Christopher Friesen wrote:
> I would like to get the IP address of one of the interfaces of the
> machine that I'm currently on from within some C++ code. It looks like
> I should be able to do this by doing an
>
> ioctl(atoi(fd, SIOCGIFADDR, &ifr)
>
> with the interface name set in the appropriate field in ifr, but I'm not
> sure how I should be getting the proper value for fd. I would
> appreciate some help on this, or if there is a better way then I'd love
> to hear it.
This isn't c++, it's plain c, but it's easy to grok. Called as: gi
[interface]
-d
-- "The difference between 'involvement' and 'commitment' is like an eggs-and-ham breakfast: the chicken was 'involved' - the pig was 'committed'."
/* * short hack to grab interface information * gcc -o gi gi.c; strip gi * * Blu3, Jan 1999 */
#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <net/if.h> #include <netinet/in.h> #include <stdio.h> #include <stdlib.h> #include <string.h>
#define SIOCGIFCONF 0x8912 /* get iface list */
int main(int argc, char *argv[]) { int numreqs = 30, sd, n, search, tick, found=0; struct ifconf ifc; struct ifreq *ifr; struct in_addr *ia;
// // if there is an arg on the command line, print out the ip of that device // only. note the numreqs in the above, modify that as is desired.
search= (argc>1); if(search && strlen(argv[1]) > 64) { fprintf(stderr, "specified device name too large, ignoring\n"); search=0; }
sd=socket(AF_INET, SOCK_STREAM, 0); ifc.ifc_buf = NULL; ifc.ifc_len = sizeof(struct ifreq) * numreqs; ifc.ifc_buf = realloc(ifc.ifc_buf, ifc.ifc_len); if (ioctl(sd, SIOCGIFCONF, &ifc) < 0) { perror("SIOCGIFCONF"); } ifr = ifc.ifc_req; for (n = 0; n < ifc.ifc_len; n += sizeof(struct ifreq)) { ia= (struct in_addr *) ((ifr->ifr_ifru.ifru_addr.sa_data)+2); if(search) tick= strcmp(ifr->ifr_ifrn.ifrn_name, argv[1]);
if(!search) fprintf(stdout, "%6s %-15s\n", ifr->ifr_ifrn.ifrn_name, inet_ntoa(*ia)); if (search && (tick==0)) { fprintf(stdout, "%s\n", inet_ntoa(*ia)); found=1; } ifr++; }
free(ifc.ifc_buf); fprintf(stderr, "exiting with %i\n", found); exit(found); }
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This archive was generated by hypermail 2b29 : Tue Nov 07 2000 - 21:00:14 EST