This example is derived from the test program ".../net/tcpip/v1_3_1/tests/ping_test.c".
//==========================================================================This single include directive is all that is required to pick up the networking support, including complete configuration information.
//
// tests/ping_test.c
//
// Simple test of PING (ICMP) and networking support
//
//==========================================================================
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s): gthomas
// Contributors: gthomas
// Date: 2000-01-10
// Purpose:
// Description:
//
//
//####DESCRIPTIONEND####
//
//==========================================================================// PING test code
#include <network.h>
#define STACK_SIZE CYGNUM_HAL_STACK_SIZE_TYPICALThis function takes an IP address and returns a string representation. Useful for printing the address.
static char stack[STACK_SIZE];
static cyg_thread thread_data;
static cyg_handle_t thread_handle;#define NUM_PINGS 16
#define MAX_PACKET 4096
static unsigned char pkt1[MAX_PACKET], pkt2[MAX_PACKET];#define UNIQUEID 0x1234
void
cyg_test_exit(void)
{
diag_printf("... Done\n");
while (1) ;
}void
pexit(char *s)
{
perror(s);
cyg_test_exit();
}// Compute INET checksum
int
inet_cksum(u_short *addr, int len)
{
register int nleft = len;
register u_short *w = addr;
register u_short answer;
register u_int sum = 0;
u_short odd_byte = 0;/*
* Our algorithm is simple, using a 32 bit accumulator (sum),
* we add sequential 16 bit words to it, and at the end, fold
* back all the carry bits from the top 16 bits into the lower
* 16 bits.
*/
while( nleft > 1 ) {
sum += *w++;
nleft -= 2;
}/* mop up an odd byte, if necessary */
if( nleft == 1 ) {
*(u_char *)(&odd_byte) = *(u_char *)w;
sum += odd_byte;
}/*
* add back carry outs from top 16 bits to low 16 bits
*/
sum = (sum >> 16) + (sum & 0x0000ffff); /* add hi 16 to low 16 */
sum += (sum >> 16); /* add carry */
answer = ~sum; /* truncate to 16 bits */
return (answer);
}static int
show_icmp(unsigned char *pkt, int len,
struct sockaddr_in *from, struct sockaddr_in *to)
{
cyg_tick_count_t *tp, tv;
struct ip *ip;
struct icmp *icmp;
tv = cyg_current_time();
ip = (struct ip *)pkt;
if ((len < sizeof(*ip)) || ip->ip_v != IPVERSION) {
diag_printf("%s: Short packet or not IP! - Len: %d, Version: %d\n",
inet_ntoa(from->sin_addr), len, ip->ip_v);
return 0;
}
icmp = (struct icmp *)(pkt + sizeof(*ip));
len -= (sizeof(*ip) + 8);
tp = (cyg_tick_count_t *)&icmp->icmp_data;
if (icmp->icmp_type != ICMP_ECHOREPLY) {
diag_printf("%s: Invalid ICMP - type: %d\n",
inet_ntoa(from->sin_addr), icmp->icmp_type);
return 0;
}
if (icmp->icmp_id != UNIQUEID) {
diag_printf("%s: ICMP received for wrong id - sent: %x, recvd: %x\n",
inet_ntoa(from->sin_addr), UNIQUEID, icmp->icmp_id);
}
diag_printf("%d bytes from %s: ", len, inet_ntoa(from->sin_addr));
diag_printf("icmp_seq=%d", icmp->icmp_seq);
diag_printf(", time=%dms\n", (int)(tv - *tp)*10);
return (from->sin_addr.s_addr == to->sin_addr.s_addr);
}static void
ping_host(int s, struct sockaddr_in *host)
{
struct icmp *icmp = (struct icmp *)pkt1;
int icmp_len = 64;
int seq, ok_recv, bogus_recv;
cyg_tick_count_t *tp;
long *dp;
struct sockaddr_in from;
int i, len, fromlen;ok_recv = 0;
bogus_recv = 0;
diag_printf("PING server %s\n", inet_ntoa(host->sin_addr));
for (seq = 0; seq < NUM_PINGS; seq++) {This function sends a single packet, in this case via the ICMP protocol. The destination address is specified by the host argument.
