diff --git a/dns/dnsmessage/message.go b/dns/dnsmessage/message.go index 624f9b69f..0ab4aab20 100644 --- a/dns/dnsmessage/message.go +++ b/dns/dnsmessage/message.go @@ -90,6 +90,7 @@ var ( errTooManyAuthorities = errors.New("too many Authorities to pack (>65535)") errTooManyAdditionals = errors.New("too many Additionals to pack (>65535)") errNonCanonicalName = errors.New("name is not in canonical format (it must end with a .)") + errStringTooLong = errors.New("character string exceeds maximum length (255)") ) // Internal constants. @@ -218,6 +219,7 @@ func (h *header) count(sec section) uint16 { return 0 } +// pack appends the wire format of the header to msg. func (h *header) pack(msg []byte) []byte { msg = packUint16(msg, h.id) msg = packUint16(msg, h.bits) @@ -280,6 +282,7 @@ type ResourceBody interface { realType() Type } +// pack appends the wire format of the Resource to msg. func (r *Resource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { if r.Body == nil { return msg, errNilResouceBody @@ -1311,9 +1314,10 @@ type ResourceHeader struct { Length uint16 } -// pack packs all of the fields in a ResourceHeader except for the length. The -// length bytes are returned as a slice so they can be filled in after the rest -// of the Resource has been packed. +// pack appends the wire format of the ResourceHeader to oldMsg. +// +// The bytes where length was packed are returned as a slice so they can be +// updated after the rest of the Resource has been packed. func (h *ResourceHeader) pack(oldMsg []byte, compression map[string]int, compressionOff int) (msg []byte, length []byte, err error) { msg = oldMsg if msg, err = h.Name.pack(msg, compression, compressionOff); err != nil { @@ -1385,6 +1389,7 @@ func skipResource(msg []byte, off int) (int, error) { return newOff, nil } +// packUint16 appends the wire format of field to msg. func packUint16(msg []byte, field uint16) []byte { return append(msg, byte(field>>8), byte(field)) } @@ -1403,6 +1408,7 @@ func skipUint16(msg []byte, off int) (int, error) { return off + uint16Len, nil } +// packType appends the wire format of field to msg. func packType(msg []byte, field Type) []byte { return packUint16(msg, uint16(field)) } @@ -1416,6 +1422,7 @@ func skipType(msg []byte, off int) (int, error) { return skipUint16(msg, off) } +// packClass appends the wire format of field to msg. func packClass(msg []byte, field Class) []byte { return packUint16(msg, uint16(field)) } @@ -1429,6 +1436,7 @@ func skipClass(msg []byte, off int) (int, error) { return skipUint16(msg, off) } +// packUint32 appends the wire format of field to msg. func packUint32(msg []byte, field uint32) []byte { return append( msg, @@ -1454,17 +1462,16 @@ func skipUint32(msg []byte, off int) (int, error) { return off + uint32Len, nil } -func packText(msg []byte, field string) []byte { - for len(field) > 0 { - l := len(field) - if l > 255 { - l = 255 - } - msg = append(msg, byte(l)) - msg = append(msg, field[:l]...) - field = field[l:] +// packText appends the wire format of field to msg. +func packText(msg []byte, field string) ([]byte, error) { + l := len(field) + if l > 255 { + return nil, errStringTooLong } - return msg + msg = append(msg, byte(l)) + msg = append(msg, field...) + + return msg, nil } func unpackText(msg []byte, off int) (string, int, error) { @@ -1490,6 +1497,7 @@ func skipText(msg []byte, off int) (int, error) { return endOff, nil } +// packBytes appends the wire format of field to msg. func packBytes(msg []byte, field []byte) []byte { return append(msg, field...) } @@ -1534,7 +1542,7 @@ func (n Name) String() string { return string(n.Data[:n.Length]) } -// pack packs a domain name. +// pack appends the wire format of the Name to msg. // // Domain names are a sequence of counted strings split at the dots. They end // with a zero-length