net: simplify internal dtoi and xtoi funcs

Callers pass strings sliced as necessary instead of giving
an offset.

Fixes #16350

Change-Id: I7ba896f6ff09e0fd0094ca6c5af5d9a81622f15e
Reviewed-on: https://go-review.googlesource.com/27206
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/conf.go

@@ -293,7 +293,7 @@ func goDebugNetDNS() (dnsMode string, debugLevel int) {
 			return
 		}
 		if '0' <= s[0] && s[0] <= '9' {
-			debugLevel, _, _ = dtoi(s, 0)
+			debugLevel, _, _ = dtoi(s)
 		} else {
 			dnsMode = s
 		}

src/net/dial.go

@@ -141,7 +141,7 @@ func parseNetwork(ctx context.Context, net string) (afnet string, proto int, err
 	switch afnet {
 	case "ip", "ip4", "ip6":
 		protostr := net[i+1:]
-		proto, i, ok := dtoi(protostr, 0)
+		proto, i, ok := dtoi(protostr)
 		if !ok || i != len(protostr) {
 			proto, err = lookupProtocol(ctx, protostr)
 			if err != nil {

src/net/dnsconfig_unix.go

@@ -91,19 +91,19 @@ func dnsReadConfig(filename string) *dnsConfig {
 			for _, s := range f[1:] {
 				switch {
 				case hasPrefix(s, "ndots:"):
-					n, _, _ := dtoi(s, 6)
+					n, _, _ := dtoi(s[6:])
 					if n < 1 {
 						n = 1
 					}
 					conf.ndots = n
 				case hasPrefix(s, "timeout:"):
-					n, _, _ := dtoi(s, 8)
+					n, _, _ := dtoi(s[8:])
 					if n < 1 {
 						n = 1
 					}
 					conf.timeout = time.Duration(n) * time.Second
 				case hasPrefix(s, "attempts:"):
-					n, _, _ := dtoi(s, 9)
+					n, _, _ := dtoi(s[9:])
 					if n < 1 {
 						n = 1
 					}

src/net/interface.go

@@ -215,7 +215,7 @@ func zoneToInt(zone string) int {
 	defer zoneCache.RUnlock()
 	index, ok := zoneCache.toIndex[zone]
 	if !ok {
-		index, _, _ = dtoi(zone, 0)
+		index, _, _ = dtoi(zone)
 	}
 	return index
 }

src/net/ip.go

@@ -504,29 +504,25 @@ func (n *IPNet) String() string {
 // Parse IPv4 address (d.d.d.d).
 func parseIPv4(s string) IP {
 	var p [IPv4len]byte
-	i := 0
-	for j := 0; j < IPv4len; j++ {
-		if i >= len(s) {
+	for i := 0; i < IPv4len; i++ {
+		if len(s) == 0 {
 			// Missing octets.
 			return nil
 		}
-		if j > 0 {
-			if s[i] != '.' {
+		if i > 0 {
+			if s[0] != '.' {
 				return nil
 			}
-			i++
+			s = s[1:]
 		}
-		var (
-			n  int
-			ok bool
-		)
-		n, i, ok = dtoi(s, i)
+		n, c, ok := dtoi(s)
 		if !ok || n > 0xFF {
 			return nil
 		}
-		p[j] = byte(n)
+		s = s[c:]
+		p[i] = byte(n)
 	}
-	if i != len(s) {
+	if len(s) != 0 {
 		return nil
 	}
 	return IPv4(p[0], p[1], p[2], p[3])
@@ -538,8 +534,7 @@ func parseIPv4(s string) IP {
 // true.
 func parseIPv6(s string, zoneAllowed bool) (ip IP, zone string) {
 	ip = make(IP, IPv6len)
-	ellipsis := -1 // position of ellipsis in p
-	i := 0         // index in string s
+	ellipsis := -1 // position of ellipsis in ip
 
 	if zoneAllowed {
 		s, zone = splitHostZone(s)
@@ -548,90 +543,91 @@ func parseIPv6(s string, zoneAllowed bool) (ip IP, zone string) {
 	// Might have leading ellipsis
 	if len(s) >= 2 && s[0] == ':' && s[1] == ':' {
 		ellipsis = 0
-		i = 2
+		s = s[2:]
 		// Might be only ellipsis
-		if i == len(s) {
+		if len(s) == 0 {
 			return ip, zone
 		}
 	}
 
