CPL/HTTP: Include Response Code in CPLHTTPResult.

[SpencerDWallace]

Feature description

APIs may use HTTP response codes to distinguish errors with the request. Currently, the caller of CPLHTTPFetch (and similar) is unable to retrieve the HTTP response code. I would request that a field for the response code is added to CPLHTTPResult.

Additional context

I could work on this if the feature is acceptable

[jratike80]

Test with a not-existing OGC API Features collection and ogrinfo shows HTTP code for me

ERROR 1: HTTP error code : 404
ERROR 1: {
  "code" : "404",
  "description" : "Exception occurred"
}
ogrinfo failed - unable to open 'oapif:https://....

With configuration option --config cpl_curl_verbose on much more info about the http traffic is shown. So perhaps the information that you want is already available, but in some other way.

[rouault]

I would request that a field for the response code is added to CPLHTTPResult.

That would indeed make sense to have a nHTTPResponseCode member in CPLHTTPResult. Contribution welcome.

Even more welcome, if you could at the same time clean up a few drivers that happen to parse the current error message to extract the error code from it, to update them to use the new member:

$ grep -r "HTTP error code" ../frmts/
../frmts/daas/daasdataset.cpp:                       "HTTP error code : ", strlen("HTTP error code : ")))
../frmts/daas/daasdataset.cpp:                    atoi(psResult->pszErrBuf + strlen("HTTP error code : "));
../frmts/eeda/eedacommon.cpp:                       "HTTP error code : ", strlen("HTTP error code : ")))
../frmts/eeda/eedacommon.cpp:                    atoi(psResult->pszErrBuf + strlen("HTTP error code : "));
../frmts/wms/gdalhttp.cpp:                strcmp(psResult->pszErrBuf, "HTTP error code : 404") == 0)