string. Compression can be used to reuse domain suffixes. @@ -1716,6 +1724,7 @@ type Question struct { Class Class } +// pack appends the wire format of the Question to msg. func (q *Question) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { msg, err := q.Name.pack(msg, compression, compressionOff) if err != nil { @@ -1796,6 +1805,7 @@ func (r *CNAMEResource) realType() Type { return TypeCNAME } +// pack appends the wire format of the CNAMEResource to msg. func (r *CNAMEResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return r.CNAME.pack(msg, compression, compressionOff) } @@ -1818,6 +1828,7 @@ func (r *MXResource) realType() Type { return TypeMX } +// pack appends the wire format of the MXResource to msg. func (r *MXResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg msg = packUint16(msg, r.Pref) @@ -1849,6 +1860,7 @@ func (r *NSResource) realType() Type { return TypeNS } +// pack appends the wire format of the NSResource to msg. func (r *NSResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return r.NS.pack(msg, compression, compressionOff) } @@ -1870,6 +1882,7 @@ func (r *PTRResource) realType() Type { return TypePTR } +// pack appends the wire format of the PTRResource to msg. func (r *PTRResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return r.PTR.pack(msg, compression, compressionOff) } @@ -1901,6 +1914,7 @@ func (r *SOAResource) realType() Type { return TypeSOA } +// pack appends the wire format of the SOAResource to msg. func (r *SOAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg msg, err := r.NS.pack(msg, compression, compressionOff) @@ -1953,19 +1967,28 @@ func unpackSOAResource(msg []byte, off int) (SOAResource, error) { // A TXTResource is a TXT Resource record. type TXTResource struct { - Txt string // Not a domain name. + TXT []string } func (r *TXTResource) realType() Type { return TypeTXT } +// pack appends the wire format of the TXTResource to msg. func (r *TXTResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { - return packText(msg, r.Txt), nil + oldMsg := msg + for _, s := range r.TXT { + var err error + msg, err = packText(msg, s) + if err != nil { + return oldMsg, err + } + } + return msg, nil } func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) { - var txt string + txts := make([]string, 0, 1) for n := uint16(0); n < length; { var t string var err error @@ -1977,9 +2000,9 @@ func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) return TXTResource{}, errCalcLen } n += uint16(len(t)) + 1 - txt += t + txts = append(txts, t) } - return TXTResource{txt}, nil + return TXTResource{txts}, nil } // An SRVResource is an SRV Resource record. @@ -1994,6 +2017,7 @@ func (r *SRVResource) realType() Type { return TypeSRV } +// pack appends the wire format of the SRVResource to msg. func (r *SRVResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg msg = packUint16(msg, r.Priority) @@ -2035,6 +2059,7 @@ func (r *AResource) realType() Type { return TypeA } +// pack appends the wire format of the AResource to msg. func (r *AResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return packBytes(msg, r.A[:]), nil } @@ -2056,6 +2081,7 @@ func (r *AAAAResource) realType() Type { return TypeAAAA } +// pack appends the wire format of the AAAAResource to msg. func (r *AAAAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return packBytes(msg, r.AAAA[:]), nil } diff --git a/dns/dnsmessage/message_test.go b/dns/dnsmessage/message_test.go index d4eca26f1..c143d7e79 100644 --- a/dns/dnsmessage/message_test.go +++ b/dns/dnsmessage/message_test.go @@ -8,6 +8,7 @@ import ( "bytes" "fmt" "reflect" + "strings" "testing" ) @@ -444,7 +445,15 @@ func TestVeryLongTxt(t *testing.T) { Type: TypeTXT, Class: ClassINET, }, - &TXTResource{loremIpsum}, + &TXTResource{[]string{ + "", + "", + "foo