Switch to using libnetwork's resolvconf package

Libnetwork provides a well-tested package for generating
resolv.conf from the host's that has some features our current
implementation does not. Swap to using their code and remove our
built-in implementation.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

libpod/container_internal.go

@@ -17,11 +17,12 @@ import (
 	"github.com/containers/libpod/pkg/hooks/exec"
 	"github.com/containers/libpod/pkg/rootless"
 	"github.com/containers/libpod/pkg/secrets"
-	"github.com/containers/libpod/pkg/util"
 	"github.com/containers/storage"
 	"github.com/containers/storage/pkg/archive"
 	"github.com/containers/storage/pkg/chrootarchive"
 	"github.com/containers/storage/pkg/mount"
+	"github.com/docker/libnetwork/netutils"
+	"github.com/docker/libnetwork/resolvconf"
 	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/opencontainers/runtime-tools/generate"
 	"github.com/opencontainers/selinux/go-selinux/label"
@@ -1017,12 +1018,6 @@ func (c *Container) writeStringToRundir(destFile, output string) (string, error)
 	return filepath.Join(c.state.DestinationRunDir, destFile), nil
 }
 
-type resolvConf struct {
-	nameServers   []string
-	searchDomains []string
-	options       []string
-}
-
 // generateResolvConf generates a containers resolv.conf
 func (c *Container) generateResolvConf() (string, error) {
 	// Determine the endpoint for resolv.conf in case it is a symlink
@@ -1030,86 +1025,51 @@ func (c *Container) generateResolvConf() (string, error) {
 	if err != nil {
 		return "", err
 	}
-	orig, err := ioutil.ReadFile(resolvPath)
+
+	contents, err := ioutil.ReadFile(resolvPath)
 	if err != nil {
 		return "", errors.Wrapf(err, "unable to read %s", resolvPath)
 	}
-	if len(c.config.DNSServer) == 0 && len(c.config.DNSSearch) == 0 && len(c.config.DNSOption) == 0 {
+
-		return c.writeStringToRundir("resolv.conf", fmt.Sprintf("%s", orig))
+	// Process the file to remove localhost nameservers
+	// TODO: set ipv6 enable bool more sanely
+	resolv, err := resolvconf.FilterResolvDNS(contents, true)
+	if err != nil {
+		return "", errors.Wrapf(err, "error parsing host resolv.conf")
 	}
 
-	// Read and organize the hosts /etc/resolv.conf
+	// Make a new resolv.conf
-	resolv := createResolv(string(orig[:]))
+	nameservers := resolvconf.GetNameservers(resolv.Content, netutils.IP)
-
-	// Populate the resolv struct with user's dns search domains
-	if len(c.config.DNSSearch) > 0 {
-		resolv.searchDomains = nil
-		// The . character means the user doesnt want any search domains in the container
-		if !util.StringInSlice(".", c.config.DNSSearch) {
-			resolv.searchDomains = append(resolv.searchDomains, c.Config().DNSSearch...)
-		}
-	}
-
-	// Populate the resolv struct with user's dns servers
 	if len(c.config.DNSServer) > 0 {
-		resolv.nameServers = nil
+		// We store DNS servers as net.IP, so need to convert to string
-		for _, i := range c.config.DNSServer {
+		nameservers = []string{}
-			resolv.nameServers = append(resolv.nameServers, i.String())
+		for _, server := range c.config.DNSServer {
+			nameservers = append(nameservers, server.String())
 		}
 	}
 
-	// Populate the resolve struct with the users dns options
+	search := resolvconf.GetSearchDomains(resolv.Content)
+	if len(c.config.DNSSearch) > 0 {
+		search = c.config.DNSSearch
+	}
+
+	options := resolvconf.GetOptions(resolv.Content)
 	if len(c.config.DNSOption) > 0 {
-		resolv.options = nil
+		options = c.config.DNSOption
-		resolv.options = append(resolv.options, c.Config().DNSOption...)
 	}
-	return c.writeStringToRundir("resolv.conf", resolv.ToString())
-}
 
-// createResolv creates a resolv struct from an input string
+	destPath := filepath.Join(c.state.RunDir, "resolv.conf")
-func createResolv(input string) resolvConf {
-	var resolv resolvConf
-	for _, line := range strings.Split(input, "\n") {
-		if strings.HasPrefix(line, "search") {
-			fields := strings.Fields(line)
-			if len(fields) < 2 {
-				logrus.Debugf("invalid resolv.conf line %s", line)
-				continue
-			}
-			resolv.searchDomains = append(resolv.searchDomains, fields[1:]...)
-		} else if strings.HasPrefix(line, "nameserver") {
-			fields := strings.Fields(line)
-			if len(fields) < 2 {
-				logrus.Debugf("invalid resolv.conf line %s", line)
-				continue
-			}
-			resolv.nameServers = append(resolv.nameServers, fields[1])
-		} else if strings.HasPrefix(line, "options") {
-			fields := strings.Fields(line)
-			if len(fields) < 2 {
-				logrus.Debugf("invalid resolv.conf line %s", line)
-				continue
-			}
-			resolv.options = append(resolv.options, fields[1:]...)
-		}
-	}
-	return resolv
-}
 
-//ToString returns a resolv struct in the form of a resolv.conf
+	if err := os.Remove(destPath); err != nil && !os.IsNotExist(err) {
-func (r resolvConf) ToString() string {
+		return "", errors.Wrapf(err, "error removing resolv.conf for container %s", c.ID())
-	var result string
-	// Populate the output string with search domains
-	result += fmt.Sprintf("search %s\n", strings.Join(r.searchDomains, " "))
-	// Populate the output string with name servers
-	for _, i := range r.nameServers {
-		result += fmt.Sprintf("nameserver %s\n", i)
 	}
-	// Populate the output string with dns options
+
-	for _, i := range r.options {
+	// Build resolv.conf
-		result += fmt.Sprintf("options %s\n", i)
+	if _, err = resolvconf.Build(destPath, nameservers, search, options); err != nil {
+		return "", errors.Wrapf(err, "error building resolv.conf for container %s")
 	}
-	return result
+
+	return destPath, nil
 }
 
