diff options
Diffstat (limited to 'vendor/github.com/docker/distribution/registry/api/v2/headerparser.go')
-rw-r--r-- | vendor/github.com/docker/distribution/registry/api/v2/headerparser.go | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/vendor/github.com/docker/distribution/registry/api/v2/headerparser.go b/vendor/github.com/docker/distribution/registry/api/v2/headerparser.go new file mode 100644 index 000000000..9bc41a3a6 --- /dev/null +++ b/vendor/github.com/docker/distribution/registry/api/v2/headerparser.go @@ -0,0 +1,161 @@ +package v2 + +import ( + "fmt" + "regexp" + "strings" + "unicode" +) + +var ( + // according to rfc7230 + reToken = regexp.MustCompile(`^[^"(),/:;<=>?@[\]{}[:space:][:cntrl:]]+`) + reQuotedValue = regexp.MustCompile(`^[^\\"]+`) + reEscapedCharacter = regexp.MustCompile(`^[[:blank:][:graph:]]`) +) + +// parseForwardedHeader is a benevolent parser of Forwarded header defined in rfc7239. The header contains +// a comma-separated list of forwarding key-value pairs. Each list element is set by single proxy. The +// function parses only the first element of the list, which is set by the very first proxy. It returns a map +// of corresponding key-value pairs and an unparsed slice of the input string. +// +// Examples of Forwarded header values: +// +// 1. Forwarded: For=192.0.2.43; Proto=https,For="[2001:db8:cafe::17]",For=unknown +// 2. Forwarded: for="192.0.2.43:443"; host="registry.example.org", for="10.10.05.40:80" +// +// The first will be parsed into {"for": "192.0.2.43", "proto": "https"} while the second into +// {"for": "192.0.2.43:443", "host": "registry.example.org"}. +func parseForwardedHeader(forwarded string) (map[string]string, string, error) { + // Following are states of forwarded header parser. Any state could transition to a failure. + const ( + // terminating state; can transition to Parameter + stateElement = iota + // terminating state; can transition to KeyValueDelimiter + stateParameter + // can transition to Value + stateKeyValueDelimiter + // can transition to one of { QuotedValue, PairEnd } + stateValue + // can transition to one of { EscapedCharacter, PairEnd } + stateQuotedValue + // can transition to one of { QuotedValue } + stateEscapedCharacter + // terminating state; can transition to one of { Parameter, Element } + statePairEnd + ) + + var ( + parameter string + value string + parse = forwarded[:] + res = map[string]string{} + state = stateElement + ) + +Loop: + for { + // skip spaces unless in quoted value + if state != stateQuotedValue && state != stateEscapedCharacter { + parse = strings.TrimLeftFunc(parse, unicode.IsSpace) + } + + if len(parse) == 0 { + if state != stateElement && state != statePairEnd && state != stateParameter { + return nil, parse, fmt.Errorf("unexpected end of input") + } + // terminating + break + } + + switch state { + // terminate at list element delimiter + case stateElement: + if parse[0] == ',' { + parse = parse[1:] + break Loop + } + state = stateParameter + + // parse parameter (the key of key-value pair) + case stateParameter: + match := reToken.FindString(parse) + if len(match) == 0 { + return nil, parse, fmt.Errorf("failed to parse token at position %d", len(forwarded)-len(parse)) + } + parameter = strings.ToLower(match) + parse = parse[len(match):] + state = stateKeyValueDelimiter + + // parse '=' + case stateKeyValueDelimiter: + if parse[0] != '=' { + return nil, parse, fmt.Errorf("expected '=', not '%c' at position %d", parse[0], len(forwarded)-len(parse)) + } + parse = parse[1:] + state = stateValue + + // parse value or quoted value + case stateValue: + if parse[0] == '"' { + parse = parse[1:] + state = stateQuotedValue + } else { + value = reToken.FindString(parse) + if len(value) == 0 { + return nil, parse, fmt.Errorf("failed to parse value at position %d", len(forwarded)-len(parse)) + } + if _, exists := res[parameter]; exists { + return nil, parse, fmt.Errorf("duplicate parameter %q at position %d", parameter, len(forwarded)-len(parse)) + } + res[parameter] = value + parse = parse[len(value):] + value = "" + state = statePairEnd + } + + // parse a part of quoted value until the first backslash + case stateQuotedValue: + match := reQuotedValue.FindString(parse) + value += match + parse = parse[len(match):] + switch { + case len(parse) == 0: + return nil, parse, fmt.Errorf("unterminated quoted string") + case parse[0] == '"': + res[parameter] = value + value = "" + parse = parse[1:] + state = statePairEnd + case parse[0] == '\\': + parse = parse[1:] + state = stateEscapedCharacter + } + + // parse escaped character in a quoted string, ignore the backslash + // transition back to QuotedValue state + case stateEscapedCharacter: + c := reEscapedCharacter.FindString(parse) + if len(c) == 0 { + return nil, parse, fmt.Errorf("invalid escape sequence at position %d", len(forwarded)-len(parse)-1) + } + value += c + parse = parse[1:] + state = stateQuotedValue + + // expect either a new key-value pair, new list or end of input + case statePairEnd: + switch parse[0] { + case ';': + parse = parse[1:] + state = stateParameter + case ',': + state = stateElement + default: + return nil, parse, fmt.Errorf("expected ',' or ';', not %c at position %d", parse[0], len(forwarded)-len(parse)) + } + } + } + + return res, parse, nil +} |