Noticed while auditing the code that we aren't respecting
(*net.Conn) SetDeadline errors which return after
a connection has been killed and is simultaneously
being used.
For example given program, without SetDeadline error checks
```go
package main
import (
"log"
"net"
"time"
)
func main() {
conn, err := net.Dial("tcp", "tendermint.com:443")
if err != nil {
log.Fatal(err)
}
go func() {
<-time.After(400 * time.Millisecond)
conn.Close()
}()
for i := 0; i < 5; i++ {
if err := conn.SetDeadline(time.Now().Add(time.Duration(10 * time.Second))); err != nil {
log.Fatalf("set deadline #%d, err: %v", i, err)
}
log.Printf("Successfully set deadline #%d", i)
<-time.After(150 * time.Millisecond)
}
}
```
erraneously gives
```shell
2017/11/14 17:46:28 Successfully set deadline #0
2017/11/14 17:46:29 Successfully set deadline #1
2017/11/14 17:46:29 Successfully set deadline #2
2017/11/14 17:46:29 Successfully set deadline #3
2017/11/14 17:46:29 Successfully set deadline #4
```
However, if we properly fix it to respect that error with
```diff
--- wild.go 2017-11-14 17:44:38.000000000 -0700
+++ main.go 2017-11-14 17:45:40.000000000 -0700
@@ -16,7 +16,9 @@
conn.Close()
}()
for i := 0; i < 5; i++ {
- conn.SetDeadline(time.Now().Add(time.Duration(10 * time.Second)))
+ if err := conn.SetDeadline(time.Now().Add(time.Duration(10 *
time.Second))); err != nil {
+ log.Fatalf("set deadline #%d, err: %v", i, err)
+ }
log.Printf("Successfully set deadline #%d", i)
<-time.After(150 * time.Millisecond)
}
```
properly catches any problems and gives
```shell
$ go run main.go
2017/11/14 17:43:44 Successfully set deadline #0
2017/11/14 17:43:45 Successfully set deadline #1
2017/11/14 17:43:45 Successfully set deadline #2
2017/11/14 17:43:45 set deadline #3, err: set tcp 10.182.253.51:57395:
use of closed network connection
exit status 1
```
Anton Kaliaev
Zach Ramsay
Emmanuel Odeke
Ethan Buchman
Petabyte Storage
Jae Kwon
Jae Kwon