forked from valyala/fasthttp
/
tcpdialer.go
154 lines (133 loc) · 2.97 KB
/
tcpdialer.go
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package fasthttp
import (
"net"
"strconv"
"sync"
"sync/atomic"
"time"
)
// TCP dialers used by client.
//
// These dialers are intended for custom code wrapping before passing
// to Client.Dial or HostClient.Dial.
//
// For instance, per-host counters and/or limits may be implemented
// by such wrappers.
//
// The addr passed to dial func must contain port. Example addr values:
//
// * foobar.baz:443
// * foo.bar:80
// * aaa.com:8080
var (
// Dial dials the given addr using tcp4.
Dial = DialFunc((&tcpDialer{}).NewDial())
// DialDualStack dials the given addr using both tcp4 and tcp6.
DialDualStack = DialFunc((&tcpDialer{DualStack: true}).NewDial())
)
type tcpDialer struct {
DualStack bool
tcpAddrsLock sync.Mutex
tcpAddrsMap map[string]*tcpAddrEntry
}
func (d *tcpDialer) NewDial() DialFunc {
if d.tcpAddrsMap != nil {
panic("BUG: NewDial() already called")
}
d.tcpAddrsMap = make(map[string]*tcpAddrEntry)
go d.tcpAddrsClean()
return func(addr string) (net.Conn, error) {
tcpAddr, err := d.getTCPAddr(addr)
if err != nil {
return nil, err
}
network := "tcp4"
if d.DualStack {
network = "tcp"
}
return net.DialTCP(network, nil, tcpAddr)
}
}
type tcpAddrEntry struct {
addrs []net.TCPAddr
addrsIdx uint32
resolveTime time.Time
pending bool
}
var tcpAddrsCacheDuration = time.Minute
func (d *tcpDialer) tcpAddrsClean() {
expireDuration := 2 * tcpAddrsCacheDuration
for {
time.Sleep(time.Second)
t := time.Now()
d.tcpAddrsLock.Lock()
for k, e := range d.tcpAddrsMap {
if t.Sub(e.resolveTime) > expireDuration {
delete(d.tcpAddrsMap, k)
}
}
d.tcpAddrsLock.Unlock()
}
}
func (d *tcpDialer) getTCPAddr(addr string) (*net.TCPAddr, error) {
d.tcpAddrsLock.Lock()
e := d.tcpAddrsMap[addr]
if e != nil && !e.pending && time.Since(e.resolveTime) > tcpAddrsCacheDuration {
e.pending = true
e = nil
}
d.tcpAddrsLock.Unlock()
if e == nil {
tcpAddrs, err := resolveTCPAddrs(addr, d.DualStack)
if err != nil {
d.tcpAddrsLock.Lock()
e = d.tcpAddrsMap[addr]
if e != nil && e.pending {
e.pending = false
}
d.tcpAddrsLock.Unlock()
return nil, err
}
e = &tcpAddrEntry{
addrs: tcpAddrs,
resolveTime: time.Now(),
}
d.tcpAddrsLock.Lock()
d.tcpAddrsMap[addr] = e
d.tcpAddrsLock.Unlock()
}
tcpAddr := &e.addrs[0]
n := len(e.addrs)
if n > 1 {
n := atomic.AddUint32(&e.addrsIdx, 1)
tcpAddr = &e.addrs[n%uint32(n)]
}
return tcpAddr, nil
}
func resolveTCPAddrs(addr string, dualStack bool) ([]net.TCPAddr, error) {
host, portS, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
port, err := strconv.Atoi(portS)
if err != nil {
return nil, err
}
ips, err := net.LookupIP(host)
if err != nil {
return nil, err
}
n := len(ips)
addrs := make([]net.TCPAddr, 0, n)
for i := 0; i < n; i++ {
ip := ips[i]
if !dualStack && ip.To4() == nil {
continue
}
addrs = append(addrs, net.TCPAddr{
IP: ip,
Port: port,
})
}
return addrs, nil
}