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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
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<meta name="GENERATOR" content="Mozilla/4.7 [en] (X11; I; Linux 2.2.14 ppc) [Netscape]">
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<body>
<center>
<h1>
Sample Networking Program</h1></center>
<p><br>This example is derived from the test program <tt>".../net/tcpip/v1_3_1/tests/ping_test.c"</tt>.
<br>
<blockquote><tt><font size=-1>//==========================================================================</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>// tests/ping_test.c</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>// Simple test of PING
(ICMP) and networking support</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>//==========================================================================</font></tt>
<br><tt><font size=-1>//==========================================================================</font></tt>
<br><tt><font size=-1>//#####DESCRIPTIONBEGIN####</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>// Author(s): gthomas</font></tt>
<br><tt><font size=-1>// Contributors: gthomas</font></tt>
<br><tt><font size=-1>// Date:
2000-01-10</font></tt>
<br><tt><font size=-1>// Purpose:</font></tt>
<br><tt><font size=-1>// Description:</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>//####DESCRIPTIONEND####</font></tt>
<br><tt><font size=-1>//</font></tt>
<br><tt><font size=-1>//==========================================================================</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>// PING test code</font></tt><b><tt><font size=-1></font></tt></b>
<p><b><tt><font size=-1>#include <network.h></font></tt></b></blockquote>
This single include directive is all that is required to pick up the networking
support, including complete configuration information.
<blockquote><tt><font size=-1>#define STACK_SIZE CYGNUM_HAL_STACK_SIZE_TYPICAL</font></tt>
<br><tt><font size=-1>static char stack[STACK_SIZE];</font></tt>
<br><tt><font size=-1>static cyg_thread thread_data;</font></tt>
<br><tt><font size=-1>static cyg_handle_t thread_handle;</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>#define NUM_PINGS 16</font></tt>
<br><tt><font size=-1>#define MAX_PACKET 4096</font></tt>
<br><tt><font size=-1>static unsigned char pkt1[MAX_PACKET], pkt2[MAX_PACKET];</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>#define UNIQUEID 0x1234</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>void</font></tt>
<br><tt><font size=-1>cyg_test_exit(void)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> diag_printf("... Done\n");</font></tt>
<br><tt><font size=-1> while (1) ;</font></tt>
<br><tt><font size=-1>}</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>void</font></tt>
<br><tt><font size=-1>pexit(char *s)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> perror(s);</font></tt>
<br><tt><font size=-1> cyg_test_exit();</font></tt>
<br><tt><font size=-1>}</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>// Compute INET checksum</font></tt>
<br><tt><font size=-1>int</font></tt>
<br><tt><font size=-1>inet_cksum(u_short *addr, int len)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> register int nleft = len;</font></tt>
<br><tt><font size=-1> register u_short *w = addr;</font></tt>
<br><tt><font size=-1> register u_short answer;</font></tt>
<br><tt><font size=-1> register u_int sum = 0;</font></tt>
<br><tt><font size=-1> u_short odd_byte = 0;</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1> /*</font></tt>
<br><tt><font size=-1> * Our algorithm is
simple, using a 32 bit accumulator (sum),</font></tt>
<br><tt><font size=-1> * we add sequential
16 bit words to it, and at the end, fold</font></tt>
<br><tt><font size=-1> * back all the carry
bits from the top 16 bits into the lower</font></tt>
<br><tt><font size=-1> * 16 bits.</font></tt>
<br><tt><font size=-1> */</font></tt>
