1 files changed, 138 insertions, 0 deletions
diff --git a/src/bind.c b/src/bind.c
new file mode 100644
index 0000000..2545003
--- /dev/null
+++ b/src/bind.c
@@ -0,0 +1,138 @@
+#include "osm/bind.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <sys/un.h>
+
+/**
+ * The required characters to represent an id as a file name
+ * id - the id to get translated to a file name
+ */
+int _need_chars(int id)
+{
+	int i = 1;
+
+	while (id > 15)
+	{
+		id /= 16;
+		i++;
+	}
+
+	return i;
+}
+
+/**
+ * Write the integer file name after the folder path.
+ * id - the id to get translated to a file name
+ * start - a pointer to just after the end of the folder path string
+ */
+void _write_name(int id, char *start)
+{
+	int i = _need_chars(id);
+	while (i > 0)
+	{
+		// Get current character
+		char c = '0';
+		if (id % 16 < 10)
+			c += id % 16;
+		else
+			c = 'a' + (id % 16) - 10;
+		
+		// Put character
+		*(start + i - 1) = c;
+
+		// divide id, sub from i
+		id /= 16;
+		i -= 1;
+	}
+}
+
+/**
+ * Bind to the next available onboard socket in the given directory
+ * sock_dir - The directory containing osm sockets (or null for the default)
+ */
+int osm_bind_local(int sockfd, const char *sock_dir)
+{
+	struct sockaddr_un name;
+	name.sun_family = AF_LOCAL;
+	
+	strncpy(name.sun_path, sock_dir, sizeof(name.sun_path));
+	name.sun_path[sizeof(name.sun_path) - 1] = 0;
+	
+	// Check for slash at end of path
+	int len = strlen(name.sun_path);
+
+	if (name.sun_path[len - 1] != '/')
+	{
+		name.sun_path[len] = '/';
+		len++;
+	}
+
+	// check that we won't overflow the buffer
+	if (len > sizeof(name.sun_path) - 2)
+	{
+		return -1;
+	}
+
+	// sequentially try to bind
+	int id = 0;
+	while(_need_chars(id) + len < sizeof(name.sun_path) - 1)
+	{
+		// write file name
+		_write_name(id, name.sun_path + len);
+		
+		// try to bind
+		int size = offsetof(struct sockaddr_un, sun_path) + strlen(name.sun_path);
+
+		if (bind(sockfd, (struct sockaddr *) &name, size) > 0)
+		{
+			return 0;
+		}
+
+		// inc id
+		id++;
+	}
+
+	return -1;
+}
+
+/**
+ * Bind a new onboard socket
+ * sock_dir - The directory containing osm sockets (or null for the default)
+ * return - a negitve number on error, or the socket fd on success
+ */
+int osm_open_onboard(char *sock_dir)
+{
+	int sockfd = socket(AF_LOCAL, SOCK_DGRAM, 0);
+	if (sockfd < 0)
+	{
+		perror("socket");
+		return sockfd;
+	}
+
+	int bound = -1;
+	if (sock_dir == NULL)
+	{
+		bound = osm_bind_local(sockfd, "/run/osm/onboard/");
+	}
+	else
+	{
+		bound = osm_bind_local(sockfd, sock_dir);
+	}
+	
+	if (bound < 0)
+	{
+		perror("bind");
+		close(sockfd);
+		return bound;
+	}
+
+	return sockfd;
+}
+
+
+
+