Add --range-prefix-length option

to require the range boundaries to lie within the same subnet
of a given size

5 files changed, 105 insertions, 15 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 6098ae5..1c43bae 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,4 +1,4 @@
-AM_CFLAGS = --pedantic -Wall -Werror -std=c99 -O2
+AM_CFLAGS = --pedantic -Wall -Werror -Wno-error=format-overflow= -std=c99 -O2
 AM_LDFLAGS = 
 
 ipaddrcheck_SOURCES = ipaddrcheck.c ipaddrcheck_functions.c
diff --git a/src/ipaddrcheck.c b/src/ipaddrcheck.c
index 230c6d6..248c248 100644
--- a/src/ipaddrcheck.c
+++ b/src/ipaddrcheck.c
@@ -88,6 +88,7 @@ static const struct option options[] =
     { "is-any-net",            no_argument, NULL, 'E' },
     { "is-ipv4-range",         no_argument, NULL, 'F' },
     { "is-ipv6-range",         no_argument, NULL, 'G' },
+    { "range-prefix-length",   required_argument, NULL, 'H' },
     { "version",               no_argument, NULL, 'z' },
     { "help",                  no_argument, NULL, '?' },
     { "verbose",               no_argument, NULL, 'V' },
@@ -109,6 +110,7 @@ int main(int argc, char* argv[])
     int optc;                  /* Option character for getopt call */
 
     int allow_loopback = NO_LOOPBACK;    /* Allow IPv4 loopback in --is-valid-intf-address */
+    int range_prefix_length = 0;
 
     int no_action = 0;   /* Indicates the option modifies program behaviour
                             but doesn't have its own action */
@@ -124,9 +126,9 @@ int main(int argc, char* argv[])
     const char* program_name = argv[0]; /* Program name for use in messages */
 
 
-    /* Parse options, convert to action codes, store in array */
+    /* Parse options, convert to action codes, store in an array. */
 
-    /* Try to allocate memory for the actions array, abort if fail */
+    /* Try to allocate memory for the actions array, abort if the attempt fails. */
     actions = (int*)calloc(argc, sizeof(int));
     if( errno == ENOMEM )
     {
@@ -134,7 +136,7 @@ int main(int argc, char* argv[])
         return(RESULT_INT_ERROR);
     }
 
-    while( (optc = getopt_long(argc, argv, "acdefghijklmnoprstuzABCDEFGV?", options, &option_index)) != -1 )
+    while( (optc = getopt_long(argc, argv, "acdefghijklmnoprstuzABCDEFGHV?", options, &option_index)) != -1 )
     {
          switch(optc)
          {
@@ -219,6 +221,26 @@ int main(int argc, char* argv[])
              case 'G':
                  ipv6_range_check = 1;
                  break;
+             case 'H':
+                 errno = 0;
+                 char* endptr = "";
+                 /* Reminder to the reader on the quirks of strtol:
+                  * errno != 0 --- internal parse error
+                  * endptr == optarg --- no digits found in the string
+                  * *endptr != '\0' --- extra characters after the last digit
+                  */
+                 range_prefix_length = (int)strtol(optarg, &endptr, 10);
+                 if( (errno != 0) || (endptr == optarg) || (*endptr != '\0') )
+                 {
+                     fprintf(stderr, "Error: \"%s\" is not a valid prefix length\n", optarg);
+                     return(RESULT_INT_ERROR);
+                 }
+                 if( (range_prefix_length < 0) || (range_prefix_length > 128) )
+                 {
+                     fprintf(stderr, "Error: \"%s\" is not a valid prefix length\n", optarg);
+                     return(RESULT_INT_ERROR);
+                 }
+                 break;
              case 'V':
                  verbose = 1;
                  break;
@@ -268,8 +290,13 @@ int main(int argc, char* argv[])
     /* If the argument is a range, use special functions that can handle it. */
     if( ipv4_range_check )
     {
-        int result = is_ipv4_range(address_str, verbose);
+        if( range_prefix_length > 32 )
+        {
+            fprintf(stderr, "Error: prefix length cannot exceed 32 for IPv4!\n");
+            return(RESULT_INT_ERROR);
+        }
 
+        int result = is_ipv4_range(address_str, range_prefix_length, verbose);
         if( result == RESULT_SUCCESS )
         {
             return(EXIT_SUCCESS);
@@ -282,8 +309,13 @@ int main(int argc, char* argv[])
 
     if( ipv6_range_check )
     {
-        int result = is_ipv6_range(address_str, verbose);
+        if( range_prefix_length > 128 )
+        {
+            fprintf(stderr, "Error: prefix length cannot exceed 32 for IPv4!\n");
+            return(RESULT_INT_ERROR);
+        }
 
