udhcpc: do in fact not allow hostname components which start with dash

function                                             old     new   delta
xmalloc_optname_optval                               879     893     +14

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

1 files changed, 6 insertions, 4 deletions

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index c2805a009..3afdb35fe 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -160,8 +160,8 @@ 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 upon success,
- * NULL otherwise.
+ * 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
@@ -173,8 +173,10 @@ static int mton(uint32_t mask)
 static const char *valid_domain_label(const char *label)
 {
         unsigned char ch;
-        unsigned pos = 0;
+        //unsigned pos = 0;
 
+        if (label[0] == '-')
+                return NULL;
         for (;;) {
                 ch = *label;
                 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
@@ -187,7 +189,7 @@ static const char *valid_domain_label(const char *label)
                         }
                 }
                 label++;
-                pos++;
+                //pos++;
                 //Do we want this?
                 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
                 //      return NULL;