 	// Loop, parsing hex numbers followed by colon.
-	j := 0
-	for j < IPv6len {
+	i := 0
+	for i < IPv6len {
 		// Hex number.
-		n, i1, ok := xtoi(s, i)
+		n, c, ok := xtoi(s)
 		if !ok || n > 0xFFFF {
 			return nil, zone
 		}
 
 		// If followed by dot, might be in trailing IPv4.
-		if i1 < len(s) && s[i1] == '.' {
-			if ellipsis < 0 && j != IPv6len-IPv4len {
+		if c < len(s) && s[c] == '.' {
+			if ellipsis < 0 && i != IPv6len-IPv4len {
 				// Not the right place.
 				return nil, zone
 			}
-			if j+IPv4len > IPv6len {
+			if i+IPv4len > IPv6len {
 				// Not enough room.
 				return nil, zone
 			}
-			ip4 := parseIPv4(s[i:])
+			ip4 := parseIPv4(s)
 			if ip4 == nil {
 				return nil, zone
 			}
-			ip[j] = ip4[12]
-			ip[j+1] = ip4[13]
-			ip[j+2] = ip4[14]
-			ip[j+3] = ip4[15]
-			i = len(s)
-			j += IPv4len
+			ip[i] = ip4[12]
+			ip[i+1] = ip4[13]
+			ip[i+2] = ip4[14]
+			ip[i+3] = ip4[15]
+			s = ""
+			i += IPv4len
 			break
 		}
 
 		// Save this 16-bit chunk.
-		ip[j] = byte(n >> 8)
-		ip[j+1] = byte(n)
-		j += 2
+		ip[i] = byte(n >> 8)
+		ip[i+1] = byte(n)
+		i += 2
 
 		// Stop at end of string.
-		i = i1
-		if i == len(s) {
+		s = s[c:]
+		if len(s) == 0 {
 			break
 		}
 
 		// Otherwise must be followed by colon and more.
-		if s[i] != ':' || i+1 == len(s) {
+		if s[0] != ':' || len(s) == 1 {
 			return nil, zone
 		}
-		i++
+		s = s[1:]
 
 		// Look for ellipsis.
-		if s[i] == ':' {
+		if s[0] == ':' {
 			if ellipsis >= 0 { // already have one
 				return nil, zone
 			}
-			ellipsis = j
-			if i++; i == len(s) { // can be at end
+			ellipsis = i
+			s = s[1:]
+			if len(s) == 0 { // can be at end
 				break
 			}
 		}
 	}
 
 	// Must have used entire string.
-	if i != len(s) {
+	if len(s) != 0 {
 		return nil, zone
 	}
 
 	// If didn't parse enough, expand ellipsis.
-	if j < IPv6len {
+	if i < IPv6len {
 		if ellipsis < 0 {
 			return nil, zone
 		}
-		n := IPv6len - j
-		for k := j - 1; k >= ellipsis; k-- {
-			ip[k+n] = ip[k]
+		n := IPv6len - i
+		for j := i - 1; j >= ellipsis; j-- {
+			ip[j+n] = ip[j]
 		}
-		for k := ellipsis + n - 1; k >= ellipsis; k-- {
-			ip[k] = 0
+		for j := ellipsis + n - 1; j >= ellipsis; j-- {
+			ip[j] = 0
 		}
 	} else if ellipsis >= 0 {
 		// Ellipsis must represent at least one 0 group.
@@ -677,7 +673,7 @@ func ParseCIDR(s string) (IP, *IPNet, error) {
 		iplen = IPv6len
 		ip, _ = parseIPv6(addr, false)
 	}
-	n, i, ok := dtoi(mask, 0)
+	n, i, ok := dtoi(mask)
 	if ip == nil || !ok || i != len(mask) || n < 0 || n > 8*iplen {
 		return nil, nil, &ParseError{Type: "CIDR address", Text: s}
 	}