 // generateHosts creates a containers hosts file

vendor.conf

@@ -97,3 +97,4 @@ github.com/openshift/imagebuilder master
 github.com/ulikunitz/xz v0.5.4
 github.com/mailru/easyjson 03f2033d19d5860aef995fe360ac7d395cd8ce65
 github.com/coreos/go-iptables 25d087f3cffd9aedc0c2b7eff25f23cbf3c20fe1
+github.com/docker/libnetwork v0.7.2-rc.1

vendor/github.com/docker/libnetwork/LICENSE

@@ -0,0 +1,202 @@
+Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
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+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
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+      including but not limited to software source code, documentation
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+
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+      transformation or translation of a Source form, including but
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+
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+      Object form, made available under the License, as indicated by a
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+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
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+      of this License, Derivative Works shall not include works that remain
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+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
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+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
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+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
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+      may provide additional or different license terms and conditions
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+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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+      PARTICULAR PURPOSE. You are solely responsible for determining the
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+      risks associated with Your exercise of permissions under this License.
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+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
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+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+

vendor/github.com/docker/libnetwork/README.md

@@ -0,0 +1,89 @@
+# libnetwork - networking for containers
+
+[![Circle CI](https://circleci.com/gh/docker/libnetwork/tree/master.svg?style=svg)](https://circleci.com/gh/docker/libnetwork/tree/master) [![Coverage Status](https://coveralls.io/repos/docker/libnetwork/badge.svg)](https://coveralls.io/r/docker/libnetwork) [![GoDoc](https://godoc.org/github.com/docker/libnetwork?status.svg)](https://godoc.org/github.com/docker/libnetwork)
+
+Libnetwork provides a native Go implementation for connecting containers
+
+The goal of libnetwork is to deliver a robust Container Network Model that provides a consistent programming interface and the required network abstractions for applications.
+
+#### Design
+Please refer to the [design](docs/design.md) for more information.
+
+#### Using libnetwork
+
+There are many networking solutions available to suit a broad range of use-cases. libnetwork uses a driver / plugin model to support all of these solutions while abstracting the complexity of the driver implementations by exposing a simple and consistent Network Model to users.
+
+
+```go
+func main() {
+	if reexec.Init() {
+		return
+	}
+
+	// Select and configure the network driver
+	networkType := "bridge"
+
+	// Create a new controller instance
+	driverOptions := options.Generic{}
+	genericOption := make(map[string]interface{})
+	genericOption[netlabel.GenericData] = driverOptions
+	controller, err := libnetwork.New(config.OptionDriverConfig(networkType, genericOption))
+	if err != nil {
+		log.Fatalf("libnetwork.New: %s", err)
+	}
+
+	// Create a network for containers to join.
+	// NewNetwork accepts Variadic optional arguments that libnetwork and Drivers can use.
+	network, err := controller.NewNetwork(networkType, "network1")
+	if err != nil {
+		log.Fatalf("controller.NewNetwork: %s", err)
+	}
+
+	// For each new container: allocate IP and interfaces. The returned network
+	// settings will be used for container infos (inspect and such), as well as
+	// iptables rules for port publishing. This info is contained or accessible
+	// from the returned endpoint.
+	ep, err := network.CreateEndpoint("Endpoint1")
+	if err != nil {
+		log.Fatalf("network.CreateEndpoint: %s", err)
+	}
+
+	// Create the sandbox for the container.
+	// NewSandbox accepts Variadic optional arguments which libnetwork can use.
+	sbx, err := controller.NewSandbox("container1",
+		libnetwork.OptionHostname("test"),
+		libnetwork.OptionDomainname("docker.io"))
+	if err != nil {
+		log.Fatalf("controller.NewSandbox: %s", err)
+	}
+
+	// A sandbox can join the endpoint via the join api.
+	err = ep.Join(sbx)
+	if err != nil {
+		log.Fatalf("ep.Join: %s", err)
+	}
+
+	// libnetwork client can check the endpoint's operational data via the Info() API
+	epInfo, err := ep.DriverInfo()
+	if err != nil {
+		log.Fatalf("ep.DriverInfo: %s", err)
+	}
+
+	macAddress, ok := epInfo[netlabel.MacAddress]
+	if !ok {
+		log.Fatalf("failed to get mac address from endpoint info")
+	}
+
+	fmt.Printf("Joined endpoint %s (%s) to sandbox %s (%s)\n", ep.Name(), macAddress, sbx.ContainerID(), sbx.Key())
+}
+```
+
+## Future
+Please refer to [roadmap](ROADMAP.md) for more information.
+
+## Contributing
+
+Want to hack on libnetwork? [Docker's contributions guidelines](https://github.com/docker/docker/blob/master/CONTRIBUTING.md) apply.
+
+## Copyright and license
+Code and documentation copyright 2015 Docker, inc. Code released under the Apache 2.0 license. Docs released under Creative commons.

