example

Author: bradh352

Gemfile

@@ -41,3 +41,4 @@ gem "kramdown-parser-gfm"
 gem "http_parser.rb", "~> 0.6.0", :platforms => [:jruby]
 
 gem "webrick"
+gem "rouge"

_config.yml

@@ -1,5 +1,4 @@
 # Welcome to Jekyll!
-#
 # This config file is meant for settings that affect your whole blog, values
 # which you are expected to set up once and rarely edit after that. If you find
 # yourself editing this file very often, consider using Jekyll's data files
@@ -26,7 +25,11 @@ url: "https://c-ares.org"
 github_username: c-ares
 
 # Build settings
-markdown: GFM
+markdown: kramdown
+highlighter: rouge
+kramdown:
+  input: GFM
+  syntax_highlighter: rouge
 theme: minima
 plugins:
 #  - jekyll-feed

docs.md

@@ -5,13 +5,115 @@ layout: page
 permalink: /docs/
 ---
 
+- [Manpages](#manpages)
+- [Example](#example)
+
 c-ares provides a set of library functions, datatypes, and enumerations
 which integrators will use for their implementations.  When you install c-ares,
 you get man pages which describe their use and meanings.
 
+## Manpages
+
 {% assign docs_paths = site.pages | where_exp: "page", "page.path contains 'docs/'" | map: "path" | sort -%}
 {%- for path in docs_paths -%}
 	{%- assign my_page = site.pages | where: "path", path | first -%}
 - [{{ my_page.path | replace: "docs/", "" | replace: ".html", "" }}](/{{ my_page.path }})
 {% endfor -%}
 
+## Example
+A simple name resolve might look like:
+
+`example.c`:
+{% highlight C %}
+#include <stdio.h>
+#include <string.h>
+#include <ares.h>
+
+/* Callback that is called when DNS query is finished */
+static void addrinfo_cb(void *arg, int status, int timeouts,
+                        struct ares_addrinfo *result)
+{
+  (void)arg; /* Example does not use user context */
+  printf("Result: %s, timeouts: %d\n", ares_strerror(status), timeouts);
+
+  if (result) {
+    struct ares_addrinfo_node *node;
+    for (node = result->nodes; node != NULL; node = node->ai_next) {
+      char        addr_buf[64] = "";
+      const void *ptr          = NULL;
+      if (node->ai_family == AF_INET) {
+        const struct sockaddr_in *in_addr =
+          (const struct sockaddr_in *)((void *)node->ai_addr);
+        ptr = &in_addr->sin_addr;
+      } else if (node->ai_family == AF_INET6) {
+        const struct sockaddr_in6 *in_addr =
+          (const struct sockaddr_in6 *)((void *)node->ai_addr);
+        ptr = &in_addr->sin6_addr;
+      } else {
+        continue;
+      }
+      ares_inet_ntop(node->ai_family, ptr, addr_buf, sizeof(addr_buf));
+      printf("Addr: %s\n", addr_buf);
+    }
+  }
+  ares_freeaddrinfo(result);
+}
+
+int main(int argc, char **argv)
+{
+  ares_channel_t            *channel = NULL;
+  struct ares_options        options;
+  int                        optmask = 0;
+  struct ares_addrinfo_hints hints;
+
+  if (argc != 2) {
+    printf("Usage: %s domain\n", argv[0]);
+    return 1;
+  }
+
+  /* Initialize library */
+  ares_library_init(ARES_LIB_INIT_ALL);
+
+  if (!ares_threadsafety()) {
+    printf("c-ares not compiled with thread support\n");
+    return 1;
+  }
+
+  memset(&options, 0, sizeof(options));
+  /* Enable event thread so we don't have to monitor file descriptors */
+  optmask      |= ARES_OPT_EVENT_THREAD;
+  options.evsys = ARES_EVSYS_DEFAULT;
+
+  /* Initialize channel to run queries, a single channel can accept unlimited
+   * queries */
+  if (ares_init_options(&channel, &options, optmask) != ARES_SUCCESS) {
+    printf("c-ares initialization issue\n");
+    return 1;
+  }
+
+
+  /* Perform an IPv4 and IPv6 request for the provided domain name */
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_flags  = ARES_AI_CANONNAME;
+  ares_getaddrinfo(channel, argv[1], NULL, &hints, addrinfo_cb,
+                   NULL /* user context not specified */);
+
+  /* Wait until no more requests are left to be processed */
+  ares_queue_wait_empty(channel, -1);
+
+  /* Cleanup */
+  ares_destroy(channel);
+
+  ares_library_cleanup();
+  return 0;
+}
+{% endhighlight %}
+
+Compilation:
+{% highlight bash %}
+cc -I/usr/local/include -o example example.c -Wl,-rpath /usr/local/lib -lcares
+{% endhighlight %}
+
+
+