frostfs-http-gw/resolver/resolver.go

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package resolver
import (
"context"
"errors"
"fmt"
"sync"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container"
cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/ns"
)
const (
NNSResolver = "nns"
DNSResolver = "dns"
)
// ErrNoResolvers returns when trying to resolve container without any resolver.
var ErrNoResolvers = errors.New("no resolvers")
// FrostFS represents virtual connection to the FrostFS network.
type FrostFS interface {
// SystemDNS reads system DNS network parameters of the FrostFS.
//
// Returns exactly on non-zero value. Returns any error encountered
// which prevented the parameter to be read.
SystemDNS(context.Context) (string, error)
}
type Config struct {
FrostFS FrostFS
RPCAddress string
}
type ContainerResolver struct {
mu sync.RWMutex
resolvers []*Resolver
}
type Resolver struct {
Name string
resolve func(context.Context, string) (*cid.ID, error)
}
func (r *Resolver) SetResolveFunc(fn func(context.Context, string) (*cid.ID, error)) {
r.resolve = fn
}
func (r *Resolver) Resolve(ctx context.Context, name string) (*cid.ID, error) {
return r.resolve(ctx, name)
}
func NewContainerResolver(resolverNames []string, cfg *Config) (*ContainerResolver, error) {
resolvers, err := createResolvers(resolverNames, cfg)
if err != nil {
return nil, err
}
return &ContainerResolver{
resolvers: resolvers,
}, nil
}
func createResolvers(resolverNames []string, cfg *Config) ([]*Resolver, error) {
resolvers := make([]*Resolver, len(resolverNames))
for i, name := range resolverNames {
cnrResolver, err := newResolver(name, cfg)
if err != nil {
return nil, err
}
resolvers[i] = cnrResolver
}
return resolvers, nil
}
func (r *ContainerResolver) Resolve(ctx context.Context, cnrName string) (*cid.ID, error) {
r.mu.RLock()
defer r.mu.RUnlock()
var err error
for _, resolver := range r.resolvers {
cnrID, resolverErr := resolver.Resolve(ctx, cnrName)
if resolverErr != nil {
resolverErr = fmt.Errorf("%s: %w", resolver.Name, resolverErr)
if err == nil {
err = resolverErr
} else {
err = fmt.Errorf("%s: %w", err.Error(), resolverErr)
}
continue
}
return cnrID, nil
}
if err != nil {
return nil, err
}
return nil, ErrNoResolvers
}
func (r *ContainerResolver) UpdateResolvers(resolverNames []string, cfg *Config) error {
r.mu.Lock()
defer r.mu.Unlock()
if r.equals(resolverNames) {
return nil
}
resolvers, err := createResolvers(resolverNames, cfg)
if err != nil {
return err
}
r.resolvers = resolvers
return nil
}
func (r *ContainerResolver) equals(resolverNames []string) bool {
if len(r.resolvers) != len(resolverNames) {
return false
}
for i := 0; i < len(resolverNames); i++ {
if r.resolvers[i].Name != resolverNames[i] {
return false
}
}
return true
}
func newResolver(name string, cfg *Config) (*Resolver, error) {
switch name {
case DNSResolver:
return NewDNSResolver(cfg.FrostFS)
case NNSResolver:
return NewNNSResolver(cfg.RPCAddress)
default:
return nil, fmt.Errorf("unknown resolver: %s", name)
}
}
func NewDNSResolver(frostFS FrostFS) (*Resolver, error) {
if frostFS == nil {
return nil, fmt.Errorf("pool must not be nil for DNS resolver")
}
var dns ns.DNS
resolveFunc := func(ctx context.Context, name string) (*cid.ID, error) {
domain, err := frostFS.SystemDNS(ctx)
if err != nil {
return nil, fmt.Errorf("read system DNS parameter of the FrostFS: %w", err)
}
domain = name + "." + domain
cnrID, err := dns.ResolveContainerName(domain)
if err != nil {
return nil, fmt.Errorf("couldn't resolve container '%s' as '%s': %w", name, domain, err)
}
return &cnrID, nil
}
return &Resolver{
Name: DNSResolver,
resolve: resolveFunc,
}, nil
}
func NewNNSResolver(rpcAddress string) (*Resolver, error) {
var nns ns.NNS
if err := nns.Dial(rpcAddress); err != nil {
return nil, fmt.Errorf("could not dial nns: %w", err)
}
resolveFunc := func(_ context.Context, name string) (*cid.ID, error) {
var d container.Domain
d.SetName(name)
cnrID, err := nns.ResolveContainerDomain(d)
if err != nil {
return nil, fmt.Errorf("couldn't resolve container '%s': %w", name, err)
}
return &cnrID, nil
}
return &Resolver{
Name: NNSResolver,
resolve: resolveFunc,
}, nil
}