dhcpc: code shrink in good_hostname
Incorporated valid_domain_label into good_hostname to simplify the implementation.
function old new delta
static.xmalloc_optname_optval 973 958 -15
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-15) Total: -15 bytes
text data bss dec hex filename
993144 16915 1872 1011931 f70db busybox_old
993129 16915 1872 1011916 f70cc busybox_unstripped
Signed-off-by: Martin Lewis <martin.lewis.x84@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 5a1f8fd..6422181 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -159,61 +159,27 @@
}
#if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
-/* Check if a given label represents a valid DNS label
- * Return pointer to the first character after the label
- * (NUL or dot) upon success, NULL otherwise.
- * See RFC1035, 2.3.1
- */
-/* We don't need to be particularly anal. For example, allowing _, hyphen
- * at the end, or leading and trailing dots would be ok, since it
- * can't be used for attacks. (Leading hyphen can be, if someone uses
- * cmd "$hostname"
- * in the script: then hostname may be treated as an option)
- */
-static const char *valid_domain_label(const char *label)
-{
- unsigned char ch;
- //unsigned pos = 0;
-
- if (label[0] == '-')
- return NULL;
- for (;;) {
- ch = *label;
- if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
- if (ch < '0' || ch > '9') {
- if (ch == '\0' || ch == '.')
- return label;
- /* DNS allows only '-', but we are more permissive */
- if (ch != '-' && ch != '_')
- return NULL;
- }
- }
- label++;
- //pos++;
- //Do we want this?
- //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
- // return NULL;
- }
-}
-
/* Check if a given name represents a valid DNS name */
/* See RFC1035, 2.3.1 */
+/* We don't need to be particularly anal. For example, allowing _, hyphen
+ * at the end, or leading and trailing dots would be ok, since it
+ * can't be used for attacks. (Leading hyphen can be, if someone uses cmd "$hostname"
+ * in the script: then hostname may be treated as an option)
+ */
static int good_hostname(const char *name)
{
- //const char *start = name;
+ if (*name == '-') /* Can't start with '-' */
+ return 0;
- for (;;) {
- name = valid_domain_label(name);
- if (!name)
- return 0;
- if (!name[0])
- return 1;
- //Do we want this?
- //return ((name - start) < 1025); /* NS_MAXDNAME */
- name++;
- if (*name == '\0')
- return 1; // We allow trailing dot too
+ while (*name) {
+ unsigned char ch = *name++;
+ if (!isalnum(ch))
+ /* DNS allows only '-', but we are more permissive */
+ if (ch != '-' && ch != '_' && ch != '.')
+ return 0;
+ // TODO: do we want to validate lengths against NS_MAXLABEL and NS_MAXDNAME?
}
+ return 1;
}
#else
# define good_hostname(name) 1