Bring the VPN wrapper to a better position

It will not work yet as-is, but this should help getting it there.

tools/libvpn.c

@@ -16,8 +16,10 @@
 
 
 #include <sys/resource.h>
+#include <limits.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 #include <errno.h>
 #include <dlfcn.h>
 #include <sys/socket.h>
@@ -29,29 +31,62 @@
 /* libVPN */
 /* private */
 /* types */
-typedef struct _VPNSocket
+typedef struct _VPNAppClient
 {
-	int fd;
+	String const * name;
-} VPNSocket;
+	AppClient * appclient;
+} VPNAppClient;
+
+typedef struct _VPNAppClientFD
+{
+	AppClient * appclient;
+	int32_t fd;
+} VPNAppClientFD;
 
 
 /* constants */
+#define APPINTERFACE	"VPN"
 #define PROGNAME	"libVPN"
 
 
 /* variables */
-static AppClient * _appclient = NULL;
+static VPNAppClient * _vpn_clients = NULL;
+static size_t _vpn_clients_cnt = 0;
+
+static VPNAppClientFD * _vpn_clients_fd = NULL;
+static size_t _vpn_clients_fd_cnt = 0;
 
 static int _vpn_offset = 1024;
 
 /* local functions */
+static int (*old_close)(int fd);
 static int (*old_connect)(int fd, const struct sockaddr * name,
 		socklen_t namelen);
+static ssize_t (*old_read)(int fd, void * buf, size_t count);
+static ssize_t (*old_recv)(int fd, void * buf, size_t count, int flags);
+static ssize_t (*old_send)(int fd, void const * buf, size_t count, int flags);
+static ssize_t (*old_write)(int fd, void const * buf, size_t count);
 
 
 /* prototypes */
 static void _libvpn_init(void);
 
+/* accessors */
+static AppClient * _libvpn_get_appclient(const struct sockaddr * name,
+		socklen_t namelen);
+static AppClient * _libvpn_get_appclient_fd(int32_t * fd);
+static String * _libvpn_get_remote_host(
+		const struct sockaddr * name, socklen_t namelen);
+static int _libvpn_get_remote_name(
+		const struct sockaddr * name, socklen_t namelen,
+		struct sockaddr ** rname, socklen_t * rnamelen);
+static unsigned int _libvpn_is_remote(const struct sockaddr * name,
+		socklen_t namelen);
+
+/* useful */
+static int _libvpn_deregister_fd(AppClient * appclient, int32_t fd);
+static int _libvpn_register_fd(AppClient * appclient, int32_t * fd);
+
 
 /* functions */
 static void _libvpn_init(void)
@@ -74,21 +109,29 @@ static void _libvpn_init(void)
 		fprintf(stderr, "%s: %s\n", PROGNAME, dlerror());
 		exit(1);
 	}
-	if((old_connect = dlsym(hdl, "connect")) == NULL)
+	if((old_close = dlsym(hdl, "close")) == NULL
+			|| (old_connect = dlsym(hdl, "connect")) == NULL
+			|| (old_read = dlsym(hdl, "read")) == NULL
+			|| (old_recv = dlsym(hdl, "recv")) == NULL
+			|| (old_send = dlsym(hdl, "send")) == NULL
+			|| (old_write = dlsym(hdl, "write")) == NULL)
 	{
 		fprintf(stderr, "%s: %s\n", PROGNAME, dlerror());
 		dlclose(hdl);
 		exit(1);
 	}
 	dlclose(hdl);
-	if((_appclient = appclient_new(NULL, "VPN", NULL)) == NULL)
+#ifdef RLIMIT_NOFILE
+	if(getrlimit(RLIMIT_NOFILE, &r) == 0)
 	{
-		error_print(PROGNAME);
+		if(r.rlim_max > INT_MAX)
+		{
+			fprintf(stderr, "%s: %s\n", PROGNAME, strerror(ERANGE));
 			exit(1);
 		}
-#ifdef RLIMIT_NOFILE
+		if(_vpn_offset < r.rlim_max)
-	if(getrlimit(RLIMIT_NOFILE, &r) == 0 && r.rlim_max > _vpn_offset)
+			_vpn_offset = (int)r.rlim_max;
-		_vpn_offset = r.rlim_max;
+	}
 # ifdef DEBUG
 	fprintf(stderr, "DEBUG: %s() %u\n", __func__, _vpn_offset);
 # endif
@@ -96,24 +139,299 @@ static void _libvpn_init(void)
 }
 
