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Diffstat (limited to 'src/pkg/encoding/asn1/common.go')
| -rw-r--r-- | src/pkg/encoding/asn1/common.go | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/src/pkg/encoding/asn1/common.go b/src/pkg/encoding/asn1/common.go deleted file mode 100644 index 33a117ece..000000000 --- a/src/pkg/encoding/asn1/common.go +++ /dev/null @@ -1,163 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package asn1 - -import ( - "reflect" - "strconv" - "strings" -) - -// ASN.1 objects have metadata preceding them: -// the tag: the type of the object -// a flag denoting if this object is compound or not -// the class type: the namespace of the tag -// the length of the object, in bytes - -// Here are some standard tags and classes - -const ( - tagBoolean = 1 - tagInteger = 2 - tagBitString = 3 - tagOctetString = 4 - tagOID = 6 - tagEnum = 10 - tagUTF8String = 12 - tagSequence = 16 - tagSet = 17 - tagPrintableString = 19 - tagT61String = 20 - tagIA5String = 22 - tagUTCTime = 23 - tagGeneralizedTime = 24 - tagGeneralString = 27 -) - -const ( - classUniversal = 0 - classApplication = 1 - classContextSpecific = 2 - classPrivate = 3 -) - -type tagAndLength struct { - class, tag, length int - isCompound bool -} - -// ASN.1 has IMPLICIT and EXPLICIT tags, which can be translated as "instead -// of" and "in addition to". When not specified, every primitive type has a -// default tag in the UNIVERSAL class. -// -// For example: a BIT STRING is tagged [UNIVERSAL 3] by default (although ASN.1 -// doesn't actually have a UNIVERSAL keyword). However, by saying [IMPLICIT -// CONTEXT-SPECIFIC 42], that means that the tag is replaced by another. -// -// On the other hand, if it said [EXPLICIT CONTEXT-SPECIFIC 10], then an -// /additional/ tag would wrap the default tag. This explicit tag will have the -// compound flag set. -// -// (This is used in order to remove ambiguity with optional elements.) -// -// You can layer EXPLICIT and IMPLICIT tags to an arbitrary depth, however we -// don't support that here. We support a single layer of EXPLICIT or IMPLICIT -// tagging with tag strings on the fields of a structure. - -// fieldParameters is the parsed representation of tag string from a structure field. -type fieldParameters struct { - optional bool // true iff the field is OPTIONAL - explicit bool // true iff an EXPLICIT tag is in use. - application bool // true iff an APPLICATION tag is in use. - defaultValue *int64 // a default value for INTEGER typed fields (maybe nil). - tag *int // the EXPLICIT or IMPLICIT tag (maybe nil). - stringType int // the string tag to use when marshaling. - set bool // true iff this should be encoded as a SET - omitEmpty bool // true iff this should be omitted if empty when marshaling. - - // Invariants: - // if explicit is set, tag is non-nil. -} - -// Given a tag string with the format specified in the package comment, -// parseFieldParameters will parse it into a fieldParameters structure, -// ignoring unknown parts of the string. -func parseFieldParameters(str string) (ret fieldParameters) { - for _, part := range strings.Split(str, ",") { - switch { - case part == "optional": - ret.optional = true - case part == "explicit": - ret.explicit = true - if ret.tag == nil { - ret.tag = new(int) - } - case part == "ia5": - ret.stringType = tagIA5String - case part == "printable": - ret.stringType = tagPrintableString - case part == "utf8": - ret.stringType = tagUTF8String - case strings.HasPrefix(part, "default:"): - i, err := strconv.ParseInt(part[8:], 10, 64) - if err == nil { - ret.defaultValue = new(int64) - *ret.defaultValue = i - } - case strings.HasPrefix(part, "tag:"): - i, err := strconv.Atoi(part[4:]) - if err == nil { - ret.tag = new(int) - *ret.tag = i - } - case part == "set": - ret.set = true - case part == "application": - ret.application = true - if ret.tag == nil { - ret.tag = new(int) - } - case part == "omitempty": - ret.omitEmpty = true - } - } - return -} - -// Given a reflected Go type, getUniversalType returns the default tag number -// and expected compound flag. -func getUniversalType(t reflect.Type) (tagNumber int, isCompound, ok bool) { - switch t { - case objectIdentifierType: - return tagOID, false, true - case bitStringType: - return tagBitString, false, true - case timeType: - return tagUTCTime, false, true - case enumeratedType: - return tagEnum, false, true - case bigIntType: - return tagInteger, false, true - } - switch t.Kind() { - case reflect.Bool: - return tagBoolean, false, true - case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: - return tagInteger, false, true - case reflect.Struct: - return tagSequence, true, true - case reflect.Slice: - if t.Elem().Kind() == reflect.Uint8 { - return tagOctetString, false, true - } - if strings.HasSuffix(t.Name(), "SET") { - return tagSet, true, true - } - return tagSequence, true, true - case reflect.String: - return tagPrintableString, false, true - } - return 0, false, false -} |