David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame^] | 1 | // Package reference provides a general type to represent any way of referencing images within the registry. |
| 2 | // Its main purpose is to abstract tags and digests (content-addressable hash). |
| 3 | // |
| 4 | // Grammar |
| 5 | // |
| 6 | // reference := name [ ":" tag ] [ "@" digest ] |
| 7 | // name := [domain '/'] path-component ['/' path-component]* |
| 8 | // domain := domain-component ['.' domain-component]* [':' port-number] |
| 9 | // domain-component := /([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])/ |
| 10 | // port-number := /[0-9]+/ |
| 11 | // path-component := alpha-numeric [separator alpha-numeric]* |
| 12 | // alpha-numeric := /[a-z0-9]+/ |
| 13 | // separator := /[_.]|__|[-]*/ |
| 14 | // |
| 15 | // tag := /[\w][\w.-]{0,127}/ |
| 16 | // |
| 17 | // digest := digest-algorithm ":" digest-hex |
| 18 | // digest-algorithm := digest-algorithm-component [ digest-algorithm-separator digest-algorithm-component ]* |
| 19 | // digest-algorithm-separator := /[+.-_]/ |
| 20 | // digest-algorithm-component := /[A-Za-z][A-Za-z0-9]*/ |
| 21 | // digest-hex := /[0-9a-fA-F]{32,}/ ; At least 128 bit digest value |
| 22 | // |
| 23 | // identifier := /[a-f0-9]{64}/ |
| 24 | // short-identifier := /[a-f0-9]{6,64}/ |
| 25 | package reference |
| 26 | |
| 27 | import ( |
| 28 | "errors" |
| 29 | "fmt" |
| 30 | "strings" |
| 31 | |
| 32 | "github.com/opencontainers/go-digest" |
| 33 | ) |
| 34 | |
| 35 | const ( |
| 36 | // NameTotalLengthMax is the maximum total number of characters in a repository name. |
| 37 | NameTotalLengthMax = 255 |
| 38 | ) |
| 39 | |
| 40 | var ( |
| 41 | // ErrReferenceInvalidFormat represents an error while trying to parse a string as a reference. |
| 42 | ErrReferenceInvalidFormat = errors.New("invalid reference format") |
| 43 | |
| 44 | // ErrTagInvalidFormat represents an error while trying to parse a string as a tag. |
| 45 | ErrTagInvalidFormat = errors.New("invalid tag format") |
| 46 | |
| 47 | // ErrDigestInvalidFormat represents an error while trying to parse a string as a tag. |
| 48 | ErrDigestInvalidFormat = errors.New("invalid digest format") |
| 49 | |
| 50 | // ErrNameContainsUppercase is returned for invalid repository names that contain uppercase characters. |
| 51 | ErrNameContainsUppercase = errors.New("repository name must be lowercase") |
| 52 | |
| 53 | // ErrNameEmpty is returned for empty, invalid repository names. |
| 54 | ErrNameEmpty = errors.New("repository name must have at least one component") |
| 55 | |
| 56 | // ErrNameTooLong is returned when a repository name is longer than NameTotalLengthMax. |
| 57 | ErrNameTooLong = fmt.Errorf("repository name must not be more than %v characters", NameTotalLengthMax) |
| 58 | |
| 59 | // ErrNameNotCanonical is returned when a name is not canonical. |
| 60 | ErrNameNotCanonical = errors.New("repository name must be canonical") |
| 61 | ) |
| 62 | |
| 63 | // Reference is an opaque object reference identifier that may include |
| 64 | // modifiers such as a hostname, name, tag, and digest. |
| 65 | type Reference interface { |
| 66 | // String returns the full reference |
| 67 | String() string |
| 68 | } |
| 69 | |
| 70 | // Field provides a wrapper type for resolving correct reference types when |
| 71 | // working with encoding. |
| 72 | type Field struct { |
| 73 | reference Reference |
| 74 | } |
| 75 | |
| 76 | // AsField wraps a reference in a Field for encoding. |
| 77 | func AsField(reference Reference) Field { |
| 78 | return Field{reference} |
| 79 | } |
| 80 | |
| 81 | // Reference unwraps the reference type from the field to |
