1 /* netstat.c - Display Linux networking subsystem.
2  *
3  * Copyright 2012 Ranjan Kumar <ranjankumar.bth@gmail.com>
4  * Copyright 2013 Kyungwan Han <asura321@gmail.com>
5  *
6  * Not in SUSv4.
7  *
8 USE_NETSTAT(NEWTOY(netstat, "pWrxwutneal", TOYFLAG_BIN))
9 config NETSTAT
10   bool "netstat"
11   default y
12   help
13     usage: netstat [-pWrxwutneal]
14 
15     Display networking information. Default is netstat -tuwx
16 
17     -r	Routing table
18     -a	All sockets (not just connected)
19     -l	Listening server sockets
20     -t	TCP sockets
21     -u	UDP sockets
22     -w	Raw sockets
23     -x	Unix sockets
24     -e	Extended info
25     -n	Don't resolve names
26     -W	Wide display
27     -p	Show PID/program name of sockets
28 */
29 
30 #define FOR_netstat
31 #include "toys.h"
32 #include <net/route.h>
33 
GLOBALS(struct num_cache * inodes;int wpad;)34 GLOBALS(
35   struct num_cache *inodes;
36   int wpad;
37 )
38 
39 static void addr2str(int af, void *addr, unsigned port, char *buf, int len,
40   char *proto)
41 {
42   char pres[INET6_ADDRSTRLEN];
43   struct servent *se = 0;
44   int pos, count;
45 
46   if (!inet_ntop(af, addr, pres, sizeof(pres))) perror_exit("inet_ntop");
47 
48   if (FLAG(n) || !port) {
49     strcpy(buf, pres);
50   } else {
51     struct addrinfo hints, *result, *rp;
52     char cut[4];
53 
54     memset(&hints, 0, sizeof(struct addrinfo));
55     hints.ai_family = af;
56 
57     if (!getaddrinfo(pres, NULL, &hints, &result)) {
58       socklen_t sock_len = (af == AF_INET) ? sizeof(struct sockaddr_in)
59         : sizeof(struct sockaddr_in6);
60 
61       // We assume that a failing getnameinfo dosn't stomp "buf" here.
62       for (rp = result; rp; rp = rp->ai_next)
63         if (!getnameinfo(rp->ai_addr, sock_len, buf, 256, 0, 0, 0)) break;
64       freeaddrinfo(result);
65       buf[len] = 0;
66     }
67 
68     // getservbyport() doesn't understand proto "tcp6", so truncate
69     memcpy(cut, proto, 3);
70     cut[3] = 0;
71     se = getservbyport(htons(port), cut);
72   }
73 
74   if (!strcmp(buf, "::")) strcpy(buf, "[::]");
75 
76   // Append :service or :* if port == 0.
77   if (se) {
78     count = snprintf(0, 0, ":%s", se->s_name);
79     // NI_MAXSERV == 32, which is greater than our minimum field width.
80     // (Although the longest service name on Debian in 2021 is only 16 bytes.)
81     if (count>=len) {
82       count = len-1;
83       se->s_name[count] = 0;
84     }
85   } else count = port ? snprintf(0, 0, ":%u", port) : 2;
86   // We always show the port, even if that means clobbering the end of the host.
87   pos = strlen(buf);
88   if (len-pos<count) pos = len-count;
89   if (se) sprintf(buf+pos, ":%s", se->s_name);
90   else sprintf(buf+pos, port ? ":%u" : ":*", port);
91 }
92 
93 // Display info for tcp/udp/raw
show_ip(char * fname)94 static void show_ip(char *fname)
95 {
96   char *ss_state = "UNKNOWN", buf[12], *s, *label = strrchr(fname, '/')+1;
97   char *state_label[] = {"", "ESTABLISHED", "SYN_SENT", "SYN_RECV", "FIN_WAIT1",
98                          "FIN_WAIT2", "TIME_WAIT", "CLOSE", "CLOSE_WAIT",
99                          "LAST_ACK", "LISTEN", "CLOSING", "UNKNOWN"};
100   FILE *fp = xfopen(fname, "r");
101 
102   // Skip header.
