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WSAENAMETOOLONG
WSAENAMETOOLONG indicates a length failure in name processing. In networking code the value may surface through BSD-compatible or provider-specific paths, so it is important to identify the exact name after all local transformations.
The original input may not be the failing name
Resolver code can append DNS search suffixes, convert an internationalized name, or construct a service lookup key. DNS itself has protocol limits: RFC 1035 defines labels with a maximum of 63 octets and a complete domain name representation limited to 255 octets. Those wire-format rules are different from filesystem path limits and from an application's own fixed buffer size.
Diagnostic checklist
- Log the name immediately before the failing Winsock call, including its byte length and encoding.
- Record suffix expansion and any IDN conversion performed before lookup.
- Check fixed-size buffers in portability layers and namespace providers.
Do not truncate a hostname merely to make the call succeed. Truncation changes the lookup key and can silently target a different name. Reject or correct the source value instead.
Microsoft: Winsock error codes · IETF: DNS domain name limits · POSIX: errno.h
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