bar", + "", + "www.example.com", + "www.example.com.", + strings.Repeat(".", 255), + }}, } buf, err := want.pack(make([]byte, 0, 8000), map[string]int{}, 0) if err != nil { @@ -468,6 +477,13 @@ func TestVeryLongTxt(t *testing.T) { } } +func TestTooLongTxt(t *testing.T) { + rb := TXTResource{[]string{strings.Repeat(".", 256)}} + if _, err := rb.pack(make([]byte, 0, 8000), map[string]int{}, 0); err != errStringTooLong { + t.Errorf("Packing TXTRecord with 256 character string: got err = %v, want = %v", err, errStringTooLong) + } +} + func TestStartAppends(t *testing.T) { buf := make([]byte, 2, 514) wantBuf := []byte{4, 44} @@ -1084,7 +1100,7 @@ func largeTestMsg() Message { Type: TypeTXT, Class: ClassINET, }, - &TXTResource{"So Long, and Thanks for All the Fish"}, + &TXTResource{[]string{"So Long, and Thanks for All the Fish"}}, }, { ResourceHeader{ @@ -1092,139 +1108,8 @@ func largeTestMsg() Message { Type: TypeTXT, Class: ClassINET, }, - &TXTResource{"Hamster Huey and the Gooey Kablooie"}, + &TXTResource{[]string{"Hamster Huey and the Gooey Kablooie"}}, }, }, } } - -const loremIpsum = ` -Lorem ipsum dolor sit amet, nec enim antiopam id, an ullum choro -nonumes qui, pro eu debet honestatis mediocritatem. No alia enim eos, -magna signiferumque ex vis. Mei no aperiri dissentias, cu vel quas -regione. Malorum quaeque vim ut, eum cu semper aliquid invidunt, ei -nam ipsum assentior. - -Nostrum appellantur usu no, vis ex probatus adipiscing. Cu usu illum -facilis eleifend. Iusto conceptam complectitur vim id. Tale omnesque -no usu, ei oblique sadipscing vim. At nullam voluptua usu, mei laudem -reformidans et. Qui ei eros porro reformidans, ius suas veritus -torquatos ex. Mea te facer alterum consequat. - -Soleat torquatos democritum sed et, no mea congue appareat, facer -aliquam nec in. Has te ipsum tritani. At justo dicta option nec, movet -phaedrum ad nam. Ea detracto verterem liberavisse has, delectus -suscipiantur in mei. Ex nam meliore complectitur. Ut nam omnis -honestatis quaerendum, ea mea nihil affert detracto, ad vix rebum -mollis. - -Ut epicurei praesent neglegentur pri, prima fuisset intellegebat ad -vim. An habemus comprehensam usu, at enim dignissim pro. Eam reque -vivendum adipisci ea. Vel ne odio choro minimum. Sea admodum -dissentiet ex. Mundi tamquam evertitur ius cu. Homero postea iisque ut -pro, vel ne saepe senserit consetetur. - -Nulla utamur facilisis ius ea, in viderer diceret pertinax eum. Mei no -enim quodsi facilisi, ex sed aeterno appareat mediocritatem, eum -sententiae deterruisset ut. At suas timeam euismod cum, offendit -appareat interpretaris ne vix. Vel ea civibus albucius, ex vim quidam -accusata intellegebat, noluisse instructior sea id. Nec te nonumes -habemus appellantur, quis dignissim vituperata eu nam. - -At vix apeirian patrioque vituperatoribus, an usu agam assum. Debet -iisque an mea. Per eu dicant ponderum accommodare. Pri alienum -placerat senserit an, ne eum ferri abhorreant vituperatoribus. Ut mea -eligendi disputationi. Ius no tation everti impedit, ei magna quidam -mediocritatem pri. - -Legendos perpetua iracundia ne usu, no ius ullum epicurei intellegam, -ad modus epicuri lucilius eam. In unum quaerendum usu. Ne diam paulo -has, ea veri virtute sed. Alia honestatis conclusionemque mea eu, ut -iudico albucius his. - -Usu essent probatus eu, sed omnis dolor delicatissimi ex. No qui augue -dissentias dissentiet. Laudem recteque no usu, vel an velit noluisse, -an sed utinam eirmod appetere. Ne mea fuisset inimicus ocurreret. At -vis dicant abhorreant, utinam forensibus nec ne, mei te docendi -consequat. Brute inermis persecuti cum id. Ut ipsum munere propriae -usu, dicit graeco disputando id has. - -Eros dolore quaerendum nam ei. Timeam ornatus inciderint pro id. Nec -torquatos sadipscing ei, ancillae molestie per in. Malis principes duo -ea, usu