dhcp-identifier: un-inline dhcp_validate_duid_len

After all it is used in more than one place and is not that short.
Also tweak the test a bit:
- do not check that duid_len > 0, because we want to allow unknown
  duid types, and there might be some which are fine with 0 length data,
  (also assert should not be called from library code),
- always check that duid_len <= MAX_DUID_LEN, because we could overwrite
  available buffer space otherwise.

1 files changed, 31 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp-identifier.c b/src/libsystemd-network/dhcp-identifier.c
index 4f7d4d8bf2..a21efc4d06 100644
--- a/src/libsystemd-network/dhcp-identifier.c
+++ b/src/libsystemd-network/dhcp-identifier.c
@@ -31,6 +31,37 @@
 #define SYSTEMD_PEN 43793
 #define HASH_KEY SD_ID128_MAKE(80,11,8c,c2,fe,4a,03,ee,3e,d6,0c,6f,36,39,14,09)
 
+int dhcp_validate_duid_len(uint16_t duid_type, size_t duid_len) {
+        struct duid d;
+
+        assert_cc(sizeof(d.raw) >= MAX_DUID_LEN);
+        if (duid_len > MAX_DUID_LEN)
+                return -EINVAL;
+
+        switch (duid_type) {
+        case DUID_TYPE_LLT:
+                if (duid_len <= sizeof(d.llt))
+                        return -EINVAL;
+                break;
+        case DUID_TYPE_EN:
+                if (duid_len != sizeof(d.en))
+                        return -EINVAL;
+                break;
+        case DUID_TYPE_LL:
+                if (duid_len <= sizeof(d.ll))
+                        return -EINVAL;
+                break;
+        case DUID_TYPE_UUID:
+                if (duid_len != sizeof(d.uuid))
+                        return -EINVAL;
+                break;
+        default:
+                /* accept unknown type in order to be forward compatible */
+                break;
+        }
+        return 0;
+}
+
 int dhcp_identifier_set_duid_en(struct duid *duid, size_t *len) {
         sd_id128_t machine_id;
         uint64_t hash;