setup dns for container

Signed-off-by: Gao feng <omarapazanadi@gmail.com>

src/container.c

@@ -175,6 +175,39 @@ static int container_setup_mount(struct hyper_container *container)
 	return 0;
 }
 
+static int container_setup_dns(struct hyper_container *container)
+{
+	int fd;
+	struct stat st;
+	char *src = "/.oldroot/tmp/hyper/resolv.conf";
+
+	if (stat(src, &st) < 0) {
+		if (errno == ENOENT) {
+			fprintf(stdout, "no dns configured\n");
+			return 0;
+		}
+
+		perror("stat resolve.conf failed");
+		return -1;
+	}
+
+	hyper_mkdir("/etc");
+
+	fd = open("/etc/resolv.conf", O_CREAT| O_WRONLY, 0644);
+	if (fd < 0) {
+		perror("create /etc/resolv.conf failed");
+		return -1;
+	}
+	close(fd);
+
+	if (mount(src, "/etc/resolv.conf", NULL, MS_BIND, NULL) < 0) {
+		perror("bind to /etc/resolv.conf failed");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int container_setup_workdir(struct hyper_container *container)
 {
 	if (container->workdir && chdir(container->workdir) < 0) {
@@ -334,6 +367,11 @@ static int hyper_container_init(void *data)
 		goto fail;
 	}
 
+	if (container_setup_dns(container) < 0) {
+		fprintf(stderr, "container sets up dns failed\n");
+		goto fail;
+	}
+
 	if (container_setup_workdir(container) < 0) {
 		fprintf(stderr, "container sets up work directory failed\n");
 		goto fail;

src/init.c

@@ -539,6 +539,11 @@ static int hyper_setup_pod(struct hyper_pod *pod)
 		return -1;
 	}
 
+	if (hyper_setup_dns(pod) < 0) {
+		fprintf(stderr, "setup network failed\n");
+		return -1;
+	}
+
 	if (hyper_setup_shared(pod) < 0) {
 		fprintf(stderr, "setup shared directory failed\n");
 		return -1;
@@ -655,6 +660,7 @@ static int hyper_stop_pod(struct hyper_pod *pod)
 	hyper_cleanup_exec(pod);
 	hyper_cleanup_container(pod);
 	hyper_cleanup_network(pod);
+	hyper_cleanup_dns(pod);
 	hyper_cleanup_shared(pod);
 
 	free(pod->hostname);

src/net.c

@@ -791,3 +791,55 @@ void hyper_cleanup_network(struct hyper_pod *pod)
 	pod->i_num = 0;
 	netlink_close(&rth);
 }
+
+int hyper_setup_dns(struct hyper_pod *pod)
+{
+	int i, fd, ret = -1;
+	char buf[28];
+
+	if (pod->dns == NULL)
+		return 0;
+
+	fd = open("/tmp/hyper/resolv.conf", O_CREAT| O_TRUNC| O_WRONLY, 0644);
+
+	if (fd < 0) {
+		perror("create /tmp/resolv.conf failed");
+		return -1;
+	}
+
+	for (i = 0; i < pod->d_num; i++) {
+		int size = snprintf(buf, sizeof(buf), "nameserver %s\n", pod->dns[i]);
+		int len = 0, l;
+
+		if (size < 0) {
+			fprintf(stderr, "sprintf resolv.conf entry failed\n");
+			goto out;
+		}
+
+		while (len < size) {
+			l = write(fd, buf, size);
+			if (l < 0) {
+				perror("fail to write resolv.conf");
+				goto out;
+			}
+			len += l;
+		}
+	}
+
+	ret = 0;
+out:
+	close(fd);
+	return ret;
+}
+
+void hyper_cleanup_dns(struct hyper_pod *pod)
+{
+	int fd = open("/tmp/hyper/resolv.conf", O_WRONLY| O_TRUNC);
+
+	if (fd < 0) {
+		perror("open /tmp/resolv.conf failed");
+		return;
+	}
+
+	close(fd);
+}

src/net.h

@@ -48,6 +48,8 @@ void hyper_set_be64(uint8_t *buf, uint64_t val);
 uint64_t hyper_get_be64(uint8_t *buf);
 int hyper_setup_network(struct hyper_pod *pod);
 void hyper_cleanup_network(struct hyper_pod *pod);
+int hyper_setup_dns(struct hyper_pod *pod);
+void hyper_cleanup_dns(struct hyper_pod *pod);
 int hyper_get_type_block(int fd, uint32_t *type);
 int hyper_send_type(int fd, uint32_t type);
 int hyper_send_type_block(int fd, uint32_t type, int need_ack);