src/net/ipsock_plan9.go

@@ -63,7 +63,7 @@ func parsePlan9Addr(s string) (ip IP, iport int, err error) {
 			return nil, 0, &ParseError{Type: "IP address", Text: s}
 		}
 	}
-	p, _, ok := dtoi(s[i+1:], 0)
+	p, _, ok := dtoi(s[i+1:])
 	if !ok {
 		return nil, 0, &ParseError{Type: "port", Text: s}
 	}

src/net/lookup_plan9.go

@@ -111,7 +111,7 @@ func lookupProtocol(ctx context.Context, name string) (proto int, err error) {
 		return 0, UnknownNetworkError(name)
 	}
 	s := f[1]
-	if n, _, ok := dtoi(s, byteIndex(s, '=')+1); ok {
+	if n, _, ok := dtoi(s[byteIndex(s, '=')+1:]); ok {
 		return n, nil
 	}
 	return 0, UnknownNetworkError(name)
@@ -186,7 +186,7 @@ func lookupPort(ctx context.Context, network, service string) (port int, err err
 	if i := byteIndex(s, '!'); i >= 0 {
 		s = s[i+1:] // remove address
 	}
-	if n, _, ok := dtoi(s, 0); ok {
+	if n, _, ok := dtoi(s); ok {
 		return n, nil
 	}
 	return 0, unknownPortError
@@ -221,9 +221,9 @@ func lookupSRV(ctx context.Context, service, proto, name string) (cname string,
 		if len(f) < 6 {
 			continue
 		}
-		port, _, portOk := dtoi(f[4], 0)
-		priority, _, priorityOk := dtoi(f[3], 0)
-		weight, _, weightOk := dtoi(f[2], 0)
+		port, _, portOk := dtoi(f[4])
+		priority, _, priorityOk := dtoi(f[3])
+		weight, _, weightOk := dtoi(f[2])
 		if !(portOk && priorityOk && weightOk) {
 			continue
 		}
@@ -244,7 +244,7 @@ func lookupMX(ctx context.Context, name string) (mx []*MX, err error) {
 		if len(f) < 4 {
 			continue
 		}
-		if pref, _, ok := dtoi(f[2], 0); ok {
+		if pref, _, ok := dtoi(f[2]); ok {
 			mx = append(mx, &MX{absDomainName([]byte(f[3])), uint16(pref)})
 		}
 	}

src/net/lookup_unix.go

@@ -26,7 +26,7 @@ func readProtocols() {
 			if len(f) < 2 {
 				continue
 			}
-			if proto, _, ok := dtoi(f[1], 0); ok {
+			if proto, _, ok := dtoi(f[1]); ok {
 				if _, ok := protocols[f[0]]; !ok {
 					protocols[f[0]] = proto
 				}

src/net/lookup_windows_test.go

@@ -169,14 +169,14 @@ func nslookupMX(name string) (mx []*MX, err error) {
 	// golang.org      mail exchanger = 2 alt1.aspmx.l.google.com.
 	rx := regexp.MustCompile(`(?m)^([a-z0-9.\-]+)\s+mail exchanger\s*=\s*([0-9]+)\s*([a-z0-9.\-]+)$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
-		pref, _, _ := dtoi(ans[2], 0)
+		pref, _, _ := dtoi(ans[2])
 		mx = append(mx, &MX{absDomainName([]byte(ans[3])), uint16(pref)})
 	}
 	// windows nslookup syntax
 	// gmail.com       MX preference = 30, mail exchanger = alt3.gmail-smtp-in.l.google.com
 	rx = regexp.MustCompile(`(?m)^([a-z0-9.\-]+)\s+MX preference\s*=\s*([0-9]+)\s*,\s*mail exchanger\s*=\s*([a-z0-9.\-]+)$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
-		pref, _, _ := dtoi(ans[2], 0)
+		pref, _, _ := dtoi(ans[2])
 		mx = append(mx, &MX{absDomainName([]byte(ans[3])), uint16(pref)})
 	}
 	return

src/net/parse.go

@@ -123,16 +123,16 @@ func getFields(s string) []string { return splitAtBytes(s, " \r\t\n") }
 // Bigger than we need, not too big to worry about overflow
 const big = 0xFFFFFF
 