vendor/github.com/docker/libnetwork/netutils/utils.go

@@ -0,0 +1,201 @@
+// Network utility functions.
+
+package netutils
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strings"
+
+	"github.com/docker/libnetwork/types"
+)
+
+// constants for the IP address type
+const (
+	IP = iota // IPv4 and IPv6
+	IPv4
+	IPv6
+)
+
+var (
+	// ErrNetworkOverlapsWithNameservers preformatted error
+	ErrNetworkOverlapsWithNameservers = errors.New("requested network overlaps with nameserver")
+	// ErrNetworkOverlaps preformatted error
+	ErrNetworkOverlaps = errors.New("requested network overlaps with existing network")
+	// ErrNoDefaultRoute preformatted error
+	ErrNoDefaultRoute = errors.New("no default route")
+)
+
+// CheckNameserverOverlaps checks whether the passed network overlaps with any of the nameservers
+func CheckNameserverOverlaps(nameservers []string, toCheck *net.IPNet) error {
+	if len(nameservers) > 0 {
+		for _, ns := range nameservers {
+			_, nsNetwork, err := net.ParseCIDR(ns)
+			if err != nil {
+				return err
+			}
+			if NetworkOverlaps(toCheck, nsNetwork) {
+				return ErrNetworkOverlapsWithNameservers
+			}
+		}
+	}
+	return nil
+}
+
+// NetworkOverlaps detects overlap between one IPNet and another
+func NetworkOverlaps(netX *net.IPNet, netY *net.IPNet) bool {
+	return netX.Contains(netY.IP) || netY.Contains(netX.IP)
+}
+
+// NetworkRange calculates the first and last IP addresses in an IPNet
+func NetworkRange(network *net.IPNet) (net.IP, net.IP) {
+	if network == nil {
+		return nil, nil
+	}
+
+	firstIP := network.IP.Mask(network.Mask)
+	lastIP := types.GetIPCopy(firstIP)
+	for i := 0; i < len(firstIP); i++ {
+		lastIP[i] = firstIP[i] | ^network.Mask[i]
+	}
+
+	if network.IP.To4() != nil {
+		firstIP = firstIP.To4()
+		lastIP = lastIP.To4()
+	}
+
+	return firstIP, lastIP
+}
+
+// GetIfaceAddr returns the first IPv4 address and slice of IPv6 addresses for the specified network interface
+func GetIfaceAddr(name string) (net.Addr, []net.Addr, error) {
+	iface, err := net.InterfaceByName(name)
+	if err != nil {
+		return nil, nil, err
+	}
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil, nil, err
+	}
+	var addrs4 []net.Addr
+	var addrs6 []net.Addr
+	for _, addr := range addrs {
+		ip := (addr.(*net.IPNet)).IP
+		if ip4 := ip.To4(); ip4 != nil {
+			addrs4 = append(addrs4, addr)
+		} else if ip6 := ip.To16(); len(ip6) == net.IPv6len {
+			addrs6 = append(addrs6, addr)
+		}
+	}
+	switch {
+	case len(addrs4) == 0:
+		return nil, nil, fmt.Errorf("Interface %v has no IPv4 addresses", name)
+	case len(addrs4) > 1:
+		fmt.Printf("Interface %v has more than 1 IPv4 address. Defaulting to using %v\n",
+			name, (addrs4[0].(*net.IPNet)).IP)
+	}
+	return addrs4[0], addrs6, nil
+}
+
+func genMAC(ip net.IP) net.HardwareAddr {
+	hw := make(net.HardwareAddr, 6)
+	// The first byte of the MAC address has to comply with these rules:
+	// 1. Unicast: Set the least-significant bit to 0.
+	// 2. Address is locally administered: Set the second-least-significant bit (U/L) to 1.
+	hw[0] = 0x02
+	// The first 24 bits of the MAC represent the Organizationally Unique Identifier (OUI).
+	// Since this address is locally administered, we can do whatever we want as long as
+	// it doesn't conflict with other addresses.
+	hw[1] = 0x42
+	// Fill the remaining 4 bytes based on the input
+	if ip == nil {
+		rand.Read(hw[2:])
+	} else {
+		copy(hw[2:], ip.To4())
+	}
+	return hw
+}
+
+// GenerateRandomMAC returns a new 6-byte(48-bit) hardware address (MAC)
+func GenerateRandomMAC() net.HardwareAddr {
+	return genMAC(nil)
+}
+
+// GenerateMACFromIP returns a locally administered MAC address where the 4 least
+// significant bytes are derived from the IPv4 address.
+func GenerateMACFromIP(ip net.IP) net.HardwareAddr {
+	return genMAC(ip)
+}
+
+// GenerateRandomName returns a new name joined with a prefix.  This size
+// specified is used to truncate the randomly generated value
+func GenerateRandomName(prefix string, size int) (string, error) {
+	id := make([]byte, 32)
+	if _, err := io.ReadFull(rand.Reader, id); err != nil {
+		return "", err
+	}
+	return prefix + hex.EncodeToString(id)[:size], nil
+}
+
+// ReverseIP accepts a V4 or V6 IP string in the canonical form and returns a reversed IP in
+// the dotted decimal form . This is used to setup the IP to service name mapping in the optimal
+// way for the DNS PTR queries.
+func ReverseIP(IP string) string {
+	var reverseIP []string
+
+	if net.ParseIP(IP).To4() != nil {
+		reverseIP = strings.Split(IP, ".")
+		l := len(reverseIP)
+		for i, j := 0, l-1; i < l/2; i, j = i+1, j-1 {
+			reverseIP[i], reverseIP[j] = reverseIP[j], reverseIP[i]
+		}
+	} else {
+		reverseIP = strings.Split(IP, ":")
+
+		// Reversed IPv6 is represented in dotted decimal instead of the typical
+		// colon hex notation
+		for key := range reverseIP {
+			if len(reverseIP[key]) == 0 { // expand the compressed 0s
+				reverseIP[key] = strings.Repeat("0000", 8-strings.Count(IP, ":"))
+			} else if len(reverseIP[key]) < 4 { // 0-padding needed
+				reverseIP[key] = strings.Repeat("0", 4-len(reverseIP[key])) + reverseIP[key]
+			}
+		}
+
+		reverseIP = strings.Split(strings.Join(reverseIP, ""), "")
+
+		l := len(reverseIP)
+		for i, j := 0, l-1; i < l/2; i, j = i+1, j-1 {
+			reverseIP[i], reverseIP[j] = reverseIP[j], reverseIP[i]
+		}
+	}
+
+	return strings.Join(reverseIP, ".")
+}
+
+// ParseAlias parses and validates the specified string as a alias format (name:alias)
+func ParseAlias(val string) (string, string, error) {
+	if val == "" {
+		return "", "", fmt.Errorf("empty string specified for alias")
+	}
+	arr := strings.Split(val, ":")
+	if len(arr) > 2 {
+		return "", "", fmt.Errorf("bad format for alias: %s", val)
+	}
+	if len(arr) == 1 {
+		return val, val, nil
+	}
+	return arr[0], arr[1], nil
+}
+
+// ValidateAlias validates that the specified string has a valid alias format (containerName:alias).
+func ValidateAlias(val string) (string, error) {
+	if _, _, err := ParseAlias(val); err != nil {
+		return val, err
+	}
+	return val, nil
+}