// Build ICMP packet
icmp->icmp_type = ICMP_ECHO;
icmp->icmp_code = 0;
icmp->icmp_cksum = 0;
icmp->icmp_seq = seq;
icmp->icmp_id = 0x1234;
// Set up ping data
tp = (cyg_tick_count_t *)&icmp->icmp_data;
*tp++ = cyg_current_time();
dp = (long *)tp;
for (i = sizeof(*tp); i < icmp_len; i += sizeof(*dp)) {
*dp++ = i;
}
// Add checksum
icmp->icmp_cksum = inet_cksum( (u_short *)icmp, icmp_len+8);
// Send it off
if (sendto(s, icmp, icmp_len+8, 0, (struct sockaddr *)host, sizeof(*host)) < 0) {
perror("sendto");This function waits for a packet to be sent to this interface. Note: this operation can fail if no packet is received with a given amount of time (this timeout value is setup in the ping_test() routine below).
continue;
}
// Wait for a response
fromlen = sizeof(from);
len = recvfrom(s, pkt2, sizeof(pkt2), 0, (struct sockaddr *)&from, &fromlen);
if (len < 0) {This function gets information about the ICMP protocol. This will be used below to set up the "socket" (the handle to a network connection).
perror("recvfrom");
} else {
if (show_icmp(pkt2, len, &from, host)) {
ok_recv++;
} else {
bogus_recv++;
}
}
}
diag_printf("Sent %d packets, received %d OK, %d bad\n", NUM_PINGS, ok_recv, bogus_recv);
}static void
ping_test(struct bootp *bp)
{
struct protoent *p;
struct timeval tv;
struct sockaddr_in host;
int s;if ((p = getprotobyname("icmp")) == (struct protoent *)0) {
perror("getprotobyname");Create the socket "s". A socket is an abstract object (sometimes called a handle or endpoint). Sockets come in many flavors, RAW sockets are used for communicating with non-structured protocols. DATAGRAM sockets are used for packet oriented protocols, such as UDP. STREAM sockets are used for reliable, sequenced byte streams, such as those provided by TCP.
return;
}
s = socket(AF_INET, SOCK_RAW, p->p_proto);
if (s < 0) {This function instructs the system that receive operations (see ping_host() above) must complete within 1 second or issue a timed out error condition.
perror("socket");
return;
}
tv.tv_sec = 1;
tv.tv_usec = 0;
setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
// Set up host addressThis function drives the test.
host.sin_family = AF_INET;
host.sin_addr = bp->bp_siaddr;
host.sin_port = 0;
ping_host(s, &host);
// Now try a bogus host
host.sin_addr.s_addr = htonl(ntohl(host.sin_addr.s_addr) + 32);
ping_host(s, &host);
}
voidThis is a call to the network initialization code. Note that it must be executed from a thread context, thus we can't put it in the cyg_start() function which follows. The init_all_network_interfaces() routine will cause the networking system to be initialized and any hardware interfaces will be set up. Using the system configuration information, an interface can be started using either BOOTP, or a predefined configuration with static IP information. It is also possible to indicate that an interface will be configured by the user code, outside of "init_all_network_interfaces()".
net_test(cyg_addrword_t p)
{
diag_printf("Start PING test\n");
init_all_network_interfaces();
ping_test(ð0_bootp_data);Notice that there is a BOOTP information structure kept about all hardware interfaces. This is created and initialized by the call to init_all_network_interfaces(), unless manual configuration is selected. This information can be used by the application to learn things such as the local IP address, server name, etc.
}
#endif
#ifdef CYGHWR_NET_DRIVER_ETH1Multiple hardware interfaces can be supported, depending on the hardware platform. If the platform provides a single ethernet device then CYGHWR_NET_DRIVER_ETH0 will be defined. If there is a second interface, then will CYGHWR_NET_DRIVER_ETH1 be defined.
if (eth1_up) {
ping_test(ð1_bootp_data);
}
#endif
cyg_test_exit();The following function creates an initial thread which runs the program. This could just as easily be done by naming the net_test() function main().
}
void
cyg_start(void)
{
// Create a main thread, so we can run the scheduler and have time 'pass'
cyg_thread_create(10, // Priority - just a number
net_test, // entry
0, // entry parameter
"Network test", // Name
&stack[0], // Stack
STACK_SIZE, // Size
&thread_handle, // Handle
&thread_data // Thread data structure
);
cyg_thread_resume(thread_handle); // Start it
cyg_scheduler_start();
}