gdal_translate cannot download from WMS interface at geoportal.cuzk.cz

[voland]

There is a WMS service in Czech Republic. It can be configured the following way:

<GDAL_WMS>
<Service name="WMS">
<Version>1.3.0</Version>
<ServerUrl>http://geoportal.cuzk.cz/wmsdata13/RASZM10/wms.asp?SID=&amp;</ServerUrl>

<CRS>EPSG:32633</CRS>
<ImageFormat>image/png</ImageFormat>
<Layers>GR_ZM10</Layers>
</Service>

<DataWindow>
<UpperLeftX>540000</UpperLeftX>
<LowerRightX>545000</LowerRightX>
<LowerRightY>5608000</LowerRightY>
<UpperLeftY>5614000</UpperLeftY>

<SizeX>2500</SizeX>
<SizeY>3000</SizeY>
</DataWindow>

<Cache>
<Path>/cache</Path>
<Depth>1</Depth>
</Cache>

<MaxConnections>1</MaxConnections>

<BlockSizeX>500</BlockSizeX>
<BlockSizeY>500</BlockSizeY>

</GDAL_WMS>

It can be run with the following command:

gdal_translate -of ENVI wms.xml test.envi

The very first URL generated by gdal_translate cannot be downloaded:

Input file size is 2500, 3000
0ERROR 1: GDALWMS: Unable to download block 0, 0.
  URL:
http://geoportal.cuzk.cz/wmsdata13/RASZM10/wms.asp?SID=&request=GetMap&version=1.3.0&layers=GR_ZM10&styles=&crs=EPSG:32633&format=image/png&width=500&height=500&bbox=540000.00000000,5613000.00000000,541000.00000000,5614000.00000000
  HTTP status code: 200, error: (null).
ERROR 1: IReadBlock failed at X offset 0, Y offset 0
ERROR 1: GetBlockRef failed at X block offset 0, Y block offset 0

But if opened in Firefox, this URL is downloaded immediately.

It is possible that gdal_translate is missing something in HTTP Header like user agent, session ID or something that allows WMS server to check if it is a web browser or other piece of software.

[warmerdam]

Adam,

Would you be interested in investigating this? If not, reassign back to me, and perhaps I can have Chaitanya look into it.

[Even Rouault]

Voland, yes, your guess is right. That server expects the User-Agent field to be a well-known string, such as "Mozilla/5.0" whereas we currently fill it with "GDAL WMS driver (​http://www.gdal.org/frmt_wms.html)".

Adam, I've attached a patch that provides a new <UserAgent> option to the GDAL WMS XML syntax. I'm not sure if it wouldn't be simpler to just default to "Mozilla/5.0" or some other common browser instead of the "GDAL WMS driver..." string ?

[Even Rouault]

Adds a <UserAgent> option

[nowakpl]

I don't think lying to the server is a good idea.

[voland]

I don't think lying to the server is a good idea.

But it is not a criminal offense to let user decide what "User Agent" they want to use, especially in such rare cases like geoportal.cuzk.cz.

[warmerdam]

I see no harm in letting folks override the user agent, but I would not want the default to be "mozilla". I think the current described and distinct user agent string is the appropriate default.

[Even Rouault]

r19082 /trunk/gdal/frmts/wms/ (5 files): WMS driver : adds a <UserAgent> optional parameter so that the user be able to provide its own useragent string for picky WMS servers (#3464)