Shared: Provide custom isURI that rejects unknown schemes [isURI]

We also export the set of known `schemes`.

The new function replaces the function of the same name
from `Network.URI`, as the latter did not check whether a scheme is
well-known.  E.g. MediaWiki wikis frequently feature pages with names
like `User:John`. These links were interpreted as URIs, thus turning
internal links into global links. This is prevented by also checking
whether the scheme of a URI is frequently used (i.e. is IANA registered
or an otherwise well-known scheme).

Fixes: #2713

Update set of well-known URIs from IANA list
All official IANA schemes (as of 2017-05-22) are included in the set of
known schemes.  The four non-official schemes doi, isbn, javascript, and
pmid are kept.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/Text/Pandoc/SelfContained.hs b/src/Text/Pandoc/SelfContained.hs
index f8ad43b1e..55df147b6 100644
--- a/src/Text/Pandoc/SelfContained.hs
+++ b/src/Text/Pandoc/SelfContained.hs
@@ -42,7 +42,7 @@ import qualified Data.ByteString.Char8 as B
 import qualified Data.ByteString.Lazy as L
 import Data.Char (isAlphaNum, isAscii, toLower)
 import Data.List (isPrefixOf)
-import Network.URI (URI (..), escapeURIString, isURI, parseURI)
+import Network.URI (URI (..), escapeURIString, parseURI)
 import System.FilePath (takeDirectory, takeExtension, (</>))
 import Text.HTML.TagSoup
 import Text.Pandoc.Class (PandocMonad (..), fetchItem, report)
@@ -50,7 +50,7 @@ import Text.Pandoc.Error
 import Text.Pandoc.Logging
 import Text.Pandoc.MIME (MimeType)
 import Text.Pandoc.Options (WriterOptions (..))
-import Text.Pandoc.Shared (renderTags', trim)
+import Text.Pandoc.Shared (isURI, renderTags', trim)
 import Text.Pandoc.UTF8 (toString)
 import Text.Parsec (ParsecT, runParserT)
 import qualified Text.Parsec as P