net.dns: Try next server if peer name can not be set (thanks wirehack7)

diff --git a/net/dns.lua b/net/dns.lua
index 55622fc81ccadf2f8c5f172d1ddaf86b1e93427c..13417ceeaa368a34b7a35fb7e6bea5f81ef1c077 100644 (file)
--- a/net/dns.lua
+++ b/net/dns.lua
@@ -622,7 +622,7 @@ function resolver:getsocket(servernum)    -- - - - - - - - - - - - - getsocket
        local sock = self.socket[servernum];
        if sock then return sock; end
 
-       local err;
+       local ok, err;
        sock, err = socket.udp();
        if sock and self.socket_wrapper then sock, err = self.socket_wrapper(sock, self); end
        if not sock then
@@ -630,10 +630,14 @@ function resolver:getsocket(servernum)    -- - - - - - - - - - - - - getsocket
        end
        sock:settimeout(0);
        -- todo: attempt to use a random port, fallback to 0
-       sock:setsockname('*', 0);
-       sock:setpeername(self.server[servernum], 53);
        self.socket[servernum] = sock;
        self.socketset[sock] = servernum;
+       -- set{sock,peer}name can fail, eg because of local routing table
+       -- if so, try the next server
+       ok, err = sock:setsockname('*', 0);
+       if not ok then return self:servfail(sock, err); end
+       ok, err = sock:setpeername(self.server[servernum], 53);
+       if not ok then return self:servfail(sock, err); end
        return sock;
 end
 
@@ -781,7 +785,7 @@ function resolver:query(qname, qtype, qclass)    -- - - - - - - - - - -- query
        return true;
 end
 
-function resolver:servfail(sock)
+function resolver:servfail(sock, err)
        -- Resend all queries for this server
 
        local num = self.socketset[sock]
@@ -804,7 +808,7 @@ function resolver:servfail(sock)
                                        --print('timeout');
                                        queries[question] = nil;
                                else
-                                       sock = self:getsocket(o.server);
+                                       sock, err = self:getsocket(o.server);
                                        if sock then sock:send(o.packet); end
                                end
                        end
@@ -821,7 +825,7 @@ function resolver:servfail(sock)
                        self.best_server = 1;
                end
        end
-       return sock;
+       return sock, err;
 end
 
 function resolver:settimeout(seconds)