1 files changed, 61 insertions, 0 deletions
diff --git a/usr/ping.c b/usr/ping.c
new file mode 100644
index 0000000..8671318
--- /dev/null
+++ b/usr/ping.c
@@ -0,0 +1,61 @@
+#include "resolve.h"
+/* ping HOST|IP - originate ICMP echo requests via the kernel socket layer.
+   Resolves a hostname via DNS first (resolve.h); default target 10.0.0.1. No
+   SLIP/IP/checksums here - the kernel owns all of that. */
+
+/* rbuf is first + large so namebuf/dst land past the arg string at 0xA000 */
+static unsigned char rbuf[96];
+static unsigned char namebuf[64];
+static unsigned char dst[4];
+static unsigned char payload[4];
+
+static void put_ip(unsigned char *ip) {
+    unsigned char i;
+    for (i = 0; i < 4; i++) { putu(ip[i]); if (i < 3) putc('.'); }
+}
+
+/* wait up to ~2s for an echo reply without blocking in the kernel: a lost
+   reply (some hosts rate-limit ICMP) must cost one "timeout" line, not
+   minutes wedged inside net_recv's pump-counted wait. */
+static unsigned char wait_reply(unsigned char s) {
+    unsigned char t, r;
+    for (t = 0; t < 40; t++) {
+        r = net_recv_nb(s, rbuf, (unsigned char)sizeof(rbuf));
+        if (r != 0xFE) return r;       /* reply (or error) */
+        msleep(50);
+    }
+    return 0xFF;                       /* ~2s with no reply */
+}
+
+void main(void) {
+    char *arg;
+    unsigned char s, seq, got = 0, i;
+    arg = getargs();
+    if (!arg || !*arg) { dst[0] = 10; dst[1] = 0; dst[2] = 0; dst[3] = 1; }
+    else {
+        for (i = 0; arg[i] && i < 63; i++) namebuf[i] = (unsigned char)arg[i];
+        namebuf[i] = 0;
+        if (!resolve((char *)namebuf, dst)) {
+            puts("ping: cannot resolve "); puts((char *)namebuf); nl(); sexit(1);
+        }
+    }
+
+    payload[0] = 'g'; payload[1] = 'b'; payload[2] = 'o'; payload[3] = 's';
+    s = net_socket(SOCK_ICMP);
+    if (s == 0xFF) { puts("ping: no socket"); nl(); sexit(1); }
+    net_connect(s, dst, 0);
+
+    puts("PING "); put_ip(dst); nl();
+    for (seq = 1; seq <= 4; seq++) {
+        net_send(s, payload, 4);
+        if (wait_reply(s) != 0xFF) {
+            got++;
+            puts("  reply from "); put_ip(dst); puts(" seq="); putu(seq); nl();
+        } else {
+            puts("  seq="); putu(seq); puts(" timeout"); nl();
+        }
+        if (seq < 4) msleep(800);      /* pace like real ping */
+    }
+    puts("-- "); putu(got); puts("/4 received"); nl();
+    net_close(s);
+}