liber postulant ei. - -Graece timeam voluptatibus eu eam. Alia probatus quo no, ea scripta -feugiat duo. Congue option meliore ex qui, noster invenire appellantur -ea vel. Eu exerci legendos vel. Consetetur repudiandae vim ut. Vix an -probo minimum, et nam illud falli tempor. - -Cum dico signiferumque eu. Sed ut regione maiorum, id veritus insolens -tacimates vix. Eu mel sint tamquam lucilius, duo no oporteat -tacimates. Atqui augue concludaturque vix ei, id mel utroque menandri. - -Ad oratio blandit aliquando pro. Vis et dolorum rationibus -philosophia, ad cum nulla molestie. Hinc fuisset adversarium eum et, -ne qui nisl verear saperet, vel te quaestio forensibus. Per odio -option delenit an. Alii placerat has no, in pri nihil platonem -cotidieque. Est ut elit copiosae scaevola, debet tollit maluisset sea -an. - -Te sea hinc debet pericula, liber ridens fabulas cu sed, quem mutat -accusam mea et. Elitr labitur albucius et pri, an labore feugait mel. -Velit zril melius usu ea. Ad stet putent interpretaris qui. Mel no -error volumus scripserit. In pro paulo iudico, quo ei dolorem -verterem, affert fabellas dissentiet ea vix. - -Vis quot deserunt te. Error aliquid detraxit eu usu, vis alia eruditi -salutatus cu. Est nostrud bonorum an, ei usu alii salutatus. Vel at -nisl primis, eum ex aperiri noluisse reformidans. Ad veri velit -utroque vis, ex equidem detraxit temporibus has. - -Inermis appareat usu ne. Eros placerat periculis mea ad, in dictas -pericula pro. Errem postulant at usu, ea nec amet ornatus mentitum. Ad -mazim graeco eum, vel ex percipit volutpat iudicabit, sit ne delicata -interesset. Mel sapientem prodesset abhorreant et, oblique suscipit -eam id. - -An maluisset disputando mea, vidit mnesarchum pri et. Malis insolens -inciderint no sea. Ea persius maluisset vix, ne vim appellantur -instructior, consul quidam definiebas pri id. Cum integre feugiat -pericula in, ex sed persius similique, mel ne natum dicit percipitur. - -Primis discere ne pri, errem putent definitionem at vis. Ei mel dolore -neglegentur, mei tincidunt percipitur ei. Pro ad simul integre -rationibus. Eu vel alii honestatis definitiones, mea no nonumy -reprehendunt. - -Dicta appareat legendos est cu. Eu vel congue dicunt omittam, no vix -adhuc minimum constituam, quot noluisse id mel. Eu quot sale mutat -duo, ex nisl munere invenire duo. Ne nec ullum utamur. Pro alterum -debitis nostrum no, ut vel aliquid vivendo. - -Aliquip fierent praesent quo ne, id sit audiam recusabo delicatissimi. -Usu postulant incorrupte cu. At pro dicit tibique intellegam, cibo -dolore impedit id eam, et aeque feugait assentior has. Quando sensibus -nec ex. Possit sensibus pri ad, unum mutat periculis cu vix. - -Mundi tibique vix te, duo simul partiendo qualisque id, est at vidit -sonet tempor. No per solet aeterno deseruisse. Petentium salutandi -definiebas pri cu. Munere vivendum est in. Ei justo congue eligendi -vis, modus offendit omittantur te mel. - -Integre voluptaria in qui, sit habemus tractatos constituam no. Utinam -melius conceptam est ne, quo in minimum apeirian delicata, ut ius -porro recusabo. Dicant expetenda vix no, ludus scripserit sed ex, eu -his modo nostro. Ut etiam sonet his, quodsi inciderint philosophia te -per. Nullam lobortis eu cum, vix an sonet efficiendi repudiandae. Vis -ad idque fabellas intellegebat. - -Eum commodo senserit conclusionemque ex. Sed forensibus sadipscing ut, -mei in facer delicata periculis, sea ne hinc putent cetero. Nec ne -alia corpora invenire, alia prima soleat te cum. Eleifend posidonium -nam at. - -Dolorum indoctum cu quo, ex dolor legendos recteque eam, cu pri zril -discere. Nec civibus officiis dissentiunt ex, est te liber ludus -elaboraret. Cum ea fabellas invenire. Ex vim nostrud eripuit -comprehensam, nam te inermis delectus, saepe inermis senserit. -`