vendor/github.com/docker/libnetwork/netutils/utils_linux.go

@@ -0,0 +1,50 @@
+// +build linux
+// Network utility functions.
+
+package netutils
+
+import (
+	"net"
+	"strings"
+
+	"github.com/docker/libnetwork/types"
+	"github.com/vishvananda/netlink"
+)
+
+var (
+	networkGetRoutesFct = netlink.RouteList
+)
+
+// CheckRouteOverlaps checks whether the passed network overlaps with any existing routes
+func CheckRouteOverlaps(toCheck *net.IPNet) error {
+	networks, err := networkGetRoutesFct(nil, netlink.FAMILY_V4)
+	if err != nil {
+		return err
+	}
+
+	for _, network := range networks {
+		if network.Dst != nil && NetworkOverlaps(toCheck, network.Dst) {
+			return ErrNetworkOverlaps
+		}
+	}
+	return nil
+}
+
+// GenerateIfaceName returns an interface name using the passed in
+// prefix and the length of random bytes. The api ensures that the
+// there are is no interface which exists with that name.
+func GenerateIfaceName(prefix string, len int) (string, error) {
+	for i := 0; i < 3; i++ {
+		name, err := GenerateRandomName(prefix, len)
+		if err != nil {
+			continue
+		}
+		if _, err := netlink.LinkByName(name); err != nil {
+			if strings.Contains(err.Error(), "not found") {
+				return name, nil
+			}
+			return "", err
+		}
+	}
+	return "", types.InternalErrorf("could not generate interface name")
+}

vendor/github.com/docker/libnetwork/resolvconf/README.md

@@ -0,0 +1 @@
+Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf

vendor/github.com/docker/libnetwork/resolvconf/dns/resolvconf.go

@@ -0,0 +1,17 @@
+package dns
+
+import (
+	"regexp"
+)
+
+// IPLocalhost is a regex patter for localhost IP address range.
+const IPLocalhost = `((127\.([0-9]{1,3}\.){2}[0-9]{1,3})|(::1)$)`
+
+var localhostIPRegexp = regexp.MustCompile(IPLocalhost)
+
+// IsLocalhost returns true if ip matches the localhost IP regular expression.
+// Used for determining if nameserver settings are being passed which are
+// localhost addresses
+func IsLocalhost(ip string) bool {
+	return localhostIPRegexp.MatchString(ip)
+}

vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go

@@ -0,0 +1,247 @@
+// Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf
+package resolvconf
+
+import (
+	"bytes"
+	"io/ioutil"
+	"regexp"
+	"strings"
+	"sync"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/docker/pkg/ioutils"
+	"github.com/docker/libnetwork/netutils"
+	"github.com/docker/libnetwork/resolvconf/dns"
+)
+
+var (
+	// Note: the default IPv4 & IPv6 resolvers are set to Google's Public DNS
+	defaultIPv4Dns = []string{"nameserver 8.8.8.8", "nameserver 8.8.4.4"}
+	defaultIPv6Dns = []string{"nameserver 2001:4860:4860::8888", "nameserver 2001:4860:4860::8844"}
+	ipv4NumBlock   = `(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)`
+	ipv4Address    = `(` + ipv4NumBlock + `\.){3}` + ipv4NumBlock
+	// This is not an IPv6 address verifier as it will accept a super-set of IPv6, and also
+	// will *not match* IPv4-Embedded IPv6 Addresses (RFC6052), but that and other variants
+	// -- e.g. other link-local types -- either won't work in containers or are unnecessary.
+	// For readability and sufficiency for Docker purposes this seemed more reasonable than a
+	// 1000+ character regexp with exact and complete IPv6 validation
+	ipv6Address = `([0-9A-Fa-f]{0,4}:){2,7}([0-9A-Fa-f]{0,4})`
+
+	localhostNSRegexp = regexp.MustCompile(`(?m)^nameserver\s+` + dns.IPLocalhost + `\s*\n*`)
+	nsIPv6Regexp      = regexp.MustCompile(`(?m)^nameserver\s+` + ipv6Address + `\s*\n*`)
+	nsRegexp          = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `)|(` + ipv6Address + `))\s*$`)
+	nsIPv6Regexpmatch = regexp.MustCompile(`^\s*nameserver\s*((` + ipv6Address + `))\s*$`)
+	nsIPv4Regexpmatch = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `))\s*$`)
+	searchRegexp      = regexp.MustCompile(`^\s*search\s*(([^\s]+\s*)*)$`)
+	optionsRegexp     = regexp.MustCompile(`^\s*options\s*(([^\s]+\s*)*)$`)
+)
+
+var lastModified struct {
+	sync.Mutex
+	sha256   string
+	contents []byte
+}
+
+// File contains the resolv.conf content and its hash
+type File struct {
+	Content []byte
+	Hash    string
+}
+
+// Get returns the contents of /etc/resolv.conf and its hash
+func Get() (*File, error) {
+	resolv, err := ioutil.ReadFile("/etc/resolv.conf")
+	if err != nil {
+		return nil, err
+	}
+	hash, err := ioutils.HashData(bytes.NewReader(resolv))
+	if err != nil {
+		return nil, err
+	}
+	return &File{Content: resolv, Hash: hash}, nil
+}
+
+// GetSpecific returns the contents of the user specified resolv.conf file and its hash
+func GetSpecific(path string) (*File, error) {
+	resolv, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	hash, err := ioutils.HashData(bytes.NewReader(resolv))
+	if err != nil {
+		return nil, err
+	}
+	return &File{Content: resolv, Hash: hash}, nil
+}
+
+// GetIfChanged retrieves the host /etc/resolv.conf file, checks against the last hash
+// and, if modified since last check, returns the bytes and new hash.
+// This feature is used by the resolv.conf updater for containers
+func GetIfChanged() (*File, error) {
+	lastModified.Lock()
+	defer lastModified.Unlock()
+
+	resolv, err := ioutil.ReadFile("/etc/resolv.conf")
+	if err != nil {
+		return nil, err
+	}
+	newHash, err := ioutils.HashData(bytes.NewReader(resolv))
+	if err != nil {
+		return nil, err
+	}
+	if lastModified.sha256 != newHash {
+		lastModified.sha256 = newHash
+		lastModified.contents = resolv
+		return &File{Content: resolv, Hash: newHash}, nil
+	}
+	// nothing changed, so return no data
+	return nil, nil
+}
+
+// GetLastModified retrieves the last used contents and hash of the host resolv.conf.
+// Used by containers updating on restart
+func GetLastModified() *File {
+	lastModified.Lock()
+	defer lastModified.Unlock()
+
+	return &File{Content: lastModified.contents, Hash: lastModified.sha256}
+}
+
+// FilterResolvDNS cleans up the config in resolvConf.  It has two main jobs:
+// 1. It looks for localhost (127.*|::1) entries in the provided
+//    resolv.conf, removing local nameserver entries, and, if the resulting
+//    cleaned config has no defined nameservers left, adds default DNS entries
+// 2. Given the caller provides the enable/disable state of IPv6, the filter
+//    code will remove all IPv6 nameservers if it is not enabled for containers
+//
+func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) (*File, error) {
+	cleanedResolvConf := localhostNSRegexp.ReplaceAll(resolvConf, []byte{})
+	// if IPv6 is not enabled, also clean out any IPv6 address nameserver
+	if !ipv6Enabled {
+		cleanedResolvConf = nsIPv6Regexp.ReplaceAll(cleanedResolvConf, []byte{})
+	}
+	// if the resulting resolvConf has no more nameservers defined, add appropriate
+	// default DNS servers for IPv4 and (optionally) IPv6
+	if len(GetNameservers(cleanedResolvConf, netutils.IP)) == 0 {
+		logrus.Infof("No non-localhost DNS nameservers are left in resolv.conf. Using default external servers : %v", defaultIPv4Dns)
+		dns := defaultIPv4Dns
+		if ipv6Enabled {
+			logrus.Infof("IPv6 enabled; Adding default IPv6 external servers : %v", defaultIPv6Dns)
+			dns = append(dns, defaultIPv6Dns...)
+		}
+		cleanedResolvConf = append(cleanedResolvConf, []byte("\n"+strings.Join(dns, "\n"))...)
+	}
+	hash, err := ioutils.HashData(bytes.NewReader(cleanedResolvConf))
+	if err != nil {
+		return nil, err
+	}
+	return &File{Content: cleanedResolvConf, Hash: hash}, nil
+}
+
+// getLines parses input into lines and strips away comments.
+func getLines(input []byte, commentMarker []byte) [][]byte {
+	lines := bytes.Split(input, []byte("\n"))
+	var output [][]byte
+	for _, currentLine := range lines {
+		var commentIndex = bytes.Index(currentLine, commentMarker)
+		if commentIndex == -1 {
+			output = append(output, currentLine)
+		} else {
+			output = append(output, currentLine[:commentIndex])
+		}
+	}
+	return output
+}
+
+// GetNameservers returns nameservers (if any) listed in /etc/resolv.conf
+func GetNameservers(resolvConf []byte, kind int) []string {
+	nameservers := []string{}
+	for _, line := range getLines(resolvConf, []byte("#")) {
+		var ns [][]byte
+		if kind == netutils.IP {
+			ns = nsRegexp.FindSubmatch(line)
+		} else if kind == netutils.IPv4 {
+			ns = nsIPv4Regexpmatch.FindSubmatch(line)
+		} else if kind == netutils.IPv6 {
+			ns = nsIPv6Regexpmatch.FindSubmatch(line)
+		}
+		if len(ns) > 0 {
+			nameservers = append(nameservers, string(ns[1]))
+		}
+	}
+	return nameservers
+}
+
+// GetNameserversAsCIDR returns nameservers (if any) listed in
+// /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32")
+// This function's output is intended for net.ParseCIDR
+func GetNameserversAsCIDR(resolvConf []byte) []string {
+	nameservers := []string{}
+	for _, nameserver := range GetNameservers(resolvConf, netutils.IP) {
+		nameservers = append(nameservers, nameserver+"/32")
+	}
+	return nameservers
+}
+
+// GetSearchDomains returns search domains (if any) listed in /etc/resolv.conf
+// If more than one search line is encountered, only the contents of the last
+// one is returned.
+func GetSearchDomains(resolvConf []byte) []string {
+	domains := []string{}
+	for _, line := range getLines(resolvConf, []byte("#")) {
+		match := searchRegexp.FindSubmatch(line)
+		if match == nil {
+			continue
+		}
+		domains = strings.Fields(string(match[1]))
+	}
+	return domains
+}
+
+// GetOptions returns options (if any) listed in /etc/resolv.conf
+// If more than one options line is encountered, only the contents of the last
+// one is returned.
+func GetOptions(resolvConf []byte) []string {
+	options := []string{}
+	for _, line := range getLines(resolvConf, []byte("#")) {
+		match := optionsRegexp.FindSubmatch(line)
+		if match == nil {
+			continue
+		}
+		options = strings.Fields(string(match[1]))
+	}
+	return options
+}
+
+// Build writes a configuration file to path containing a "nameserver" entry
+// for every element in dns, a "search" entry for every element in
+// dnsSearch, and an "options" entry for every element in dnsOptions.
+func Build(path string, dns, dnsSearch, dnsOptions []string) (*File, error) {
+	content := bytes.NewBuffer(nil)
+	if len(dnsSearch) > 0 {
+		if searchString := strings.Join(dnsSearch, " "); strings.Trim(searchString, " ") != "." {
+			if _, err := content.WriteString("search " + searchString + "\n"); err != nil {
+				return nil, err
+			}
+		}
+	}
+	for _, dns := range dns {
+		if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil {
+			return nil, err
+		}
+	}
+	if len(dnsOptions) > 0 {
+		if optsString := strings.Join(dnsOptions, " "); strings.Trim(optsString, " ") != "" {
+			if _, err := content.WriteString("options " + optsString + "\n"); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	hash, err := ioutils.HashData(bytes.NewReader(content.Bytes()))
+	if err != nil {
+		return nil, err
+	}
+
+	return &File{Content: content.Bytes(), Hash: hash}, ioutil.WriteFile(path, content.Bytes(), 0644)
+}