 
+/* accessors */
+/* libvpn_get_appclient */
+static AppClient * _libvpn_get_appclient(const struct sockaddr * name,
+		socklen_t namelen)
+{
+	String * host;
+	size_t i;
+	VPNAppClient * p;
+
+	if((host = _libvpn_get_remote_host(name, namelen)) == NULL)
+		return NULL;
+	for(i = 0; i < _vpn_clients_cnt; i++)
+		if(_vpn_clients[i].name == NULL)
+			continue;
+		else if(string_compare(_vpn_clients[i].name, host) == 0)
+		{
+			string_delete(host);
+			return _vpn_clients[i].appclient;
+		}
+	if((p = realloc(_vpn_clients, sizeof(*_vpn_clients) * (i + 1))) == NULL)
+	{
+		string_delete(host);
+		return NULL;
+	}
+	_vpn_clients = p;
+	p = &_vpn_clients[_vpn_clients_cnt++];
+	if((p->appclient = appclient_new(NULL, APPINTERFACE, host)) == NULL)
+	{
+		string_delete(host);
+		return NULL;
+	}
+	p->name = host;
+	return p->appclient;
+}
+
+
+/* libvpn_get_appclient_fd */
+static AppClient * _libvpn_get_appclient_fd(int32_t * fd)
+{
+	size_t i;
+
+	if(*fd < _vpn_offset)
+		return NULL;
+	i = (size_t)*fd - _vpn_offset;
+	if(i >= _vpn_clients_fd_cnt)
+		return NULL;
+	*fd = _vpn_clients_fd[i].fd;
+	return _vpn_clients_fd[i].appclient;
+}
+
+
+/* libvpn_get_remote_host */
+static String * _libvpn_get_remote_host(
+		const struct sockaddr * name, socklen_t namelen)
+{
+	(void) name;
+	(void) namelen;
+
+	/* FIXME really implement through gethostbyname()/getaddrinfo() */
+	return getenv("APPSERVER_VPN");
+}
+
+
+/* libvpn_get_remote_name */
+static int _libvpn_get_remote_name(
+		const struct sockaddr * name, socklen_t namelen,
+		struct sockaddr ** rname, socklen_t * rnamelen)
+{
+	/* FIXME really implement through gethostbyname()/getaddrinfo() */
+	if(rname == NULL && rnamelen == NULL)
+		return 0;
+	return -1;
+}
+
+
+/* libvpn_is_remote */
+static unsigned int _libvpn_is_remote(const struct sockaddr * name,
+		socklen_t namelen)
+{
+	return (_libvpn_get_remote_name(name, namelen, NULL, NULL) == 0)
+		? 1 : 0;
+}
+
+
+/* useful */
+/* libvpn_deregister_fd */
+static int _libvpn_deregister_fd(AppClient * appclient, int32_t fd)
+{
+	if(fd < 0 || (size_t)fd >= _vpn_clients_fd_cnt)
+		return -1;
+	/* sanity check */
+	if(_vpn_clients_fd[fd].appclient != appclient)
+		return -1;
+	_vpn_clients_fd[fd].appclient = NULL;
+	_vpn_clients_fd[fd].fd = -1;
+	return 0;
+}
+
+
+/* libvpn_register_fd */
+static int _libvpn_register_fd(AppClient * appclient, int32_t * fd)
+{
+	size_t i;
+	VPNAppClientFD * p;
+
+	for(i = 0; i < _vpn_clients_fd_cnt; i++)
+		if(_vpn_clients_fd[i].fd < 0)
+		{
+			_vpn_clients_fd[i].appclient = appclient;
+			_vpn_clients_fd[i].fd = *fd;
+			*fd = _vpn_offset + i;
+			return 0;
+		}
+	if((p = realloc(_vpn_clients_fd, sizeof(*p) * (i + 1))) == NULL)
+		return -1;
+	_vpn_clients_fd = p;
+	p = &_vpn_clients_fd[_vpn_clients_fd_cnt++];
+	p->appclient = appclient;
+	p->fd = *fd;
+	*fd = _vpn_offset + i;
+	return 0;
+}
+
+
 /* public */
 /* interface */
+/* close */
+int close(int fd)
+{
+	int ret;
+	AppClient * appclient;
+
+	_libvpn_init();
+	if((appclient = _libvpn_get_appclient_fd(&fd)) == NULL)
+		return old_close(fd);
+	if(appclient_call(appclient, (void **)&ret, "close", fd) != 0)
+		return -1;
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(%p:%d) => %d\n", __func__,
+			(void *)appclient, fd, ret);
+#endif
+	if(ret != 0)
+		return _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
+	else
+		_libvpn_deregister_fd(appclient, fd);
+	return ret;
+}
+
+
 /* connect */
 int connect(int fd, const struct sockaddr * name, socklen_t namelen)
 {
 	int ret;
+	AppClient * appclient;
 
