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proxy.go
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proxy.go
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/**
* proxy.go - proxy utils
*
* @author Yaroslav Pogrebnyak <yyyaroslav@gmail.com>
*/
package server
import (
"../core"
"../logging"
"io"
"net"
"time"
)
const (
/* Buffer size to handle data from socket */
BUFFER_SIZE = 16 * 1024
/* Interval of pushing aggregated read/write stats */
PROXY_STATS_PUSH_INTERVAL = 1 * time.Second
)
/**
* Perform copy/proxy data from 'from' to 'to' socket, counting r/w stats and
* dropping connection if timeout exceeded
*/
func proxy(to net.Conn, from net.Conn, timeout time.Duration) <-chan core.ReadWriteCount {
log := logging.For("proxy")
stats := make(chan core.ReadWriteCount)
outStats := make(chan core.ReadWriteCount)
rwcBuffer := core.ReadWriteCount{}
ticker := time.NewTicker(PROXY_STATS_PUSH_INTERVAL)
flushed := false
// Stats collecting goroutine
go func() {
if timeout > 0 {
to.SetReadDeadline(time.Now().Add(timeout))
}
for {
select {
case <-ticker.C:
if !rwcBuffer.IsZero() {
outStats <- rwcBuffer
}
flushed = true
case rwc, ok := <-stats:
if !ok {
ticker.Stop()
if !flushed && !rwcBuffer.IsZero() {
outStats <- rwcBuffer
}
close(outStats)
return
}
if timeout > 0 && rwc.CountRead > 0 {
to.SetReadDeadline(time.Now().Add(timeout))
}
// Remove non blocking
if flushed {
rwcBuffer = rwc
} else {
rwcBuffer.CountWrite += rwc.CountWrite
rwcBuffer.CountRead = rwc.CountRead
}
flushed = false
}
}
}()
// Run proxy copier
go func() {
err := Copy(to, from, stats)
// hack to determine normal close. TODO: fix when it will be exposed in golang
if err != nil && err.(*net.OpError).Err.Error() != "use of closed network connection" {
log.Warn(err)
}
to.Close()
from.Close()
// Stop stats collecting goroutine
close(stats)
}()
return outStats
}
/**
* It's build by analogy of io.Copy
*/
func Copy(to io.Writer, from io.Reader, ch chan<- core.ReadWriteCount) error {
buf := make([]byte, BUFFER_SIZE)
var err error = nil
for {
readN, readErr := from.Read(buf)
if readN > 0 {
writeN, writeErr := to.Write(buf[0:readN])
if writeN > 0 {
ch <- core.ReadWriteCount{CountRead: uint(readN), CountWrite: uint(writeN)}
}
if writeErr != nil {
err = writeErr
break
}
if readN != writeN {
err = io.ErrShortWrite
break
}
}
if readErr == io.EOF {
break
}
if readErr != nil {
err = readErr
break
}
}
return err
}