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Avoid creating copies of locks (#121)

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tls.Config contains fields of type sync.Once and sync.RWMutex. My understanding
is that if the copy happens to occur while the lock is in a locked state, the
lock will remain locked indefinitely and cause a deadlock. Instead use
tls.Config.Clone() to create a shallow copy.

Also the lock copy made `go vet` upset:

$ go vet ./...
./xmpp.go:242:17: assignment copies lock value to newconfig: crypto/tls.Config contains sync.Once contains sync.Mutex
./xmpp.go:530:9: assignment copies lock value to *tc: crypto/tls.Config contains sync.Once contains sync.Mutex
This commit is contained in:
Steven Santos Erenst 2021-01-21 00:25:57 -08:00 committed by GitHub
parent 37fa6ef92f
commit da2b7586cd
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 4 additions and 6 deletions
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10
xmpp.go
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@ -43,7 +43,7 @@ const (
) )
// Default TLS configuration options // Default TLS configuration options
var DefaultConfig tls.Config var DefaultConfig = &tls.Config{}
// DebugWriter is the writer used to write debugging output to. // DebugWriter is the writer used to write debugging output to.
var DebugWriter io.Writer = os.Stderr var DebugWriter io.Writer = os.Stderr
@ -238,10 +238,9 @@ func (o Options) NewClient() (*Client, error) {
if o.TLSConfig != nil { if o.TLSConfig != nil {
tlsconn = tls.Client(c, o.TLSConfig) tlsconn = tls.Client(c, o.TLSConfig)
} else { } else {
DefaultConfig.ServerName = host newconfig := DefaultConfig.Clone()
newconfig := DefaultConfig
newconfig.ServerName = host newconfig.ServerName = host
tlsconn = tls.Client(c, &newconfig) tlsconn = tls.Client(c, newconfig)
} }
if err = tlsconn.Handshake(); err != nil { if err = tlsconn.Handshake(); err != nil {
return nil, err return nil, err
@ -526,8 +525,7 @@ func (c *Client) startTLSIfRequired(f *streamFeatures, o *Options, domain string
tc := o.TLSConfig tc := o.TLSConfig
if tc == nil { if tc == nil {
tc = new(tls.Config) tc = DefaultConfig.Clone()
*tc = DefaultConfig
//TODO(scott): we should consider using the server's address or reverse lookup //TODO(scott): we should consider using the server's address or reverse lookup
tc.ServerName = domain tc.ServerName = domain
} }