vendor/github.com/docker/libnetwork/types/types.go

@@ -0,0 +1,609 @@
+// Package types contains types that are common across libnetwork project
+package types
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+)
+
+// UUID represents a globally unique ID of various resources like network and endpoint
+type UUID string
+
+// TransportPort represent a local Layer 4 endpoint
+type TransportPort struct {
+	Proto Protocol
+	Port  uint16
+}
+
+// Equal checks if this instance of Transportport is equal to the passed one
+func (t *TransportPort) Equal(o *TransportPort) bool {
+	if t == o {
+		return true
+	}
+
+	if o == nil {
+		return false
+	}
+
+	if t.Proto != o.Proto || t.Port != o.Port {
+		return false
+	}
+
+	return true
+}
+
+// GetCopy returns a copy of this TransportPort structure instance
+func (t *TransportPort) GetCopy() TransportPort {
+	return TransportPort{Proto: t.Proto, Port: t.Port}
+}
+
+// String returns the TransportPort structure in string form
+func (t *TransportPort) String() string {
+	return fmt.Sprintf("%s/%d", t.Proto.String(), t.Port)
+}
+
+// FromString reads the TransportPort structure from string
+func (t *TransportPort) FromString(s string) error {
+	ps := strings.Split(s, "/")
+	if len(ps) == 2 {
+		t.Proto = ParseProtocol(ps[0])
+		if p, err := strconv.ParseUint(ps[1], 10, 16); err == nil {
+			t.Port = uint16(p)
+			return nil
+		}
+	}
+	return BadRequestErrorf("invalid format for transport port: %s", s)
+}
+
+// PortBinding represent a port binding between the container and the host
+type PortBinding struct {
+	Proto       Protocol
+	IP          net.IP
+	Port        uint16
+	HostIP      net.IP
+	HostPort    uint16
+	HostPortEnd uint16
+}
+
+// HostAddr returns the host side transport address
+func (p PortBinding) HostAddr() (net.Addr, error) {
+	switch p.Proto {
+	case UDP:
+		return &net.UDPAddr{IP: p.HostIP, Port: int(p.HostPort)}, nil
+	case TCP:
+		return &net.TCPAddr{IP: p.HostIP, Port: int(p.HostPort)}, nil
+	default:
+		return nil, ErrInvalidProtocolBinding(p.Proto.String())
+	}
+}
+
+// ContainerAddr returns the container side transport address
+func (p PortBinding) ContainerAddr() (net.Addr, error) {
+	switch p.Proto {
+	case UDP:
+		return &net.UDPAddr{IP: p.IP, Port: int(p.Port)}, nil
+	case TCP:
+		return &net.TCPAddr{IP: p.IP, Port: int(p.Port)}, nil
+	default:
+		return nil, ErrInvalidProtocolBinding(p.Proto.String())
+	}
+}
+
+// GetCopy returns a copy of this PortBinding structure instance
+func (p *PortBinding) GetCopy() PortBinding {
+	return PortBinding{
+		Proto:       p.Proto,
+		IP:          GetIPCopy(p.IP),
+		Port:        p.Port,
+		HostIP:      GetIPCopy(p.HostIP),
+		HostPort:    p.HostPort,
+		HostPortEnd: p.HostPortEnd,
+	}
+}
+
+// String return the PortBinding structure in string form
+func (p *PortBinding) String() string {
+	ret := fmt.Sprintf("%s/", p.Proto)
+	if p.IP != nil {
+		ret = fmt.Sprintf("%s%s", ret, p.IP.String())
+	}
+	ret = fmt.Sprintf("%s:%d/", ret, p.Port)
+	if p.HostIP != nil {
+		ret = fmt.Sprintf("%s%s", ret, p.HostIP.String())
+	}
+	ret = fmt.Sprintf("%s:%d", ret, p.HostPort)
+	return ret
+}
+
+// FromString reads the TransportPort structure from string
+func (p *PortBinding) FromString(s string) error {
+	ps := strings.Split(s, "/")
+	if len(ps) != 3 {
+		return BadRequestErrorf("invalid format for port binding: %s", s)
+	}
+
+	p.Proto = ParseProtocol(ps[0])
+
+	var err error
+	if p.IP, p.Port, err = parseIPPort(ps[1]); err != nil {
+		return BadRequestErrorf("failed to parse Container IP/Port in port binding: %s", err.Error())
+	}
+
+	if p.HostIP, p.HostPort, err = parseIPPort(ps[2]); err != nil {
+		return BadRequestErrorf("failed to parse Host IP/Port in port binding: %s", err.Error())
+	}
+
+	return nil
+}
+
+func parseIPPort(s string) (net.IP, uint16, error) {
+	pp := strings.Split(s, ":")
+	if len(pp) != 2 {
+		return nil, 0, BadRequestErrorf("invalid format: %s", s)
+	}
+
+	var ip net.IP
+	if pp[0] != "" {
+		if ip = net.ParseIP(pp[0]); ip == nil {
+			return nil, 0, BadRequestErrorf("invalid ip: %s", pp[0])
+		}
+	}
+
+	port, err := strconv.ParseUint(pp[1], 10, 16)
+	if err != nil {
+		return nil, 0, BadRequestErrorf("invalid port: %s", pp[1])
+	}
+
+	return ip, uint16(port), nil
+}
+
+// Equal checks if this instance of PortBinding is equal to the passed one
+func (p *PortBinding) Equal(o *PortBinding) bool {
+	if p == o {
+		return true
+	}
+
+	if o == nil {
+		return false
+	}
+
+	if p.Proto != o.Proto || p.Port != o.Port ||
+		p.HostPort != o.HostPort || p.HostPortEnd != o.HostPortEnd {
+		return false
+	}
+
+	if p.IP != nil {
+		if !p.IP.Equal(o.IP) {
+			return false
+		}
+	} else {
+		if o.IP != nil {
+			return false
+		}
+	}
+
+	if p.HostIP != nil {
+		if !p.HostIP.Equal(o.HostIP) {
+			return false
+		}
+	} else {
+		if o.HostIP != nil {
+			return false
+		}
+	}
+
+	return true
+}
+
+// ErrInvalidProtocolBinding is returned when the port binding protocol is not valid.
+type ErrInvalidProtocolBinding string
+
+func (ipb ErrInvalidProtocolBinding) Error() string {
+	return fmt.Sprintf("invalid transport protocol: %s", string(ipb))
+}
+
+const (
+	// ICMP is for the ICMP ip protocol
+	ICMP = 1
+	// TCP is for the TCP ip protocol
+	TCP = 6
+	// UDP is for the UDP ip protocol
+	UDP = 17
+)
+