| 82 | // return the Reference object. This object should be |
| 83 | // of the appropriate type to further check for different |
| 84 | // reference types. |
| 85 | func (f Field) Reference() Reference { |
| 86 | return f.reference |
| 87 | } |
| 88 | |
| 89 | // MarshalText serializes the field to byte text which |
| 90 | // is the string of the reference. |
| 91 | func (f Field) MarshalText() (p []byte, err error) { |
| 92 | return []byte(f.reference.String()), nil |
| 93 | } |
| 94 | |
| 95 | // UnmarshalText parses text bytes by invoking the |
| 96 | // reference parser to ensure the appropriately |
| 97 | // typed reference object is wrapped by field. |
| 98 | func (f *Field) UnmarshalText(p []byte) error { |
| 99 | r, err := Parse(string(p)) |
| 100 | if err != nil { |
| 101 | return err |
| 102 | } |
| 103 | |
| 104 | f.reference = r |
| 105 | return nil |
| 106 | } |
| 107 | |
| 108 | // Named is an object with a full name |
| 109 | type Named interface { |
| 110 | Reference |
| 111 | Name() string |
| 112 | } |
| 113 | |
| 114 | // Tagged is an object which has a tag |
| 115 | type Tagged interface { |
| 116 | Reference |
| 117 | Tag() string |
| 118 | } |
| 119 | |
| 120 | // NamedTagged is an object including a name and tag. |
| 121 | type NamedTagged interface { |
| 122 | Named |
| 123 | Tag() string |
| 124 | } |
| 125 | |
| 126 | // Digested is an object which has a digest |
| 127 | // in which it can be referenced by |
| 128 | type Digested interface { |
| 129 | Reference |
| 130 | Digest() digest.Digest |
| 131 | } |
| 132 | |
| 133 | // Canonical reference is an object with a fully unique |
| 134 | // name including a name with domain and digest |
| 135 | type Canonical interface { |
| 136 | Named |
| 137 | Digest() digest.Digest |
| 138 | } |
| 139 | |
| 140 | // namedRepository is a reference to a repository with a name. |
| 141 | // A namedRepository has both domain and path components. |
| 142 | type namedRepository interface { |
| 143 | Named |
| 144 | Domain() string |
| 145 | Path() string |
| 146 | } |
| 147 | |
| 148 | // Domain returns the domain part of the Named reference |
| 149 | func Domain(named Named) string { |
| 150 | if r, ok := named.(namedRepository); ok { |
| 151 | return r.Domain() |
| 152 | } |
| 153 | domain, _ := splitDomain(named.Name()) |
| 154 | return domain |
| 155 | } |
| 156 | |
| 157 | // Path returns the name without the domain part of the Named reference |
| 158 | func Path(named Named) (name string) { |
| 159 | if r, ok := named.(namedRepository); ok { |
| 160 | return r.Path() |
| 161 | } |
| 162 | _, path := splitDomain(named.Name()) |
| 163 | return path |
| 164 | } |
| 165 | |
| 166 | func splitDomain(name string) (string, string) { |
| 167 | match := anchoredNameRegexp.FindStringSubmatch(name) |
| 168 | if len(match) != 3 { |
| 169 | return "", name |
| 170 | } |
| 171 | return match[1], match[2] |
| 172 | } |
| 173 | |
| 174 | // SplitHostname splits a named reference into a |
| 175 | // hostname and name string. If no valid hostname is |
| 176 | // found, the hostname is empty and the full value |
| 177 | // is returned as name |
| 178 | // DEPRECATED: Use Domain or Path |
| 179 | func SplitHostname(named Named) (string, string) { |
| 180 | if r, ok := named.(namedRepository); ok { |
| 181 | return r.Domain(), r.Path() |
| 182 | } |
| 183 | return splitDomain(named.Name()) |
| 184 | } |
| 185 | |
| 186 | // Parse parses s and returns a syntactically valid Reference. |
| 187 | // If an error was encountered it is returned, along with a nil Reference. |
| 188 | // NOTE: Parse will not handle short digests. |
| 189 | func Parse(s string) (Reference, error) { |
