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package endpoints
import (
"fmt"
"regexp"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
)
const (
defaultProtocol = "https"
defaultSigner = "v4"
)
var (
protocolPriority = []string{"https", "http"}
signerPriority = []string{"v4"}
)
// Options provide configuration needed to direct how endpoints are resolved.
type Options struct {
// Disable usage of HTTPS (TLS / SSL)
DisableHTTPS bool
}
// Partitions is a slice of partition
type Partitions []Partition
// ResolveEndpoint resolves a service endpoint for the given region and options.
func (ps Partitions) ResolveEndpoint(region string, opts Options) (aws.Endpoint, error) {
if len(ps) == 0 {
return aws.Endpoint{}, fmt.Errorf("no partitions found")
}
for i := 0; i < len(ps); i++ {
if !ps[i].canResolveEndpoint(region) {
continue
}
return ps[i].ResolveEndpoint(region, opts)
}
// fallback to first partition format to use when resolving the endpoint.
return ps[0].ResolveEndpoint(region, opts)
}
// Partition is an AWS partition description for a service and its' region endpoints.
type Partition struct {
ID string
RegionRegex *regexp.Regexp
PartitionEndpoint string
IsRegionalized bool
Defaults Endpoint
Endpoints Endpoints
}
func (p Partition) canResolveEndpoint(region string) bool {
_, ok := p.Endpoints[region]
return ok || p.RegionRegex.MatchString(region)
}
// ResolveEndpoint resolves and service endpoint for the given region and options.
func (p Partition) ResolveEndpoint(region string, options Options) (resolved aws.Endpoint, err error) {
if len(region) == 0 && len(p.PartitionEndpoint) != 0 {
region = p.PartitionEndpoint
}
e, _ := p.endpointForRegion(region)
return e.resolve(p.ID, region, p.Defaults, options), nil
}
func (p Partition) endpointForRegion(region string) (Endpoint, bool) {
if e, ok := p.Endpoints[region]; ok {
return e, true
}
if !p.IsRegionalized {
return p.Endpoints[p.PartitionEndpoint], region == p.PartitionEndpoint
}
// Unable to find any matching endpoint, return
// blank that will be used for generic endpoint creation.
return Endpoint{}, false
}
// Endpoints is a map of service config regions to endpoints
type Endpoints map[string]Endpoint
// CredentialScope is the credential scope of a region and service
type CredentialScope struct {
Region string
Service string
}
// Endpoint is a service endpoint description
type Endpoint struct {
// True if the endpoint cannot be resolved for this partition/region/service
Unresolveable aws.Ternary
Hostname string
Protocols []string
CredentialScope CredentialScope
SignatureVersions []string `json:"signatureVersions"`
}
func (e Endpoint) resolve(partition, region string, def Endpoint, options Options) aws.Endpoint {
var merged Endpoint
merged.mergeIn(def)
merged.mergeIn(e)
e = merged
var u string
if e.Unresolveable != aws.TrueTernary {
// Only attempt to resolve the endpoint if it can be resolved.
hostname := strings.Replace(e.Hostname, "{region}", region, 1)
scheme := getEndpointScheme(e.Protocols, options.DisableHTTPS)
u = scheme + "://" + hostname
}
signingRegion := e.CredentialScope.Region
if len(signingRegion) == 0 {
signingRegion = region
}
signingName := e.CredentialScope.Service
return aws.Endpoint{
URL: u,
PartitionID: partition,
SigningRegion: signingRegion,
SigningName: signingName,
SigningMethod: getByPriority(e.SignatureVersions, signerPriority, defaultSigner),
}
}
func (e *Endpoint) mergeIn(other Endpoint) {
if other.Unresolveable != aws.UnknownTernary {
e.Unresolveable = other.Unresolveable
}
if len(other.Hostname) > 0 {
e.Hostname = other.Hostname
}
if len(other.Protocols) > 0 {
e.Protocols = other.Protocols
}
if len(other.CredentialScope.Region) > 0 {
e.CredentialScope.Region = other.CredentialScope.Region
}
if len(other.CredentialScope.Service) > 0 {
e.CredentialScope.Service = other.CredentialScope.Service
}
if len(other.SignatureVersions) > 0 {
e.SignatureVersions = other.SignatureVersions
}
}
func getEndpointScheme(protocols []string, disableHTTPS bool) string {
if disableHTTPS {
return "http"
}
return getByPriority(protocols, protocolPriority, defaultProtocol)
}
func getByPriority(s []string, p []string, def string) string {
if len(s) == 0 {
return def
}
for i := 0; i < len(p); i++ {
for j := 0; j < len(s); j++ {
if s[j] == p[i] {
return s[j]
}
}
}
return s[0]
}
|
