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net: fix inconsistent error values on Lookup
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This change fixes inconsistent error values on
Lookup{Addr,CNAME,Host,IP.MX,NS,Port,SRV,TXT}.

Updates #4856.

Change-Id: I059bc8ffb96ee74dff8a8c4e8e6ae3e4a462a7ef
Reviewed-on: https://go-review.googlesource.com/9108
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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@cixtor
cixtor committed Apr 21, 2015
1 parent 456cf0f commit 0fc582e
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Showing 9 changed files with 177 additions and 192 deletions.
14 changes: 6 additions & 8 deletions src/net/cgo_unix.go
View file
Expand Up @@ -54,7 +54,7 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
hints.ai_socktype = C.SOCK_DGRAM
hints.ai_protocol = C.IPPROTO_UDP
default:
return 0, UnknownNetworkError(network), true
return 0, &DNSError{Err: "unknown network", Name: network + "/" + service}, true
}
if len(network) >= 4 {
switch network[3] {
Expand All @@ -78,7 +78,7 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
default:
err = addrinfoErrno(gerrno)
}
return 0, err, true
return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}, true
}
defer C.freeaddrinfo(res)

Expand All @@ -94,7 +94,7 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
return int(p[0])<<8 | int(p[1]), nil, true
}
}
return 0, &AddrError{"unknown port", network + "/" + service}, true
return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}, true
}

func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, completed bool) {
Expand All @@ -110,7 +110,6 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
var res *C.struct_addrinfo
gerrno, err := C.getaddrinfo(h, nil, &hints, &res)
if gerrno != 0 {
var str string
switch gerrno {
case C.EAI_SYSTEM:
if err == nil {
Expand All @@ -123,13 +122,12 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
// comes up again. golang.org/issue/6232.
err = syscall.EMFILE
}
str = err.Error()
case C.EAI_NONAME:
str = noSuchHost
err = errNoSuchHost
default:
str = addrinfoErrno(gerrno).Error()
err = addrinfoErrno(gerrno)
}
return nil, "", &DNSError{Err: str, Name: name}, true
return nil, "", &DNSError{Err: err.Error(), Name: name}, true
}
defer C.freeaddrinfo(res)

Expand Down
52 changes: 7 additions & 45 deletions src/net/dnsclient.go
View file
Expand Up @@ -9,38 +9,6 @@ import (
"sort"
)

// DNSError represents a DNS lookup error.
type DNSError struct {
Err string // description of the error
Name string // name looked for
Server string // server used
IsTimeout bool // if true, timed out; not all timeouts set this
}

func (e *DNSError) Error() string {
if e == nil {
return "<nil>"
}
s := "lookup " + e.Name
if e.Server != "" {
s += " on " + e.Server
}
s += ": " + e.Err
return s
}

// Timeout reports whether the DNS lookup is known to have timed out.
// This is not always known; a DNS lookup may fail due to a timeout
// and return a DNSError for which Timeout returns false.
func (e *DNSError) Timeout() bool { return e.IsTimeout }

// Temporary reports whether the DNS error is known to be temporary.
// This is not always known; a DNS lookup may fail due to a temporary
// error and return a DNSError for which Temporary returns false.
func (e *DNSError) Temporary() bool { return e.IsTimeout }

const noSuchHost = "no such host"

// reverseaddr returns the in-addr.arpa. or ip6.arpa. hostname of the IP
// address addr suitable for rDNS (PTR) record lookup or an error if it fails
// to parse the IP address.
Expand All @@ -50,8 +18,7 @@ func reverseaddr(addr string) (arpa string, err error) {
return "", &DNSError{Err: "unrecognized address", Name: addr}
}
if ip.To4() != nil {
return uitoa(uint(ip[15])) + "." + uitoa(uint(ip[14])) + "." + uitoa(uint(ip[13])) + "." +
uitoa(uint(ip[12])) + ".in-addr.arpa.", nil
return uitoa(uint(ip[15])) + "." + uitoa(uint(ip[14])) + "." + uitoa(uint(ip[13])) + "." + uitoa(uint(ip[12])) + ".in-addr.arpa.", nil
}
// Must be IPv6
buf := make([]byte, 0, len(ip)*4+len("ip6.arpa."))
Expand All @@ -74,7 +41,7 @@ func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs
addrs = make([]dnsRR, 0, len(dns.answer))