-// Decimal to integer starting at &s[i0].
-// Returns number, new offset, success.
-func dtoi(s string, i0 int) (n int, i int, ok bool) {
+// Decimal to integer.
+// Returns number, characters consumed, success.
+func dtoi(s string) (n int, i int, ok bool) {
 	n = 0
 	neg := false
 	if len(s) > 0 && s[0] == '-' {
 		neg = true
 		s = s[1:]
 	}
-	for i = i0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
+	for i = 0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
 		n = n*10 + int(s[i]-'0')
 		if n >= big {
 			if neg {
@@ -141,7 +141,7 @@ func dtoi(s string, i0 int) (n int, i int, ok bool) {
 			return big, i, false
 		}
 	}
-	if i == i0 {
+	if i == 0 {
 		return 0, i, false
 	}
 	if neg {
@@ -151,11 +151,11 @@ func dtoi(s string, i0 int) (n int, i int, ok bool) {
 	return n, i, true
 }
 
-// Hexadecimal to integer starting at &s[i0].
-// Returns number, new offset, success.
-func xtoi(s string, i0 int) (n int, i int, ok bool) {
+// Hexadecimal to integer.
+// Returns number, characters consumed, success.
+func xtoi(s string) (n int, i int, ok bool) {
 	n = 0
-	for i = i0; i < len(s); i++ {
+	for i = 0; i < len(s); i++ {
 		if '0' <= s[i] && s[i] <= '9' {
 			n *= 16
 			n += int(s[i] - '0')
@@ -172,7 +172,7 @@ func xtoi(s string, i0 int) (n int, i int, ok bool) {
 			return 0, i, false
 		}
 	}
-	if i == i0 {
+	if i == 0 {
 		return 0, i, false
 	}
 	return n, i, true
@@ -186,7 +186,7 @@ func xtoi2(s string, e byte) (byte, bool) {
 	if len(s) > 2 && s[2] != e {
 		return 0, false
 	}
-	n, ei, ok := xtoi(s[:2], 0)
+	n, ei, ok := xtoi(s[:2])
 	return byte(n), ok && ei == 2
 }
 

src/net/parse_test.go

@@ -93,7 +93,7 @@ func TestDtoi(t *testing.T) {
 		{"65536", 65536, 5, true},
 		{"123456789", big, 8, false},
 	} {
-		n, i, ok := dtoi(tt.in, 0)
+		n, i, ok := dtoi(tt.in)
 		if n != tt.out || i != tt.off || ok != tt.ok {
 			t.Errorf("got %d, %d, %v; want %d, %d, %v", n, i, ok, tt.out, tt.off, tt.ok)
 		}

src/net/port_unix.go

@@ -34,7 +34,7 @@ func readServices() {
 			continue
 		}
 		portnet := f[1] // "80/tcp"
-		port, j, ok := dtoi(portnet, 0)
+		port, j, ok := dtoi(portnet)
 		if !ok || port <= 0 || j >= len(portnet) || portnet[j] != '/' {
 			continue
 		}

src/net/sock_linux.go

@@ -17,7 +17,7 @@ func maxListenerBacklog() int {
 		return syscall.SOMAXCONN
 	}
 	f := getFields(l)
-	n, _, ok := dtoi(f[0], 0)
+	n, _, ok := dtoi(f[0])
 	if n == 0 || !ok {
 		return syscall.SOMAXCONN
 	}