sys/src/cmd/cifs/ping.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <fcall.h>
   4 #include <thread.h>
   5 #include <libsec.h>
   6 #include <9p.h>
   7
   8 extern char *Debug;
   9
  10 typedef struct Pingcache Pingcache;
  11 struct Pingcache {
  12         Pingcache*next;
  13         long    rtt;
  14         char    *host;
  15         long    expire;
  16 };
  17
  18 typedef struct {
  19         uchar   vihl;           /* Version and header length */
  20         uchar   tos;            /* Type of service */
  21         uchar   length[2];      /* packet length */
  22         uchar   id[2];          /* Identification */
  23         uchar   frag[2];        /* Fragment information */
  24         uchar   ttl;            /* Time to live */
  25         uchar   proto;          /* Protocol */
  26         uchar   ipcksum[2];     /* Header checksum */
  27         uchar   src[4];         /* Ip source */
  28         uchar   dst[4];         /* Ip destination */
  29         uchar   type;
  30         uchar   code;
  31         uchar   cksum[2];
  32         uchar   icmpid[2];
  33         uchar   seq[2];
  34         uchar   data[1];
  35 } Icmp;
  36
  37 enum {                  /* Packet Types */
  38         EchoReply       = 0,
  39         Unreachable     = 3,
  40         SrcQuench       = 4,
  41         EchoRequest     = 8,
  42         TimeExceed      = 11,
  43         Timestamp       = 13,
  44         TimestampReply  = 14,
  45         InfoRequest     = 15,
  46         InfoReply       = 16,
  47
  48         ICMP_IPSIZE     = 20,
  49         ICMP_HDRSIZE    = 8,
  50
  51         Npings          = 8,
  52         Payload         = 32,
  53
  54         Cachetime       = 60,
  55 };
  56
  57 static Pingcache *Cache;
  58
  59 /*
  60  * We ignore the first result as that is probably bigger
  61  * than expected due to IP sorting out the routing to the host
  62  */
  63 int
  64 ping(char *host, int timeout)
  65 {
  66         int rtt, fd, i, seq;
  67         long now;
  68         vlong then;
  69         uchar buf[128];
  70         Icmp *ip;
  71         Pingcache *c;
  72
  73         now = time(nil);
  74         for(c = Cache; c; c = c->next)
  75                 if(strcmp(c->host, host) == 0 && now < c->expire){
  76                         if(Debug && strstr(Debug, "dfs") != nil)
  77                                 print("\t\tping host=%s timeout=%d - cache hit\n",
  78                                         host, timeout);
  79                         return c->rtt;
  80                 }
  81
  82         rtt = -1;
  83         ip = (Icmp*)buf;
  84
  85         if((fd = dial(netmkaddr(host, "icmp", "1"), 0, 0, 0)) == -1)
  86                 goto fail;
  87
  88         for(seq = 0; seq < Npings; seq++){
  89                 then = nsec();
  90                 for(i = Payload; i < sizeof buf; i++)
  91                         buf[i] = i + seq;
  92                 ip->type = EchoRequest;
  93                 ip->code = 0;
  94                 ip->seq[0] = seq;
  95                 ip->seq[1] = seq;
  96                 alarm(timeout);
  97                 if(write(fd, ip, sizeof buf) != sizeof buf ||
  98                     read(fd, ip, sizeof buf) != sizeof buf)
  99                         goto fail;
 100                 alarm(0);
 101                 if(ip->type != EchoReply || ip->code != 0 ||
 102                     ip->seq[0] != seq || ip->seq[1] != seq)
 103                         goto fail;
 104                 for(i = Payload; i < sizeof buf; i++)
 105                         if((uchar)buf[i] != (uchar)(i + seq))
 106                                 goto fail;
 107                 rtt = (rtt + nsec() - then) / 2;
 108         }
 109 fail:
 110         if(fd != -1)
 111                 close(fd);
 112
 113         if(Debug && strstr(Debug, "dfs") != nil)
 114                 print("\t\tping host=%s timeout=%d rtt=%d - failed\n",
 115                         host, timeout, rtt);
 116
 117         /*
 118          * failures get cached too
 119          */
 120         for(c = Cache; c; c = c->next)
 121                 if(strcmp(c->host, host) == 0)
 122                         break;
 123         if(c == nil){
 124                 c = emalloc9p(sizeof(Pingcache));
 125                 c->host = estrdup9p(host);
 126                 c->next = Cache;
 127                 Cache = c;
 128         }
 129         c->rtt = rtt;
 130         c->expire = now+Cachetime;
 131         return rtt;
 132 }