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Diffstat (limited to 'networking/udhcp/options.c')
-rw-r--r--networking/udhcp/options.c96
1 files changed, 49 insertions, 47 deletions
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c
index 581a7b6..143a1fd 100644
--- a/networking/udhcp/options.c
+++ b/networking/udhcp/options.c
@@ -119,58 +119,61 @@ const uint8_t dhcp_option_lengths[] ALIGN1 = {
};
-/* get an option with bounds checking (warning, not aligned). */
+/* get an option with bounds checking (warning, result is not aligned). */
uint8_t* FAST_FUNC get_option(struct dhcpMessage *packet, int code)
{
- int i, length;
uint8_t *optionptr;
- int over = 0;
- int curr = OPTION_FIELD;
-
+ int len;
+ int rem;
+ int overload = 0;
+ enum {
+ FILE_FIELD101 = FILE_FIELD * 0x101,
+ SNAME_FIELD101 = SNAME_FIELD * 0x101,
+ };
+
+ /* option bytes: [code][len][data1][data2]..[dataLEN] */
optionptr = packet->options;
- i = 0;
- length = sizeof(packet->options);
+ rem = sizeof(packet->options);
while (1) {
- if (i >= length) {
- bb_error_msg("bogus packet, option fields too long");
+ if (rem <= 0) {
+ bb_error_msg("bogus packet, malformed option field");
return NULL;
}
- if (optionptr[i + OPT_CODE] == code) {
- if (i + 1 + optionptr[i + OPT_LEN] >= length) {
- bb_error_msg("bogus packet, option fields too long");
- return NULL;
- }
- return optionptr + i + 2;
+ if (optionptr[OPT_CODE] == DHCP_PADDING) {
+ rem--;
+ optionptr++;
+ continue;
}
- switch (optionptr[i + OPT_CODE]) {
- case DHCP_PADDING:
- i++;
- break;
- case DHCP_OPTION_OVER:
- if (i + 1 + optionptr[i + OPT_LEN] >= length) {
- bb_error_msg("bogus packet, option fields too long");
- return NULL;
- }
- over = optionptr[i + 3];
- i += optionptr[OPT_LEN] + 2;
- break;
- case DHCP_END:
- if (curr == OPTION_FIELD && (over & FILE_FIELD)) {
+ if (optionptr[OPT_CODE] == DHCP_END) {
+ if ((overload & FILE_FIELD101) == FILE_FIELD) {
+ /* can use packet->file, and didn't look at it yet */
+ overload |= FILE_FIELD101; /* "we looked at it" */
optionptr = packet->file;
- i = 0;
- length = sizeof(packet->file);
- curr = FILE_FIELD;
- } else if (curr == FILE_FIELD && (over & SNAME_FIELD)) {
+ rem = sizeof(packet->file);
+ continue;
+ }
+ if ((overload & SNAME_FIELD101) == SNAME_FIELD) {
+ /* can use packet->sname, and didn't look at it yet */
+ overload |= SNAME_FIELD101; /* "we looked at it" */
optionptr = packet->sname;
- i = 0;
- length = sizeof(packet->sname);
- curr = SNAME_FIELD;
- } else
- return NULL;
- break;
- default:
- i += optionptr[OPT_LEN + i] + 2;
+ rem = sizeof(packet->sname);
+ continue;
+ }
+ return NULL;
+ }
+ len = 2 + optionptr[OPT_LEN];
+ rem -= len;
+ if (rem < 0)
+ continue; /* complain and return NULL */
+
+ if (optionptr[OPT_CODE] == code)
+ return optionptr + OPT_DATA;
+
+ if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
+ overload |= optionptr[OPT_DATA];
+ /* fall through */
}
+ optionptr += len;
}
return NULL;
}
@@ -182,17 +185,16 @@ int FAST_FUNC end_option(uint8_t *optionptr)
int i = 0;
while (optionptr[i] != DHCP_END) {
- if (optionptr[i] == DHCP_PADDING)
- i++;
- else
- i += optionptr[i + OPT_LEN] + 2;
+ if (optionptr[i] != DHCP_PADDING)
+ i += optionptr[i + OPT_LEN] + 1;
+ i++;
}
return i;
}
-/* add an option string to the options (an option string contains an option code,
- * length, then data) */
+/* add an option string to the options */
+/* option bytes: [code][len][data1][data2]..[dataLEN] */
int FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string)
{
int end = end_option(optionptr);