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Ignore UTF8 BOM #142

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Ignore UTF8 BOM #142

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6340803
Ignore UTF8 BOM
sgissi Aug 3, 2018
4a59aa9
Error if Unicode BOM is present instead of skipping.
sgissi Aug 6, 2018
139de7f
Move BOM checks to its own function.
sgissi Aug 6, 2018
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32 changes: 32 additions & 0 deletions expfmt/text_parse.go
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,13 @@ type TextParser struct {
// input concurrently, instantiate a separate Parser for each goroutine.
func (p *TextParser) TextToMetricFamilies(in io.Reader) (map[string]*dto.MetricFamily, error) {
p.reset(in)

// Some clients might throw in Unicode BOM chars which is explicitly forbidden.
if bomType := p.hasBOM(); bomType != "" {
p.parseError(bomType + " BOM detected but not supported")
return p.metricFamiliesByName, p.err
}

for nextState := p.startOfLine; nextState != nil; nextState = nextState() {
// Magic happens here...
}
Expand All @@ -118,6 +125,31 @@ func (p *TextParser) TextToMetricFamilies(in io.Reader) (map[string]*dto.MetricF
return p.metricFamiliesByName, p.err
}

func (p *TextParser) hasBOM() string {
maybeBOM, err := p.buf.Peek(4)

// Can't read, no BOM found.
if err != nil {
return ""
}
// UTF-32 BOM.
if len(maybeBOM) == 4 &&
((maybeBOM[0] == 0x00 && maybeBOM[1] == 0x00 && maybeBOM[2] == 0xFE && maybeBOM[3] == 0xFF) ||
(maybeBOM[0] == 0xFF && maybeBOM[1] == 0xFE && maybeBOM[2] == 0x00 && maybeBOM[3] == 0x00)) {
return "UTF-32"
}
// UTF-16 BOM.
if len(maybeBOM) >= 2 && ((maybeBOM[0] == 0xFE && maybeBOM[1] == 0xFF) || (maybeBOM[0] == 0xFF && maybeBOM[1] == 0xFE)) {
return "UTF-16"
}
// UTF-8 BOM.
if len(maybeBOM) >= 3 && maybeBOM[0] == 0xEF && maybeBOM[1] == 0xBB && maybeBOM[2] == 0xBF {
return "UTF-8"
}
// No BOM.
return ""
}

func (p *TextParser) reset(in io.Reader) {
p.metricFamiliesByName = map[string]*dto.MetricFamily{}
if p.buf == nil {
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25 changes: 25 additions & 0 deletions expfmt/text_parse_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -564,6 +564,31 @@ metric_bucket{le="bla"} 3.14
in: "metric{l=\"\xbd\"} 3.14\n",
err: "text format parsing error in line 1: invalid label value \"\\xbd\"",
},
// 20: UTF-8 BOM present.
{
in: "\xef\xbb\xbfafter_utf8_bom 1\n",
err: "text format parsing error in line 0: UTF-8 BOM detected but not supported",
},
// 21: UTF-16 LE BOM present.
{
in: "\xfe\xffafter_utf16le_bom 1\n",
err: "text format parsing error in line 0: UTF-16 BOM detected but not supported",
},
// 22: UTF-16 BE BOM present.
{
in: "\xff\xfeafter_utf16be_bom 1\n",
err: "text format parsing error in line 0: UTF-16 BOM detected but not supported",
},
// 23: UTF-32 LE BOM present.
{
in: "\xff\xfe\x00\x00after_utf32le_bom 1\n",
err: "text format parsing error in line 0: UTF-32 BOM detected but not supported",
},
// 24: UTF-32 BE BOM present.
{
in: "\x00\x00\xfe\xffafter_utf32be_bom 1\n",
err: "text format parsing error in line 0: UTF-32 BOM detected but not supported",
},
}

for i, scenario := range scenarios {
Expand Down