allow for exact decoding of values.

if we expect a byte and we get 4 bytes, then it should be a raw
option.

diff --git a/src/protocols/dhcpv4/decode.c b/src/protocols/dhcpv4/decode.c
index 71e9376d074f505be25f906489b94d1f29c664d7..ee754dacd5983fea6bcda2497cad77775d07866c 100644 (file)
--- a/src/protocols/dhcpv4/decode.c
+++ b/src/protocols/dhcpv4/decode.c
@@ -42,7 +42,7 @@ static ssize_t decode_array(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
                            uint8_t const *data, size_t data_len, void *decode_ctx);
 
 static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
-                           uint8_t const *data, size_t data_len, void *decode_ctx);
+                           uint8_t const *data, size_t data_len, void *decode_ctx, bool exact);
 
 /** Returns the number of array members for arrays with fixed element sizes
  *
@@ -77,7 +77,7 @@ static int fr_dhcpv4_array_members(size_t *out, size_t len, fr_dict_attr_t const
  *     Decode ONE value into a VP
  */
 static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *da,
-                           uint8_t const *data, size_t data_len, UNUSED void *decode_ctx)
+                           uint8_t const *data, size_t data_len, UNUSED void *decode_ctx, bool exact)
 {
        fr_pair_t *vp;
        uint8_t const *p = data;
@@ -128,6 +128,8 @@ static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
        case FR_TYPE_IPV6_ADDR:
                if ((size_t) (end - p) < sizeof(vp->vp_ipv6addr)) goto raw;
 
+               if (exact && ((size_t) (end - p) > sizeof(vp->vp_ipv6addr))) goto raw;
+
                memcpy(&vp->vp_ipv6addr, p, sizeof(vp->vp_ipv6addr));
                vp->vp_ip.af = AF_INET6;
                vp->vp_ip.scope_id = 0;
@@ -139,6 +141,8 @@ static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
        case FR_TYPE_IPV6_PREFIX:
                if ((size_t) (end - (p + 1)) < sizeof(vp->vp_ipv6addr)) goto raw;
 
+               if (exact && ((size_t) (end - p) > sizeof(vp->vp_ipv6addr))) goto raw;
+
                memcpy(&vp->vp_ipv6addr, p + 1, sizeof(vp->vp_ipv6addr));
                vp->vp_ip.af = AF_INET6;
                vp->vp_ip.scope_id = 0;
@@ -163,8 +167,15 @@ static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
                        FR_PROTO_TRACE("decoding as unknown type");
                        if (fr_pair_to_unknown(vp) < 0) return -1;
                        fr_pair_value_memdup(vp, p, end - p, true);
-                       ret = data_len;
+                       p = end;
+                       break;
                }
+
+               if (exact && (ret != (end - p))) {
+                       talloc_free(vp);
+                       goto raw;
+               }
+
                p += (size_t) ret;
        }
        }
@@ -305,6 +316,10 @@ static ssize_t decode_tlv(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t c
                         *      options" option.  Return it as random crap.
                         */
                raw:
+                       /*
+                        *      @todo - the "goto raw" can leave partially decoded VPs in the output.  we'll
+                        *      need a temporary cursor / pair_list to fix that.
+                        */
                        slen = decode_raw(ctx, out, parent, p, end - p, decode_ctx);
                        if (slen < 0) return slen - (p - data);
 
@@ -355,6 +370,10 @@ static ssize_t decode_array(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
                p = data;
 
        raw:
+               /*
+                *      @todo - the "goto raw" can leave partially decoded VPs in the output.  we'll
+                *      need a temporary cursor / pair_list to fix that.
+                */
                vp = fr_raw_from_network(ctx, parent, p, (data + data_len) - p);
                if (!vp) return -1;
                fr_pair_append(out, vp);
@@ -367,9 +386,11 @@ static ssize_t decode_array(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
         */
        for (i = 0, p = data; i < values; i++) {
                fr_assert((p + value_len) <= (data + data_len));
-               len = decode_value(ctx, out, parent, p, value_len, decode_ctx);
+               len = decode_value(ctx, out, parent, p, value_len, decode_ctx, false);
                if (len <= 0) return len;
-               if (len != (ssize_t)value_len) goto raw;
+               if (len != (ssize_t)value_len) {
+                       goto raw;
+               }
                p += len;
        }
 
@@ -545,7 +566,7 @@ static ssize_t decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                slen = decode_tlv(ctx, out, da, data + 2, len, decode_ctx);
 
        } else {
-               slen = decode_value(ctx, out, da, data + 2, len, decode_ctx);
+               slen = decode_value(ctx, out, da, data + 2, len, decode_ctx, true);
        }
 
        if (slen < 0) {
@@ -653,7 +674,7 @@ ssize_t fr_dhcpv4_decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                        slen = decode_array(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx);
 
                } else {
-                       slen = decode_value(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx);
+                       slen = decode_value(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx, true);
                }
                if (slen <= 0) return slen;