ref: d1cebf608b05e45b148108ac6c16ae94f6862097
dir: /sys/src/cmd/ip/udpecho.c/
#include <u.h> #include <libc.h> #include <ip.h> void usage(void) { fprint(2, "usage: %s [-x netmtpt]\n", argv0); exits("usage"); } void main(int argc, char **argv) { int fd, cfd, n; char buf[4096], data[128], devdir[40], net[32]; setnetmtpt(net, sizeof net, nil); ARGBEGIN{ case 'x': setnetmtpt(net, sizeof net, EARGF(usage())); break; }ARGEND; sprint(data, "%s/udp!*!echo", net); cfd = announce(data, devdir); if(cfd < 0) sysfatal("can't announce %s: %r", data); if(fprint(cfd, "headers") < 0) sysfatal("can't set header mode: %r"); sprint(data, "%s/data", devdir); fd = open(data, ORDWR); if(fd < 0) sysfatal("open %s: %r", data); while ((n = read(fd, buf, sizeof buf)) > 0) write(fd, buf, n); if (n < 0) sysfatal("error reading: %r"); exits(0); }