Prevent Context.RemoteAddr() from exploding when called from ConnCallback

amery · belak · commit c7b4a1b92ef7 · 2021-06-28T00:37:57.000-07:00
When calling ctx.RemoteAddr() within ConnCallback one gets a panic due to
unsafe casting within the accessor. I understand it's not a valid scenario
as such, but I accidentally called a logger that expected that checked
for RemoteAddr() in ssh.Context

panic: interface conversion: interface is nil, not net.Addr

Signed-off-by: Alejandro Mery &lt;amery@geeks.cl&gt;
diff --git a/context.go b/context.go
@@ -140,7 +140,10 @@ func (ctx *sshContext) ServerVersion() string {
 }
 
 func (ctx *sshContext) RemoteAddr() net.Addr {
-	return ctx.Value(ContextKeyRemoteAddr).(net.Addr)
+	if addr, ok := ctx.Value(ContextKeyRemoteAddr).(net.Addr); ok {
+		return addr
+	}
+	return nil
 }
 
 func (ctx *sshContext) LocalAddr() net.Addr {

Original file line number	Diff line number	Diff line change
`@@ -140,7 +140,10 @@ func (ctx *sshContext) ServerVersion() string {`
`140`	`140`	`}`
`141`	`141`
`142`	`142`	`func (ctx *sshContext) RemoteAddr() net.Addr {`
`143`		`- return ctx.Value(ContextKeyRemoteAddr).(net.Addr)`
	`143`	`+ if addr, ok := ctx.Value(ContextKeyRemoteAddr).(net.Addr); ok {`
	`144`	`+ return addr`
	`145`	`+ }`
	`146`	`+ return nil`
`144`	`147`	`}`
`145`	`148`
`146`	`149`	`func (ctx *sshContext) LocalAddr() net.Addr {`