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all: fix bug that causes ctrld stop working if bootstrap failed

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The bootstrap process has two issues that can make ctrld stop resolving
after restarting machine host.

ctrld uses bootstrap DNS and os nameservers for resolving upstream. On
unix, /etc/resolv.conf content is used to get available nameservers.
This works well when installing ctrld. However, after being installed,
ctrld may modify the content of /etc/resolv.conf itself, to make other
apps use its listener as DNS resolver. So when ctrld starts after OS
restart, it ends up using [bootstrap DNS + ctrld's listener], for
resolving upstream. At this moment, if ctrld could not contact bootstrap
DNS for any reason, upstream domain will not be resolved.

For above reason, an upstream may not have bootstrap IPs after ctrld
starts. When re-bootstrapping, if there's no bootstrap IPs, ctrld should
call the setup bootstrap process again. Currently, it does not, causing
all queries failed.

This commit fixes above issue by adding mechanism for retrieving OS
nameservers properly, by querying routing table information:

 - Parsing /proc/net subsystem on Linux.
 - For BSD variants, just fetching routing information base from OS.
 - On Windows, just include the gateway information when reading iface.

The fixing for second issue is trivial, just kickoff a bootstrap process
if there's no bootstrap IPs when re-boostrapping.

While at it, also ensure that fetching resolver information from
ControlD API is also used the same approach.

Fixes #34
This commit is contained in:
Cuong Manh Le
2023-03-30 18:25:36 +07:00
committed by Cuong Manh Le
parent ba48ff5965
commit b65a5ac283
10 changed files with 280 additions and 64 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
go.mod
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@@ -20,6 +20,7 @@ require (
github.com/spf13/cobra v1.4.0
github.com/spf13/viper v1.14.0
github.com/stretchr/testify v1.8.1
golang.org/x/net v0.7.0
golang.org/x/sync v0.1.0
golang.org/x/sys v0.5.0
golang.zx2c4.com/wireguard/windows v0.5.3
@@ -68,7 +69,6 @@ require (
golang.org/x/crypto v0.4.0 // indirect
golang.org/x/exp v0.0.0-20221205204356-47842c84f3db // indirect
golang.org/x/mod v0.6.0 // indirect
golang.org/x/net v0.7.0 // indirect
golang.org/x/text v0.7.0 // indirect
golang.org/x/tools v0.2.0 // indirect
gopkg.in/ini.v1 v1.67.0 // indirect