Merge branch 'master' of ssh://gapil.gnulinux.it/srv/git/gapil

[gapil.git] / sources / iflist.c

diff --git a/sources/iflist.c b/sources/iflist.c
index 6020b5282b97f8f3e40918f3ee0f481797f9c4ce..3cdc0f3773eb81594f0cc2714d61650296b87525 100644 (file)
--- a/sources/iflist.c
+++ b/sources/iflist.c
@@ -23,16 +23,15 @@
  * Author: S. Piccardi Sep. 2006
  *
  *****************************************************************************/
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <stdlib.h>        /* C standard library */
-#include <stdio.h>         /* I/O standard library */
-#include <unistd.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <sys/ioctl.h>
-#include <net/if.h>
-#include <arpa/inet.h>
+#include <sys/types.h>   /* primitive system data types */
+#include <sys/stat.h>    /* file characteristics constants and functions */
+#include <stdlib.h>      /* C standard library */
+#include <stdio.h>       /* standard I/O library */
+#include <unistd.h>      /* unix standard library */
+#include <sys/socket.h>  /* socket constants, types and functions */
+#include <arpa/inet.h>   /* IP addresses conversion utilities */
+#include <sys/ioctl.h>   /* ioctl syscall and constants */
+#include <net/if.h>      /* network interfaces constants and types */
 
 /*
  * Program iflist
@@ -85,19 +84,21 @@ int main(int argc, char *argv[])
        printf("Wrong number of arguments %d\n", argc - optind);
         usage();
     }
-    iflist.ifc_len = sizeof(buffer);
-    iflist.ifc_buf = buffer;
-    
+    /* create a socket for the operation */
     sock = socket(PF_INET, SOCK_STREAM, 0);
     if (sock < 0) {
         perror("Socket creation error");
         return 1;
     }
+    /* init values for the ifcon structure and do SIOCGIFCONF */
+    iflist.ifc_len = sizeof(buffer);
+    iflist.ifc_buf = buffer;
     ret = ioctl(sock, SIOCGIFCONF, &iflist);
     if (ret < 0) {
        perror("ioctl failed");
         return 1;
     }
+    /* check that we have all data */
     if (iflist.ifc_len == sizeof(buffer)) {
        printf("Probable overflow, too many interfaces, cannot read\n");
        return 1;
@@ -105,6 +106,7 @@ int main(int argc, char *argv[])
        num = iflist.ifc_len/sizeof(struct ifreq);
        printf("Found %i interfaces \n", num);
     }
+    /* loop on interface to write data */
     for (i=0; i < num; i++) {
        address = (struct sockaddr_in *) &iflist.ifc_req[i].ifr_addr;
        printf("Interface %s, address %s\n", iflist.ifc_req[i].ifr_name,