+// Protocol represents a IP protocol number
+type Protocol uint8
+
+func (p Protocol) String() string {
+	switch p {
+	case ICMP:
+		return "icmp"
+	case TCP:
+		return "tcp"
+	case UDP:
+		return "udp"
+	default:
+		return fmt.Sprintf("%d", p)
+	}
+}
+
+// ParseProtocol returns the respective Protocol type for the passed string
+func ParseProtocol(s string) Protocol {
+	switch strings.ToLower(s) {
+	case "icmp":
+		return ICMP
+	case "udp":
+		return UDP
+	case "tcp":
+		return TCP
+	default:
+		return 0
+	}
+}
+
+// GetMacCopy returns a copy of the passed MAC address
+func GetMacCopy(from net.HardwareAddr) net.HardwareAddr {
+	if from == nil {
+		return nil
+	}
+	to := make(net.HardwareAddr, len(from))
+	copy(to, from)
+	return to
+}
+
+// GetIPCopy returns a copy of the passed IP address
+func GetIPCopy(from net.IP) net.IP {
+	if from == nil {
+		return nil
+	}
+	to := make(net.IP, len(from))
+	copy(to, from)
+	return to
+}
+
+// GetIPNetCopy returns a copy of the passed IP Network
+func GetIPNetCopy(from *net.IPNet) *net.IPNet {
+	if from == nil {
+		return nil
+	}
+	bm := make(net.IPMask, len(from.Mask))
+	copy(bm, from.Mask)
+	return &net.IPNet{IP: GetIPCopy(from.IP), Mask: bm}
+}
+
+// GetIPNetCanonical returns the canonical form for the passed network
+func GetIPNetCanonical(nw *net.IPNet) *net.IPNet {
+	if nw == nil {
+		return nil
+	}
+	c := GetIPNetCopy(nw)
+	c.IP = c.IP.Mask(nw.Mask)
+	return c
+}
+
+// CompareIPNet returns equal if the two IP Networks are equal
+func CompareIPNet(a, b *net.IPNet) bool {
+	if a == b {
+		return true
+	}
+	if a == nil || b == nil {
+		return false
+	}
+	return a.IP.Equal(b.IP) && bytes.Equal(a.Mask, b.Mask)
+}
+
+// GetMinimalIP returns the address in its shortest form
+func GetMinimalIP(ip net.IP) net.IP {
+	if ip != nil && ip.To4() != nil {
+		return ip.To4()
+	}
+	return ip
+}
+
+// GetMinimalIPNet returns a copy of the passed IP Network with congruent ip and mask notation
+func GetMinimalIPNet(nw *net.IPNet) *net.IPNet {
+	if nw == nil {
+		return nil
+	}
+	if len(nw.IP) == 16 && nw.IP.To4() != nil {
+		m := nw.Mask
+		if len(m) == 16 {
+			m = m[12:16]
+		}
+		return &net.IPNet{IP: nw.IP.To4(), Mask: m}
+	}
+	return nw
+}
+
+var v4inV6MaskPrefix = []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}
+
+// compareIPMask checks if the passed ip and mask are semantically compatible.
+// It returns the byte indexes for the address and mask so that caller can
+// do bitwise operations without modifying address representation.
+func compareIPMask(ip net.IP, mask net.IPMask) (is int, ms int, err error) {
+	// Find the effective starting of address and mask
+	if len(ip) == net.IPv6len && ip.To4() != nil {
+		is = 12
+	}
+	if len(ip[is:]) == net.IPv4len && len(mask) == net.IPv6len && bytes.Equal(mask[:12], v4inV6MaskPrefix) {
+		ms = 12
+	}
+	// Check if address and mask are semantically compatible
+	if len(ip[is:]) != len(mask[ms:]) {
+		err = fmt.Errorf("ip and mask are not compatible: (%#v, %#v)", ip, mask)
+	}
+	return
+}
+
+// GetHostPartIP returns the host portion of the ip address identified by the mask.
+// IP address representation is not modified. If address and mask are not compatible
+// an error is returned.
+func GetHostPartIP(ip net.IP, mask net.IPMask) (net.IP, error) {
+	// Find the effective starting of address and mask
+	is, ms, err := compareIPMask(ip, mask)
+	if err != nil {
+		return nil, fmt.Errorf("cannot compute host portion ip address because %s", err)
+	}
+
+	// Compute host portion
+	out := GetIPCopy(ip)
+	for i := 0; i < len(mask[ms:]); i++ {
+		out[is+i] &= ^mask[ms+i]
+	}
+
+	return out, nil
+}
+
+// GetBroadcastIP returns the broadcast ip address for the passed network (ip and mask).
+// IP address representation is not modified. If address and mask are not compatible
+// an error is returned.
+func GetBroadcastIP(ip net.IP, mask net.IPMask) (net.IP, error) {
+	// Find the effective starting of address and mask
+	is, ms, err := compareIPMask(ip, mask)
+	if err != nil {
+		return nil, fmt.Errorf("cannot compute broadcast ip address because %s", err)
+	}
+
+	// Compute broadcast address
+	out := GetIPCopy(ip)
+	for i := 0; i < len(mask[ms:]); i++ {
+		out[is+i] |= ^mask[ms+i]
+	}
+
+	return out, nil
+}
+
+// ParseCIDR returns the *net.IPNet represented by the passed CIDR notation
+func ParseCIDR(cidr string) (n *net.IPNet, e error) {
+	var i net.IP
+	if i, n, e = net.ParseCIDR(cidr); e == nil {
+		n.IP = i
+	}
+	return
+}
+
+const (
+	// NEXTHOP indicates a StaticRoute with an IP next hop.
+	NEXTHOP = iota
+
+	// CONNECTED indicates a StaticRoute with an interface for directly connected peers.
+	CONNECTED
+)
+
+// StaticRoute is a statically-provisioned IP route.
+type StaticRoute struct {
+	Destination *net.IPNet
+
+	RouteType int // NEXT_HOP or CONNECTED
+
+	// NextHop will be resolved by the kernel (i.e. as a loose hop).
+	NextHop net.IP
+}
+
+// GetCopy returns a copy of this StaticRoute structure
+func (r *StaticRoute) GetCopy() *StaticRoute {
+	d := GetIPNetCopy(r.Destination)
+	nh := GetIPCopy(r.NextHop)
+	return &StaticRoute{Destination: d,
+		RouteType: r.RouteType,
+		NextHop:   nh,
+	}
+}
+
+// InterfaceStatistics represents the interface's statistics
+type InterfaceStatistics struct {
+	RxBytes   uint64
+	RxPackets uint64
+	RxErrors  uint64
