-// explicitly to each function that needs it.  The Context should be the first
+// explicitly to each function that needs it. The Context should be the first
 // parameter, typically named ctx:
 //
 // 	func DoSomething(ctx context.Context, arg Arg) error {
 // 		// ... use ctx ...
 // 	}
 //
-// Do not pass a nil Context, even if a function permits it.  Pass context.TODO
+// Do not pass a nil Context, even if a function permits it. Pass context.TODO
 // if you are unsure about which Context to use.
 //
 // Use context Values only for request-scoped data that transits processes and
@@ -44,13 +44,13 @@ import "time"
 // Context's methods may be called by multiple goroutines simultaneously.
 type Context interface {
 	// Deadline returns the time when work done on behalf of this context
-	// should be canceled.  Deadline returns ok==false when no deadline is
-	// set.  Successive calls to Deadline return the same results.
+	// should be canceled. Deadline returns ok==false when no deadline is
+	// set. Successive calls to Deadline return the same results.
 	Deadline() (deadline time.Time, ok bool)
 
 	// Done returns a channel that's closed when work done on behalf of this
-	// context should be canceled.  Done may return nil if this context can
-	// never be canceled.  Successive calls to Done return the same value.
+	// context should be canceled. Done may return nil if this context can
+	// never be canceled. Successive calls to Done return the same value.
 	//
 	// WithCancel arranges for Done to be closed when cancel is called;
 	// WithDeadline arranges for Done to be closed when the deadline
@@ -79,24 +79,24 @@ type Context interface {
 	// a Done channel for cancelation.
 	Done() <-chan struct{}
 
-	// Err returns a non-nil error value after Done is closed.  Err returns
+	// Err returns a non-nil error value after Done is closed. Err returns
 	// Canceled if the context was canceled or DeadlineExceeded if the
-	// context's deadline passed.  No other values for Err are defined.
+	// context's deadline passed. No other values for Err are defined.
 	// After Done is closed, successive calls to Err return the same value.
 	Err() error
 
 	// Value returns the value associated with this context for key, or nil
-	// if no value is associated with key.  Successive calls to Value with
+	// if no value is associated with key. Successive calls to Value with
 	// the same key returns the same result.
 	//
 	// Use context values only for request-scoped data that transits
 	// processes and API boundaries, not for passing optional parameters to
 	// functions.
 	//
-	// A key identifies a specific value in a Context.  Functions that wish
+	// A key identifies a specific value in a Context. Functions that wish
 	// to store values in Context typically allocate a key in a global
 	// variable then use that key as the argument to context.WithValue and
-	// Context.Value.  A key can be any type that supports equality;
+	// Context.Value. A key can be any type that supports equality;
 	// packages should define keys as an unexported type to avoid
 	// collisions.
 	//
@@ -115,7 +115,7 @@ type Context interface {
 	// 	// This prevents collisions with keys defined in other packages.
 	// 	type key int
 	//
-	// 	// userKey is the key for user.User values in Contexts.  It is
+	// 	// userKey is the key for user.User values in Contexts. It is
 	// 	// unexported; clients use user.NewContext and user.FromContext
 	// 	// instead of using this key directly.
 	// 	var userKey key = 0
@@ -134,14 +134,14 @@ type Context interface {
 }
 
 // Background returns a non-nil, empty Context. It is never canceled, has no
-// values, and has no deadline.  It is typically used by the main function,
+// values, and has no deadline. It is typically used by the main function,
 // initialization, and tests, and as the top-level Context for incoming
 // requests.
 func Background() Context {
 	return background
 }
 
-// TODO returns a non-nil, empty Context.  Code should use context.TODO when
+// TODO returns a non-nil, empty Context. Code should use context.TODO when
 // it's unclear which Context to use or it is not yet available (because the
 // surrounding function has not yet been extended to accept a Context
 // parameter).  TODO is recognized by static analysis tools that determine
diff --git a/build/_vendor/src/golang.org/x/net/context/go17.go b/vendor/golang.org/x/net/context/go17.go
index f8cda19ad..d20f52b7d 100644
--- a/build/_vendor/src/golang.org/x/net/context/go17.go
+++ b/vendor/golang.org/x/net/context/go17.go
@@ -35,8 +35,8 @@ func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
 }
 