| 190 | matches := ReferenceRegexp.FindStringSubmatch(s) |
| 191 | if matches == nil { |
| 192 | if s == "" { |
| 193 | return nil, ErrNameEmpty |
| 194 | } |
| 195 | if ReferenceRegexp.FindStringSubmatch(strings.ToLower(s)) != nil { |
| 196 | return nil, ErrNameContainsUppercase |
| 197 | } |
| 198 | return nil, ErrReferenceInvalidFormat |
| 199 | } |
| 200 | |
| 201 | if len(matches[1]) > NameTotalLengthMax { |
| 202 | return nil, ErrNameTooLong |
| 203 | } |
| 204 | |
| 205 | var repo repository |
| 206 | |
| 207 | nameMatch := anchoredNameRegexp.FindStringSubmatch(matches[1]) |
| 208 | if nameMatch != nil && len(nameMatch) == 3 { |
| 209 | repo.domain = nameMatch[1] |
| 210 | repo.path = nameMatch[2] |
| 211 | } else { |
| 212 | repo.domain = "" |
| 213 | repo.path = matches[1] |
| 214 | } |
| 215 | |
| 216 | ref := reference{ |
| 217 | namedRepository: repo, |
| 218 | tag: matches[2], |
| 219 | } |
| 220 | if matches[3] != "" { |
| 221 | var err error |
| 222 | ref.digest, err = digest.Parse(matches[3]) |
| 223 | if err != nil { |
| 224 | return nil, err |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | r := getBestReferenceType(ref) |
| 229 | if r == nil { |
| 230 | return nil, ErrNameEmpty |
| 231 | } |
| 232 | |
| 233 | return r, nil |
| 234 | } |
| 235 | |
| 236 | // ParseNamed parses s and returns a syntactically valid reference implementing |
| 237 | // the Named interface. The reference must have a name and be in the canonical |
| 238 | // form, otherwise an error is returned. |
| 239 | // If an error was encountered it is returned, along with a nil Reference. |
| 240 | // NOTE: ParseNamed will not handle short digests. |
| 241 | func ParseNamed(s string) (Named, error) { |
| 242 | named, err := ParseNormalizedNamed(s) |
| 243 | if err != nil { |
| 244 | return nil, err |
| 245 | } |
| 246 | if named.String() != s { |
| 247 | return nil, ErrNameNotCanonical |
| 248 | } |
| 249 | return named, nil |
| 250 | } |
| 251 | |
| 252 | // WithName returns a named object representing the given string. If the input |
| 253 | // is invalid ErrReferenceInvalidFormat will be returned. |
| 254 | func WithName(name string) (Named, error) { |
| 255 | if len(name) > NameTotalLengthMax { |
| 256 | return nil, ErrNameTooLong |
| 257 | } |
| 258 | |
| 259 | match := anchoredNameRegexp.FindStringSubmatch(name) |
| 260 | if match == nil || len(match) != 3 { |
| 261 | return nil, ErrReferenceInvalidFormat |
| 262 | } |
| 263 | return repository{ |
| 264 | domain: match[1], |
| 265 | path: match[2], |
| 266 | }, nil |
| 267 | } |
| 268 | |
| 269 | // WithTag combines the name from "name" and the tag from "tag" to form a |
| 270 | // reference incorporating both the name and the tag. |
| 271 | func WithTag(name Named, tag string) (NamedTagged, error) { |
| 272 | if !anchoredTagRegexp.MatchString(tag) { |
| 273 | return nil, ErrTagInvalidFormat |
| 274 | } |
| 275 | var repo repository |
| 276 | if r, ok := name.(namedRepository); ok { |
| 277 | repo.domain = r.Domain() |
| 278 | repo.path = r.Path() |
| 279 | } else { |
| 280 | repo.path = name.Name() |
| 281 | } |
| 282 | if canonical, ok := name.(Canonical); ok { |
| 283 | return reference{ |
| 284 | namedRepository: repo, |
| 285 | tag: tag, |
| 286 | digest: canonical.Digest(), |
| 287 | }, nil |
| 288 | } |
| 289 | return taggedReference{ |
| 290 | namedRepository: repo, |
| 291 | tag: tag, |
| 292 | }, nil |
| 293 | } |
| 294 | |
| 295 | // WithDigest combines the name from "name" and the digest from "digest" to form |
| 296 | // a reference incorporating both the name and the digest. |
| 297 | func WithDigest(name Named, digest digest.Digest) (Canonical, error) { |
