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1 /* ping.c - check network connectivity
2  *
3  * Copyright 2014 Rob Landley <rob@landley.net>
4  *
5  * Not in SUSv4.
6  *
7  * Note: ping_group_range should never have existed. To disable it, do:
8  *   echo 0 $(((1<<31)-1)) > /proc/sys/net/ipv4/ping_group_range
9  * (Android does this by default in its init script.)
10  *
11  * Yes, I wimped out and capped -s at sizeof(toybuf), waiting for a complaint...
12 
13 USE_PING(NEWTOY(ping, "<1>1t#<0>255=64c#<0=3s#<0>4088=56I:i:W#<0=10w#<0qf46[-46]", TOYFLAG_ROOTONLY|TOYFLAG_USR|TOYFLAG_BIN))
14 
15 config PING
16   bool "ping"
17   default n
18   help
19     usage: ping [OPTIONS] HOST
20 
21     Check network connectivity by sending packets to a host and reporting
22     its response.
23 
24     Send ICMP ECHO_REQUEST packets to ipv4 or ipv6 addresses and prints each
25     echo it receives back, with round trip time. Returns true if host alive.
26 
27     Options:
28     -4, -6      Force IPv4 or IPv6
29     -c CNT      Send CNT many packets (default 3, 0 = infinite)
30     -f          Flood (. on send, backspace on receive, to show packet drops)
31     -i TIME     Interval between packets (default 1, need root for < .2)
32     -I IFACE/IP Source interface or address
33     -q          Quiet (stops after one returns true if host is alive)
34     -s SIZE     Data SIZE in bytes (default 56)
35     -t TTL      Set Time To Live (number of hops)
36     -W SEC      Seconds to wait for response after -c (default 10)
37     -w SEC      Exit after this many seconds
38 */
39 
40 #define FOR_ping
41 #include "toys.h"
42 
43 #include <ifaddrs.h>
44 #include <netinet/ip_icmp.h>
45 
GLOBALS(long w;long W;char * i;char * I;long s;long c;long t;int sock;long i_ms;)46 GLOBALS(
47   long w;
48   long W;
49   char *i;
50   char *I;
51   long s;
52   long c;
53   long t;
54 
55   int sock;
56   long i_ms;
57 )
58 
59 static void xsendto(int sockfd, void *buf, size_t len, struct sockaddr *dest)
60 {
61   int rc = sendto(TT.sock, buf, len, 0, dest,
62     dest->sa_family == AF_INET ? sizeof(struct sockaddr_in) :
63       sizeof(struct sockaddr_in6));
64 
65   if (rc != len) perror_exit("sendto");
66 }
67 
68 // assumes aligned and can read even number of bytes
pingchksum(unsigned short * data,int len)69 static unsigned short pingchksum(unsigned short *data, int len)
70 {
71   unsigned short u = 0, d;
72 
73   // circular carry is endian independent: bits from high byte go to low byte
74   while (len>0) {
75     d = *data++;
76     if (len == 1) d &= 255<<IS_BIG_ENDIAN;
77     if (d >= (u += d)) u++;
78     len -= 2;
79   }
80 
81   return u;
82 }
83 
ping_main(void)84 void ping_main(void)
85 {
86   struct addrinfo *ai, *ai2;
87   struct ifaddrs *ifa, *ifa2 = 0;
88   union {
89     struct sockaddr_in in;
90     struct sockaddr_in6 in6;
91   } src_addr, src_addr2;
92   struct sockaddr *sa = (void *)&src_addr, *sa2 = (void *)&src_addr2;
93   struct pollfd pfd;
94   int family = 0, sent = 0, len;
95   long long tnext, tW, tnow, tw;
96   unsigned short seq = 0;
97   struct icmphdr *ih = (void *)toybuf;
98 
99   // Interval
100   if (TT.i) {
101     long frac;
102 
103     TT.i_ms = xparsetime(TT.i, 1000, &frac) * 1000;
104     TT.i_ms += frac;
105     if (TT.i_ms<200 && getuid()) error_exit("need root for -i <200");
106   } else TT.i_ms = 1000;
107   if (!(toys.optflags&FLAG_s)) TT.s = 56; // 64-PHDR_LEN
108 
109   // ipv4 or ipv6? (0 = autodetect if -I or arg have only one address type.)
110   if (toys.optflags&FLAG_6) family = AF_INET6;
111   else if (toys.optflags&FLAG_4) family = AF_INET;
112   else family = 0;
113 
114   // If -I src_addr look it up. Allow numeric address of correct type.
115   memset(&src_addr, 0, sizeof(src_addr));
116   if (TT.I) {
117     if (!(toys.optflags&FLAG_6) && inet_pton(AF_INET, TT.I,
118       (void *)&src_addr.in.sin_addr))
119         family = AF_INET;
120     else if (!(toys.optflags&FLAG_4) && inet_pton(AF_INET6, TT.I,
121       (void *)&src_addr.in6.sin6_addr))
122         family = AF_INET6;
123     else if (getifaddrs(&ifa2)) perror_exit("getifaddrs");
124   }
125 
126   // Look up HOST address, filtering for correct type and interface.
