Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

1 files changed, 58 insertions, 82 deletions

diff --git a/cmd.c b/cmd.c
index b13d0cc4..9fda3dcc 100644
--- a/cmd.c
+++ b/cmd.c
@@ -109,6 +109,64 @@ struct session	*cmd_lookup_session(const char *, int *);
 struct winlink	*cmd_lookup_window(struct session *, const char *, int *);
 int		 cmd_lookup_index(struct session *, const char *, int *);
 
+int
+cmd_pack_argv(int argc, char **argv, char *buf, size_t len)
+{
+	size_t	arglen;
+	int	i;
+
+	*buf = '\0';
+	for (i = 0; i < argc; i++) {
+		if (strlcpy(buf, argv[i], len) >= len)
+			return (-1);
+		arglen = strlen(argv[i]) + 1;
+		buf += arglen;
+		len -= arglen;
+	}
+
+	return (0);
+}
+
+int
+cmd_unpack_argv(char *buf, size_t len, int argc, char ***argv)
+{
+	int	i;
+	size_t	arglen;
+
+	if (argc == 0)
+		return (0);
+	*argv = xcalloc(argc, sizeof **argv);
+
+	buf[len - 1] = '\0';
+	for (i = 0; i < argc; i++) {
+		if (len == 0) {
+			cmd_free_argv(argc, *argv);
+			return (-1);
+		}
+
+		arglen = strlen(buf) + 1;
+		(*argv)[i] = xstrdup(buf);
+		buf += arglen;
+		len -= arglen;
+	}
+
+	return (0);
+}
+
+void
+cmd_free_argv(int argc, char **argv)
+{
+	int	i;
+
+	if (argc == 0)
+		return; 
+	for (i = 0; i < argc; i++) {
+		if (argv[i] != NULL)
+			xfree(argv[i]);
+	}
+	xfree(argv);
+}
+
 struct cmd *
 cmd_parse(int argc, char **argv, char **cause)
 {
@@ -205,53 +263,6 @@ cmd_exec(struct cmd *cmd, struct cmd_ctx *ctx)
 }
 
 void
-cmd_send(struct cmd *cmd, struct buffer *b)
-{
-	const struct cmd_entry **entryp;
-	u_int			 n;
-
-	n = 0;
-	for (entryp = cmd_table; *entryp != NULL; entryp++) {
-		if (*entryp == cmd->entry)
-			break;
-		n++;
-	}
-	if (*entryp == NULL)
-		fatalx("command not found");
-
-	buffer_write(b, &n, sizeof n);
-
-	if (cmd->entry->send != NULL)
-		cmd->entry->send(cmd, b);
-}
-
-struct cmd *
-cmd_recv(struct buffer *b)
-{
-	const struct cmd_entry **entryp;
-	struct cmd   	        *cmd;
-	u_int			 m, n;
-
-	buffer_read(b, &m, sizeof m);
-
-	n = 0;
-	for (entryp = cmd_table; *entryp != NULL; entryp++) {
-		if (n == m)
-			break;
-		n++;
-	}
-	if (*entryp == NULL)
-		fatalx("command not found");
-
-	cmd = xmalloc(sizeof *cmd);
-	cmd->entry = *entryp;
-
-	if (cmd->entry->recv != NULL)
-		cmd->entry->recv(cmd, b);
-	return (cmd);
-}
-
-void
 cmd_free(struct cmd *cmd)
 {
 	if (cmd->data != NULL && cmd->entry->free != NULL)
@@ -268,41 +279,6 @@ cmd_print(struct cmd *cmd, char *buf, size_t len)
 	return (cmd->entry->print(cmd, buf, len));
 }
 
-void
-cmd_send_string(struct buffer *b, const char *s)
-{
-	size_t	n;
-
-	if (s == NULL) {
-		n = 0;
-		buffer_write(b, &n, sizeof n);
-		return;
-	}
-
-	n = strlen(s) + 1;
-	buffer_write(b, &n, sizeof n);
-
-	buffer_write(b, s, n);
-}
-
-char *
-cmd_recv_string(struct buffer *b)
-{
-	char   *s;
-	size_t	n;
-
-	buffer_read(b, &n, sizeof n);
-
-	if (n == 0)
-		return (NULL);
-
-	s = xmalloc(n);
-	buffer_read(b, s, n);
-	s[n - 1] = '\0';
-
-	return (s);
-}
-
 /*
  * Figure out the current session. Use: 1) the current session, if the command
  * context has one; 2) the session specified in the TMUX variable from the