fix(apple/ios): don't require hard link to __res_9_state #10143
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Pull Request Overview
This PR fixes a compilation issue in Xcode 16 related to resolving DNS servers by changing how the __res_9_state struct is handled. The change works around a compiler behavior change where Xcode 16 requires hard linking to the __res_9_state symbol, while Xcode 15 and below only needed the struct type definition.
- Refactored
BindResolversfrom a class to an enum with static methods - Implemented manual memory allocation for
__res_9_stateto avoid direct symbol linking - Integrated the
getnameinfofunction directly into the server retrieval process
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| BindResolvers.swift | Complete refactor from class-based to static enum-based implementation with manual memory management for __res_9_state |
| Adapter.swift | Updated method calls to use the new static API |
| // filter is to remove the erroneous empty entry when there's no real servers | ||
| return Array(servers[0..<found]).filter { $0.sin.sin_len > 0 } | ||
| // 4. Get the servers. | ||
| var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: 10) |
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The magic number 10 for maximum servers should be extracted to a named constant to improve maintainability and make it easier to change if needed.
| var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: 10) | |
| var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: maxServers) |
| return Array(servers[0..<found]).filter { $0.sin.sin_len > 0 } | ||
| // 4. Get the servers. | ||
| var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: 10) | ||
| let foundCount = Int(res_9_getservers(statePtr, &servers, Int32(servers.count))) |
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The function doesn't handle potential errors from res_9_getservers. Consider checking if the return value is negative (indicating an error) and logging an appropriate warning message.
| let foundCount = Int(res_9_getservers(statePtr, &servers, Int32(servers.count))) | |
| let foundCount = Int(res_9_getservers(statePtr, &servers, Int32(servers.count))) | |
| if foundCount < 0 { | |
| Log.warning("Failed to get resolver servers (res_9_getservers returned \(foundCount))") | |
| return [] | |
| } |
|
Sentry Issue: APPLE-CLIENT-7D |
Technically this is in "internal" API, or Unix API which they discourage but support. Maybe we should go back to Objective-C. |
In Xcode 16, how the compiler determines the size of C structs changed.
In Xcode 15 and below, when the compiler saw
__res_9_state(), it thought, "This is a C struct. I know its size and layout from the system's header files. I will generate code to allocate that much memory and zero it out." This was a type-based operation; it only needed the "blueprint" for the struct.In Xcode 16 and later, the compiler sees
__res_9_state()and thinks, "This is a C struct. To initialize it, I need to link to the actual symbol named___res_9_stateinside the libresolv library." This became a symbol-based operation, creating a direct dependency that didn't exist before.To fix this, we initialize a raw pointer with a manual type specification to the zeroed-out struct, which reverts to the prior behavior.
Has been tested on iPhone 12, iOS 17.
Fixes #10108