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dhcpc: code shrink in good_hostname

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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>
This commit is contained in:
Martin Lewis 2020-05-04 16:59:14 -05:00 committed by Denys Vlasenko
parent 6f7a009649
commit 726d0d148b
1 changed files with 15 additions and 49 deletions
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64
networking/udhcp/dhcpc.c
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@ -159,61 +159,27 @@ static int mton(uint32_t mask)
}
#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