<br><tt><font size=-1> while( nleft > 1 ) {</font></tt>
<br><tt><font size=-1> sum +=
*w++;</font></tt>
<br><tt><font size=-1> nleft
-= 2;</font></tt>
<br><tt><font size=-1> }</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1> /* mop up an odd byte, if necessary
*/</font></tt>
<br><tt><font size=-1> if( nleft == 1 ) {</font></tt>
<br><tt><font size=-1> *(u_char
*)(&odd_byte) = *(u_char *)w;</font></tt>
<br><tt><font size=-1> sum +=
odd_byte;</font></tt>
<br><tt><font size=-1> }</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1> /*</font></tt>
<br><tt><font size=-1> * add back carry outs from
top 16 bits to low 16 bits</font></tt>
<br><tt><font size=-1> */</font></tt>
<br><tt><font size=-1> sum = (sum >> 16) + (sum &
0x0000ffff); /* add hi 16 to low 16 */</font></tt>
<br><tt><font size=-1> sum += (sum >> 16);
/* add carry */</font></tt>
<br><tt><font size=-1> answer = ~sum;
/* truncate to 16 bits */</font></tt>
<br><tt><font size=-1> return (answer);</font></tt>
<br><tt><font size=-1>}</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>static int</font></tt>
<br><tt><font size=-1>show_icmp(unsigned char *pkt, int len,</font></tt>
<br><tt><font size=-1>
struct sockaddr_in *from, struct sockaddr_in *to)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> cyg_tick_count_t *tp, tv;</font></tt>
<br><tt><font size=-1> struct ip *ip;</font></tt>
<br><tt><font size=-1> struct icmp *icmp;</font></tt>
<br><tt><font size=-1> tv = cyg_current_time();</font></tt>
<br><tt><font size=-1> ip = (struct ip *)pkt;</font></tt>
<br><tt><font size=-1> if ((len < sizeof(*ip)) ||
ip->ip_v != IPVERSION) {</font></tt>
<br><tt><font size=-1> diag_printf("%s:
Short packet or not IP! - Len: %d, Version: %d\n",</font></tt>
<br><tt><font size=-1>
inet_ntoa(from->sin_addr), len, ip->ip_v);</font></tt>
<br><tt><font size=-1> return
0;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> icmp = (struct icmp *)(pkt + sizeof(*ip));</font></tt>
<br><tt><font size=-1> len -= (sizeof(*ip) + 8);</font></tt>
<br><tt><font size=-1> tp = (cyg_tick_count_t *)&icmp->icmp_data;</font></tt>
<br><tt><font size=-1> if (icmp->icmp_type != ICMP_ECHOREPLY)
{</font></tt>
<br><tt><font size=-1> diag_printf("%s:
Invalid ICMP - type: %d\n",</font></tt>
<br><tt><font size=-1>
inet_ntoa(from->sin_addr), icmp->icmp_type);</font></tt>
<br><tt><font size=-1> return
0;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> if (icmp->icmp_id != UNIQUEID)
{</font></tt>
<br><tt><font size=-1> diag_printf("%s:
ICMP received for wrong id - sent: %x, recvd: %x\n",</font></tt>
<br><tt><font size=-1>
inet_ntoa(from->sin_addr), UNIQUEID, icmp->icmp_id);</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> diag_printf("%d bytes from %s:
", len, inet_ntoa(from->sin_addr));</font></tt>
<br><tt><font size=-1> diag_printf("icmp_seq=%d", icmp->icmp_seq);</font></tt>
<br><tt><font size=-1> diag_printf(", time=%dms\n", (int)(tv
- *tp)*10);</font></tt>
<br><tt><font size=-1> return (from->sin_addr.s_addr
== to->sin_addr.s_addr);</font></tt>
<br><tt><font size=-1>}</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>static void</font></tt>
<br><tt><font size=-1>ping_host(int s, struct sockaddr_in *host)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> struct icmp *icmp = (struct icmp
*)pkt1;</font></tt>
<br><tt><font size=-1> int icmp_len = 64;</font></tt>
<br><tt><font size=-1> int seq, ok_recv, bogus_recv;</font></tt>
<br><tt><font size=-1> cyg_tick_count_t *tp;</font></tt>
<br><tt><font size=-1> long *dp;</font></tt>
<br><tt><font size=-1> struct sockaddr_in from;</font></tt>
<br><tt><font size=-1> int i, len, fromlen;</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1> ok_recv = 0;</font></tt>
<br><tt><font size=-1> bogus_recv = 0;</font></tt>
<br><tt><font size=-1> diag_printf("PING server %s\n",
<b>inet_ntoa(host->sin_addr)</b>);</font></tt></blockquote>
This function takes an IP address and returns a string representation.
Useful for printing the address.
