net: make SplitHostPort return an empty host on error

This change also refactors SplitHostPort to avoid using gotos and
naked returns.

Fixes #14827

Change-Id: I4dca528936757fd06da76c23af8a0f6175bbedd1
Reviewed-on: https://go-review.googlesource.com/20726
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/ip_test.go b/src/net/ip_test.go
index 2b24baf58e96338060b6862cbaad6a716121d8c1..20060858187f96de143d00dad0039c7243e258a9 100644 (file)
--- a/src/net/ip_test.go
+++ b/src/net/ip_test.go
@@ -421,13 +421,16 @@ func TestSplitHostPort(t *testing.T) {
                }
        }
        for _, tt := range splitFailureTests {
-               if _, _, err := SplitHostPort(tt.hostPort); err == nil {
+               if host, port, err := SplitHostPort(tt.hostPort); err == nil {
                        t.Errorf("SplitHostPort(%q) should have failed", tt.hostPort)
                } else {
                        e := err.(*AddrError)
                        if e.Err != tt.err {
                                t.Errorf("SplitHostPort(%q) = _, _, %q; want %q", tt.hostPort, e.Err, tt.err)
                        }
+                       if host != "" || port != "" {
+                               t.Errorf("SplitHostPort(%q) = %q, %q, err; want %q, %q, err on failure", tt.hostPort, host, port, "", "")
+                       }
                }
        }
 }

diff --git a/src/net/ipsock.go b/src/net/ipsock.go
index d6a6785e066558ae8f7353746d98b752677bf1ba..f3ac00df052dfdb24a7c934c304e3bf9199617c6 100644 (file)
--- a/src/net/ipsock.go
+++ b/src/net/ipsock.go
@@ -110,69 +110,61 @@ func ipv6only(addr IPAddr) bool {
 // must be enclosed in square brackets, as in "[::1]:80",
 // "[ipv6-host]:http" or "[ipv6-host%zone]:80".
 func SplitHostPort(hostport string) (host, port string, err error) {
+       const (
+               missingPort   = "missing port in address"
+               tooManyColons = "too many colons in address"
+       )
+       addrErr := func(addr, why string) (host, port string, err error) {
+               return "", "", &AddrError{Err: why, Addr: addr}
+       }
        j, k := 0, 0
 
        // The port starts after the last colon.
        i := last(hostport, ':')
        if i < 0 {
-               goto missingPort
+               return addrErr(hostport, missingPort)
        }
 
        if hostport[0] == '[' {
                // Expect the first ']' just before the last ':'.
                end := byteIndex(hostport, ']')
                if end < 0 {
-                       err = &AddrError{Err: "missing ']' in address", Addr: hostport}
-                       return
+                       return addrErr(hostport, "missing ']' in address")
                }
                switch end + 1 {
                case len(hostport):
                        // There can't be a ':' behind the ']' now.
-                       goto missingPort
+                       return addrErr(hostport, missingPort)
                case i:
                        // The expected result.
                default:
                        // Either ']' isn't followed by a colon, or it is
                        // followed by a colon that is not the last one.
                        if hostport[end+1] == ':' {
-                               goto tooManyColons
+                               return addrErr(hostport, tooManyColons)
                        }
-                       goto missingPort
+                       return addrErr(hostport, missingPort)
                }
                host = hostport[1:end]
                j, k = 1, end+1 // there can't be a '[' resp. ']' before these positions
        } else {
                host = hostport[:i]
                if byteIndex(host, ':') >= 0 {
-                       goto tooManyColons
+                       return addrErr(hostport, tooManyColons)
                }
                if byteIndex(host, '%') >= 0 {
-                       goto missingBrackets
+                       return addrErr(hostport, "missing brackets in address")
                }
        }
        if byteIndex(hostport[j:], '[') >= 0 {
-               err = &AddrError{Err: "unexpected '[' in address", Addr: hostport}
-               return
+               return addrErr(hostport, "unexpected '[' in address")
        }
        if byteIndex(hostport[k:], ']') >= 0 {
-               err = &AddrError{Err: "unexpected ']' in address", Addr: hostport}
-               return
+               return addrErr(hostport, "unexpected ']' in address")
        }
 
        port = hostport[i+1:]
-       return
-
-missingPort:
-       err = &AddrError{Err: "missing port in address", Addr: hostport}
-       return
-
-tooManyColons:
-       err = &AddrError{Err: "too many colons in address", Addr: hostport}
-       return
-
-missingBrackets:
-       err = &AddrError{Err: "missing brackets in address", Addr: hostport}
-       return
+       return host, port, nil
 }
 
 func splitHostZone(s string) (host, zone string) {