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Fix duplicate iptables rules

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If iptables version is < 1.4.11, try to delete the rule vs. checking if it exists. Fixes #6831.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jfrazelle@users.noreply.github.com> (github: jfrazelle)
This commit is contained in:
Jessica Frazelle 2014-07-10 00:22:01 -04:00 committed by Jessica Frazelle
parent 884c3c7461
commit 3ed103c543
1 changed files with 21 additions and 3 deletions
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24
iptables/iptables.go
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@ -6,6 +6,7 @@ import (
"net"
"os"
"os/exec"
"regexp"
"strconv"
"strings"
)
@ -141,12 +142,29 @@ func (c *Chain) Remove() error {
// Check if an existing rule exists
func Exists(args ...string) bool {
if _, err := Raw(append([]string{"-C"}, args...)...); err != nil {
return false
}
// iptables -C, --check option was added in v.1.4.11
// http://ftp.netfilter.org/pub/iptables/changes-iptables-1.4.11.txt
// try -C
// if exit status is 0 then return true, the rule exists
if _, err := Raw(append([]string{"-C"}, args...)...); err == nil {
return true
}
// parse iptables-save for the rule
rule := strings.Replace(strings.Join(args, " "), "-t nat ", "", -1)
existingRules, _ := exec.Command("iptables-save").Output()
// regex to replace ips in rule
// because MASQUERADE rule will not be exactly what was passed
re := regexp.MustCompile(`[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]{1,2}`)
return strings.Contains(
re.ReplaceAllString(string(existingRules), "?"),
re.ReplaceAllString(rule, "?"),
)
}
func Raw(args ...string) ([]byte, error) {
path, err := exec.LookPath("iptables")
if err != nil {