| 2e58f12722e308719177949f6850492ffe30c369 |
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15-Jul-2017 |
Bjoern Johansson <bjoernj@google.com> |
Create a DHCP server and client for the emulator
In order to have the system image be flexible about what networks it can
run in it needs to have a DHCP client running on eth0. The emulator
already has a DHCP server and will hand out the same address, gateway
and DNS servers we had already hardcoded so the configuration will
remain the same for user networking. When bridging networks the
hardcoded settings won't work. In this situation the DHCP client will
pick up the configuration from the bridged network and set everything up
so that the system image can work. The repo currently contains a version
of dhcpcd which is also a DHCP client but it doesn't work when running
inside the router namespace because it attempts to read information out
of /sys that is not there when run by execns. This is because execns
does not remount /sys as this is not allowed by the SELinux
configuration on Android (the configuration won't even allow giving the
permission to execns). Additionally dhcpcd would not correctly configure
the system properties for DNS that RIL uses to give access to the
cellular network.
The DHCP server is intended to run on the wireless interface in the
router namespace. Previously the WiFi solution used dnsmasq for this
purpose but it was too inflexible to work on bridged networks. The DHCP
server needs to forward the DNS servers from the outside network to the
WiFi client and dnsmasq could not do this on a bridged network where it
was impossible to know the DNS server address(es) beforehand. The DHCP
server implementation here simply picks up the DNS servers from the
system properties set by the DHCP client. If we are to support multiple
virtual access points we need to have even more control of the DHCP
server in the router namespace since it will have to be aware of the
multiple network interfaces created by hostapd and make sure to hand out
leases that matches the configuration of each of those interfaces.
BUG: 74514143
Test: Build emulator image and manually verify that WiFi is working
Change-Id: I1bff8968ff2af93f01a9509b9557aaa13b0a0874
(cherry picked from commit fdc59b88391cedc4829c590b87c2df466fa7fd33)
(cherry picked from commit 623df714384bd8b86c030f82cb7f301dbd025d1c)
(cherry picked from commit 724322528f159e1a475127d01443ffa5995af881)
/device/generic/goldfish/dhcp/common/dhcp.h
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