 // WithDeadline returns a copy of the parent context with the deadline adjusted
-// to be no later than d.  If the parent's deadline is already earlier than d,
-// WithDeadline(parent, d) is semantically equivalent to parent.  The returned
+// to be no later than d. If the parent's deadline is already earlier than d,
+// WithDeadline(parent, d) is semantically equivalent to parent. The returned
 // context's Done channel is closed when the deadline expires, when the returned
 // cancel function is called, or when the parent context's Done channel is
 // closed, whichever happens first.
diff --git a/build/_vendor/src/golang.org/x/net/context/pre_go17.go b/vendor/golang.org/x/net/context/pre_go17.go
index 5a30acabd..0f35592df 100644
--- a/build/_vendor/src/golang.org/x/net/context/pre_go17.go
+++ b/vendor/golang.org/x/net/context/pre_go17.go
@@ -13,7 +13,7 @@ import (
 	"time"
 )
 
-// An emptyCtx is never canceled, has no values, and has no deadline.  It is not
+// An emptyCtx is never canceled, has no values, and has no deadline. It is not
 // struct{}, since vars of this type must have distinct addresses.
 type emptyCtx int
 
@@ -104,7 +104,7 @@ func propagateCancel(parent Context, child canceler) {
 }
 
 // parentCancelCtx follows a chain of parent references until it finds a
-// *cancelCtx.  This function understands how each of the concrete types in this
+// *cancelCtx. This function understands how each of the concrete types in this
 // package represents its parent.
 func parentCancelCtx(parent Context) (*cancelCtx, bool) {
 	for {
@@ -134,14 +134,14 @@ func removeChild(parent Context, child canceler) {
 	p.mu.Unlock()
 }
 
-// A canceler is a context type that can be canceled directly.  The
+// A canceler is a context type that can be canceled directly. The
 // implementations are *cancelCtx and *timerCtx.
 type canceler interface {
 	cancel(removeFromParent bool, err error)
 	Done() <-chan struct{}
 }
 
-// A cancelCtx can be canceled.  When canceled, it also cancels any children
+// A cancelCtx can be canceled. When canceled, it also cancels any children
 // that implement canceler.
 type cancelCtx struct {
 	Context
@@ -193,8 +193,8 @@ func (c *cancelCtx) cancel(removeFromParent bool, err error) {
 }
 
 // WithDeadline returns a copy of the parent context with the deadline adjusted
-// to be no later than d.  If the parent's deadline is already earlier than d,
-// WithDeadline(parent, d) is semantically equivalent to parent.  The returned
+// to be no later than d. If the parent's deadline is already earlier than d,
+// WithDeadline(parent, d) is semantically equivalent to parent. The returned
 // context's Done channel is closed when the deadline expires, when the returned
 // cancel function is called, or when the parent context's Done channel is
 // closed, whichever happens first.
@@ -226,8 +226,8 @@ func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
 	return c, func() { c.cancel(true, Canceled) }
 }
 
-// A timerCtx carries a timer and a deadline.  It embeds a cancelCtx to
-// implement Done and Err.  It implements cancel by stopping its timer then
+// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
+// implement Done and Err. It implements cancel by stopping its timer then
 // delegating to cancelCtx.cancel.
 type timerCtx struct {
 	*cancelCtx
@@ -281,7 +281,7 @@ func WithValue(parent Context, key interface{}, val interface{}) Context {
 	return &valueCtx{parent, key, val}
 }
 
-// A valueCtx carries a key-value pair.  It implements Value for that key and
+// A valueCtx carries a key-value pair. It implements Value for that key and
 // delegates all other calls to the embedded Context.
 type valueCtx struct {
 	Context
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 58bbd82ff..eaaf0290d 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -1,6 +1,6 @@
 {
 	"comment": "",
-	"ignore": "test golang.org/x/net/context",
+	"ignore": "test",
 	"package": [
 		{
 			"checksumSHA1": "M30X+Wqn7AnUr1numUOkQRI7ET0=",
@@ -384,6 +384,12 @@
 			"revisionTime": "2017-02-08T20:51:15Z"
 		},
 		{
+			"checksumSHA1": "Y+HGqEkYM15ir+J93MEaHdyFy0c=",
+			"path": "golang.org/x/net/context",
+			"revision": "a6577fac2d73be281a500b310739095313165611",
+			"revisionTime": "2017-03-08T20:54:49Z"
+		},
+		{
 			"checksumSHA1": "vqc3a+oTUGX8PmD0TS+qQ7gmN8I=",
 			"path": "golang.org/x/net/html",
 			"revision": "b4690f45fa1cafc47b1c280c2e75116efe40cc13",