[PATCH 3/3] conf: Use the same optstring for passt and pasta modes

[David Gibson <david@gibson.dropbear.id.au>]

Currently we rely on detecting our mode first and use different sets of
(single character) options for each.  This means that if you use an option
valid in only one mode in another you'll get the generic usage() message.

We can give more helpful errors with little extra effort by combining all
the options into a single value of the option string and giving bespoke
messages if an option for the wrong mode is used; in fact we already did
this for some single mode options like '-1'.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 conf.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/conf.c b/conf.c
index b26249a8..9f0313f8 100644
--- a/conf.c
+++ b/conf.c
@@ -1427,6 +1427,7 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"repair-path",	required_argument,	NULL,		28 },
 		{ 0 },
 	};
+	const char *optstring = "+dqfel:hs:F:I:p:P:m:a:n:M:g:i:o:D:S:H:461t:u:T:U:";
 	const char *logname = (c->mode == MODE_PASTA) ? "pasta" : "passt";
 	char userns[PATH_MAX] = { 0 }, netns[PATH_MAX] = { 0 };
 	bool copy_addrs_opt = false, copy_routes_opt = false;
@@ -1436,7 +1437,6 @@ void conf(struct ctx *c, int argc, char **argv)
 	struct fqdn *dnss = c->dns_search;
 	unsigned int ifi4 = 0, ifi6 = 0;
 	const char *logfile = NULL;
-	const char *optstring;
 	size_t logsize = 0;
 	char *runas = NULL;
 	long fd_tap_opt;
@@ -1447,9 +1447,6 @@ void conf(struct ctx *c, int argc, char **argv)
 	if (c->mode == MODE_PASTA) {
 		c->no_dhcp_dns = c->no_dhcp_dns_search = 1;
 		fwd_default = FWD_AUTO;
-		optstring = "+dqfel:hF:I:p:P:m:a:n:M:g:i:o:D:S:H:46t:u:T:U:";
-	} else {
-		optstring = "+dqfel:hs:F:p:P:m:a:n:M:g:i:o:D:S:H:461t:u:";
 	}
 
 	c->mtu = ROUND_DOWN(ETH_MAX_MTU - ETH_HLEN, sizeof(uint32_t));
@@ -1659,6 +1656,9 @@ void conf(struct ctx *c, int argc, char **argv)
 			c->foreground = 1;
 			break;
 		case 's':
+			if (c->mode == MODE_PASTA)
+				die("-s is for passt / vhost-user mode only");
+
 			ret = snprintf(c->sock_path, sizeof(c->sock_path), "%s",
 				       optarg);
 			if (ret <= 0 || ret >= (int)sizeof(c->sock_path))
@@ -1679,6 +1679,9 @@ void conf(struct ctx *c, int argc, char **argv)
 			*c->sock_path = 0;
 			break;
 		case 'I':
+			if (c->mode != MODE_PASTA)
+				die("-I is for pasta mode only");
+
 			ret = snprintf(c->pasta_ifn, IFNAMSIZ, "%s",
 				       optarg);
 			if (ret <= 0 || ret >= IFNAMSIZ)
@@ -1835,11 +1838,16 @@ void conf(struct ctx *c, int argc, char **argv)
 			break;
 		case 't':
 		case 'u':
-		case 'T':
-		case 'U':
 		case 'D':
 			/* Handle these later, once addresses are configured */
 			break;
+		case 'T':
+		case 'U':
+			if (c->mode != MODE_PASTA)
+				die("-%c is for pasta mode only", name);
+
+			/* Handle properly later, once addresses are configured */
+			break;
 		case 'h':
 			usage(argv[0], stdout, EXIT_SUCCESS);
 			break;
-- 
@@ -1427,6 +1427,7 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"repair-path",	required_argument,	NULL,		28 },
 		{ 0 },
 	};
+	const char *optstring = "+dqfel:hs:F:I:p:P:m:a:n:M:g:i:o:D:S:H:461t:u:T:U:";
 	const char *logname = (c->mode == MODE_PASTA) ? "pasta" : "passt";
 	char userns[PATH_MAX] = { 0 }, netns[PATH_MAX] = { 0 };
 	bool copy_addrs_opt = false, copy_routes_opt = false;
@@ -1436,7 +1437,6 @@ void conf(struct ctx *c, int argc, char **argv)
 	struct fqdn *dnss = c->dns_search;
 	unsigned int ifi4 = 0, ifi6 = 0;
 	const char *logfile = NULL;
-	const char *optstring;
 	size_t logsize = 0;
 	char *runas = NULL;
 	long fd_tap_opt;
@@ -1447,9 +1447,6 @@ void conf(struct ctx *c, int argc, char **argv)
 	if (c->mode == MODE_PASTA) {
 		c->no_dhcp_dns = c->no_dhcp_dns_search = 1;
 		fwd_default = FWD_AUTO;
-		optstring = "+dqfel:hF:I:p:P:m:a:n:M:g:i:o:D:S:H:46t:u:T:U:";
-	} else {
-		optstring = "+dqfel:hs:F:p:P:m:a:n:M:g:i:o:D:S:H:461t:u:";
 	}
 
 	c->mtu = ROUND_DOWN(ETH_MAX_MTU - ETH_HLEN, sizeof(uint32_t));
@@ -1659,6 +1656,9 @@ void conf(struct ctx *c, int argc, char **argv)
 			c->foreground = 1;
 			break;
 		case 's':
+			if (c->mode == MODE_PASTA)
+				die("-s is for passt / vhost-user mode only");
+
 			ret = snprintf(c->sock_path, sizeof(c->sock_path), "%s",
 				       optarg);
 			if (ret <= 0 || ret >= (int)sizeof(c->sock_path))
@@ -1679,6 +1679,9 @@ void conf(struct ctx *c, int argc, char **argv)
 			*c->sock_path = 0;
 			break;
 		case 'I':
+			if (c->mode != MODE_PASTA)
+				die("-I is for pasta mode only");
+
 			ret = snprintf(c->pasta_ifn, IFNAMSIZ, "%s",
 				       optarg);
 			if (ret <= 0 || ret >= IFNAMSIZ)
@@ -1835,11 +1838,16 @@ void conf(struct ctx *c, int argc, char **argv)
 			break;
 		case 't':
 		case 'u':
-		case 'T':
-		case 'U':
 		case 'D':
 			/* Handle these later, once addresses are configured */
 			break;
+		case 'T':
+		case 'U':
+			if (c->mode != MODE_PASTA)
+				die("-%c is for pasta mode only", name);
+
+			/* Handle properly later, once addresses are configured */
+			break;
 		case 'h':
 			usage(argv[0], stdout, EXIT_SUCCESS);
 			break;
-- 
2.48.1