udhcp: abort if we see unknown option, and show valid options if so

function                                             old     new   delta
udhcp_option_idx                                       -      77     +77
udhcp_str2optset                                     366     351     -15
udhcpc_main                                         2845    2801     -44
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 77/-59)             Total: 18 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 26 insertions, 12 deletions

diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 9316774ff..6e8ec3e64 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -146,6 +146,25 @@ static void log_option(const char *pfx, const uint8_t *opt)
 # define log_option(pfx, opt) ((void)0)
 #endif
 
+unsigned FAST_FUNC udhcp_option_idx(const char *name)
+{
+        int n = index_in_strings(dhcp_option_strings, name);
+        if (n >= 0)
+                return n;
+
+        {
+                char buf[sizeof(dhcp_option_strings)];
+                char *d = buf;
+                const char *s = dhcp_option_strings;
+                while (s < dhcp_option_strings + sizeof(dhcp_option_strings) - 2) {
+                        *d++ = (*s == '\0' ? ' ' : *s);
+                        s++;
+                }
+                *d = '\0';
+                bb_error_msg_and_die("unknown option '%s', known options: %s", name, buf);
+        }
+}
+
 /* get an option with bounds checking (warning, result is not aligned). */
 uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code)
 {
@@ -372,7 +391,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
         char *opt, *val, *endptr;
         char *str;
         const struct dhcp_option *option;
-        int retval, length, idx;
+        int retval, length;
         char buffer[8] ALIGNED(4);
         uint16_t *result_u16 = (uint16_t *) buffer;
         uint32_t *result_u32 = (uint32_t *) buffer;
@@ -383,10 +402,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
         if (!opt)
                 return 0;
 
-        idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
-        if (idx < 0)
-                return 0;
-        option = &dhcp_options[idx];
+        option = &dhcp_options[udhcp_option_idx(opt)];
 
         retval = 0;
         do {
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index b4e8b5d43..1c5afa6f9 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -169,6 +169,8 @@ extern const struct dhcp_option dhcp_options[];
 extern const char dhcp_option_strings[];
 extern const uint8_t dhcp_option_lengths[];
 
+unsigned FAST_FUNC udhcp_option_idx(const char *name);
+
 uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC;
 int udhcp_end_option(uint8_t *optionptr) FAST_FUNC;
 void udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) FAST_FUNC;
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 478ca5c21..c36d4180b 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -879,21 +879,17 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                 client_config.no_default_options = 1;
         while (list_O) {
                 char *optstr = llist_pop(&list_O);
-                int n = index_in_strings(dhcp_option_strings, optstr);
-                if (n < 0)
-                        bb_error_msg_and_die("unknown option '%s'", optstr);
+                unsigned n = udhcp_option_idx(optstr);
                 n = dhcp_options[n].code;
                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
         }
         while (list_x) {
-                int n;
+                unsigned n;
                 char *optstr = llist_pop(&list_x);
                 char *colon = strchr(optstr, ':');
                 if (colon)
                         *colon = '\0';
-                n = index_in_strings(dhcp_option_strings, optstr);
-                if (n < 0)
-                        bb_error_msg_and_die("unknown option '%s'", optstr);
+                n = udhcp_option_idx(optstr);
                 if (colon)
                         *colon = ' ';
                 udhcp_str2optset(optstr, &client_config.options);