--- /dev/null
+/* Async DNS lookup. Shows passing complex data through pool. */
+#include "ccan/antithread/antithread.h"
+#include "ccan/string/string.h"
+#include "ccan/talloc/talloc.h"
+#include "md5_finder.h"
+#include <err.h>
+#include <sys/select.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <netdb.h>
+
+struct lookup_answer {
+ bool ok;
+ union {
+ struct hostent hent;
+ int herrno; /* If !ok */
+ };
+};
+
+/* Including NULL terminator. */
+static inline unsigned count_entries(char **entries)
+{
+ unsigned int i;
+
+ for (i = 0; entries[i]; i++);
+ return i+1;
+}
+
+/* Copy as one nice tallocated object. Since ans is in the pool, it
+ * all gets put in the pool. */
+static void copy_answer(struct lookup_answer *ans, const struct hostent *host)
+{
+ unsigned int i;
+
+ ans->hent.h_name = talloc_strdup(ans, host->h_name);
+ ans->hent.h_aliases = talloc_array(ans, char *,
+ count_entries(host->h_aliases));
+ for (i = 0; host->h_aliases[i]; i++)
+ ans->hent.h_aliases[i] = talloc_strdup(ans->hent.h_aliases,
+ host->h_aliases[i]);
+ ans->hent.h_aliases[i] = NULL;
+ ans->hent.h_addrtype = host->h_addrtype;
+ ans->hent.h_length = host->h_length;
+ ans->hent.h_addr_list = talloc_array(ans, char *,
+ count_entries(host->h_addr_list));
+ for (i = 0; host->h_addr_list[i]; i++)
+ ans->hent.h_addr_list[i] = talloc_memdup(ans->hent.h_addr_list,
+ host->h_addr_list[i],
+ ans->hent.h_length);
+}
+
+static void *lookup_dns(struct at_pool *atp, char *name)
+{
+ struct lookup_answer *ans;
+ struct hostent *host;
+
+ host = gethostbyname(name);
+
+ ans = talloc(at_pool_ctx(atp), struct lookup_answer);
+ if (!host) {
+ ans->ok = false;
+ ans->herrno = h_errno;
+ } else {
+ ans->ok = true;
+ copy_answer(ans, host);
+ }
+
+ return ans;
+}
+
+static void report_answer(const char *name, const struct lookup_answer *ans)
+{
+ unsigned int i;
+
+ if (!ans->ok) {
+ printf("%s: %s\n", name, hstrerror(ans->herrno));
+ return;
+ }
+
+ printf("%s: ", name);
+ for (i = 0; ans->hent.h_aliases[i]; i++)
+ printf("%c%s", i == 0 ? '[' : ' ', ans->hent.h_aliases[i]);
+ if (i)
+ printf("]");
+ printf("%#x", ans->hent.h_addrtype);
+ for (i = 0; ans->hent.h_addr_list[i]; i++) {
+ unsigned int j;
+ printf(" ");
+ for (j = 0; j < ans->hent.h_length; j++)
+ printf("%02x", ans->hent.h_addr_list[i][j]);
+ }
+ printf("\n");
+}
+
+int main(int argc, char *argv[])
+{
+ struct at_pool *atp;
+ struct athread **at;
+ unsigned int i;
+
+ if (argc < 2)
+ errx(1, "Usage: dns_lookup [--sync] name...");
+
+ /* Give it plenty of room. */
+ atp = at_pool(argc * 1024*1024);
+ if (!atp)
+ err(1, "Can't create pool");
+
+ /* Free pool on exit. */
+ talloc_steal(talloc_autofree_context(), atp);
+
+ if (streq(argv[1], "--sync")) {
+ for (i = 2; i < argc; i++) {
+ struct lookup_answer *ans = lookup_dns(atp, argv[i]);
+ report_answer(argv[i], ans);
+ talloc_free(ans);
+ }
+ return 0;
+ }
+
+ at = talloc_array(atp, struct athread *, argc);
+
+ for (i = 1; i < argc; i++) {
+ at[i] = at_run(atp, lookup_dns, argv[i]);
+ if (!at[i])
+ err(1, "Can't spawn child");
+ }
+
+ for (i = 1; i < argc; i++) {
+ struct lookup_answer *ans = at_read(at[i]);
+ if (!ans)
+ warn("Child died on '%s'", argv[i]);
+ else {
+ report_answer(argv[i], ans);
+ talloc_free(ans);
+ }
+ }
+ return 0;
+}