if dns.rcode == dnsRcodeNameError && dns.recursion_available {
return "", nil, &DNSError{Err: noSuchHost, Name: name}
return "", nil, &DNSError{Err: errNoSuchHost.Error(), Name: name}
}
if dns.rcode != dnsRcodeSuccess {
// None of the error codes make sense
Expand Down Expand Up @@ -113,7 +80,7 @@ Cname:
}
}
if len(addrs) == 0 {
return "", nil, &DNSError{Err: noSuchHost, Name: name, Server: server}
return "", nil, &DNSError{Err: errNoSuchHost.Error(), Name: name, Server: server}
}
return name, addrs, nil
}
Expand Down Expand Up @@ -201,13 +168,10 @@ type SRV struct {
type byPriorityWeight []*SRV

func (s byPriorityWeight) Len() int { return len(s) }

func (s byPriorityWeight) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

func (s byPriorityWeight) Less(i, j int) bool {
return s[i].Priority < s[j].Priority ||
(s[i].Priority == s[j].Priority && s[i].Weight < s[j].Weight)
return s[i].Priority < s[j].Priority || (s[i].Priority == s[j].Priority && s[i].Weight < s[j].Weight)
}
func (s byPriorityWeight) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

// shuffleByWeight shuffles SRV records by weight using the algorithm
// described in RFC 2782.
Expand Down Expand Up @@ -255,11 +219,9 @@ type MX struct {
// byPref implements sort.Interface to sort MX records by preference
type byPref []*MX

func (s byPref) Len() int { return len(s) }

func (s byPref) Len() int { return len(s) }
func (s byPref) Less(i, j int) bool { return s[i].Pref < s[j].Pref }

func (s byPref) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s byPref) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

// sort reorders MX records as specified in RFC 5321.
func (s byPref) sort() {
Expand Down
10 changes: 5 additions & 5 deletions src/net/dnsclient_unix.go
View file
Expand Up @@ -185,7 +185,7 @@ func tryOneName(cfg *dnsConfig, name string, qtype uint16) (string, []dnsRR, err
continue
}
cname, addrs, err := answer(name, server, msg, qtype)
if err == nil || err.(*DNSError).Err == noSuchHost {
if err == nil || err.(*DNSError).Err == errNoSuchHost.Error() {
return cname, addrs, err
}
lastErr = err
Expand Down Expand Up @@ -269,7 +269,7 @@ func loadConfig(resolvConfPath string, reloadTime time.Duration, quit <-chan cha
}()
}

func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err error) {
func lookup(name string, qtype uint16) (cname string, rrs []dnsRR, err error) {
if !isDomainName(name) {
return name, nil, &DNSError{Err: "invalid domain name", Name: name}
}
Expand All @@ -296,7 +296,7 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err error)
rname += "."
}
// Can try as ordinary name.
cname, addrs, err = tryOneName(cfg.dnsConfig, rname, qtype)
cname, rrs, err = tryOneName(cfg.dnsConfig, rname, qtype)
if rooted || err == nil {
return
}
Expand All @@ -308,7 +308,7 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err error)
if rname[len(rname)-1] != '.' {
rname += "."
}
cname, addrs, err = tryOneName(cfg.dnsConfig, rname, qtype)
cname, rrs, err = tryOneName(cfg.dnsConfig, rname, qtype)
if err == nil {
return
}
Expand All @@ -317,7 +317,7 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err error)
// Last ditch effort: try unsuffixed only if we haven't already,
// that is, name is not rooted and has less than ndots dots.
if count(name, '.') < cfg.dnsConfig.ndots {
cname, addrs, err = tryOneName(cfg.dnsConfig, name+".", qtype)
cname, rrs, err = tryOneName(cfg.dnsConfig, name+".", qtype)
if err == nil {
return
}
Expand Down
8 changes: 4 additions & 4 deletions src/net/lookup.go
View file
Expand Up @@ -132,22 +132,22 @@ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err err
}

// LookupMX returns the DNS MX records for the given domain name sorted by preference.
func LookupMX(name string) (mx []*MX, err error) {
func LookupMX(name string) (mxs []*MX, err error) {
return lookupMX(name)
}

// LookupNS returns the DNS NS records for the given domain name.
func LookupNS(name string) (ns []*NS, err error) {
func LookupNS(name string) (nss []*NS, err error) {
return lookupNS(name)
}

// LookupTXT returns the DNS TXT records for the given domain name.
func LookupTXT(name string) (txt []string, err error) {
func LookupTXT(name string) (txts []string, err error) {
return lookupTXT(name)
}

// LookupAddr performs a reverse lookup for the given address, returning a list
// of names mapping to that address.
func LookupAddr(addr string) (name []string, err error) {
func LookupAddr(addr string) (names []string, err error) {
return lookupAddr(addr)
}

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