net: set DNSError.IsTemporary from addrinfoErrno errors

Today it is not possible (AFAICT) to detect if a DNSError if of type EAI_AGAIN, i.e. if it is something temporary that should be retried. This information is available inside addrinfoErrno but when the DNSError is created this information is lost.

This PR fixes this so that the addinfoErrno.Temporary information is added to DNSError as well. With that a user who gets a DNSError can check now is its a temporary error (for errors that resulted from a addrinfoErrno this is EAI_AGAIN).

Change-Id: I64badb2ebd904e41fc2e0755416f7f32560534d8
GitHub-Last-Rev: ced7238a6597039fb23f36f372bd1cf33d60d4a6
GitHub-Pull-Request: golang/go#31676
Reviewed-on: https://go-review.googlesource.com/c/go/+/174557
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/cgo_unix.go b/src/net/cgo_unix.go
index 2baab5f193396886ac28767e24019fb838d18fd7..69c99fe7dbbc6f50435a19364016568f4e0b861d 100644 (file)
--- a/src/net/cgo_unix.go
+++ b/src/net/cgo_unix.go
@@ -106,6 +106,7 @@ func cgoLookupServicePort(hints *C.struct_addrinfo, network, service string) (po
        var res *C.struct_addrinfo
        gerrno, err := C.getaddrinfo(nil, (*C.char)(unsafe.Pointer(&cservice[0])), hints, &res)
        if gerrno != 0 {
+               isTemporary := false
                switch gerrno {
                case C.EAI_SYSTEM:
                        if err == nil { // see golang.org/issue/6232
@@ -113,8 +114,9 @@ func cgoLookupServicePort(hints *C.struct_addrinfo, network, service string) (po
                        }
                default:
                        err = addrinfoErrno(gerrno)
+                       isTemporary = addrinfoErrno(gerrno).Temporary()
                }
-               return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
+               return 0, &DNSError{Err: err.Error(), Name: network + "/" + service, IsTemporary: isTemporary}
        }
        defer C.freeaddrinfo(res)
 
@@ -159,6 +161,7 @@ func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err e
        gerrno, err := C.getaddrinfo((*C.char)(unsafe.Pointer(&h[0])), nil, &hints, &res)
        if gerrno != 0 {
                isErrorNoSuchHost := false
+               isTemporary := false
                switch gerrno {
                case C.EAI_SYSTEM:
                        if err == nil {
@@ -176,9 +179,10 @@ func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err e
                        isErrorNoSuchHost = true
                default:
                        err = addrinfoErrno(gerrno)
+                       isTemporary = addrinfoErrno(gerrno).Temporary()
                }
 
-               return nil, "", &DNSError{Err: err.Error(), Name: name, IsNotFound: isErrorNoSuchHost}
+               return nil, "", &DNSError{Err: err.Error(), Name: name, IsNotFound: isErrorNoSuchHost, IsTemporary: isTemporary}
        }
        defer C.freeaddrinfo(res)
 
@@ -299,6 +303,7 @@ func cgoLookupAddrPTR(addr string, sa *C.struct_sockaddr, salen C.socklen_t) (na
                }
        }
        if gerrno != 0 {
+               isTemporary := false
                switch gerrno {
                case C.EAI_SYSTEM:
                        if err == nil { // see golang.org/issue/6232
@@ -306,8 +311,9 @@ func cgoLookupAddrPTR(addr string, sa *C.struct_sockaddr, salen C.socklen_t) (na
                        }
                default:
                        err = addrinfoErrno(gerrno)
+                       isTemporary = addrinfoErrno(gerrno).Temporary()
                }
-               return nil, &DNSError{Err: err.Error(), Name: addr}
+               return nil, &DNSError{Err: err.Error(), Name: addr, IsTemporary: isTemporary}
        }
        for i := 0; i < len(b); i++ {
                if b[i] == 0 {