diff options
| -rw-r--r-- | networking/udhcp/dhcpc.c | 62 |
1 files changed, 14 insertions, 48 deletions
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 @@ 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 - */ +/* 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 "$hostname" + * can't be used for attacks. (Leading hyphen can be, if someone uses cmd "$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 */ static int good_hostname(const char *name) { - //const char *start = name; - - 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 + if (*name == '-') /* Can't start with '-' */ + return 0; + + 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 |