asyn-ares: make a single alloc out of hostname + async data

This saves one alloc per name resolve and simplifies the exit path.

Closes #9310

1 files changed, 7 insertions, 17 deletions

diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c
index 8b620a1d6..fb933b5ed 100644
--- a/lib/asyn-ares.c
+++ b/lib/asyn-ares.c
@@ -115,6 +115,7 @@ struct thread_data {
 #ifndef HAVE_CARES_GETADDRINFO
   struct curltime happy_eyeballs_dns_time; /* when this timer started, or 0 */
 #endif
+  char hostname[1];
 };
 
 /* How long we are willing to wait for additional parallel responses after
@@ -252,8 +253,6 @@ void Curl_resolver_kill(struct Curl_easy *data)
  */
 static void destroy_async_data(struct Curl_async *async)
 {
-  free(async->hostname);
-
   if(async->tdata) {
     struct thread_data *res = async->tdata;
     if(res) {
@@ -265,8 +264,6 @@ static void destroy_async_data(struct Curl_async *async)
     }
     async->tdata = NULL;
   }
-
-  async->hostname = NULL;
 }
 
 /*
@@ -758,25 +755,18 @@ struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct Curl_easy *data,
                                                 int port,
                                                 int *waitp)
 {
-  char *bufp;
-
+  struct thread_data *res = NULL;
+  size_t namelen = strlen(hostname);
   *waitp = 0; /* default to synchronous response */
 
-  bufp = strdup(hostname);
-  if(bufp) {
-    struct thread_data *res = NULL;
-    free(data->state.async.hostname);
-    data->state.async.hostname = bufp;
+  res = calloc(sizeof(struct thread_data) + namelen, 1);
+  if(res) {
+    strcpy(res->hostname, hostname);
+    data->state.async.hostname = res->hostname;
     data->state.async.port = port;
     data->state.async.done = FALSE;   /* not done */
     data->state.async.status = 0;     /* clear */
     data->state.async.dns = NULL;     /* clear */
-    res = calloc(sizeof(struct thread_data), 1);
-    if(!res) {
-      free(data->state.async.hostname);
-      data->state.async.hostname = NULL;
-      return NULL;
-    }
     data->state.async.tdata = res;
 
     /* initial status - failed */