<blockquote><tt><font size=-1> for (seq = 0; seq
< NUM_PINGS; seq++) {</font></tt>
<br><tt><font size=-1> // Build
ICMP packet</font></tt>
<br><tt><font size=-1> icmp->icmp_type
= ICMP_ECHO;</font></tt>
<br><tt><font size=-1> icmp->icmp_code
= 0;</font></tt>
<br><tt><font size=-1> icmp->icmp_cksum
= 0;</font></tt>
<br><tt><font size=-1> icmp->icmp_seq
= seq;</font></tt>
<br><tt><font size=-1> icmp->icmp_id
= 0x1234;</font></tt>
<br><tt><font size=-1> // Set
up ping data</font></tt>
<br><tt><font size=-1> tp = (cyg_tick_count_t
*)&icmp->icmp_data;</font></tt>
<br><tt><font size=-1> *tp++
= cyg_current_time();</font></tt>
<br><tt><font size=-1> dp = (long
*)tp;</font></tt>
<br><tt><font size=-1> for (i
= sizeof(*tp); i < icmp_len; i += sizeof(*dp)) {</font></tt>
<br><tt><font size=-1>
*dp++ = i;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> // Add
checksum</font></tt>
<br><tt><font size=-1> icmp->icmp_cksum
= inet_cksum( (u_short *)icmp, icmp_len+8);</font></tt>
<br><tt><font size=-1> // Send
it off</font></tt>
<br><tt><font size=-1> <b>if
(sendto(s, icmp, icmp_len+8, 0, (struct sockaddr *)host, sizeof(*host))
< 0) {</b></font></tt></blockquote>
This function sends a single packet, in this case via the ICMP protocol.
The destination address is specified by the <tt>host</tt> argument.
<blockquote><tt><font size=-1>
perror("sendto");</font></tt>
<br><tt><font size=-1>
continue;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> // Wait
for a response</font></tt>
<br><tt><font size=-1> fromlen
= sizeof(from);</font></tt>
<br><tt><font size=-1> <b>len
= recvfrom(s, pkt2, sizeof(pkt2), 0, (struct sockaddr *)&from, &fromlen);</b></font></tt></blockquote>
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 <tt>ping_test()</tt> routine below).
<blockquote><tt><font size=-1>
if (len < 0) {</font></tt>
<br><tt><font size=-1>
perror("recvfrom");</font></tt>
<br><tt><font size=-1> } else
{</font></tt>
<br><tt><font size=-1>
if (show_icmp(pkt2, len, &from, host)) {</font></tt>
<br><tt><font size=-1>
ok_recv++;</font></tt>
<br><tt><font size=-1>
} else {</font></tt>
<br><tt><font size=-1>
bogus_recv++;</font></tt>
<br><tt><font size=-1>
}</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> diag_printf("Sent %d packets,
received %d OK, %d bad\n", NUM_PINGS, ok_recv, bogus_recv);</font></tt>
<br><tt><font size=-1>}</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1>static void</font></tt>
<br><tt><font size=-1>ping_test(struct bootp *bp)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> struct protoent *p;</font></tt>
<br><tt><font size=-1> struct timeval tv;</font></tt>
<br><tt><font size=-1> struct sockaddr_in host;</font></tt>
<br><tt><font size=-1> int s;</font></tt><tt><font size=-1></font></tt>
<p><tt><font size=-1> <b>if ((p = getprotobyname("icmp"))
== (struct protoent *)0) {</b></font></tt></blockquote>
This function gets information about the ICMP protocol. This will
be used below to set up the "socket" (the handle to a network connection).
<blockquote><tt><font size=-1>
perror("getprotobyname");</font></tt>
<br><tt><font size=-1> return;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> <b>s = socket(AF_INET, SOCK_RAW,
p->p_proto);</b></font></tt></blockquote>
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.
<blockquote><tt><font size=-1> if (s < 0) {</font></tt>
<br><tt><font size=-1> perror("socket");</font></tt>
<br><tt><font size=-1> return;</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1> tv.tv_sec = 1;</font></tt>
<br><tt><font size=-1> tv.tv_usec = 0;</font></tt>
<br><tt><font size=-1> <b>setsockopt(s, SOL_SOCKET, SO_RCVTIMEO,
&tv, sizeof(tv));</b></font></tt></blockquote>
This function instructs the system that receive operations (see <tt>ping_host()</tt>
above) must complete within 1 second or issue a timed out error condition.
