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114 lines
3.8 KiB
Go
114 lines
3.8 KiB
Go
/*
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Package namesys implements resolvers and publishers for the IPFS
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naming system (IPNS).
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The core of IPFS is an immutable, content-addressable Merkle graph.
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That works well for many use cases, but doesn't allow you to answer
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questions like "what is Alice's current homepage?". The mutable name
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system allows Alice to publish information like:
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The current homepage for alice.example.com is
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/ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj
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or:
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The current homepage for node
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QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy
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is
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/ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj
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The mutable name system also allows users to resolve those references
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to find the immutable IPFS object currently referenced by a given
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mutable name.
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For command-line bindings to this functionality, see:
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ipfs name
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ipfs dns
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ipfs resolve
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*/
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package namesys
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import (
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"errors"
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"time"
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context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
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ci "github.com/ipfs/go-ipfs/p2p/crypto"
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path "github.com/ipfs/go-ipfs/path"
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)
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const (
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// DefaultDepthLimit is the default depth limit used by Resolve.
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DefaultDepthLimit = 32
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// UnlimitedDepth allows infinite recursion in ResolveN. You
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// probably don't want to use this, but it's here if you absolutely
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// trust resolution to eventually complete and can't put an upper
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// limit on how many steps it will take.
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UnlimitedDepth = 0
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)
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// ErrResolveFailed signals an error when attempting to resolve.
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var ErrResolveFailed = errors.New("could not resolve name.")
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// ErrResolveRecursion signals a recursion-depth limit.
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var ErrResolveRecursion = errors.New(
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"could not resolve name (recursion limit exceeded).")
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// ErrPublishFailed signals an error when attempting to publish.
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var ErrPublishFailed = errors.New("could not publish name.")
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// Namesys represents a cohesive name publishing and resolving system.
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//
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// Publishing a name is the process of establishing a mapping, a key-value
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// pair, according to naming rules and databases.
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//
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// Resolving a name is the process of looking up the value associated with the
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// key (name).
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type NameSystem interface {
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Resolver
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Publisher
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}
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// Resolver is an object capable of resolving names.
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type Resolver interface {
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// Resolve performs a recursive lookup, returning the dereferenced
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// path. For example, if ipfs.io has a DNS TXT record pointing to
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// /ipns/QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy
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// and there is a DHT IPNS entry for
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// QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy
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// -> /ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj
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// then
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// Resolve(ctx, "/ipns/ipfs.io")
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// will resolve both names, returning
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// /ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj
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//
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// There is a default depth-limit to avoid infinite recursion. Most
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// users will be fine with this default limit, but if you need to
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// adjust the limit you can use ResolveN.
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Resolve(ctx context.Context, name string) (value path.Path, err error)
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// ResolveN performs a recursive lookup, returning the dereferenced
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// path. The only difference from Resolve is that the depth limit
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// is configurable. You can use DefaultDepthLimit, UnlimitedDepth,
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// or a depth limit of your own choosing.
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//
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// Most users should use Resolve, since the default limit works well
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// in most real-world situations.
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ResolveN(ctx context.Context, name string, depth int) (value path.Path, err error)
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}
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// Publisher is an object capable of publishing particular names.
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type Publisher interface {
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// Publish establishes a name-value mapping.
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// TODO make this not PrivKey specific.
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Publish(ctx context.Context, name ci.PrivKey, value path.Path) error
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// TODO: to be replaced by a more generic 'PublishWithValidity' type
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// call once the records spec is implemented
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PublishWithEOL(ctx context.Context, name ci.PrivKey, value path.Path, eol time.Time) error
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}
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