1  /*
       2   * Check decoding of SIOCGIFCONF command of ioctl syscall.
       3   *
       4   * Copyright (c) 2016 Eugene Syromyatnikov <evgsyr@gmail.com>
       5   * Copyright (c) 2016-2021 The strace developers.
       6   * All rights reserved.
       7   *
       8   * SPDX-License-Identifier: GPL-2.0-or-later
       9   */
      10  
      11  #include "tests.h"
      12  
      13  #include <stdio.h>
      14  #include <string.h>
      15  
      16  #include <arpa/inet.h>
      17  #include <net/if.h>
      18  #include <sys/ioctl.h>
      19  #include <sys/socket.h>
      20  
      21  #define MAX_STRLEN 1
      22  
      23  static void
      24  print_ifc_len(const int val)
      25  {
      26  	printf("%d", val);
      27  	if (val > 0 && val % (int) sizeof(struct ifreq) == 0)
      28  		printf(" /* %d * sizeof(struct ifreq) */",
      29  		       val / (int) sizeof(struct ifreq));
      30  }
      31  
      32  static void
      33  print_ifconf(const struct ifconf *const ifc, const int in_len,
      34  	     const char *const in_buf, const long rc)
      35  {
      36  	if (in_buf) {
      37  		printf("{ifc_len=");
      38  		print_ifc_len(in_len);
      39  
      40  		if (in_len != ifc->ifc_len) {
      41  			printf(" => ");
      42  			print_ifc_len(ifc->ifc_len);
      43  		}
      44  	} else {
      45  		printf("{ifc_len=");
      46  		print_ifc_len(ifc->ifc_len);
      47  	}
      48  
      49  	printf(", ifc_buf=");
      50  
      51  	if ((rc < 0) || !in_buf) {
      52  		if (in_buf)
      53  			printf("%p", in_buf);
      54  		else
      55  			printf("NULL");
      56  	} else {
      57  		int i;
      58  
      59  		printf("[");
      60  		for (i = 0; i < (ifc->ifc_len) &&
      61  		    i < (int) (MAX_STRLEN * sizeof(struct ifreq));
      62  		    i += sizeof(struct ifreq)) {
      63  			struct ifreq *ifr = (struct ifreq *) (ifc->ifc_buf + i);
      64  			struct sockaddr_in *const sa_in =
      65  				(struct sockaddr_in *) &(ifr->ifr_addr);
      66  
      67  			if (i)
      68  				printf(", ");
      69  			printf("{ifr_name=\"%s\", ifr_addr={sa_family=AF_INET, "
      70  			       "sin_port=htons(%u), sin_addr=inet_addr(\"%s\")}"
      71  			       "}", ifr->ifr_name, ntohs(sa_in->sin_port),
      72  			       inet_ntoa(sa_in->sin_addr));
      73  		}
      74  
      75  		if ((size_t) (ifc->ifc_len - i) >= sizeof(struct ifreq))
      76  			printf(", ...");
      77  
      78  		printf("]");
      79  	}
      80  
      81  	printf("}");
      82  }
      83  
      84  static void
      85  gifconf_ioctl(const int fd, struct ifconf *const ifc, const bool ifc_valid)
      86  {
      87  	const int in_len = ifc_valid ? ifc->ifc_len : 0;
      88  	const char *const in_buf = ifc_valid ? ifc->ifc_buf : NULL;
      89  	long rc = ioctl(fd, SIOCGIFCONF, ifc);
      90  	const char *errstr = sprintrc(rc);
      91  
      92  	printf("ioctl(%d, SIOCGIFCONF, ", fd);
      93  	if (ifc_valid) {
      94  		print_ifconf(ifc, in_len, in_buf, rc);
      95  	} else {
      96  		if (ifc)
      97  			printf("%p", ifc);
      98  		else
      99  			printf("NULL");
     100  	}
     101  
     102  	printf(") = %s\n", errstr);
     103  }
     104  
     105  int
     106  main(int argc, char *argv[])
     107  {
     108  	struct ifreq *const ifr = tail_alloc(2 * sizeof(*ifr));
     109  	TAIL_ALLOC_OBJECT_CONST_PTR(struct ifconf, ifc);
     110  	const int fd = socket(AF_INET, SOCK_STREAM, 0);
     111  	if (fd < 0)
     112  		perror_msg_and_skip("socket AF_INET");
     113  
     114  	gifconf_ioctl(fd, NULL, false);
     115  	gifconf_ioctl(fd, ifc + 1, false);
     116  
     117  	ifc->ifc_len = 3141592653U;
     118  	ifc->ifc_buf = NULL;
     119  	gifconf_ioctl(fd, ifc, true);
     120  
     121  	ifc->ifc_len = 0;
     122  	ifc->ifc_buf = (char *) (ifr + 2);
     123  	gifconf_ioctl(fd, ifc, true);
     124  
     125  	ifc->ifc_len = 1;
     126  	ifc->ifc_buf = (char *) (ifr + 1);
     127  	gifconf_ioctl(fd, ifc, true);
     128  
     129  	ifc->ifc_len = 1 * sizeof(*ifr);
     130  	ifc->ifc_buf = (char *) (ifr + 1);
     131  	gifconf_ioctl(fd, ifc, true);
     132  
     133  	ifc->ifc_len = 2 * sizeof(*ifr);
     134  	ifc->ifc_buf = (char *) (ifr + 1);
     135  	gifconf_ioctl(fd, ifc, true);
     136  
     137  	ifc->ifc_len = 2 * sizeof(*ifr) + 2;
     138  	ifc->ifc_buf = (char *) ifr;
     139  	gifconf_ioctl(fd, ifc, true);
     140  
     141  	ifc->ifc_len = 3 * sizeof(*ifr) + 4;
     142  	ifc->ifc_buf = (char *) ifr;
     143  	gifconf_ioctl(fd, ifc, true);
     144  
     145  	puts("+++ exited with 0 +++");
     146  	return 0;
     147  }