[PR #6797] [MERGED] [client] Fix DNS probe listener impossible panic on unparseable local address #29008

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saavagebueno · 2026-08-05T08:07:18-04:00

saavagebueno commented

2026-08-05 08:07:18 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/6797
Author: @pappz
Created: 7/16/2026
Status: ✅ Merged
Merged: 7/16/2026
Merged by: @pappz

Base: main ← Head: fix/must-parse-err

📝 Commits (2)

c46a101 [client] Fix DNS probe listener panic on unparseable local address
5048c59 [client] Force IPv4 for DNS probe listener

📊 Changes

1 file changed (+4 additions, -6 deletions)

View changed files

📝 client/internal/dns/service_listener.go (+4 -6)

📄 Description

generateFreePort used netip.MustParseAddrPort on the OS-produced LocalAddr().String(), which panics on address strings that don't parse. Eliminate the parsing entirely by reading the port from the concrete *net.UDPAddr that net.ListenUDP returns, and construct the bind address directly. The probe listener is bound with udp4 so only an IPv4 wildcard address is ever used.

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Is it a bug fix
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Created tests that fail without the change (if possible)
This change does not modify the public API, gRPC protocols, functionality behavior, CLI / service flags, or introduce a new feature — OR I have discussed it with the NetBird team beforehand (link the issue / Slack thread in the description). See CONTRIBUTING.md.

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Summary by CodeRabbit

Bug Fixes
- Improved reliability when selecting an ephemeral UDP port.
- Avoided potential failures when determining the assigned port.
- Preserved existing error handling and diagnostic logging for listener operations.

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/netbirdio/netbird/pull/6797 **Author:** [@pappz](https://github.com/pappz) **Created:** 7/16/2026 **Status:** ✅ Merged **Merged:** 7/16/2026 **Merged by:** [@pappz](https://github.com/pappz) **Base:** `main` ← **Head:** `fix/must-parse-err` --- ### 📝 Commits (2) - [`c46a101`](https://github.com/netbirdio/netbird/commit/c46a101c1fe0ad66097d4ca548b6a58eabd09b22) [client] Fix DNS probe listener panic on unparseable local address - [`5048c59`](https://github.com/netbirdio/netbird/commit/5048c5914340fcf8bbbfd7fdd9e5b3645cb5e0f6) [client] Force IPv4 for DNS probe listener ### 📊 Changes **1 file changed** (+4 additions, -6 deletions) <details> <summary>View changed files</summary> 📝 `client/internal/dns/service_listener.go` (+4 -6) </details> ### 📄 Description generateFreePort used netip.MustParseAddrPort on the OS-produced LocalAddr().String(), which panics on address strings that don't parse. Eliminate the parsing entirely by reading the port from the concrete *net.UDPAddr that net.ListenUDP returns, and construct the bind address directly. The probe listener is bound with udp4 so only an IPv4 wildcard address is ever used. ## Describe your changes ## Issue ticket number and link ## Stack  ### Checklist - [x] Is it a bug fix - [ ] Is a typo/documentation fix - [ ] Is a feature enhancement - [ ] It is a refactor - [ ] Created tests that fail without the change (if possible) - [ ] This change does **not** modify the public API, gRPC protocols, functionality behavior, CLI / service flags, or introduce a new feature — **OR** I have discussed it with the NetBird team beforehand (link the issue / Slack thread in the description). See [CONTRIBUTING.md](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTING.md#discuss-changes-with-the-netbird-team-first). > By submitting this pull request, you confirm that you have read and agree to the terms of the [Contributor License Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md). ## Documentation Select exactly one: - [ ] I added/updated documentation for this change - [x] Documentation is **not needed** for this change (explain why) ### Docs PR URL (required if "docs added" is checked) Paste the PR link from https://github.com/netbirdio/docs here: https://github.com/netbirdio/docs/pull/__  ## Summary by CodeRabbit ## Summary by CodeRabbit * **Bug Fixes** * Improved reliability when selecting an ephemeral UDP port. * Avoided potential failures when determining the assigned port. * Preserved existing error handling and diagnostic logging for listener operations.  --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

saavagebueno added the pull-request label 2026-08-05 08:07:18 -04:00

saavagebueno closed this issue

2026-08-05 08:07:18 -04:00

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Reference: DYNR/netbird#29008