Merge pull request #1108 from SmartThingsCommunity/fix/sonos-discover…

…y-non-ascii-name-failure

drivers/SmartThings/sonos/src/ssdp.lua

@@ -8,9 +8,32 @@ SONOS_SSDP_SEARCH_TERM = "urn:smartspeaker-audio:service:SpeakerGroup:1"
 local SSDP = {}
 
 local function process_response(val)
-  local info = {}
+  -- check first line assuming it's the HTTP Status Line, which if not is invalid
+  local status_line = string.match(val, "([^\r\n]*)\r\n")
+  if not (status_line and string.match(status_line, "HTTP/1.1 200 OK"))  then
+    return nil, string.format("SSDP Response HTTP Status Line missing or not '200 OK': %q", status_line)
+  end
+  -- strip status line from payload
   val = string.gsub(val, "HTTP/1.1 200 OK\r\n", "", 1)
-  for k, v in string.gmatch(val, "([%g]+): ([%g ]*)\r\n") do
+
+  local info = {}
+  -- iterate line-by-line by splitting on `\r\n`
+  for l in string.gmatch(val, "([^\r\n]*)\r\n") do
+    if l == nil or l == "" then
+      break
+    end
+    -- SSDP Messages use the HTTP/1.1 Header Field rules described in RFC 2616, 4.2: https://datatracker.ietf.org/doc/html/rfc2616#section-4.2
+    -- This pattern extracts the Key/Value pairs in to a Lua table via the two capture groups.
+    -- The key capture group is composed entirely of a negating matcher to exclude illegal characters, ending at the `:`.
+    -- The RFC states that after the colon there may be any arbitrary amount of leading space between the colon
+    -- and the value, and that the value shouldn't have any trailing whitespace, so we exclude those as well.
+    -- The original Luncheon implementation of this Lua Pattern used iteration and detected the `;` separator
+    -- that indicates key/value parameters, however, we don't make that distinction here and instead leave parsing
+    -- values with parameters to the consumers of the output of this function.
+    local k, v = string.match(l, '([^%c()<>@,;:\\"/%[%]?={} \t]+):%s*(.-)%s*$')
+    if k == nil or k == "" then
+      return nil, string.format("Couldn't parse header/value pair for line %q", l)
+    end
     info[string.lower(k)] = v
   end
   return info
@@ -21,7 +44,10 @@ function SSDP.check_headers_contain(response, ...)
   local header_vals = table.pack(...)
   for _, header in ipairs(header_vals) do
     if header ~= nil then
-      if not response[header] then return false end
+      if not response[header] then
+        log.warn("No header available for key " .. st_utils.stringify_table(header))
+        return false
+      end
     end
   end
   return true
@@ -74,12 +100,28 @@ function SSDP.search(search_term, callback)
     local val, rip, _ = s:receivefrom()
 
     if val then
-      local headers = process_response(val)
+      local headers, err = process_response(val)
+
+      if err ~= nil then
+        log.error(err or "Unknown error while parsing SSDP response headers")
+        goto continue
+      end
+
+      if headers == nil then
+        log.error("No headers found in SSDP response")
+        goto continue
+      end
+
+      if headers["st"] ~= search_term then
+        log.trace("Received SSDP response for different search term, skipping.")
+        goto continue
+      end
 
-      -- log all SSDP responses, even if they don't have proper headers
+      -- log all parseable SSDP responses for the search term,
+      -- even if they don't have proper headers.
       log.debug_with({ hub_logs = true },
-        string.format("Received response for Sonos search with headers [%s], processing details",
-          st_utils.stringify_table(headers)))
+      string.format("Received response for Sonos search with headers [%s], processing details",
+        st_utils.stringify_table(headers)))
       if
       -- we don't explicitly check "st" because we don't index in to the contained
       -- value so the equality check suffices as a nil check as well.
@@ -89,8 +131,7 @@ function SSDP.search(search_term, callback)
             "location",
             "groupinfo.smartspeaker.audio",
             "websock.smartspeaker.audio",
-            "household.smartspeaker.audio") and
-          headers["st"] == search_term and headers["server"]:find("Sonos")
+            "household.smartspeaker.audio") and headers["server"]:find("Sonos")
       then
         local ip =
             headers["location"]:match("http://([^,/]+):[^/]+/.+%.xml")
@@ -145,6 +186,7 @@ function SSDP.search(search_term, callback)
         "error receiving discovery replies for search term: %s",
         rip))
     end
+    ::continue::
   end
   s:close()
 end