Fix string field value escaping

Commas and quotes could get escaped and parsed incorrectly if they
were both present in a string value.

Fixes #3013

tsdb/points.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"hash/fnv"
 	"math"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -55,6 +56,9 @@ type point struct {
 	data []byte
 }
 
+// Compile the regex that detects unquoted double quote sequences
+var quoteReplacer = regexp.MustCompile(`([^\\])"`)
+
 var escapeCodes = map[byte][]byte{
 	',': []byte(`\,`),
 	'"': []byte(`\"`),
@@ -604,7 +608,8 @@ func scanFieldValue(buf []byte, i int) (int, []byte) {
 			break
 		}
 
-		if buf[i] == '"' {
+		// If we see a double quote, makes sure it is not escaped
+		if buf[i] == '"' && buf[i-1] != '\\' {
 			i += 1
 			quoted = !quoted
 			continue
@@ -651,6 +656,21 @@ func unescapeString(in string) string {
 	return in
 }
 
+// escapeQuoteString returns a copy of in with any double quotes that
+// have not been escaped with escaped quotes
+func escapeQuoteString(in string) string {
+	if strings.IndexAny(in, `"`) == -1 {
+		return in
+	}
+	return quoteReplacer.ReplaceAllString(in, `$1\"`)
+}
+
+// unescapeQuoteString returns a copy of in with any escaped double-quotes
+// with unescaped double quotes
+func unescapeQuoteString(in string) string {
+	return strings.Replace(in, `\"`, `"`, -1)
+}
+
 // NewPoint returns a new point with the given measurement name, tags, fiels and timestamp
 func NewPoint(name string, tags Tags, fields Fields, time time.Time) Point {
 	return &point{
@@ -895,7 +915,7 @@ func newFieldsFromBinary(buf []byte) Fields {
 
 		// If the first char is a double-quote, then unmarshal as string
 		if valueBuf[0] == '"' {
-			value = unescapeString(string(valueBuf[1 : len(valueBuf)-1]))
+			value = unescapeQuoteString(string(valueBuf[1 : len(valueBuf)-1]))
 			// Check for numeric characters
 		} else if (valueBuf[0] >= '0' && valueBuf[0] <= '9') || valueBuf[0] == '-' || valueBuf[0] == '.' {
 			value, err = parseNumber(valueBuf)
@@ -955,7 +975,7 @@ func (p Fields) MarshalBinary() []byte {
 			b = append(b, t...)
 		case string:
 			b = append(b, '"')
-			b = append(b, []byte(t)...)
+			b = append(b, []byte(escapeQuoteString(t))...)
 			b = append(b, '"')
 		case nil:
 			// skip

tsdb/points_test.go

@@ -453,7 +453,7 @@ func TestParsePointWithStringWithCommas(t *testing.T) {
 			},
 			Fields{
 				"value": 1.0,
-				"str":   "foo,bar", // commas in string value
+				"str":   `foo\,bar`, // commas in string value
 			},
 			time.Unix(1, 0)),
 	)
@@ -475,6 +475,37 @@ func TestParsePointWithStringWithCommas(t *testing.T) {
 
 }
 
+func TestParsePointEscapedStringsAndCommas(t *testing.T) {
+	// non-escaped comma and quotes
+	test(t, `cpu,host=serverA,region=us-east value="{Hello\"{,}\" World}" 1000000000`,
+		NewPoint(
+			"cpu",
+			Tags{
+				"host":   "serverA",
+				"region": "us-east",
+			},
+			Fields{
+				"value": `{Hello"{,}" World}`,
+			},
+			time.Unix(1, 0)),
+	)
+
+	// escaped comma and quotes
+	test(t, `cpu,host=serverA,region=us-east value="{Hello\"{\,}\" World}" 1000000000`,
+		NewPoint(
+			"cpu",
+			Tags{
+				"host":   "serverA",
+				"region": "us-east",
+			},
+			Fields{
+				"value": `{Hello"{\,}" World}`,
+			},
+			time.Unix(1, 0)),
+	)
+
+}
+
 func TestParsePointWithStringWithEquals(t *testing.T) {
 	test(t, `cpu,host=serverA,region=us-east str="foo=bar",value=1.0, 1000000000`,
 		NewPoint(