New upstream version 1.25.90 upstream/1.25.90

1 files changed, 58 insertions, 16 deletions

diff --git a/shared/systemd/src/basic/in-addr-util.c b/shared/systemd/src/basic/in-addr-util.c
index 0e770621..cddc269f 100644
--- a/shared/systemd/src/basic/in-addr-util.c
+++ b/shared/systemd/src/basic/in-addr-util.c
@@ -180,47 +180,89 @@ int in_addr_prefix_next(int family, union in_addr_union *u, unsigned prefixlen)
         assert(u);
 
         /* Increases the network part of an address by one. Returns
-         * positive it that succeeds, or 0 if this overflows. */
+         * positive if that succeeds, or -ERANGE if this overflows. */
+
+        return in_addr_prefix_nth(family, u, prefixlen, 1);
+}
+
+/*
+ * Calculates the nth prefix of size prefixlen starting from the address denoted by u.
+ *
+ * On success 1 will be returned and the calculated prefix will be available in
+ * u. In the case nth == 0 the input will be left unchanged and 1 will be returned.
+ * In case the calculation cannot be performed (invalid prefix length,
+ * overflows would occur) -ERANGE is returned. If the address family given isn't
+ * supported -EAFNOSUPPORT will be returned.
+ *
+ *
+ * Examples:
+ *   - in_addr_prefix_nth(AF_INET, 192.168.0.0, 24, 2), returns 1, writes 192.168.2.0 to u
+ *   - in_addr_prefix_nth(AF_INET, 192.168.0.0, 24, 0), returns 1, no data written
+ *   - in_addr_prefix_nth(AF_INET, 255.255.255.0, 24, 1), returns -ERANGE, no data written
+ *   - in_addr_prefix_nth(AF_INET, 255.255.255.0, 0, 1), returns -ERANGE, no data written
+ *   - in_addr_prefix_nth(AF_INET6, 2001:db8, 64, 0xff00) returns 1, writes 2001:0db8:0000:ff00:: to u
+ */
+int in_addr_prefix_nth(int family, union in_addr_union *u, unsigned prefixlen, uint64_t nth) {
+        assert(u);
 
         if (prefixlen <= 0)
-                return 0;
+                return -ERANGE;
 
-        if (family == AF_INET) {
-                uint32_t c, n;
+        if (nth == 0)
+                return 1;
 
+        if (family == AF_INET) {
+                uint32_t c, n, t;
                 if (prefixlen > 32)
                         prefixlen = 32;
 
                 c = be32toh(u->in.s_addr);
-                n = c + (1UL << (32 - prefixlen));
-                if (n < c)
-                        return 0;
-                n &= 0xFFFFFFFFUL << (32 - prefixlen);
 
+                t = nth << (32 - prefixlen);
+
+                /* Check for wrap */
+                if (c > UINT32_MAX - t)
+                        return -ERANGE;
+
+                n = c + t;
+
+                n &= UINT32_C(0xFFFFFFFF) << (32 - prefixlen);
                 u->in.s_addr = htobe32(n);
                 return 1;
         }
 
         if (family == AF_INET6) {
-                struct in6_addr add = {}, result;
+                struct in6_addr result = {};
                 uint8_t overflow = 0;
-                unsigned i;
+                uint64_t delta;  /* this assumes that we only ever have to up to 1<<64 subnets */
+                unsigned start_byte = (prefixlen - 1) / 8;
 
                 if (prefixlen > 128)
                         prefixlen = 128;
 
                 /* First calculate what we have to add */
-                add.s6_addr[(prefixlen-1) / 8] = 1 << (7 - (prefixlen-1) % 8);
+                delta = nth << ((128 - prefixlen) % 8);
 
-                for (i = 16; i > 0; i--) {
+                for (unsigned i = 16; i > 0; i--) {
                         unsigned j = i - 1;
+                        unsigned d = 0;
 
-                        result.s6_addr[j] = u->in6.s6_addr[j] + add.s6_addr[j] + overflow;
-                        overflow = (result.s6_addr[j] < u->in6.s6_addr[j]);
+                        if (j <= start_byte) {
+                                int16_t t;
+
+                                d = delta & 0xFF;
+                                delta >>= 8;
+
+                                t = u->in6.s6_addr[j] + d + overflow;
+                                overflow = t > UINT8_MAX ? t - UINT8_MAX : 0;
+
+                                result.s6_addr[j] = (uint8_t)t;
+                        } else
+                                result.s6_addr[j] = u->in6.s6_addr[j];
                 }
 
-                if (overflow)
-                        return 0;
+                if (overflow || delta != 0)
+                        return -ERANGE;
 
                 u->in6 = result;
                 return 1;