+        int result = is_ipv6_range(address_str, range_prefix_length, verbose);
         if( result == RESULT_SUCCESS )
         {
             return(EXIT_SUCCESS);
@@ -633,8 +665,11 @@ Address checking options:\n\
   --is-ipv6-range            Check if STRING is a valid IPv6 address range\n\
   \n\
 Behavior options:\n\
-  --allow-loopback           When used with --is-valid-intf-address,\n\
-                               makes IPv4 loopback addresses pass the check\n\
+  --allow-loopback             When used with --is-valid-intf-address,\n\
+                                 makes IPv4 loopback addresses pass the check\n\
+  --range-prefix-length <INT>  When used with --is-ipv4-range or --is-ipv6-range,\n\
+                                 requires the range boundaries to lie within\n\
+                                 a prefix of given length\n\
 \n\
 Other options:\n\
   --version                  Print version information and exit \n\
diff --git a/src/ipaddrcheck_functions.c b/src/ipaddrcheck_functions.c
index e3e2c86..2b3cc22 100644
--- a/src/ipaddrcheck_functions.c
+++ b/src/ipaddrcheck_functions.c
@@ -460,7 +460,7 @@ int is_any_net(CIDR *address)
  * This function is patently unsafe,
  * whether it's safe to do what it does should be determined by its callers.
  */
-void split_range(char* range_str, char* left, char*right)
+void split_range(char* range_str, char* left, char* right)
 {
     char* ptr = left;
     int length = strlen(range_str);
@@ -487,6 +487,9 @@ void split_range(char* range_str, char* left, char*right)
     return;
 }
 
+/* in6_addr fields are byte arrays, so we cannot compare them as numbers
+ * and needs custom comparison logic
+ */
 int compare_ipv6(struct in6_addr *left, struct in6_addr *right)
 {
     int i = 0;
@@ -501,7 +504,7 @@ int compare_ipv6(struct in6_addr *left, struct in6_addr *right)
 }
 
 /* Is it a valid IPv4 address range? */
-int is_ipv4_range(char* range_str, int verbose)
+int is_ipv4_range(char* range_str, int prefix_length, int verbose)
 {
     int result = RESULT_SUCCESS;
 
@@ -553,7 +556,33 @@ int is_ipv4_range(char* range_str, int verbose)
 
             if( left_in_addr->s_addr <= right_in_addr->s_addr )
             {
-                result = RESULT_SUCCESS;
+                /* If non-zero prefix_length is given,
+                   check if the right address is within the network of the first one. */
+                if( prefix_length > 0 )
+                {
+                    char left_pref_str[19];
+
+                    /* XXX: Prefix length size is checked elsewhere, so it can't be more than 2 characters (32)
+                       and overflow cannot occur.
+                     */
+                    sprintf(left_pref_str, "%s/%u", left, prefix_length);
+                    CIDR* left_addr_with_pref = cidr_from_str(left_pref_str);
+                    CIDR* left_net = cidr_addr_network(left_addr_with_pref);
+                    if( cidr_contains(left_net, right_addr) == 0 )
+                    {
+                        result = RESULT_SUCCESS;
+                    }
+                    else
+                    {
+                        result = RESULT_FAILURE;
+                    }
+                    cidr_free(left_addr_with_pref);
+                    cidr_free(left_net);
+                }
+                else
+                {
+                    result = RESULT_SUCCESS;
+                }
             }
             else
             {
@@ -573,7 +602,7 @@ int is_ipv4_range(char* range_str, int verbose)
 }
 
 /* Is it a valid IPv6 address range? */
-int is_ipv6_range(char* range_str, int verbose)
+int is_ipv6_range(char* range_str, int prefix_length, int verbose)
 {
     int result = RESULT_SUCCESS;
 
@@ -625,7 +654,33 @@ int is_ipv6_range(char* range_str, int verbose)
 
             if( compare_ipv6(left_in6_addr, right_in6_addr) <= 0 )
             {
-                result = RESULT_SUCCESS;
+                /* If non-zero prefix_length is given,
+                   check if the right address is within the network of the first one. */
+                if( prefix_length > 0 )
+                {
+                    char left_pref_str[44];
+
+                    /* XXX: Prefix length size is checked elsewhere, so it can't be more than 3 characters (128)
+                       and overflow cannot occur.
+                     */
+                    sprintf(left_pref_str, "%s/%u", left, prefix_length);
+                    CIDR* left_addr_with_pref = cidr_from_str(left_pref_str);
+                    CIDR* left_net = cidr_addr_network(left_addr_with_pref);
+                    if( cidr_contains(left_net, right_addr) == 0 )
+                    {
+                        result = RESULT_SUCCESS;
+                    }
+                    else
+                    {
+                        result = RESULT_FAILURE;
+                    }
+                    cidr_free(left_addr_with_pref);
+                    cidr_free(left_net);
+                }
+                else
+                {
+                    result = RESULT_SUCCESS;
+                }
             }
             else
             {
diff --git a/src/ipaddrcheck_functions.h b/src/ipaddrcheck_functions.h
index c0d8603..9b5e55f 100644
--- a/src/ipaddrcheck_functions.h
+++ b/src/ipaddrcheck_functions.h
@@ -76,7 +76,7 @@ int is_ipv6_link_local(CIDR *address);
 int is_valid_intf_address(CIDR *address, char* address_str, int allow_loopback);
 int is_any_host(CIDR *address);
 int is_any_net(CIDR *address);
-int is_ipv4_range(char* range_str, int verbose);
-int is_ipv6_range(char* range_str, int verbose);
+int is_ipv4_range(char* range_str, int prefix_length, int verbose);
+int is_ipv6_range(char* range_str, int prefix_length, int verbose);
 
 #endif /* IPADDRCHECK_FUNCTIONS_H */
diff --git a/src/ipaddrcheck_functions.o b/src/ipaddrcheck_functions.o
index e8e714d..a689dac 100644
--- a/src/ipaddrcheck_functions.o
+++ b/src/ipaddrcheck_functions.o