There is a class EPiServer.Globalization.HostLanguageResolver that might help you. There is a method GetHostForLanguage that you can use. The second parameter is the siteUrl for the site you want a host for, to use current site you can pass in EPiServer.Web.SiteDefinition.Current.SiteUrl.ToString()

Any example code you could provide?

Below is some code that iterates over all enabled languages and checks if they are mapped to a specific host (for current site). Note that the method returns null if the langauge is not mapped.

var languageHostResolver = ServiceLocator.Current.GetInstance<HostLanguageResolver>();
var currentSiteUrl = SiteDefinition.Current.SiteUrl.ToString();
foreach (var languageBranch in ServiceLocator.Current.GetInstance<ILanguageBranchRepository>().ListEnabled())
{
        var host = languageHostResolver.GetHostForLanguage(languageBranch.LanguageID, currentSiteUrl);
}

This dosen't work: var currentSiteUrl = SiteDefinition.Current.SiteUrl.ToString();

I get the error: 'EPiServer.Licensing.Services.SiteDefinition' does not contain a definition for 'Current'

What reference am i missing?

SiteDefinition resides in EPiServer.Web namespace (in EPiServer.dll)

Thanks, found it the second you reply. Now it works. :)

Thanks, Johan your solution helped me as well