| 298 | if !anchoredDigestRegexp.MatchString(digest.String()) { |
| 299 | return nil, ErrDigestInvalidFormat |
| 300 | } |
| 301 | var repo repository |
| 302 | if r, ok := name.(namedRepository); ok { |
| 303 | repo.domain = r.Domain() |
| 304 | repo.path = r.Path() |
| 305 | } else { |
| 306 | repo.path = name.Name() |
| 307 | } |
| 308 | if tagged, ok := name.(Tagged); ok { |
| 309 | return reference{ |
| 310 | namedRepository: repo, |
| 311 | tag: tagged.Tag(), |
| 312 | digest: digest, |
| 313 | }, nil |
| 314 | } |
| 315 | return canonicalReference{ |
| 316 | namedRepository: repo, |
| 317 | digest: digest, |
| 318 | }, nil |
| 319 | } |
| 320 | |
| 321 | // TrimNamed removes any tag or digest from the named reference. |
| 322 | func TrimNamed(ref Named) Named { |
| 323 | domain, path := SplitHostname(ref) |
| 324 | return repository{ |
| 325 | domain: domain, |
| 326 | path: path, |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | func getBestReferenceType(ref reference) Reference { |
| 331 | if ref.Name() == "" { |
| 332 | // Allow digest only references |
| 333 | if ref.digest != "" { |
| 334 | return digestReference(ref.digest) |
| 335 | } |
| 336 | return nil |
| 337 | } |
| 338 | if ref.tag == "" { |
| 339 | if ref.digest != "" { |
| 340 | return canonicalReference{ |
| 341 | namedRepository: ref.namedRepository, |
| 342 | digest: ref.digest, |
| 343 | } |
| 344 | } |
| 345 | return ref.namedRepository |
| 346 | } |
| 347 | if ref.digest == "" { |
| 348 | return taggedReference{ |
| 349 | namedRepository: ref.namedRepository, |
| 350 | tag: ref.tag, |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | return ref |
| 355 | } |
| 356 | |
| 357 | type reference struct { |
| 358 | namedRepository |
| 359 | tag string |
| 360 | digest digest.Digest |
| 361 | } |
| 362 | |
| 363 | func (r reference) String() string { |
| 364 | return r.Name() + ":" + r.tag + "@" + r.digest.String() |
| 365 | } |
| 366 | |
| 367 | func (r reference) Tag() string { |
| 368 | return r.tag |
| 369 | } |
| 370 | |
| 371 | func (r reference) Digest() digest.Digest { |
| 372 | return r.digest |
| 373 | } |
| 374 | |
| 375 | type repository struct { |
| 376 | domain string |
| 377 | path string |
| 378 | } |
| 379 | |
| 380 | func (r repository) String() string { |
| 381 | return r.Name() |
| 382 | } |
| 383 | |
| 384 | func (r repository) Name() string { |
| 385 | if r.domain == "" { |
| 386 | return r.path |
| 387 | } |
| 388 | return r.domain + "/" + r.path |
| 389 | } |
| 390 | |
| 391 | func (r repository) Domain() string { |
| 392 | return r.domain |
| 393 | } |
| 394 | |
| 395 | func (r repository) Path() string { |
| 396 | return r.path |
| 397 | } |
| 398 | |
| 399 | type digestReference digest.Digest |
| 400 | |
| 401 | func (d digestReference) String() string { |
| 402 | return digest.Digest(d).String() |
| 403 | } |
| 404 | |
| 405 | func (d digestReference) Digest() digest.Digest { |
| 406 | return digest.Digest(d) |
| 407 | } |
| 408 | |
| 409 | type taggedReference struct { |
| 410 | namedRepository |
| 411 | tag string |
| 412 | } |
| 413 | |
| 414 | func (t taggedReference) String() string { |
| 415 | return t.Name() + ":" + t.tag |
| 416 | } |
| 417 | |
| 418 | func (t taggedReference) Tag() string { |
| 419 | return t.tag |
| 420 | } |
| 421 | |
| 422 | type canonicalReference struct { |
| 423 | namedRepository |
| 424 | digest digest.Digest |
| 425 | } |
| 426 | |
| 427 | func (c canonicalReference) String() string { |
| 428 | return c.Name() + "@" + c.digest.String() |
| 429 | } |
| 430 | |
| 431 | func (c canonicalReference) Digest() digest.Digest { |
| 432 | return c.digest |
| 433 | } |