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| 1 | +package namesys |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "errors" |
| 6 | + "time" |
| 7 | + |
| 8 | + "github.com/ipfs/boxo/path" |
| 9 | + logging "github.com/ipfs/go-log/v2" |
| 10 | + ci "github.com/libp2p/go-libp2p/core/crypto" |
| 11 | +) |
| 12 | + |
| 13 | +var log = logging.Logger("namesys") |
| 14 | + |
| 15 | +var ( |
| 16 | + // ErrResolveFailed signals an error when attempting to resolve. |
| 17 | + ErrResolveFailed = errors.New("could not resolve name") |
| 18 | + |
| 19 | + // ErrResolveRecursion signals a recursion-depth limit. |
| 20 | + ErrResolveRecursion = errors.New("could not resolve name (recursion limit exceeded)") |
| 21 | +) |
| 22 | + |
| 23 | +const ( |
| 24 | + // DefaultDepthLimit is the default depth limit used by [Resolver]. |
| 25 | + DefaultDepthLimit = 32 |
| 26 | + |
| 27 | + // UnlimitedDepth allows infinite recursion in [Resolver]. You probably don't want |
| 28 | + // to use this, but it's here if you absolutely trust resolution to eventually |
| 29 | + // complete and can't put an upper limit on how many steps it will take. |
| 30 | + UnlimitedDepth = 0 |
| 31 | + |
| 32 | + // DefaultIPNSRecordTTL specifies the time that the record can be cached before |
| 33 | + // checking if its validity again. |
| 34 | + DefaultIPNSRecordTTL = time.Minute |
| 35 | + |
| 36 | + // DefaultIPNSRecordEOL specifies the time that the network will cache IPNS |
| 37 | + // records after being published. Records should be re-published before this |
| 38 | + // interval expires. We use the same default expiration as the DHT. |
| 39 | + DefaultIPNSRecordEOL = 48 * time.Hour |
| 40 | + |
| 41 | + // DefaultResolverCacheTTL defines max TTL of a record placed in [NameSystem] cache. |
| 42 | + DefaultResolverCacheTTL = time.Minute |
| 43 | +) |
| 44 | + |
| 45 | +// NameSystem represents a cohesive name publishing and resolving system. |
| 46 | +// |
| 47 | +// Publishing a name is the process of establishing a mapping, a key-value |
| 48 | +// pair, according to naming rules and databases. |
| 49 | +// |
| 50 | +// Resolving a name is the process of looking up the value associated with the |
| 51 | +// key (name). |
| 52 | +type NameSystem interface { |
| 53 | + Resolver |
| 54 | + Publisher |
| 55 | +} |
| 56 | + |
| 57 | +// ResolveResult is the return type for [Resolver.ResolveAsync]. |
| 58 | +type ResolveResult struct { |
| 59 | + Path path.Path |
| 60 | + TTL time.Duration |
| 61 | + Err error |
| 62 | +} |
| 63 | + |
| 64 | +// Resolver is an object capable of resolving names. |
| 65 | +type Resolver interface { |
| 66 | + // Resolve performs a recursive lookup, returning the dereferenced path. For example, |
| 67 | + // if example.com has a DNS TXT record pointing to: |
| 68 | + // |
| 69 | + // /ipns/QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy |
| 70 | + // |
| 71 | + // and there is a DHT IPNS entry for |
| 72 | + // |
| 73 | + // QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy |
| 74 | + // -> /ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj |
| 75 | + // |
| 76 | + // then |
| 77 | + // |
| 78 | + // Resolve(ctx, "/ipns/ipfs.io") |
| 79 | + // |
| 80 | + // will resolve both names, returning |
| 81 | + // |
| 82 | + // /ipfs/Qmcqtw8FfrVSBaRmbWwHxt3AuySBhJLcvmFYi3Lbc4xnwj |
| 83 | + // |
| 84 | + // There is a default depth-limit to avoid infinite recursion. Most users will be fine with |
| 85 | + // this default limit, but if you need to adjust the limit you can specify it as an option. |
| 86 | + Resolve(ctx context.Context, name string, options ...ResolveOption) (value path.Path, ttl time.Duration, err error) |
| 87 | + |
| 88 | + // ResolveAsync performs recursive name lookup, like Resolve, but it returns entries as |
| 89 | + // they are discovered in the DHT. Each returned result is guaranteed to be "better" |
| 90 | + // (which usually means newer) than the previous one. |
| 91 | + ResolveAsync(ctx context.Context, name string, options ...ResolveOption) <-chan ResolveResult |
| 92 | +} |
| 93 | + |
| 94 | +// ResolveOptions specifies options for resolving an IPNS Path. |
| 95 | +type ResolveOptions struct { |
| 96 | + // Depth is the recursion depth limit. |
| 97 | + Depth uint |
| 98 | + |
