libgit2: dispose connections in SubTransport.Close

The average SubTransport lifecycle encompass two Actions calls. Previously,
it was attempted to share the same connection across both calls. That did
not work as some Git Servers do not support multiple sessions from the same
connection. The implementation was not fully transitioned into the
"one connection per action" model, which led to connection being leaked.

The transition to RW mutex was to avoid the unnecessary blocking in the
goroutine at the start of the second action call.

It is worth mentioning that now when the context is done,  the client level
resources (connection) will also be freed. This ensures that SSH connections
will not outlive the subtransport.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>
This commit is contained in:
Paulo Gomes 2022-06-08 19:39:50 +01:00
parent a00d0edcd7
commit bfa4e38b84
No known key found for this signature in database
GPG Key ID: 9995233870E99BEE
1 changed files with 21 additions and 25 deletions

View File

@ -95,12 +95,11 @@ type sshSmartSubtransport struct {
}
type connection struct {
conn net.Conn
client *ssh.Client
session *ssh.Session
currentStream *sshSmartSubtransportStream
connected bool
m sync.Mutex
m sync.RWMutex
}
func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.SmartServiceAction) (git2go.SmartSubtransportStream, error) {
@ -155,11 +154,6 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
return nil, fmt.Errorf("unexpected action: %v", action)
}
if t.con.connected {
// Disregard errors from previous stream, futher details inside Close().
_ = t.Close()
}
port := "22"
if u.Port() != "" {
port = u.Port()
@ -189,13 +183,18 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
return nil
}
t.con.m.RLock()
if t.con.connected == true {
// The connection is no longer shared across actions, so ensures
// all has been released before starting a new connection.
_ = t.Close()
}
t.con.m.RUnlock()
err = t.createConn(t.addr, sshConfig)
if err != nil {
return nil, err
}
t.con.m.Lock()
t.con.connected = true
t.con.m.Unlock()
traceLog.Info("[ssh]: creating new ssh session")
if t.con.session, err = t.con.client.NewSession(); err != nil {
@ -244,12 +243,12 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
return nil
default:
t.con.m.Lock()
t.con.m.RLock()
if !t.con.connected {
t.con.m.Unlock()
t.con.m.RUnlock()
return nil
}
t.con.m.Unlock()
t.con.m.RUnlock()
_, err := io.Copy(w, reader)
if err != nil {
@ -286,8 +285,10 @@ func (t *sshSmartSubtransport) createConn(addr string, sshConfig *ssh.ClientConf
return err
}
t.con.conn = conn
t.con.m.Lock()
t.con.connected = true
t.con.client = ssh.NewClient(c, chans, reqs)
t.con.m.Unlock()
return nil
}
@ -309,7 +310,7 @@ func (t *sshSmartSubtransport) Close() error {
if t.con.client != nil && t.stdin != nil {
_ = t.stdin.Close()
}
t.con.client = nil
t.stdin = nil
if t.con.session != nil {
traceLog.Info("[ssh]: session.Close()", "server", t.addr)
@ -317,21 +318,16 @@ func (t *sshSmartSubtransport) Close() error {
}
t.con.session = nil
return nil
}
func (t *sshSmartSubtransport) Free() {
traceLog.Info("[ssh]: sshSmartSubtransport.Free()")
if t.con.client != nil {
_ = t.con.client.Close()
}
if t.con.conn != nil {
_ = t.con.conn.Close()
}
t.con.m.Lock()
t.con.connected = false
t.con.m.Unlock()
return nil
}
func (t *sshSmartSubtransport) Free() {
}
type sshSmartSubtransportStream struct {