options.c

ADAM2 sources (modified by Oleg)

	
	optionptr = packet->options;
	i = 0;
	length = 308;
	while (!done) {
		if (i >= length) {
			sys_printf("bogus packet, option fields too long.\n");
			return NULL;
		}
		if (optionptr[i + OPT_CODE] == code) {
			if (i + 1 + optionptr[i + OPT_LEN] >= length) {
				sys_printf("bogus packet, option fields too long.\n");
				return NULL;
			}
			return optionptr + i + 2;
		}			
		switch (optionptr[i + OPT_CODE]) {
		case DHCP_PADDING:
			i++;
			break;
		case DHCP_OPTION_OVER:
			if (i + 1 + optionptr[i + OPT_LEN] >= length) {
				sys_printf("bogus packet, option fields too long.\n");
				return NULL;
			}
			over = optionptr[i + 3];
			i += optionptr[OPT_LEN] + 2;
			break;
		case DHCP_END:
			if (curr == OPTION_FIELD && over & FILE_FIELD) {
				optionptr = packet->file;
				i = 0;
				length = 128;
				curr = FILE_FIELD;
			} else if (curr == FILE_FIELD && over & SNAME_FIELD) {
				optionptr = packet->sname;
				i = 0;
				length = 64;
				curr = SNAME_FIELD;
			} else done = 1;
			break;
		default:
			i += optionptr[OPT_LEN + i] + 2;
		}
	}
	return NULL;
}

/* return the position of the 'end' option (no bounds checking) */
int end_option(unsigned char *optionptr) 
{
	int i = 0;
	
	while (optionptr[i] != DHCP_END) {
		if (optionptr[i] == DHCP_PADDING) i++;
		else i += optionptr[i + OPT_LEN] + 2;
	}
	return i;
}

/* add an option string to the options (an option string contains an option code,
 * length, then data) */
int add_option_string(unsigned char *optionptr, unsigned char *string)
{
	int end = end_option(optionptr);
	
	/* end position + string length + option code/length + end option */
	if (end + string[OPT_LEN] + 2 + 1 >= 308) {
		sys_printf("Option 0x%02x did not fit into the packet!\n", string[OPT_CODE]);
		return 0;
	}
	sys_memcpy(optionptr + end, string, string[OPT_LEN] + 2);
	optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
	return string[OPT_LEN] + 2;
}

/* add a one to four byte option to a packet */
int add_simple_option(unsigned char *optionptr, unsigned char code, UINT32 data)
{
	char length = 0;
	int i;
	unsigned char option[2 + 4];
	unsigned char *u8;
	UINT16 *u16;
	UINT32 *u32;
	UINT32 aligned;
	u8 = (unsigned char *) &aligned;
	u16 = (UINT16 *) &aligned;
	u32 = &aligned;

	for (i = 0; options[i].code; i++)
		if (options[i].code == code) {
			length = option_lengths[options[i].flags & TYPE_MASK];
		}
		
	if (!length) {
		sys_printf("Could not add option 0x%02x\n", code);
		return 0;
	}
	
	option[OPT_CODE] = code;
	option[OPT_LEN] = length;

	switch (length) {
		case 1: *u8 =  data; break;
		case 2: *u16 = data; break;
		case 4: *u32 = data; break;
	}
	sys_memcpy(option + 2, &aligned, length);
	return add_option_string(optionptr, option);
}

#if 0
/* find option 'code' in opt_list */
struct option_set *find_option(struct option_set *opt_list, char code)
{
	while (opt_list && opt_list->data[OPT_CODE] < code)
		opt_list = opt_list->next;

	if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list;
	else return NULL;
}


/* add an option to the opt_list */
void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length)
{
	struct option_set *existing, *new, **curr;

	/* add it to an existing option */
	if ((existing = find_option(*opt_list, option->code))) {
		sys_printf("Attaching option %s to existing member of list", option->name);
		if (option->flags & OPTION_LIST) {
			if (existing->data[OPT_LEN] + length <= 255) {
				existing->data = realloc(existing->data, 
						existing->data[OPT_LEN] + length + 2);
				memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
				existing->data[OPT_LEN] += length;
			} /* else, ignore the data, we could put this in a second option in the future */
		} /* else, ignore the new data */
	} else {
		sys_printf("Attaching option %s to list", option->name);
		
		/* make a new option */
		new = malloc(sizeof(struct option_set));
		new->data = malloc(length + 2);
		new->data[OPT_CODE] = option->code;
		new->data[OPT_LEN] = length;
		memcpy(new->data + 2, buffer, length);
		
		curr = opt_list;
		while (*curr && (*curr)->data[OPT_CODE] < option->code)
			curr = &(*curr)->next;
			
		new->next = *curr;
		*curr = new;		
	}
}
#endif

/* Add a paramater request list for stubborn DHCP servers. Pull the data
 * from the struct in options.c. Don't do bounds checking here because it
 * goes towards the head of the packet. */
void add_requests(dhcpMessage *packet)
{
    int end = end_option(packet->options);
    int i, len = 0;

    packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
    for (i = 0; options[i].code; i++)
        if (options[i].flags & OPTION_REQ)
            packet->options[end + OPT_DATA + len++] = options[i].code;
    packet->options[end + OPT_LEN] = len;
    packet->options[end + OPT_DATA + len] = DHCP_END;

}