connect: Try to re-connect to proxy

Try to re-connect to proxy if connection is lost (e.g. proxy died)
with RECONNECT_TIMEOUT_S timeout.

This patch is needed to implement high availability of cc-proxy.

Fixes #53.

Signed-off-by: Dmitry Voytik <dmitry.voytik@huawei.com>

src/shim.c

@@ -37,6 +37,7 @@
 #include <sys/socket.h>
 #include <unistd.h>
 #include <netdb.h>
+#include <time.h>
 
 #include "config.h"
 #include "utils.h"
@@ -359,9 +360,7 @@ bool read_wire_data(int fd, uint8_t *buf, size_t size)
 		ret = recv(fd, buf+offset, size-offset, 0);
 		if (ret == 0) {
 			shim_debug("Received EOF on file descriptor\n");
-			// TODO: Exit for now, add logic to try to reconnect
-			// to proxy.
-			exit(EXIT_FAILURE);
+			return false;
 		} else if (ret < 0) {
 			shim_error("Failed to read from fd: %s\n",
 				strerror(errno));
@@ -691,6 +690,8 @@ handle_proxy_notification(struct cc_shim *shim, struct frame *fr)
 	}
 }
 
+bool reconnect_to_proxy(struct cc_shim *shim);
+
 /*!
  * Handle message received from proxy
  *
@@ -703,6 +704,9 @@ handle_proxy_message(struct cc_shim *shim)
 
 	fr = read_frame(shim);
 	if ( !fr) {
+		if (! reconnect_to_proxy(shim)) {
+			exit(EXIT_FAILURE);
+		}
 		return;
 	}
 
@@ -876,7 +880,7 @@ connect_to_proxy(struct cc_shim *shim)
 
 		if (connect(sockfd, (struct sockaddr *)&remote,
 				sizeof(struct sockaddr_un)) == -1) {
-			shim_error("Error while connecting to proxy "
+			shim_warning("Error while connecting to proxy "
 				"with address %s: %s\n", shim->proxy_address,
 				 strerror(errno));
 			goto out;
@@ -954,6 +958,52 @@ connect_to_proxy(struct cc_shim *shim)
 	return false;
 }
 
+inline void sleep_ms(int ms)
+{
+	struct timespec ts = { 0, ms * 1000000L };
+	nanosleep(&ts, NULL);
+}
+
+/*
+ * Try to re-establish tcp/unix connection with proxy in RECONNECT_TIMEOUT_S
+ * seconds.
+ *
+ * \param shim \ref cc_shim
+ *
+ * \return true on success, false on failure
+ */
+bool reconnect_to_proxy(struct cc_shim *shim)
+{
+	// How many seconds shim tries to reconnect to proxy
+	const int RECONNECT_TIMEOUT_S = 10;
+	// Period between each attempt in milliseconds
+	const int RECONNECT_POLL_MS = 333;
+
+	shim_warning("Reconnecting to proxy\n");
+	int time = 0;
+
+try_again:
+	sleep_ms(RECONNECT_POLL_MS);
+	time += RECONNECT_POLL_MS;
+	if (time >= RECONNECT_TIMEOUT_S * 1000) {
+		shim_error("Failed to reconnect to proxy in %d sec\n",
+				RECONNECT_TIMEOUT_S);
+		return false;
+	}
+	if (! connect_to_proxy(shim)) {
+		goto try_again;
+	}
+
+	shim_debug("Sending connect command\n");
+	if (! send_connect_command(shim)) {
+		shim_error("Could not send connect command to proxy\n");
+		goto try_again;
+	}
+	add_pollfd(poll_fds, PROXY_SOCK_INDEX, shim->proxy_sock_fd,
+			POLLIN | POLLPRI);
+	return true;
+}
+
 /*
  * Print version information.
  */