| 99 | + // DhtRecordCount is the number of IPNS Records to retrieve from the DHT |
| 100 | + // (the best record is selected from this set). |
| 101 | + DhtRecordCount uint |
| 102 | + |
| 103 | + // DhtTimeout is the amount of time to wait for DHT records to be fetched |
| 104 | + // and verified. A zero value indicates that there is no explicit timeout |
| 105 | + // (although there is an implicit timeout due to dial timeouts within the DHT). |
| 106 | + DhtTimeout time.Duration |
| 107 | +} |
| 108 | + |
| 109 | +// DefaultResolveOptions returns the default options for resolving an IPNS Path. |
| 110 | +func DefaultResolveOptions() ResolveOptions { |
| 111 | + return ResolveOptions{ |
| 112 | + Depth: DefaultDepthLimit, |
| 113 | + DhtRecordCount: 16, |
| 114 | + DhtTimeout: time.Minute, |
| 115 | + } |
| 116 | +} |
| 117 | + |
| 118 | +// ResolveOption is used to set a resolve option. |
| 119 | +type ResolveOption func(*ResolveOptions) |
| 120 | + |
| 121 | +// ResolveWithDepth sets [ResolveOptions.Depth]. |
| 122 | +func ResolveWithDepth(depth uint) ResolveOption { |
| 123 | + return func(o *ResolveOptions) { |
| 124 | + o.Depth = depth |
| 125 | + } |
| 126 | +} |
| 127 | + |
| 128 | +// ResolveWithDhtRecordCount sets [ResolveOptions.DhtRecordCount]. |
| 129 | +func ResolveWithDhtRecordCount(count uint) ResolveOption { |
| 130 | + return func(o *ResolveOptions) { |
| 131 | + o.DhtRecordCount = count |
| 132 | + } |
| 133 | +} |
| 134 | + |
| 135 | +// ResolveWithDhtTimeout sets [ResolveOptions.ResolveWithDhtTimeout]. |
| 136 | +func ResolveWithDhtTimeout(timeout time.Duration) ResolveOption { |
| 137 | + return func(o *ResolveOptions) { |
| 138 | + o.DhtTimeout = timeout |
| 139 | + } |
| 140 | +} |
| 141 | + |
| 142 | +// ProcessResolveOptions converts an array of [ResolveOption] into a [ResolveOptions] object. |
| 143 | +func ProcessResolveOptions(opts []ResolveOption) ResolveOptions { |
| 144 | + resolveOptions := DefaultResolveOptions() |
| 145 | + for _, option := range opts { |
| 146 | + option(&resolveOptions) |
| 147 | + } |
| 148 | + return resolveOptions |
| 149 | +} |
| 150 | + |
| 151 | +// Publisher is an object capable of publishing particular names. |
| 152 | +type Publisher interface { |
| 153 | + // Publish establishes a name-value mapping. |
| 154 | + // TODO make this not PrivKey specific. |
| 155 | + Publish(ctx context.Context, name ci.PrivKey, value path.Path, options ...PublishOption) error |
| 156 | +} |
| 157 | + |
| 158 | +// PublishOptions specifies options for publishing an IPNS Record. |
| 159 | +type PublishOptions struct { |
| 160 | + EOL time.Time |
| 161 | + TTL time.Duration |
| 162 | + CompatibleWithV1 bool |
| 163 | +} |
| 164 | + |
| 165 | +// DefaultPublishOptions returns the default options for publishing an IPNS Record. |
| 166 | +func DefaultPublishOptions() PublishOptions { |
| 167 | + return PublishOptions{ |
| 168 | + EOL: time.Now().Add(DefaultIPNSRecordEOL), |
| 169 | + TTL: DefaultIPNSRecordTTL, |
| 170 | + } |
| 171 | +} |
| 172 | + |
| 173 | +// PublishOption is used to set an option for [PublishOptions]. |
| 174 | +type PublishOption func(*PublishOptions) |
| 175 | + |
| 176 | +// PublishWithEOL sets [PublishOptions.EOL]. |
| 177 | +func PublishWithEOL(eol time.Time) PublishOption { |
| 178 | + return func(o *PublishOptions) { |
| 179 | + o.EOL = eol |
| 180 | + } |
| 181 | +} |
| 182 | + |
| 183 | +// PublishWithEOL sets [PublishOptions.TTL]. |
| 184 | +func PublishWithTTL(ttl time.Duration) PublishOption { |
| 185 | + return func(o *PublishOptions) { |
| 186 | + o.TTL = ttl |
| 187 | + } |
| 188 | +} |
| 189 | + |
| 190 | +// PublishCompatibleWithV1 sets [PublishOptions.CompatibleWithV1]. |
| 191 | +func PublishCompatibleWithV1(compatible bool) PublishOption { |
| 192 | + return func(o *PublishOptions) { |
| 193 | + o.CompatibleWithV1 = compatible |
| 194 | + } |
| 195 | +} |
| 196 | + |
| 197 | +// ProcessPublishOptions converts an array of [PublishOption] into a [PublishOptions] object. |
| 198 | +func ProcessPublishOptions(opts []PublishOption) PublishOptions { |
| 199 | + publishOptions := DefaultPublishOptions() |
| 200 | + for _, option := range opts { |
| 201 | + option(&publishOptions) |
| 202 | + } |
| 203 | + return publishOptions |
| 204 | +} |
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