net: introduce net.Error interface

Adds two more methods, Timeout and Temporary.
Implemented by os.Errno too.  The intent is to make
the checks for os.EAGAIN a little less clunky.
It should also let us clean up a bug that Mike Solomon
pointed out: if a network server gets an "out of file descriptors"
error from Accept, the listener should not stop.
It will be able to check this because that error would
have Temporary() == true.

Also clean up some underscore names.

Fixes issue 442.

R=r
CC=golang-dev, msolo
http://codereview.appspot.com/957045

1 files changed, 15 insertions, 7 deletions

diff --git a/src/pkg/net/ipsock.go b/src/pkg/net/ipsock.go
index 879bae33e..fcbd5079f 100644
--- a/src/pkg/net/ipsock.go
+++ b/src/pkg/net/ipsock.go
@@ -49,6 +49,7 @@ type sockaddr interface {
 func internetSocket(net string, laddr, raddr sockaddr, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
 	// Figure out IP version.
 	// If network has a suffix like "tcp4", obey it.
+	var oserr os.Error
 	family := syscall.AF_INET6
 	switch net[len(net)-1] {
 	case '4':
@@ -67,16 +68,16 @@ func internetSocket(net string, laddr, raddr sockaddr, proto int, mode string, t
 
 	var la, ra syscall.Sockaddr
 	if laddr != nil {
-		if la, err = laddr.sockaddr(family); err != nil {
+		if la, oserr = laddr.sockaddr(family); err != nil {
 			goto Error
 		}
 	}
 	if raddr != nil {
-		if ra, err = raddr.sockaddr(family); err != nil {
+		if ra, oserr = raddr.sockaddr(family); err != nil {
 			goto Error
 		}
 	}
-	fd, err = socket(net, family, proto, 0, la, ra, toAddr)
+	fd, oserr = socket(net, family, proto, 0, la, ra, toAddr)
 	if err != nil {
 		goto Error
 	}
@@ -87,7 +88,7 @@ Error:
 	if mode == "listen" {
 		addr = laddr
 	}
-	return nil, &OpError{mode, net, addr, err}
+	return nil, &OpError{mode, net, addr, oserr}
 }
 
 func getip(fd int, remote bool) (ip []byte, port int, ok bool) {
@@ -109,6 +110,13 @@ func getip(fd int, remote bool) (ip []byte, port int, ok bool) {
 	return
 }
 
+type InvalidAddrError string
+
+func (e InvalidAddrError) String() string  { return string(e) }
+func (e InvalidAddrError) Timeout() bool   { return false }
+func (e InvalidAddrError) Temporary() bool { return false }
+
+
 func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
 	switch family {
 	case syscall.AF_INET:
@@ -116,7 +124,7 @@ func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
 			ip = IPv4zero
 		}
 		if ip = ip.To4(); ip == nil {
-			return nil, os.EINVAL
+			return nil, InvalidAddrError("non-IPv4 address")
 		}
 		s := new(syscall.SockaddrInet4)
 		for i := 0; i < IPv4len; i++ {
@@ -135,7 +143,7 @@ func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
 			ip = IPzero
 		}
 		if ip = ip.To16(); ip == nil {
-			return nil, os.EINVAL
+			return nil, InvalidAddrError("non-IPv6 address")
 		}
 		s := new(syscall.SockaddrInet6)
 		for i := 0; i < IPv6len; i++ {
@@ -144,7 +152,7 @@ func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
 		s.Port = port
 		return s, nil
 	}
-	return nil, os.EINVAL
+	return nil, InvalidAddrError("unexpected socket family")
 }
 
 // Split "host:port" into "host" and "port".