Fixing OpenSSL Build Errors On Raspberry Pi

Decoding the `libcrypto.so: undefined reference to

poly1305_emit Error in OpenWrt

Hey guys, if you're here, chances are you've run into a nasty build error when trying to compile OpenWrt (or related firmware like LEDE or CoolSnowflake) for your Raspberry Pi. Specifically, the error message libcrypto.so: undefined reference to 'poly1305_emit' is staring you in the face. Don't worry; we've all been there! This often pops up when the build process can't find the necessary functions within the OpenSSL library.

Let's break down what's happening and how to fix it. This error suggests that the linker (the part of the compiler that puts everything together) is missing the poly1305_emit, poly1305_blocks, and poly1305_init functions. These are related to the Poly1305 message authentication code, a cryptographic algorithm. The most common culprit is an incompatibility between the OpenSSL version your build system is using and the other components. Or perhaps, the build configuration isn't linking the necessary libraries properly.

Understanding the Root Cause

OpenSSL Version Conflicts: The core issue is often a mismatch between the OpenSSL version your build environment expects and the one it's finding (or not finding). OpenWrt and its forks rely on a specific set of libraries, and if the OpenSSL version is too old or too new, it can cause these kinds of linking problems. Check your OpenWrt configuration. Some configurations might be missing or disabled.

Build Environment Issues: Sometimes, the problem isn't the version itself, but how your build environment is set up. This could involve missing dependencies, incorrect paths, or problems with how the build system is configured to link against the OpenSSL libraries. Make sure that the dependencies are installed correctly.

Raspberry Pi Specifics: Raspberry Pi boards can be tricky. Ensure your toolchain (the set of compilers, linkers, and other tools) is correctly set up for your specific Pi model (e.g., Raspberry Pi 3, 4, or Zero). The architecture (ARM) and the floating-point options (like hard float) can impact how libraries are built and linked.

Step-by-Step Solutions

1. Update Your OpenWrt Feed:

The first step is always to update your package feeds. Run these commands in your OpenWrt source directory:

./scripts/feeds update -a
./scripts/feeds install -a

This updates the list of available packages and their dependencies. Sometimes, simply updating the feeds resolves the issue by pulling in the correct versions of the required libraries.

2. Clean and Rebuild OpenSSL:

If the feed update doesn't work, try cleaning and rebuilding the OpenSSL package. Inside your OpenWrt source directory, use these commands:

make package/libs/openssl/clean
make package/libs/openssl/compile V=s

The V=s flag provides verbose output, which can be helpful in diagnosing the problem. Cleaning ensures you are starting with a clean slate.

3. Force Rebuild All Packages:

Sometimes, a more aggressive approach is needed. Try this, but be warned, it takes longer.

make clean
make defconfig
make -j$(nproc) world

make clean removes all previously built files, make defconfig configures your build with the default settings, and make -j$(nproc) world builds everything. The -j$(nproc) option uses multiple cores to speed up the build process.

4. Check OpenSSL Version:

Inspect the OpenSSL version in your build configuration. The OpenWrt build system should allow you to select a specific version. If there's a newer or older version available, try switching to it. It might resolve the compatibility issues.

5. Inspect the Build Logs:

Carefully examine the full build logs (the output from the make commands). Look for any other errors or warnings that might provide clues. Sometimes, the poly1305_emit error is a symptom of a larger problem.

• Dependency Issues: Check if there are errors related to missing dependencies. You might need to install additional packages on your build machine (e.g., libtool, automake, autoconf).
• Compiler Flags: Review the compiler flags used during the build. Ensure that the correct flags are being passed to the compiler to properly link the OpenSSL libraries.

6. Modify the OpenWrt Build Configuration:

Use make menuconfig to enter the configuration interface. Search for OpenSSL-related settings.

• Ensure OpenSSL is Selected: Make sure the OpenSSL package is selected for building. It should be under the libraries or security sections.
• Library Linking: Verify that the correct linking options are set. This includes the paths to the OpenSSL libraries and any specific flags required for your target architecture.

7. Consider a Clean Build Environment:

If all else fails, it might be worth setting up a clean build environment. This could involve:

• Using a Docker Container: Docker provides a consistent environment for building OpenWrt. It ensures that all dependencies are installed correctly and reduces conflicts with your host system.
• Reinstalling Build Tools: Sometimes, the tools on your build machine might be corrupted. Reinstalling the build tools (e.g., the toolchain, make, and other utilities) can help.

Example: Troubleshooting Steps

Let's say you're building for a Raspberry Pi 3. Here's how you might approach it:

1. Update Feeds: Run ./scripts/feeds update -a and ./scripts/feeds install -a.
2. Clean and Rebuild OpenSSL: Execute make package/libs/openssl/clean and make package/libs/openssl/compile V=s. Carefully examine the output.
3. Check OpenSSL Version: Go to make menuconfig and make sure you have the correct OpenSSL version selected. If you're using an older OpenWrt version, you may need to downgrade OpenSSL. If you're using a newer OpenWrt version, you may need to upgrade OpenSSL.
4. Full Rebuild: If the above steps fail, try make clean, make defconfig, and make -j$(nproc) world.
5. Examine Logs: Carefully inspect the build logs for any other errors.

Pro Tips and Best Practices

• Backups: Before making significant changes, back up your OpenWrt source directory. This allows you to revert to a working state if something goes wrong.
• Incremental Builds: After fixing a problem, don't always rebuild everything. Use make to rebuild only the necessary packages, which saves time.
• Community Support: Don't hesitate to ask for help on the OpenWrt forums or other relevant communities. Provide detailed information about your build environment, the error messages, and the steps you've taken.
• Documentation: Refer to the OpenWrt documentation. It provides valuable information on building firmware, troubleshooting issues, and configuring packages.
• Consistency: Build in a consistent environment. Use the same build tools and configuration settings each time to avoid unexpected issues.

Final Thoughts

Building OpenWrt firmware can be challenging, but it's also rewarding. The libcrypto.so: undefined reference to 'poly1305_emit' error is a common hurdle, and by following these steps, you should be able to get past it. Remember to be patient, persistent, and don't be afraid to experiment. Good luck, and happy building!

If you're looking for more details on OpenWrt, check out the official OpenWrt documentation at: OpenWrt Documentation