<blockquote><tt><font size=-1> // Set up host address</font></tt>
<br><tt><font size=-1> host.sin_family = AF_INET;</font></tt>
<br><tt><font size=-1> host.sin_addr = bp->bp_siaddr;</font></tt>
<br><tt><font size=-1> host.sin_port = 0;</font></tt>
<br><tt><font size=-1> ping_host(s, &host);</font></tt>
<br><tt><font size=-1> // Now try a bogus host</font></tt>
<br><tt><font size=-1> host.sin_addr.s_addr = htonl(ntohl(host.sin_addr.s_addr)
+ 32);</font></tt>
<br><tt><font size=-1> ping_host(s, &host);</font></tt>
<br><tt><font size=-1>}</font></tt>
<br><tt><font size=-1></font></tt> </blockquote>
This function drives the test.
<blockquote><tt><font size=-1>void</font></tt>
<br><tt><font size=-1>net_test(cyg_addrword_t p)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> diag_printf("Start PING test\n");</font></tt>
<br><tt><font size=-1> <b>init_all_network_interfaces();</b></font></tt></blockquote>
This 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 <tt>cyg_start()
</tt>function which follows. The <tt>init_all_network_interfaces()</tt>
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 <b>BOOTP</b>, 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 "<tt>init_all_network_interfaces()</tt>".
<br><tt><font size=-1> </font></tt>
<br><tt><font size=-1> #ifdef CYGHWR_NET_DRIVER_ETH0</font></tt>
<br><tt><font size=-1> if (eth0_up)
{</font></tt>
<blockquote><tt><font size=-1>
ping_test(&eth0_bootp_data);</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1>#endif</font></tt></blockquote>
Notice that there is a BOOTP information structure kept about all hardware
interfaces. This is created and initialized by the call to <tt>init_all_network_interfaces()</tt>,
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.
<blockquote><tt><font size=-1>#ifdef CYGHWR_NET_DRIVER_ETH1</font></tt>
<br><tt><font size=-1> if (eth1_up) {</font></tt>
<br><tt><font size=-1> ping_test(&eth1_bootp_data);</font></tt>
<br><tt><font size=-1> }</font></tt>
<br><tt><font size=-1>#endif</font></tt></blockquote>
Multiple hardware interfaces can be supported, depending on the hardware
platform. If the platform provides a single ethernet device then
<b><tt>CYGHWR_NET_DRIVER_ETH0 </tt></b>will be defined. If there
is a second interface, then will <b><tt>CYGHWR_NET_DRIVER_ETH1 </tt></b>be
defined.
<blockquote><tt><font size=-1> cyg_test_exit();</font></tt>
<br><tt><font size=-1>}</font></tt>
<br><tt><font size=-1></font></tt> </blockquote>
The following function creates an initial thread which runs the program.
This could just as easily be done by naming the <tt>net_test()</tt> function
<tt>main()</tt>.
<blockquote><tt><font size=-1>void</font></tt>
<br><tt><font size=-1>cyg_start(void)</font></tt>
<br><tt><font size=-1>{</font></tt>
<br><tt><font size=-1> // Create a main thread, so we
can run the scheduler and have time 'pass'</font></tt>
<br><tt><font size=-1> cyg_thread_create(10,
// Priority - just a number</font></tt>
<br><tt><font size=-1>
net_test, // entry</font></tt>
<br><tt><font size=-1>
0,
// entry parameter</font></tt>
<br><tt><font size=-1>
"Network test", // Name</font></tt>
<br><tt><font size=-1>
&stack[0], // Stack</font></tt>
<br><tt><font size=-1>
STACK_SIZE, // Size</font></tt>
<br><tt><font size=-1>
&thread_handle, // Handle</font></tt>
<br><tt><font size=-1>
&thread_data // Thread data structure</font></tt>
<br><tt><font size=-1>
);</font></tt>
<br><tt><font size=-1> cyg_thread_resume(thread_handle);
// Start it</font></tt>
<br><tt><font size=-1> cyg_scheduler_start();</font></tt>
<br><tt><font size=-1>}</font></tt></blockquote>
</body>
</html>
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