127   // If -I but no -46 then find compatible type between -I and HOST
128   ai2 = xgetaddrinfo(*toys.optargs, 0, family, 0, 0, 0);
129   for (ai = ai2; ai; ai = ai->ai_next) {
130 
131     // correct type?
132     if (family && family!=ai->ai_family) continue;
133     if (ai->ai_family!=AF_INET && ai->ai_family!=AF_INET6) continue;
134 
135     // correct interface?
136     if (!TT.I || !ifa2) break;
137     for (ifa = ifa2; ifa; ifa = ifa->ifa_next) {
138       if (!ifa->ifa_addr || ifa->ifa_addr->sa_family!=ai->ai_family
139           || strcmp(ifa->ifa_name, TT.I)) continue;
140       sa = (void *)ifa->ifa_addr;
141 
142       break;
143     }
144     if (ifa) break;
145   }
146 
147   if (!ai)
148     error_exit("no v%d addr for -I %s", 4+2*(family==AF_INET6), TT.I);
149 
150   // Open DGRAM socket
151   sa->sa_family = ai->ai_family;
152   TT.sock = xsocket(ai->ai_family, SOCK_DGRAM,
153     (ai->ai_family == AF_INET) ? IPPROTO_ICMP : IPPROTO_ICMPV6);
154   if (TT.I && bind(TT.sock, sa, sizeof(src_addr))) perror_exit("bind");
155 
156   if (TT.t) {
157     len = TT.t;
158 
159     if (ai->ai_family == AF_INET)
160       setsockopt(TT.sock, IPPROTO_IP, IP_TTL, &len, 4);
161     else setsockopt(TT.sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &len, 4);
162   }
163 
164   if (!(toys.optflags&FLAG_q)) {
165     printf("Ping %s (%s)", *toys.optargs, ntop(ai->ai_addr));
166     if (TT.I) {
167       *toybuf = 0;
168       printf(" from %s (%s)", TT.I, ntop(sa));
169     }
170     // 20 byte TCP header, 8 byte ICMP header, plus data payload
171     printf(": %ld(%ld) bytes.\n", TT.s, TT.s+28);
172   }
173   toys.exitval = 1;
174 
175   tW = tw = 0;
176   tnext = millitime();
177   if (TT.w) tw = TT.w*1000+tnext;
178 
179   // Send/receive packets
180   for (;;) {
181     int waitms = INT_MAX;
182 
183     // Exit due to timeout? (TODO: timeout is after last packet, waiting if
184     // any packets ever dropped. Not timeout since packet was dropped.)
185     tnow = millitime();
186     if (tW) if (0>=(waitms = tW-tnow) || !sent) break;
187     if (tw) {
188       if (tnow>tw) break;
189       else if (waitms>tw-tnow) waitms = tw-tnow;
190     // Time to send the next packet?
191     } else if (tnext-tnow <= 0) {
192       tnext += TT.i_ms;
193 
194       memset(ih, 0, sizeof(*ih));
195       ih->type = (ai->ai_family == AF_INET) ? 8 : 128;
196       ih->un.echo.id = getpid();
197       ih->un.echo.sequence = ++seq;
198       if (TT.s >= 4) *(unsigned *)(ih+1) = tnow;
199 
200       ih->checksum = 0;
201       ih->checksum = pingchksum((void *)toybuf, TT.s+sizeof(*ih));
202       xsendto(TT.sock, toybuf, TT.s+sizeof(*ih), ai->ai_addr);
203       sent++;
204       if (toys.optflags&FLAG_f) printf(".");
205 
206       // last packet?
207       if (TT.c) if (!--TT.c) {
208         if (!TT.W) break;
209         tW = tnow + TT.W*1000;
210       }
211     }
212 
213     // This is down here so it's against new period if we just sent a packet
214     if (!tw && waitms>tnext-tnow) waitms = tnext-tnow;
215 
216     // wait for next packet or timeout
217 
218     if (waitms<0) waitms = 0;
219     pfd.fd = TT.sock;
220     pfd.events = POLLIN;
221     if (0>(len = poll(&pfd, 1, waitms))) break;
222     if (!len) continue;
223 
224     len = sizeof(src_addr2);
225     len = recvfrom(TT.sock, toybuf, sizeof(toybuf), 0, sa2, (void *)&len);
226     sent--;
227 
228     // reply id == 0 for ipv4, 129 for ipv6
229 
230     if (!(toys.optflags&FLAG_q)) {
231       printf("%d bytes from %s: icmp_seq=%d ttl=%d", len, ntop(sa2),
232              ih->un.echo.sequence, 0);
233       if (len >= sizeof(*ih)+4) {
234         unsigned lunchtime = millitime()-*(unsigned *)(ih+1);
235 
236         printf(" time=%u.%03u", lunchtime/1000, lunchtime%1000);
237       }
238       xputc('\n');
239     }
240 
241     toys.exitval = 0;
242   }
243 
244   if (CFG_TOYBOX_FREE) {
245     freeaddrinfo(ai2);
246     if (ifa2) freeifaddrs(ifa2);
247   }
248 }
249