103   fgets(toybuf, sizeof(toybuf), fp);
104 
105   while (fgets(toybuf, sizeof(toybuf), fp)) {
106     char lip[256], rip[256];
107     union {
108       struct {unsigned u; unsigned char b[4];} i4;
109       struct {struct {unsigned a, b, c, d;} u; unsigned char b[16];} i6;
110     } laddr, raddr;
111     unsigned lport, rport, state, txq, rxq, num, uid, af = AF_INET6;
112     unsigned long inode;
113 
114     // Try ipv6, then try ipv4
115     if (16 != sscanf(toybuf,
116       " %d: %8x%8x%8x%8x:%x %8x%8x%8x%8x:%x %x %x:%x %*X:%*X %*X %d %*d %ld",
117       &num, &laddr.i6.u.a, &laddr.i6.u.b, &laddr.i6.u.c,
118       &laddr.i6.u.d, &lport, &raddr.i6.u.a, &raddr.i6.u.b,
119       &raddr.i6.u.c, &raddr.i6.u.d, &rport, &state, &txq, &rxq,
120       &uid, &inode))
121     {
122       af = AF_INET;
123       if (10 != sscanf(toybuf,
124         " %d: %x:%x %x:%x %x %x:%x %*X:%*X %*X %d %*d %ld",
125         &num, &laddr.i4.u, &lport, &raddr.i4.u, &rport, &state, &txq,
126         &rxq, &uid, &inode)) continue;
127     }
128 
129     // Should we display this? (listening or all or TCP/UDP/RAW)
130     if (!(FLAG(l) && (!rport && (state&0xA))) && !FLAG(a) && !(rport&0x70))
131       continue;
132 
133     addr2str(af, &laddr, lport, lip, TT.wpad, label);
134     addr2str(af, &raddr, rport, rip, TT.wpad, label);
135 
136     // Display data
137     s = label;
138     if (strstart(&s, "tcp")) {
139       int sz = ARRAY_LEN(state_label);
140       if (!state || state >= sz) state = sz-1;
141       ss_state = state_label[state];
142     } else if (strstart(&s, "udp")) {
143       if (state == 1) ss_state = state_label[state];
144       else if (state == 7) ss_state = "";
145     } else if (strstart(&s, "raw")) sprintf(ss_state = buf, "%u", state);
146 
147     printf("%-6s%6d%7d %*.*s %*.*s %-11s", label, rxq, txq, -TT.wpad, TT.wpad,
148       lip, -TT.wpad, TT.wpad, rip, ss_state);
149     if (FLAG(e)) {
150       if (FLAG(n)) sprintf(s = toybuf, "%d", uid);
151       else s = getusername(uid);
152       printf(" %-10s %-11ld", s, inode);
153     }
154     if (FLAG(p)) {
155       struct num_cache *nc = get_num_cache(TT.inodes, inode);
156 
157       printf(" %s", nc ? nc->data : "-");
158     }
159     xputc('\n');
160   }
161   fclose(fp);
162 }
163 
show_unix_sockets(void)164 static void show_unix_sockets(void)
165 {
166   char *types[] = {"","STREAM","DGRAM","RAW","RDM","SEQPACKET","DCCP","PACKET"},
167        *states[] = {"","LISTENING","CONNECTING","CONNECTED","DISCONNECTING"},
168        *filename = 0;
169   unsigned long refcount, flags, type, state, inode;
170   FILE *fp = xfopen("/proc/net/unix", "r");
171 
172   // Skip header.
173   fgets(toybuf, sizeof(toybuf), fp);
174 
175   while (fscanf(fp, "%*p: %lX %*X %lX %lX %lX %lu%m[^\n]", &refcount, &flags,
176                 &type, &state, &inode, &filename) >= 5) {
177     // Linux exports only SO_ACCEPTCON since 2.3.15pre3 in 1999, but let's
178     // filter in case they add more someday.
179     flags &= 1<<16;
180 
181     // Only show unconnected listening sockets with -a or -l.
182     if (state==1 && flags && !(FLAG(a) || FLAG(l))) continue;
183 
184     if (type==10) type = 7; // move SOCK_PACKET into line
185     if (type>ARRAY_LEN(types)) type = 0;
186     if (state>ARRAY_LEN(states) || (state==1 && !flags)) state = 0;
187 
188     if (state!=1 && FLAG(l)) continue;
189 
190     sprintf(toybuf, "[ %s]", flags ? "ACC " : "");
191     printf("unix  %-6ld %-11s %-10s %-13s %-8lu ",
192       refcount, toybuf, types[type], states[state], inode);
193     if (FLAG(p)) {
194       struct num_cache *nc = get_num_cache(TT.inodes, inode);
195 
196       printf("%-19.19s ", nc ? nc->data : "-");
197     }
198 
199     if (filename) {
200       printf("%s\n", filename+!FLAG(p));
201       free(filename);
202       filename = 0;
203     } else xputc('\n');
204   }
205   fclose(fp);
206 }
207 
scan_pids(struct dirtree * node)208 static int scan_pids(struct dirtree *node)
209 {
210   char *s = toybuf+256;
211   struct dirent *entry;
212   DIR *dp;
213   int pid, dirfd;
214 
215   if (!node->parent) return DIRTREE_RECURSE;
216   if (!(pid = atol(node->name))) return 0;
217 
218   sprintf(toybuf, "/proc/%d/cmdline", pid);
219   if (!(readfile(toybuf, toybuf, 256))) return 0;
220 
221   sprintf(s, "%d/fd", pid);
222   if (-1==(dirfd = openat(dirtree_parentfd(node), s, O_RDONLY))) return 0;
223   if (!(dp = fdopendir(dirfd))) close(dirfd);
224   else while ((entry = readdir(dp))) {
225     s = toybuf+256;
226     if (!readlinkat0(dirfd, entry->d_name, s, sizeof(toybuf)-256)) continue;
227     // Can the "[0000]:" happen in a modern kernel?
