From f61d49c98fcc4574b01dca3bca45a3a6372545b9 Mon Sep 17 00:00:00 2001
From: folkert van heusden <mail@vanheusden.com>
Date: Wed, 22 Mar 2023 07:33:08 +0100
Subject: [PATCH] connect

---
 ESP32/disk_backend_nbd.cpp |  1 +
 ESP32/disk_backend_nbd.h   |  1 +
 disk_backend_nbd.cpp       | 79 +++++++++++++++++++++++++++++++-------
 disk_backend_nbd.h         |  6 +--
 4 files changed, 70 insertions(+), 17 deletions(-)
 create mode 120000 ESP32/disk_backend_nbd.cpp
 create mode 120000 ESP32/disk_backend_nbd.h

diff --git a/ESP32/disk_backend_nbd.cpp b/ESP32/disk_backend_nbd.cpp
new file mode 120000
index 0000000..2a6ef58
--- /dev/null
+++ b/ESP32/disk_backend_nbd.cpp
@@ -0,0 +1 @@
+../disk_backend_nbd.cpp
\ No newline at end of file
diff --git a/ESP32/disk_backend_nbd.h b/ESP32/disk_backend_nbd.h
new file mode 120000
index 0000000..722191b
--- /dev/null
+++ b/ESP32/disk_backend_nbd.h
@@ -0,0 +1 @@
+../disk_backend_nbd.h
\ No newline at end of file
diff --git a/disk_backend_nbd.cpp b/disk_backend_nbd.cpp
index 2ad6e30..0210ca8 100644
--- a/disk_backend_nbd.cpp
+++ b/disk_backend_nbd.cpp
@@ -1,12 +1,15 @@
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/types.h>
 
 #include "disk_backend_nbd.h"
 #include "log.h"
 
 #ifdef ESP32
+#include <lwip/netdb.h>
 #include <lwip/sockets.h>
 #else
+#include <netdb.h>
 #include <sys/socket.h>
 #endif
 
@@ -24,30 +27,73 @@ disk_backend_nbd::~disk_backend_nbd()
 
 bool disk_backend_nbd::begin()
 {
-	addrinfo *res   = nullptr;
-
-	addrinfo hints { 0 };
-	hints.ai_family = AF_INET;
-	hints.ai_socktype = SOCK_STREAM;
-
-	char port_str[8] { 0 };
-	snprintf(port_str, sizeof port_str, "%d", port);
-
-	int rc = getaddrinfo(host.c_str(), port_str, &hints, &res);
-
-	if (rc != 0) {
-		DOLOG(ll_error, true, "disk_backend_nbd: cannot resolve \"%s\":%s: %s", host.c_str(), port_str, gai_strerror(rc));
-
+	if (!connect(false)) {
+		DOLOG(ll_error, true, "disk_backend_nbd: cannot connect to NBD server");
 		return false;
 	}
 
+	DOLOG(info, true, "disk_backend_nbd: connected to NBD server");
+
 	return true;
 }
 
+bool disk_backend_nbd::connect(const bool retry)
+{
+	do {
+		// LOOP until connected, logging message, exponential backoff?
+		addrinfo *res   = nullptr;
+
+		addrinfo hints { 0 };
+		hints.ai_family = AF_INET;
+		hints.ai_socktype = SOCK_STREAM;
+
+		char port_str[8] { 0 };
+		snprintf(port_str, sizeof port_str, "%d", port);
+
+		int rc = getaddrinfo(host.c_str(), port_str, &hints, &res);
+
+		if (rc != 0) {
+#ifdef ESP32
+			DOLOG(ll_error, true, "disk_backend_nbd: cannot resolve \"%s\":%s", host.c_str(), port_str);
+#else
+			DOLOG(ll_error, true, "disk_backend_nbd: cannot resolve \"%s\":%s: %s", host.c_str(), port_str, gai_strerror(rc));
+#endif
+
+			sleep(1);
+
+			continue;
+		}
+
+		for(addrinfo *p = res; p != NULL; p = p->ai_next) {
+			if ((fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) {
+				continue;
+			}
+
+			if (::connect(fd, p->ai_addr, p->ai_addrlen) == -1) {
+				close(fd);
+				fd = -1;
+				DOLOG(ll_error, true, "disk_backend_nbd: cannot connect");
+				continue;
+			}
+
+			break;
+		}
+
+		freeaddrinfo(res);
+	}
+	while(fd == -1 && retry);
+
+	return fd != -1;
+}
+
 bool disk_backend_nbd::read(const off_t offset, const size_t n, uint8_t *const target)
 {
 	DOLOG(debug, false, "disk_backend_nbd::read: read %zu bytes from offset %zu", n, offset);
 
+	connect(true);
+
+	// TODO: loop dat als read() aangeeft dat de peer weg is, dat er dan gereconnect wordt
+	// anders return false
 	return pread(fd, target, n, offset) == ssize_t(n);
 }
 
@@ -55,5 +101,10 @@ bool disk_backend_nbd::write(const off_t offset, const size_t n, const uint8_t *
 {
 	DOLOG(debug, false, "disk_backend_nbd::write: write %zu bytes to offset %zu", n, offset);
 
+	connect(true);
+
+	// TODO: loop dat als write() aangeeft dat de peer weg is, dat er dan gereconnect wordt
+	// anders return false
+
 	return pwrite(fd, from, n, offset) == ssize_t(n);
 }
diff --git a/disk_backend_nbd.h b/disk_backend_nbd.h
index a86b89f..b5d4129 100644
--- a/disk_backend_nbd.h
+++ b/disk_backend_nbd.h
@@ -1,6 +1,4 @@
-#include <netdb.h>
 #include <string>
-#include <sys/socket.h>
 #include <sys/types.h>
 
 #include "disk_backend.h"
@@ -10,9 +8,11 @@ class disk_backend_nbd : public disk_backend
 {
 private:
 	const std::string host;
-	const int         port;
+	const int         port {  0 };
 	int               fd   { -1 };
 
+	bool connect(const bool retry);
+
 public:
 	disk_backend_nbd(const std::string & host, const int port);
 	virtual ~disk_backend_nbd();