+	RxDropped uint64
+	TxBytes   uint64
+	TxPackets uint64
+	TxErrors  uint64
+	TxDropped uint64
+}
+
+func (is *InterfaceStatistics) String() string {
+	return fmt.Sprintf("\nRxBytes: %d, RxPackets: %d, RxErrors: %d, RxDropped: %d, TxBytes: %d, TxPackets: %d, TxErrors: %d, TxDropped: %d",
+		is.RxBytes, is.RxPackets, is.RxErrors, is.RxDropped, is.TxBytes, is.TxPackets, is.TxErrors, is.TxDropped)
+}
+
+/******************************
+ * Well-known Error Interfaces
+ ******************************/
+
+// MaskableError is an interface for errors which can be ignored by caller
+type MaskableError interface {
+	// Maskable makes implementer into MaskableError type
+	Maskable()
+}
+
+// RetryError is an interface for errors which might get resolved through retry
+type RetryError interface {
+	// Retry makes implementer into RetryError type
+	Retry()
+}
+
+// BadRequestError is an interface for errors originated by a bad request
+type BadRequestError interface {
+	// BadRequest makes implementer into BadRequestError type
+	BadRequest()
+}
+
+// NotFoundError is an interface for errors raised because a needed resource is not available
+type NotFoundError interface {
+	// NotFound makes implementer into NotFoundError type
+	NotFound()
+}
+
+// ForbiddenError is an interface for errors which denote a valid request that cannot be honored
+type ForbiddenError interface {
+	// Forbidden makes implementer into ForbiddenError type
+	Forbidden()
+}
+
+// NoServiceError is an interface for errors returned when the required service is not available
+type NoServiceError interface {
+	// NoService makes implementer into NoServiceError type
+	NoService()
+}
+
+// TimeoutError is an interface for errors raised because of timeout
+type TimeoutError interface {
+	// Timeout makes implementer into TimeoutError type
+	Timeout()
+}
+
+// NotImplementedError is an interface for errors raised because of requested functionality is not yet implemented
+type NotImplementedError interface {
+	// NotImplemented makes implementer into NotImplementedError type
+	NotImplemented()
+}
+
+// InternalError is an interface for errors raised because of an internal error
+type InternalError interface {
+	// Internal makes implementer into InternalError type
+	Internal()
+}
+
+/******************************
+ * Well-known Error Formatters
+ ******************************/
+
+// BadRequestErrorf creates an instance of BadRequestError
+func BadRequestErrorf(format string, params ...interface{}) error {
+	return badRequest(fmt.Sprintf(format, params...))
+}
+
+// NotFoundErrorf creates an instance of NotFoundError
+func NotFoundErrorf(format string, params ...interface{}) error {
+	return notFound(fmt.Sprintf(format, params...))
+}
+
+// ForbiddenErrorf creates an instance of ForbiddenError
+func ForbiddenErrorf(format string, params ...interface{}) error {
+	return forbidden(fmt.Sprintf(format, params...))
+}
+
+// NoServiceErrorf creates an instance of NoServiceError
+func NoServiceErrorf(format string, params ...interface{}) error {
+	return noService(fmt.Sprintf(format, params...))
+}
+
+// NotImplementedErrorf creates an instance of NotImplementedError
+func NotImplementedErrorf(format string, params ...interface{}) error {
+	return notImpl(fmt.Sprintf(format, params...))
+}
+
+// TimeoutErrorf creates an instance of TimeoutError
+func TimeoutErrorf(format string, params ...interface{}) error {
+	return timeout(fmt.Sprintf(format, params...))
+}
+
+// InternalErrorf creates an instance of InternalError
+func InternalErrorf(format string, params ...interface{}) error {
+	return internal(fmt.Sprintf(format, params...))
+}
+
+// InternalMaskableErrorf creates an instance of InternalError and MaskableError
+func InternalMaskableErrorf(format string, params ...interface{}) error {
+	return maskInternal(fmt.Sprintf(format, params...))
+}
+
+// RetryErrorf creates an instance of RetryError
+func RetryErrorf(format string, params ...interface{}) error {
+	return retry(fmt.Sprintf(format, params...))
+}
+
+/***********************
+ * Internal Error Types
+ ***********************/
+type badRequest string
+
+func (br badRequest) Error() string {
+	return string(br)
+}
+func (br badRequest) BadRequest() {}
+
+type maskBadRequest string
+
+type notFound string
+
+func (nf notFound) Error() string {
+	return string(nf)
+}
+func (nf notFound) NotFound() {}
+
+type forbidden string
+
+func (frb forbidden) Error() string {
+	return string(frb)
+}
+func (frb forbidden) Forbidden() {}
+
+type noService string
+
+func (ns noService) Error() string {
+	return string(ns)
+}
+func (ns noService) NoService() {}
+
+type maskNoService string
+
+type timeout string
+
+func (to timeout) Error() string {
+	return string(to)
+}
+func (to timeout) Timeout() {}
+
+type notImpl string
+
+func (ni notImpl) Error() string {
+	return string(ni)
+}
+func (ni notImpl) NotImplemented() {}
+
+type internal string
+
+func (nt internal) Error() string {
+	return string(nt)
+}
+func (nt internal) Internal() {}
+
+type maskInternal string
+
+func (mnt maskInternal) Error() string {
+	return string(mnt)
+}
+func (mnt maskInternal) Internal() {}
+func (mnt maskInternal) Maskable() {}
+
+type retry string
+
+func (r retry) Error() string {
+	return string(r)
+}
+func (r retry) Retry() {}