 	_libvpn_init();
-	if(fd < _vpn_offset)
+	if(_libvpn_is_remote(name, namelen) == 0)
 		return old_connect(fd, name, namelen);
-	if(appclient_call(_appclient, (void **)&ret, "connect",
+	if((appclient = _libvpn_get_appclient(name, namelen)) == NULL)
-				fd - _vpn_offset)
+		return -1;
-			!= 0)
+	if(appclient_call(appclient, (void **)&ret, "connect", fd) != 0)
 		return -1;
 #ifdef DEBUG
-	fprintf(stderr, "DEBUG: connect(%d) => %d\n", fd - VFS_OFFSET, ret);
+	fprintf(stderr, "DEBUG: connect(%d) => %d\n", fd, ret);
 #endif
-	if(ret != 0)
+	if(ret < 0)
+		return _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
+	if(_libvpn_register_fd(appclient, &ret) != 0)
+	{
+		appclient_call(appclient, NULL, "close", ret);
+		return -1;
+	}
+	return ret;
+}
+
+
+/* read */
+ssize_t read(int fd, void * buf, size_t count)
+{
+	int32_t ret;
+	AppClient * appclient;
+	Buffer * b;
+
+	_libvpn_init();
+	if((appclient = _libvpn_get_appclient_fd(&fd)) == NULL)
+		return old_read(fd, buf, count);
+	if((b = buffer_new(0, NULL)) == NULL)
+		return -1;
+	if(appclient_call(appclient, (void **)&ret, "recv", fd, b, count,
+				0) != 0)
+	{
+		buffer_delete(b);
+		/* FIXME define errno */
+		return -1;
+	}
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(%p:%d, buf, %lu) => %d\n", __func__,
+			(void *)appclient, fd, count, ret);
+#endif
+	if(ret < 0)
+		ret = _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
+	else if(ret > 0)
+		memcpy(buf, buffer_get_data(b), ret);
+	buffer_delete(b);
+	return ret;
+}
+
+
+/* recv */
+ssize_t recv(int fd, void * buf, size_t count, int flags)
+{
+	int32_t ret;
+	AppClient * appclient;
+	Buffer * b;
+
+	_libvpn_init();
+	if((appclient = _libvpn_get_appclient_fd(&fd)) == NULL)
+		return old_read(fd, buf, count);
+	if((b = buffer_new(0, NULL)) == NULL)
+		return -1;
+	if(appclient_call(appclient, (void **)&ret, "recv", fd, b, count,
+				flags) != 0)
+	{
+		buffer_delete(b);
+		/* FIXME define errno */
+		return -1;
+	}
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(%p:%d, buf, %lu, %#x) => %d\n", __func__,
+			(void *)appclient, fd, count, flags, ret);
+#endif
+	if(ret < 0)
+		ret = _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
+	else if(ret > 0)
+		memcpy(buf, buffer_get_data(b), ret);
+	buffer_delete(b);
+	return ret;
+}
+
+
+/* send */
+ssize_t send(int fd, void const * buf, size_t count, int flags)
+{
+	int32_t ret;
+	AppClient * appclient;
+	Buffer * b;
+
+	_libvpn_init();
+	if((appclient = _libvpn_get_appclient_fd(&fd)) == NULL)
+		return old_write(fd, buf, count);
+	if((b = buffer_new(count, buf)) == NULL)
+		return -1;
+	if(appclient_call(appclient, (void **)&ret, "send", fd, b, count,
+				flags) != 0)
+	{
+		buffer_delete(b);
+		return -1;
+	}
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(%d, buf, %lu, %#x) => %d\n", __func__,
+			fd, count, flags, ret);
+#endif
+	buffer_delete(b);
+	if(ret < 0)
+		return _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
+	return ret;
+}
+
+
+/* write */
+ssize_t write(int fd, void const * buf, size_t count)
+{
+	int32_t ret;
+	AppClient * appclient;
+	Buffer * b;
+
+	_libvpn_init();
+	if((appclient = _libvpn_get_appclient_fd(&fd)) == NULL)
+		return old_write(fd, buf, count);
+	if((b = buffer_new(count, buf)) == NULL)
+		return -1;
+	if(appclient_call(appclient, (void **)&ret, "send", fd, b, count,
+				0) != 0)
+	{
+		buffer_delete(b);
+		return -1;
+	}
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(%d, buf, %lu) => %d\n", __func__,
+			fd, count, ret);
+#endif
+	buffer_delete(b);
+	if(ret < 0)
 		return _vpn_errno(_vpn_error, _vpn_error_cnt, -ret, 1);
 	return ret;
 }