void test_icmp_checksum(void)
{
struct icmphdr header;
CU_ASSERT_EQUAL(icmp_checksum(NULL), -1);
CU_ASSERT_EQUAL(icmp_checksum(&header), 0);
}
// ------------------------------------------------
// Function: ping_request()
// ------------------------------------------------
// Input: IP address
// Network interface ID
// Output: -
// ------------------------------------------------
// Description: Sends a ping request message
// ------------------------------------------------
void ping_request(IPV4 ip, BYTE interface)
{
PPBUF buf;
buf = ip_new(ip, 64, interface);
if(buf == NULL) return;
// ---------------------
// assemble ICMP message
// ---------------------
IPH(buf->start)->prot = IP_PROT_ICMP;
ICMP(buf->data)->type = PING_REQUEST;
ICMP(buf->data)->code = 0;
ICMP(buf->data)->checksum = 0;
ICMP(buf->data)->id = random();
ICMP(buf->data)->seq = random();
buf->size = sizeof(ICMP_HDR);
// ------------------
// calculate checksum
// ------------------
icmp_checksum(buf->data, buf->size);
ICMP(buf->data)->checksum = HTONS(~WORDOF(chk_H, chk_L));
// -----------------------------
// sends message to IP interface
// -----------------------------
ip_send(buf);
release_buffer(buf);
}
// ------------------------------------------------
// Function: icmp_parse()
// ------------------------------------------------
// Input: Message buffer
// Output: -
// ------------------------------------------------
// Description: Parse a ICMP message
// ------------------------------------------------
void icmp_parse(PPBUF pbuf)
{
// ---------------------
// checksum verification
// ---------------------
icmp_checksum(pbuf->data, pbuf->size);
if(chk_H != 0xff) return;
if(chk_L != 0xff) return;
// -------------------------------
// checks recognized message types
// -------------------------------
switch(ICMP(pbuf->data)->type) {
case PING_REQUEST:
// ---------
// answer it
// ---------
retain_buffer(pbuf);
ip_answer(pbuf);
ICMP(pbuf->data)->type = PING_REPLY;
// ---------------
// update checksum
// ---------------
ICMP(pbuf->data)->checksum = 0;
icmp_checksum(pbuf->data, pbuf->size);
ICMP(pbuf->data)->checksum = HTONS(~WORDOF(chk_H, chk_L));
// ----------------------------
// sends answer to IP interface
// ----------------------------
ip_send(pbuf);
release_buffer(pbuf);
break;
case PING_REPLY:
// --------------------------------------
// answer received, signal waiting thread
// --------------------------------------
os_signal(SIG_ICMP);
break;
}
}
static size_t __icmp_gen(icmp_hdr_t *hdr, uint8_t type, uint8_t code, size_t dlen)
{
size_t len;
hdr->type = type;
hdr->code = code;
len = sizeof(icmp_hdr_t) + dlen;
icmp_checksum(hdr, len);
debug(ICMP, "snd ICMP %s rest 0x%x\n", __icmp_type_str(type), hdr->rest);
return len;
}