228     if (strstart(&s, "socket:[") || strstart(&s, "[0000]:")) {
229       long long ll = atoll(s);
230 
231       sprintf(s, "%d/%s", pid, getbasename(toybuf));
232       add_num_cache(&TT.inodes, ll, s, strlen(s)+1);
233     }
234   }
235   closedir(dp);
236 
237   return 0;
238 }
239 
240 // extract inet4 route info from /proc/net/route file and display it.
display_routes(void)241 static void display_routes(void)
242 {
243   static const char flagchars[] = "GHRDMDAC";
244   static const unsigned flagarray[] = {
245     RTF_GATEWAY, RTF_HOST, RTF_REINSTATE, RTF_DYNAMIC, RTF_MODIFIED
246   };
247   unsigned dest, gate, mask;
248   int flags, ref, use, metric, mss, win, irtt;
249   char *out = toybuf, *flag_val;
250   char iface[64]={0};
251   FILE *fp = xfopen("/proc/net/route", "r");
252 
253   // Skip header.
254   fgets(toybuf, sizeof(toybuf), fp);
255 
256   printf("Kernel IP routing table\n"
257           "Destination\tGateway \tGenmask \tFlags %s Iface\n",
258           !FLAG(e) ? "  MSS Window  irtt" : "Metric Ref    Use");
259 
260   while (fscanf(fp, "%63s%x%x%X%d%d%d%x%d%d%d", iface, &dest, &gate, &flags,
261                 &ref, &use, &metric, &mask, &mss, &win, &irtt) == 11) {
262     char *destip = 0, *gateip = 0, *maskip = 0;
263 
264     // skip down interfaces.
265     if (!(flags & RTF_UP)) continue;
266 
267 // TODO /proc/net/ipv6_route
268 
269     if (dest) {
270       if (inet_ntop(AF_INET, &dest, out, 16)) destip = out;
271     } else destip = FLAG(n) ? "0.0.0.0" : "default";
272     out += 16;
273 
274     if (gate) {
275       if (inet_ntop(AF_INET, &gate, out, 16)) gateip = out;
276     } else gateip = FLAG(n) ? "0.0.0.0" : "*";
277     out += 16;
278 
279 // TODO /24
280     //For Mask
281     if (inet_ntop(AF_INET, &mask, out, 16)) maskip = out;
282     else maskip = "?";
283     out += 16;
284 
285     //Get flag Values
286     flag_val = out;
287     *out++ = 'U';
288     for (dest = 0; dest < ARRAY_LEN(flagarray); dest++)
289       if (flags&flagarray[dest]) *out++ = flagchars[dest];
290     *out = 0;
291     if (flags & RTF_REJECT) *flag_val = '!';
292 
293     printf("%-15.15s %-15.15s %-16s%-6s", destip, gateip, maskip, flag_val);
294     if (!FLAG(e)) printf("%5d %-5d %6d %s\n", mss, win, irtt, iface);
295     else printf("%-6d %-2d %7d %s\n", metric, ref, use, iface);
296   }
297   fclose(fp);
298 }
299 
netstat_main(void)300 void netstat_main(void)
301 {
302   int tuwx = FLAG_t|FLAG_u|FLAG_w|FLAG_x;
303   char *type = "w/o servers";
304 
305   TT.wpad = FLAG(W) ? 51 : 23;
306   if (!(toys.optflags&(FLAG_r|tuwx))) toys.optflags |= tuwx;
307   if (FLAG(r)) display_routes();
308   if (!(toys.optflags&tuwx)) return;
309 
310   if (FLAG(a)) type = "servers and established";
311   else if (FLAG(l)) type = "only servers";
312 
313   if (FLAG(p)) dirtree_read("/proc", scan_pids);
314 
315   if (toys.optflags&(FLAG_t|FLAG_u|FLAG_w)) {
316     printf("Active Internet connections (%s)\n", type);
317     printf("Proto Recv-Q Send-Q %*s %*s State      ", -TT.wpad, "Local Address",
318       -TT.wpad, "Foreign Address");
319     if (FLAG(e)) printf(" User       Inode      ");
320     if (FLAG(p)) printf(" PID/Program Name");
321     xputc('\n');
322 
323     if (FLAG(t)) {
324       show_ip("/proc/net/tcp");
325       show_ip("/proc/net/tcp6");
326     }
327     if (FLAG(u)) {
328       show_ip("/proc/net/udp");
329       show_ip("/proc/net/udp6");
330     }
331     if (FLAG(w)) {
332       show_ip("/proc/net/raw");
333       show_ip("/proc/net/raw6");
334     }
335   }
336 
337   if (FLAG(x)) {
338     printf("Active UNIX domain sockets (%s)\n", type);
339     printf("Proto RefCnt Flags       Type       State         I-Node%sPath\n",
340            FLAG(p) ? "   PID/Program Name     " : "   ");
341     show_unix_sockets();
342   }
343 
344   if (FLAG(p) && CFG_TOYBOX_FREE) llist_traverse(TT.inodes, free);
345   toys.exitval = 0;
346 }
347