[network] handle dns_common not being installed

network/bin/ping.lua

@@ -17,11 +17,17 @@ if (opts["help"] or opts["h"] or #args == 0) then
 end
 ---=============================================================================
 for k, v in pairs(opts) do print(k, v) end
-opts.W         = tonumber(opts.W) or 5
-opts.s         = tonumber(opts.s) or 56
-opts.p         = opts.p or "A"
+opts.W      = tonumber(opts.W) or 5
+opts.s      = tonumber(opts.s) or 56
+opts.p      = opts.p or "A"
 
-local targetIP = ipv4Address.fromString(assert(dns.toip(args[1])))
+--in case dns_common is not installed
+local rawIP = args[1]
+if (dns) then
+    rawIP = assert(dns.toip(args[1]))
+end
+
+local targetIP = ipv4Address.fromString(assert(rawIP))
 local route    = network.router:getRoute(targetIP)
 if (not route) then
     print("No route to destination")
@@ -47,7 +53,7 @@ local function ping()
     if (sent) then
         sentICMP[i] = t
     else
-        print(reason)
+        io.stderr:write(reason .. "\n")
         os.sleep(1)
         ping()
     end

network/lib/socket/dns.lua

@@ -1,7 +1,8 @@
 local os = require("os")
-local resolv = require("resolv")
 local ipv4Address = require("network.ipv4.address")
-local dnsTypes = require("dns")
+local resolvLoaded, resolv = pcall(require, "resolv")
+local dnsTypes
+if (resolvLoaded) then dnsTypes = require("dns") end
 
 ---@class socketdns
 local dns = {}
@@ -21,28 +22,37 @@ function dns.tohostname(address)
     return nil, "not implemented"
 end
 
+---Converts from host name to IP address.\
+---address can be an IP address or host name.\
+---Returns a string with the first IP address found for address, followed by a table with all information returned by the resolver. In case of error, the function returns nil followed by an error message.
+---@param address string
+---@return string? ip
+---@return table|string resolvedOrReason
 function dns.toip(address)
     if (pcall(ipv4Address.fromString, address)) then
         return address, {name = address, alias = {address}, ip = {address}}
     else
-        local msg = resolv.resolve(address, dnsTypes.CLASS.IN, dnsTypes.TYPE.A)
-        if (not msg) then return nil, "address not found" end
-        if (#msg.answer == 0) then
-            return nil, "address not found"
-        end
-        local resolved = {
-            name = (msg.answer[1] --[[@as DNSRessourceRecord]]):getName(),
-            alias = {},
-            ip = {}
-        }
+        if (resolvLoaded) then --resolv may not be installed
+            local msg = resolv.resolve(address, dnsTypes.CLASS.IN, dnsTypes.TYPE.A)
+            if (not msg) then return nil, "address not found" end
+            if (#msg.answer == 0) then
+                return nil, "address not found"
+            end
+            local resolved = {
+                name = (msg.answer[1] --[[@as DNSRessourceRecord]]):getName(),
+                alias = {},
+                ip = {}
+            }
 
-        local ip = ipv4Address.tostring((msg.answer[1] --[[@as DNSRessourceRecord]]):getRdata())
-        for _, answer in pairs(msg.answer) do
-            ---@cast answer DNSRessourceRecord
-            table.insert(resolved.ip, ipv4Address.tostring(answer:getRdata()))
-            table.insert(resolved.alias, answer:getName())
+            local ip = ipv4Address.tostring((msg.answer[1] --[[@as DNSRessourceRecord]]):getRdata())
+            for _, answer in pairs(msg.answer) do
+                ---@cast answer DNSRessourceRecord
+                table.insert(resolved.ip, ipv4Address.tostring(answer:getRdata()))
+                table.insert(resolved.alias, answer:getName())
+            end
+            return ip, resolved
         end
-        return ip, resolved
+        return nil, "No dns resolver installed"
     end
 end
 

network/lib/socket/init.lua

@@ -1,4 +1,5 @@
 return {
     udp = require("socket.udp"),
-    dns = require("socket.dns")
+    ---@type socketdns
+    dns = select(2, pcall(require, "socket.dns"))
 }