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#include "netlib.h"
/* ping - originate ICMP echo requests from the Game Boy (10.0.0.2) and print
the replies. Target defaults to 10.0.0.1 (the SLIP peer / host); with NAT on
the bridge it can reach real internet hosts too. Usage: ping [A.B.C.D] */
static unsigned char pkt[128];
static unsigned char dst[4];
static unsigned int sum16(unsigned char *d, unsigned int len, unsigned int sum) {
unsigned int w, i = 0;
while (i + 1 < len) { w = ((unsigned int)d[i] << 8) | d[i + 1]; sum += w; if (sum < w) sum++; i += 2; }
if (len & 1) { w = (unsigned int)d[len - 1] << 8; sum += w; if (sum < w) sum++; }
return sum;
}
static unsigned char parse_ip(char *s, unsigned char *out) {
unsigned char i, v;
for (i = 0; i < 4; i++) {
if (*s < '0' || *s > '9') return 0;
v = 0;
while (*s >= '0' && *s <= '9') { v = (unsigned char)(v * 10 + (*s - '0')); s++; }
out[i] = v;
if (i < 3) { if (*s != '.') return 0; s++; }
}
return 1;
}
static void put_ip(unsigned char *ip) {
unsigned char i;
for (i = 0; i < 4; i++) { putu(ip[i]); if (i < 3) putc('.'); }
}
static void send_echo(unsigned char seq) {
unsigned int c;
pkt[0] = 0x45; pkt[1] = 0; pkt[2] = 0; pkt[3] = 28; /* 20 IP + 8 ICMP */
pkt[4] = 0; pkt[5] = 0; pkt[6] = 0; pkt[7] = 0;
pkt[8] = 64; pkt[9] = 1; pkt[10] = 0; pkt[11] = 0; /* TTL, proto ICMP */
pkt[12] = 10; pkt[13] = 0; pkt[14] = 0; pkt[15] = 2; /* src 10.0.0.2 */
pkt[16] = dst[0]; pkt[17] = dst[1]; pkt[18] = dst[2]; pkt[19] = dst[3];
c = ~sum16(pkt, 20, 0); pkt[10] = (unsigned char)(c >> 8); pkt[11] = (unsigned char)c;
pkt[20] = 8; pkt[21] = 0; pkt[22] = 0; pkt[23] = 0; /* echo request */
pkt[24] = 0x12; pkt[25] = 0x34; pkt[26] = 0; pkt[27] = seq;
c = ~sum16(pkt + 20, 8, 0); pkt[22] = (unsigned char)(c >> 8); pkt[23] = (unsigned char)c;
slip_send((char *)pkt, 28);
}
/* wait for the ICMP echo reply for 'seq', skipping unrelated frames (the shared
10.0.0.0/24 carries IGMP/mDNS/SSDP noise). Returns 1 on match, 0 on timeout.
The emulator runs uncapped, so the spin budget is generous to span the
wall-clock round trip through the host bridge. */
static unsigned char ping_wait(unsigned char seq) {
unsigned int o, i;
unsigned char len = 0, c, ihl;
int b;
for (o = 0; o < 20; o++) {
for (i = 0; i < 60000; i++) {
b = srecv_nb();
if (b < 0) continue;
c = (unsigned char)b;
if (c == SLIP_END) {
if (len) {
ihl = (unsigned char)((pkt[0] & 0x0f) << 2);
if (len >= (unsigned char)(ihl + 8) && pkt[9] == 1
&& pkt[ihl] == 0 && pkt[ihl + 7] == seq) return 1;
len = 0; /* not ours - keep waiting */
}
continue;
}
if (c == SLIP_ESC) {
c = srecv();
if (c == SLIP_ESC_END) c = SLIP_END;
else if (c == SLIP_ESC_ESC) c = SLIP_ESC;
}
if (len < 128) pkt[len++] = c; else len = 0;
}
}
return 0;
}
void main(void) {
char *arg;
unsigned char seq, got = 0;
arg = getargs();
if (!arg || !*arg) { dst[0] = 10; dst[1] = 0; dst[2] = 0; dst[3] = 1; }
else if (!parse_ip(arg, dst)) { puts("ping: bad address"); nl(); sexit(1); }
puts("PING "); put_ip(dst); nl();
for (seq = 1; seq <= 4; seq++) {
send_echo(seq);
if (ping_wait(seq)) {
got++;
puts(" reply from "); put_ip(pkt + 12);
puts(" seq="); putu(seq);
puts(" ttl="); putu(pkt[8]); nl();
} else {
puts(" seq="); putu(seq); puts(" timeout"); nl();
}
}
puts("-- "); putu(got); puts("/4 received"); nl();
}
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