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Re-Add DHCP discover fallback for ISPs that don't advertise DHCP

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This commit is contained in:
lordwelch 2021-05-23 19:38:38 -07:00
parent e34b880a55
commit b801bf699f
1 changed files with 15 additions and 1 deletions
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16
internal/dhcp4/dhcp4.go
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@ -52,6 +52,8 @@ type Client struct {
timeNow func() time.Time timeNow func() time.Time
generateXID func() uint32 generateXID func() uint32
timeoutCount int
// last DHCPACK packet for renewal/release // last DHCPACK packet for renewal/release
Ack *layers.DHCPv4 Ack *layers.DHCPv4
} }
@ -129,7 +131,18 @@ func (c *Client) ObtainOrRenew() bool {
ack, err := c.dhcpRequest() ack, err := c.dhcpRequest()
if err != nil { if err != nil {
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EAGAIN { if errno, ok := err.(syscall.Errno); ok && errno == syscall.EAGAIN {
c.err = fmt.Errorf("DHCP: timeout (server(s) unreachable)") var serverip net.IP
for _, opt := range c.Ack.Options {
if opt.Type == layers.DHCPOptServerID {
serverip = opt.Data
}
}
c.err = fmt.Errorf("DHCP: timeout (server(s) unreachable: %v)", serverip)
c.timeoutCount++
if c.timeoutCount > 3 {
c.timeoutCount = 0
c.Ack = nil // start over at DHCPDISCOVER it has failed 3 times
}
return true // temporary error return true // temporary error
} }
if err == errNAK { if err == errNAK {
@ -154,6 +167,7 @@ func (c *Client) ObtainOrRenew() bool {
} }
} }
c.cfg.RenewAfter = c.timeNow().Add(lease.RenewalTime) c.cfg.RenewAfter = c.timeNow().Add(lease.RenewalTime)
c.timeoutCount = 0
return true return true
} }