doc: add code samples from uvbook (unadapted)

PR-URL: https://github.com/libuv/libuv/pull/1246
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/docs/code/dns/main.c b/docs/code/dns/main.c
new file mode 100644
index 00000000..77a7005f
--- /dev/null
+++ b/docs/code/dns/main.c
@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <uv.h>
+
+uv_loop_t *loop;
+
+void alloc_buffer(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf) {
+  buf->base = malloc(suggested_size);
+  buf->len = suggested_size;
+}
+
+void on_read(uv_stream_t *client, ssize_t nread, const uv_buf_t *buf) {
+    if (nread < 0) {
+        if (nread != UV_EOF)
+            fprintf(stderr, "Read error %s\n", uv_err_name(nread));
+        uv_close((uv_handle_t*) client, NULL);
+        free(buf->base);
+        free(client);
+        return;
+    }
+
+    char *data = (char*) malloc(sizeof(char) * (nread+1));
+    data[nread] = '\0';
+    strncpy(data, buf->base, nread);
+
+    fprintf(stderr, "%s", data);
+    free(data);
+    free(buf->base);
+}
+
+void on_connect(uv_connect_t *req, int status) {
+    if (status < 0) {
+        fprintf(stderr, "connect failed error %s\n", uv_err_name(status));
+        free(req);
+        return;
+    }
+
+    uv_read_start((uv_stream_t*) req->handle, alloc_buffer, on_read);
+    free(req);
+}
+
+void on_resolved(uv_getaddrinfo_t *resolver, int status, struct addrinfo *res) {
+    if (status < 0) {
+        fprintf(stderr, "getaddrinfo callback error %s\n", uv_err_name(status));
+        return;
+    }
+
+    char addr[17] = {'\0'};
+    uv_ip4_name((struct sockaddr_in*) res->ai_addr, addr, 16);
+    fprintf(stderr, "%s\n", addr);
+
+    uv_connect_t *connect_req = (uv_connect_t*) malloc(sizeof(uv_connect_t));
+    uv_tcp_t *socket = (uv_tcp_t*) malloc(sizeof(uv_tcp_t));
+    uv_tcp_init(loop, socket);
+
+    uv_tcp_connect(connect_req, socket, (const struct sockaddr*) res->ai_addr, on_connect);
+
+    uv_freeaddrinfo(res);
+}
+
+int main() {
+    loop = uv_default_loop();
+
+    struct addrinfo hints;
+    hints.ai_family = PF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_protocol = IPPROTO_TCP;
+    hints.ai_flags = 0;
+
+    uv_getaddrinfo_t resolver;
+    fprintf(stderr, "irc.freenode.net is... ");
+    int r = uv_getaddrinfo(loop, &resolver, on_resolved, "irc.freenode.net", "6667", &hints);
+
+    if (r) {
+        fprintf(stderr, "getaddrinfo call error %s\n", uv_err_name(r));
+        return 1;
+    }
+    return uv_run(loop, UV_RUN_DEFAULT);
+}