ifconfig.c revision 54a1eb7677a10c1591ba48562ae480cd71721bf6 
1
2#include <stdio.h>
3#include <stdlib.h>
4#include <unistd.h>
5
6#include <errno.h>
7#include <string.h>
8#include <ctype.h>
9
10#include <sys/socket.h>
11#include <netinet/in.h>
12#include <linux/if.h>
13#include <linux/sockios.h>
14#include <arpa/inet.h>
15
16static void die(const char *s)
17{
18    fprintf(stderr,"error: %s (%s)\n", s, strerror(errno));
19    exit(-1);
20}
21
22static void setflags(int s, struct ifreq *ifr, int set, int clr)
23{
24    if(ioctl(s, SIOCGIFFLAGS, ifr) < 0) die("SIOCGIFFLAGS");
25    ifr->ifr_flags = (ifr->ifr_flags & (~clr)) | set;
26    if(ioctl(s, SIOCSIFFLAGS, ifr) < 0) die("SIOCSIFFLAGS");
27}
28
29static inline void init_sockaddr_in(struct sockaddr_in *sin, const char *addr)
30{
31    sin->sin_family = AF_INET;
32    sin->sin_port = 0;
33    sin->sin_addr.s_addr = inet_addr(addr);
34}
35
36static void setmtu(int s, struct ifreq *ifr, const char *mtu)
37{
38    int m = atoi(mtu);
39    ifr->ifr_mtu = m;
40    if(ioctl(s, SIOCSIFMTU, ifr) < 0) die("SIOCSIFMTU");
41}
42static void setdstaddr(int s, struct ifreq *ifr, const char *addr)
43{
44    init_sockaddr_in((struct sockaddr_in *) &ifr->ifr_dstaddr, addr);
45    if(ioctl(s, SIOCSIFDSTADDR, ifr) < 0) die("SIOCSIFDSTADDR");
46}
47
48static void setnetmask(int s, struct ifreq *ifr, const char *addr)
49{
50    init_sockaddr_in((struct sockaddr_in *) &ifr->ifr_netmask, addr);
51    if(ioctl(s, SIOCSIFNETMASK, ifr) < 0) die("SIOCSIFNETMASK");
52}
53
54static void setaddr(int s, struct ifreq *ifr, const char *addr)
55{
56    init_sockaddr_in((struct sockaddr_in *) &ifr->ifr_addr, addr);
57    if(ioctl(s, SIOCSIFADDR, ifr) < 0) die("SIOCSIFADDR");
58}
59
60int ifconfig_main(int argc, char *argv[])
61{
62    struct ifreq ifr;
63    int s;
64    unsigned int addr, mask, flags;
65    char astring[20];
66    char mstring[20];
67    char *updown, *brdcst, *loopbk, *ppp, *running, *multi;
68
69    argc--;
70    argv++;
71
72    if(argc == 0) return 0;
73
74    memset(&ifr, 0, sizeof(struct ifreq));
75    strncpy(ifr.ifr_name, argv[0], IFNAMSIZ);
76    ifr.ifr_name[IFNAMSIZ-1] = 0;
77    argc--, argv++;
78
79    if((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
80        die("cannot open control socket\n");
81    }
82
83    if (argc == 0) {
84        if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
85            perror(ifr.ifr_name);
86            return -1;
87        } else
88            addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;
89
90        if (ioctl(s, SIOCGIFNETMASK, &ifr) < 0) {
91            perror(ifr.ifr_name);
92            return -1;
93        } else
94            mask = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;
95
96        if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0) {
97            perror(ifr.ifr_name);
98            return -1;
99        } else
100            flags = ifr.ifr_flags;
101
102        sprintf(astring, "%d.%d.%d.%d",
103                addr & 0xff,
104                ((addr >> 8) & 0xff),
105                ((addr >> 16) & 0xff),
106                ((addr >> 24) & 0xff));
107        sprintf(mstring, "%d.%d.%d.%d",
108                mask & 0xff,
109                ((mask >> 8) & 0xff),
110                ((mask >> 16) & 0xff),
111                ((mask >> 24) & 0xff));
112        printf("%s: ip %s mask %s flags [", ifr.ifr_name,
113               astring,
114               mstring
115               );
116
117        updown =  (flags & IFF_UP)           ? "up" : "down";
118        brdcst =  (flags & IFF_BROADCAST)    ? " broadcast" : "";
119        loopbk =  (flags & IFF_LOOPBACK)     ? " loopback" : "";
120        ppp =     (flags & IFF_POINTOPOINT)  ? " point-to-point" : "";
121        running = (flags & IFF_RUNNING)      ? " running" : "";
122        multi =   (flags & IFF_MULTICAST)    ? " multicast" : "";
123        printf("%s%s%s%s%s%s]\n", updown, brdcst, loopbk, ppp, running, multi);
124        return 0;
125    }
126
127    while(argc > 0) {
128        if (!strcmp(argv[0], "up")) {
129            setflags(s, &ifr, IFF_UP, 0);
130        } else if (!strcmp(argv[0], "mtu")) {
131            argc--, argv++;
132            if (!argc) {
133                errno = EINVAL;
134                die("expecting a value for parameter \"mtu\"");
135            }
136            setmtu(s, &ifr, argv[0]);
137        } else if (!strcmp(argv[0], "-pointopoint")) {
138            setflags(s, &ifr, IFF_POINTOPOINT, 1);
139        } else if (!strcmp(argv[0], "pointopoint")) {
140            argc--, argv++;
141            if (!argc) {
142                errno = EINVAL;
143                die("expecting an IP address for parameter \"pointtopoint\"");
144            }
145            setdstaddr(s, &ifr, argv[0]);
146            setflags(s, &ifr, IFF_POINTOPOINT, 0);
147        } else if (!strcmp(argv[0], "down")) {
148            setflags(s, &ifr, 0, IFF_UP);
149        } else if (!strcmp(argv[0], "netmask")) {
150            argc--, argv++;
151            if (!argc) {
152                errno = EINVAL;
153                die("expecting an IP address for parameter \"netmask\"");
154            }
155            setnetmask(s, &ifr, argv[0]);
156        } else if (isdigit(argv[0][0])) {
157            setaddr(s, &ifr, argv[0]);
158            setflags(s, &ifr, IFF_UP, 0);
159        }
160        argc--, argv++;
161    }
162    return 0;
163}
164