lightningd: trim whitespaces from end of config parameters

Signed-off-by: Max Rantil <rantil@pm.me>

common/configvar.c

@@ -51,6 +51,20 @@ const struct opt_table *configvar_unparsed(struct configvar *cv)
 	return ot;
 }
 
+static void trim_whitespace(const char *s)
+{
+	size_t len = strlen(s);
+
+	/* Cast away const to allow modifications */
+	char *mutable_s = (char *)s;
+
+	while (len > 0 && isspace((unsigned char)mutable_s[len - 1]))
+		len--;
+
+	/* Move null terminator to the end of the trimmed string */
+	memmove(mutable_s + len, mutable_s + strlen(s), 1);
+}
+
 const char *configvar_parse(struct configvar *cv,
 			    bool early,
 			    bool full_knowledge,
@@ -82,6 +96,8 @@ const char *configvar_parse(struct configvar *cv,
 	} else {
 		if (!cv->optarg)
 			return "requires an argument";
+		if (!(ot->type & OPT_KEEP_WHITESPACE))
+			trim_whitespace(cv->optarg);
 		return ot->cb_arg(cv->optarg, ot->u.arg);
 	}
 }

common/configvar.h

@@ -60,6 +60,8 @@ struct configvar {
 #define OPT_SHOWBOOL (1 << (OPT_USER_START+5))
 /* Can be changed at runtime: cb will get called with NULL for `check`! */
 #define OPT_DYNAMIC (1 << (OPT_USER_START+6))
+/* Keep whitespace at the end of the option argument */
+#define OPT_KEEP_WHITESPACE (1 << (OPT_USER_START+7))
 
 /* Use this instead of opt_register_*_arg if you want OPT_* from above */
 #define clnopt_witharg(names, type, cb, show, arg, desc)		\

doc/lightningd-config.5.md

@@ -83,6 +83,14 @@ re-enable it.  Unless we've made a horrible mistake it's probably time
 to complain or fix to whatever is using the old API.  It can be
 specified multiple times for different features.
 
+### Whitespace Handling
+
+Because it's a common error, we automatically trim whitespace from the
+end of most configuration options. Exceptions are noted below:
+
+- `log-prefix`: Preserves whitespace at the end.
+- `alias`: Preserves whitespace at the end.
+
 ### Bitcoin control options:
 
 Bitcoin control options:

lightningd/log.c

@@ -915,9 +915,8 @@ void opt_register_logging(struct lightningd *ld)
 		       opt_set_bool_arg, opt_show_bool,
 		       &ld->log_book->print_timestamps,
 		       "prefix log messages with timestamp");
-	opt_register_early_arg("--log-prefix", arg_log_prefix, show_log_prefix,
-			       ld->log_book,
-			       "log prefix");
+	clnopt_witharg("--log-prefix", OPT_EARLY|OPT_KEEP_WHITESPACE,
+		       arg_log_prefix, show_log_prefix, ld->log_book, "log prefix");
 	clnopt_witharg("--log-file=<file>",
 		       OPT_EARLY|OPT_MULTI,
 		       arg_log_to_file, NULL, ld,

lightningd/options.c

@@ -1525,9 +1525,8 @@ static void register_opts(struct lightningd *ld)
 		     opt_lightningd_usage, ld, "Print this message.");
 	opt_register_arg("--rgb", opt_set_rgb, opt_show_rgb, ld,
 			 "RRGGBB hex color for node");
-	opt_register_arg("--alias", opt_set_alias, opt_show_alias, ld,
-			 "Up to 32-byte alias for node");
-
+	clnopt_witharg("--alias", OPT_KEEP_WHITESPACE, opt_set_alias,
+		       opt_show_alias, ld, "Up to 32-byte alias for node");
 	opt_register_arg("--pid-file=<file>", opt_set_talstr, opt_show_charp,
 			 &ld->pidfile,
 			 "Specify pid file");

tests/test_misc.py

@@ -3867,6 +3867,43 @@ def test_fast_shutdown(node_factory):
         break
 
 
+def test_config_whitespace(node_factory):
+    """ Test the configuration parsing with extra
+        whitespace in the configuration file. """
+    l1 = node_factory.get_node()
+
+    configfile = os.path.join(l1.daemon.opts.get("lightning-dir"), TEST_NETWORK, 'config')
+
+    # Stop the node to modify the configuration file safely
+    l1.stop()
+
+    # Ensure the log-prefix option is not set in the command line arguments
+    if 'log-prefix' in l1.daemon.opts:
+        del l1.daemon.opts['log-prefix']
+
+    # Write configuration parameters with extra whitespace
+    with open(configfile, "a") as f:
+        f.write("\n\n# Test whitespace\n")
+        f.write("funder-policy-mod=100             \n")
+        f.write("funder-min-their-funding=10000\n")
+        f.write("allow-deprecated-apis=false       \n")
+        f.write("alias=MyLightningNode   \n")
+        f.write("log-prefix=MyNode   \n")
+
+    l1.start()
+
+    configs = l1.rpc.listconfigs()
+
+    # Verify that the trimmed configuration values are correctly set
+    assert configs['configs']['funder-policy-mod']['value_str'] == '100', "funder-policy-mod should be '100'"
+    assert configs['configs']['funder-min-their-funding']['value_str'] == '10000', "funder-min-their-funding should be '10000'"
+    assert configs['configs']['allow-deprecated-apis']['value_bool'] is False, "allow-deprecated-apis should be False"
+
+    # We want to keep the whitespaces at the parameter 'alias' & 'log-prefix'
+    assert configs['configs']['alias']['value_str'] == 'MyLightningNode   ', "alias should be 'MyLightningNode   '"
+    assert configs['configs']['log-prefix']['value_str'] == 'MyNode   ', "log-prefix should be 'MyNode   '"
+
+
 def test_setconfig(node_factory, bitcoind):
     l1, l2 = node_factory.line_graph(2, fundchannel=False)
     configfile = os.path.join(l2.daemon.opts.get("lightning-dir"), TEST_NETWORK, 'config')