Fix bugs and optimize VPC NAT Gateway script

[zbb88888]

This PR addresses multiple issues in the VPC NAT Gateway data plane script (nat-gateway.sh) and its integration with the Go controller.

Key improvements:

1. Accurate IP Matching: Replaced unreliable grep -w and plain dot matching with escaped dots and precise regex boundaries ((\s|$)) to prevent false positives between single IPs and CIDR prefixes.
2. Security & Robustness: Refactored execNatGwRules in the Go controller to pass arguments as a slice directly to ExecuteCommandInContainer. This eliminates the use of bash -c with string concatenation, closing a potential shell injection vector.
3. Performance Optimization: Minimized expensive iptables-save calls by caching output in local variables within functions that perform multiple rule checks.
4. Shell Script Best Practices:
   • Added set -euo pipefail for immediate failure on errors.
   • Implemented proper positional argument handling using shift and correctly quoted "$@" to preserve argument boundaries.
   • Added explicit argument count validation for all public functions.
   • Added || true to grep assignments to ensure the script doesn't crash when a rule is not found during idempotency checks.
5. Reliable Initialization: Replaced iptables-save | grep chain checks with more direct iptables -t nat -S <CHAIN> checks.

The changes have been verified with a dedicated shell test script covering edge cases and by running relevant controller unit tests.

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PR created automatically by Jules for task 14568608022772563601 started by @zbb88888

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refines the VPC NAT Gateway data plane script and its Go controller integration. The changes focus on improving the accuracy of IP matching, bolstering security by preventing shell injection, and enhancing performance through optimized iptables operations. Additionally, the script now adheres to modern shell scripting best practices, making it more robust and reliable.

Highlights

• Enhanced IP Matching Accuracy: Replaced grep -w with escaped dots and precise regex boundaries ((\s|$)) in nat-gateway.sh to prevent incorrect matches between single IPs and CIDR prefixes, ensuring rules are applied and removed accurately.
• Improved Security and Robustness: Refactored the Go controller's execNatGwRules to pass arguments as a slice directly to ExecuteCommandInContainer, eliminating bash -c string concatenation and mitigating potential shell injection vulnerabilities.
• Optimized Performance: Minimized redundant iptables-save calls in nat-gateway.sh by caching their output in local variables within functions that perform multiple rule checks, reducing execution time.
• Adherence to Shell Script Best Practices: Implemented set -euo pipefail for immediate failure on errors, proper positional argument handling using shift and "$@", explicit argument count validation for all public functions, and added || true to grep assignments for graceful failure when rules are not found.
• Reliable Initialization Checks: Switched from iptables-save | grep to more direct and efficient iptables -t nat -S <CHAIN> commands for verifying the existence of iptables chains during initialization and other checks.

Changelog

• dist/images/vpcnatgateway/nat-gateway.sh
  • Added set -euo pipefail to ensure script exits immediately on errors.
  • Replaced iptables-save | grep checks with iptables -t nat -S for more reliable chain existence verification in check_inited and init functions.
  • Introduced a new escape_for_regex function to properly escape dots in IP addresses for grep patterns.
  • Modified del_eip to use the new escape_for_regex function and a more precise grep -E pattern for accurate IP matching.
  • Updated add_floating_ip, del_floating_ip, add_snat, del_snat, add_hairpin_snat, del_hairpin_snat, add_dnat, and del_dnat functions to cache iptables-save output in local variables to reduce execution time.
  • Enhanced rule matching in add_floating_ip, del_floating_ip, add_snat, del_snat, add_hairpin_snat, del_hairpin_snat, add_dnat, and del_dnat by using escape_for_regex and grep -E with precise regex boundaries ((\s|$)) to avoid false positives.
  • Added argument count validation (if [ $# -lt 1 ]; then ... exit 1; fi) to all public functions.
  • Changed the main script's argument parsing to use shift and "$@" for correct handling of multiple arguments and proper quoting.
  • Added || true to iptables-save and grep commands where their failure is an expected part of idempotency checks, preventing script termination.
  • Updated randomFullyOption assignment in add_snat and add_hairpin_snat to handle cases where it might be empty (${arr[2]:-}).
• pkg/controller/vpc_nat_gateway.go
  • Refactored execNatGwRules to pass command arguments as a slice (args...) directly to util.ExecuteCommandInContainer, removing the insecure bash -c string concatenation.

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[gemini-code-assist]

Code Review

This pull request introduces a comprehensive set of improvements to the VPC NAT Gateway script (nat-gateway.sh) and its Go controller integration. The changes address correctness by using precise regular expressions for IP matching, enhance security by refactoring command execution to prevent shell injection, and improve performance by caching iptables-save results. The shell script is also made significantly more robust through the adoption of best practices like set -euo pipefail, proper argument handling, and input validation. I have reviewed the changes and have no further suggestions.