Configuration-Option on how OAPIF-Driver generates error-messages

[hebersgit]

Feature description

Provide an option on how in OGROAPIFDataset::Download, in conditional block if (psResult->pszErrBuf != nullptr) (currently line 434 ff) the error is generated. There is an assumption made that psResult->pabyData contains the error-text which isn't true in all cases and depends on the server and the type of error which occured in CPLHTTPFetchEx . It would be safer to prefer content of psResult->pszErrBuf instead of psResult->pabyData.

Additional context

On some computer I have no debugging-access to, the following occured:
While processing the OAPIF-Download within CPLHTTPFetchEx (gdal/port/cpl_http.cpp) and using curl, an error "Send failure: Connection was aborted." occured, but the download-result seems to be completely fetched. So psResult->pabyData contains the regular GeoJson-response from the server, while psResult->pszErrBuf contains the error-text ("Send failure: Connection was aborted."). In OGROAPIFDataset::Download in the conditional block if (psResult->pszErrBuf != nullptr), an error is generated containing the whole OGC Feature-API GeoJson as error-text!

[rouault]

@hebersgit Can you point to this server? But at first sight, I don't see anything wrong in the current implementation of the OAPIF driver. The pabyData could very well be corrupted if pszErrBuf is not null. This looks like a server issue, not a client one

[hebersgit]

Hi Even, thank you for inspecting this request. I'm sorry, but this server can't be accessed from outside at the moment. We use geoserver with an own API-gateway before it. I fully agree to you, that this is a problem with the server or the connection to it. Additionally, the problem occurs only occasionally.
What I mean is the following: In OGROAPIFDataset::Download, if psResult->pszErrBuf != nullptr, one can't rely on the fact that psResult->pabyData contains an error-message. If one handles the received errors (if GetFeature() returns null e.g.) by inspecting the last error message, the information on the error is lost because psResult->pszErrBuf isn't used. Therefore, I would propose to change ogroapifdriver.cpp, lines 435-437 to always use psResult->pszErrBuf and never psResult->pabyData (or at least a concatenation of psResult->pszErrBuf and psResult->pabyData).