libs/web: merge luci.http.protocol fix from Fonosfera

See http://trac.fonosfera.org/fon-ng/changeset/2102/trunk/luci/libs/http .

libs/web/luasrc/http/protocol.lua

@@ -434,23 +434,21 @@ function mimedecode_message_body( src, msg, filecb )
 			until not spos
 
 			if found then
-				if #data > 78 then
+				-- We found at least some boundary. Save
-					lchunk = data:sub( #data - 78 + 1, #data )
+				-- the unparsed remaining data for the
-					data   = data:sub( 1, #data - 78 )
+				-- next chunk.
-
-					if store then
-						store( field, data, false )
-					else
-						return nil, "Invalid MIME section header"
-					end
-				else
 				lchunk, data = data, nil
-				end
 			else
+				-- There was a complete chunk without a boundary. Parse it as headers or
+				-- append it as data, depending on our current state.
 				if inhdr then
 					lchunk, eof = parse_headers( data, field )
 					inhdr = not eof
 				else
+					-- We're inside data, so append the data. Note that we only append
+					-- lchunk, not all of data, since there is a chance that chunk
+					-- contains half a boundary. Assuming that each chunk is at least the
+					-- boundary in size, this should prevent problems
 					store( field, lchunk, false )
 					lchunk, chunk = chunk, nil
 				end