panic: runtime error: invalid memory address or nil pointer dereference

[darrencloutier]

Not sure if this is a bug or just something with my setup. Occasionally seeing this error below (every few days). The container restarts itself and all is good, but I do lose my cache when it happens. I did just turn on prometheus metrics...might be related?

Here's my docker logs:

========================================
========================================
================= dns ==================
========================================
=========== Made with ❤️ by ============
======= https://github.com/qdm12 =======
========================================
========================================

Running version v2.0.0-beta built on 2021-10-30T19:50:35Z (commit a750d22)

📣 Check out qmcgaw/dns:v2.0.0-beta

🔧 Need help? https://github.com/qdm12/dns/discussions/new
🐛 Bug? https://github.com/qdm12/dns/issues/new
✨ New feature? https://github.com/qdm12/dns/issues/new
☕ Discussion? https://github.com/qdm12/dns/discussions/new
💻 Email? quentin.mcgaw@gmail.com
💰 Help me? https://www.paypal.me/qmcgaw https://github.com/sponsors/qdm12
2021/11/16 20:44:40 INFO Settings summary:
 |--Upstream type: DoT
 |--DoT settings:
    |--Resolver:
       |--DNS over TLS providers:
          |--Cloudflare
          |--Google
       |--Fallback plaintext DNS providers:
          |--Google
       |--Query timeout: 3s
       |--Connecting over: IPv4
    |--Listening address: :53
 |--Cache settings:
    |--Cache type: lru
    |--Max entries: 10000
 |--Log settings:
    |--Level: INFO
 |--Metrics settings:
    |--Type: prometheus
    |--Listening address: :9090
 |--Filter settings:
    |--Blocked categories: 
    |--IP networks unblocked: 0
    |--Additional IP networks blocked: 13
 |--Check DNS: enabled
 |--Update: every 24h0m0s
2021/11/16 20:44:40 INFO healthcheck server: listening on 127.0.0.1:9999
2021/11/16 20:44:40 INFO using DNS address 127.0.0.1 internally
2021/11/16 20:44:40 INFO prometheus serverlistening on :9090
2021/11/16 20:44:40 INFO starting DNS server
2021/11/16 20:44:40 INFO DNS server listening on :53
2021/11/16 20:44:40 INFO restarting DNS server the first time to get updated files
2021/11/16 20:44:40 INFO downloading and building DNS block lists
2021/11/16 20:44:40 INFO 0 hostnames blocked overall
2021/11/16 20:44:40 INFO 0 IP addresses blocked overall
2021/11/16 20:44:40 INFO 13 IP networks blocked overall
2021/11/16 20:44:40 INFO starting DNS server
2021/11/16 20:44:40 INFO DNS server listening on :53
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47538->1.1.1.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47554->1.1.1.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49796->1.0.0.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49758->1.0.0.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49784->1.0.0.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47614->1.1.1.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47628->1.1.1.1:853: i/o timeout
2021/11/17 00:54:18 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49780->1.0.0.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47594->1.1.1.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47640->1.1.1.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49820->1.0.0.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47630->1.1.1.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:49776->1.0.0.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47668->1.1.1.1:853: i/o timeout
2021/11/17 00:54:19 WARN cannot exchange over DoT connection: write tcp 172.24.0.3:47582->1.1.1.1:853: i/o timeout
2021/11/17 20:44:40 INFO planned periodic restart of DNS server
2021/11/17 20:44:40 INFO downloading and building DNS block lists
2021/11/17 20:44:40 INFO 0 hostnames blocked overall
2021/11/17 20:44:40 INFO 0 IP addresses blocked overall
2021/11/17 20:44:40 INFO 13 IP networks blocked overall
2021/11/17 20:44:40 INFO starting DNS server
2021/11/17 20:44:40 INFO DNS server listening on :53
2021/11/18 20:44:40 INFO planned periodic restart of DNS server
2021/11/18 20:44:40 INFO downloading and building DNS block lists
2021/11/18 20:44:40 INFO 0 hostnames blocked overall
2021/11/18 20:44:40 INFO 0 IP addresses blocked overall
2021/11/18 20:44:40 INFO 13 IP networks blocked overall
2021/11/18 20:44:40 INFO starting DNS server
2021/11/18 20:44:40 INFO DNS server listening on :53
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x4195a4]

goroutine 97688 [running]:
github.com/qdm12/dns/pkg/dot.onDialError({0x61645c, 0x23544e0}, {0x4e0ab6, 0x12}, {0x21e6900, 0xb}, 0x22e34f0, {0x615488, 0x200e6b8}, 0x0, ...)
	github.com/qdm12/dns/pkg/dot/dial.go:78 +0x14
github.com/qdm12/dns/pkg/dot.newDoTDial.func1({0x61645c, 0x23544e0}, {0x0, 0x0}, {0x0, 0x0})
	github.com/qdm12/dns/pkg/dot/dial.go:35 +0x2f4
github.com/qdm12/dns/pkg/dot.(*handler).ServeDNS(0x2354510, {0x61b520, 0x2404990}, 0x265c140)
	github.com/qdm12/dns/pkg/dot/handler.go:48 +0x2d0
github.com/qdm12/dns/pkg/middlewares/log.(*handler).ServeDNS(0x20b28b8, {0x61b520, 0x2404888}, 0x265c140)
	github.com/qdm12/dns/pkg/middlewares/log/log.go:34 +0xcc
github.com/qdm12/dns/pkg/middlewares/metrics.(*handler).ServeDNS(0x21e4090, {0x61b4c0, 0x2216540}, 0x265c140)
	github.com/qdm12/dns/pkg/middlewares/metrics/middleware.go:41 +0x108
github.com/miekg/dns.(*Server).serveDNS(0x2208140, {0x2176200, 0x27, 0x200}, 0x2216540)
	github.com/miekg/dns@v1.1.43/server.go:651 +0x500
github.com/miekg/dns.(*Server).serveUDPPacket(0x2208140, 0x21e6560, {0x2176200, 0x27, 0x200}, {0x61a5a0, 0x200e6d0}, 0x28c2300, {0x0, 0x0})
	github.com/miekg/dns@v1.1.43/server.go:591 +0x18c
created by github.com/miekg/dns.(*Server).serveUDP
	github.com/miekg/dns@v1.1.43/server.go:521 +0x3ac

[qdm12]

Thanks for taking the time to report the issue! It's fixed now, I was trying to log out an 'empty' (nil) error instead of the actual error when DoT dialing failed, so that was panicking (occasionally because it fails occasionally).

[darrencloutier]

Wow! Thanks so much for the help! I just pulled the latest version and will give it a shot! Thanks for all your work...I appreciate it!