add and use FR_DBUFF_ERROR_OFFSET

so that we don't have int64 underflow when subtracting offsets
from error slen

arguably we should instead have an error pointer like is done in
the sbuffs, and with fr_sbuff_error()

diff --git a/src/lib/util/dbuff.h b/src/lib/util/dbuff.h
index f613c11bd1cf7f12b7c883e81b37568639df5491..32e64f2ff1b14c14d9709f3018d6b56da922a5e6 100644 (file)
--- a/src/lib/util/dbuff.h
+++ b/src/lib/util/dbuff.h
@@ -189,6 +189,14 @@ do { \
        if (_slen < 0) return _slen; \
 } while (0)
 
+/** Generic wrapper to return an error and an offset from encoding.
+ *
+ *  Some encoders return PAIR_ENCODE_FATAL_ERROR.  Substracting an
+ *  offset from that values means it wraps be be a positive number
+ *  near INT64_MAX.  This macro ensures that doesn't happen.
+ */
+#define FR_DBUFF_ERROR_OFFSET(_slen, _offset) ((_slen < INT32_MAX) ? _slen : _slen - (ssize_t) _offset)
+
 /** @name Initialisers
  * @{
  */

diff --git a/src/protocols/cbor/base.c b/src/protocols/cbor/base.c
index 77c31d3de56e355ecc66b89d2fc04aa765939bd8..fd6f2f970cb1a73f05cadb6e9ef05c85d62eec36 100644 (file)
--- a/src/protocols/cbor/base.c
+++ b/src/protocols/cbor/base.c
@@ -30,7 +30,7 @@ static ssize_t decode_pair(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t
                }
 
                slen = fr_cbor_decode_pair(ctx, out, &dbuff, parent, false);
-               if (slen <= 0) return slen - fr_dbuff_used(&dbuff);
+               if (slen <= 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&dbuff));
        } while (true);
 
        return fr_dbuff_used(&dbuff);
@@ -49,7 +49,7 @@ static ssize_t encode_pair(fr_dbuff_t *dbuff, fr_dcursor_t *cursor, UNUSED void
                ssize_t slen;
 
                slen = fr_cbor_encode_pair(&work_dbuff, vp);
-               if (slen <= 0) return slen - fr_dbuff_used(&work_dbuff);
+               if (slen <= 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
        }
 
        FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, (uint8_t) 0xff); /* end of indefinite array */

diff --git a/src/protocols/dhcpv6/base.c b/src/protocols/dhcpv6/base.c
index 9c147b0c8d021a5955dcbd20804bdcf5b5153a7d..6b104bedba0e57849d9e5f3d32cc128d9e2ca3ad 100644 (file)
--- a/src/protocols/dhcpv6/base.c
+++ b/src/protocols/dhcpv6/base.c
@@ -791,7 +791,7 @@ ssize_t     fr_dhcpv6_encode(fr_dbuff_t *dbuff, uint8_t const *original, size_t leng
        fr_pair_dcursor_iter_init(&cursor, vps, fr_dhcpv6_next_encodable, dict_dhcpv6);
        while ((fr_dbuff_extend(&frame_dbuff) > 0) && (fr_dcursor_current(&cursor) != NULL)) {
                slen = fr_dhcpv6_encode_option(&frame_dbuff, &cursor, &packet_ctx);
-               if (slen < 0) return slen - fr_dbuff_used(&frame_dbuff);
+               if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&frame_dbuff));
        }
 
        return fr_dbuff_set(dbuff, &frame_dbuff);

diff --git a/src/protocols/dns/encode.c b/src/protocols/dns/encode.c
index fe43f3bec65f031997d2b047be675da50d3183bd..f0b6be20befcf07aa597af99762161cd8b74e88a 100644 (file)
--- a/src/protocols/dns/encode.c
+++ b/src/protocols/dns/encode.c
@@ -486,25 +486,25 @@ ssize_t fr_dns_encode(fr_dbuff_t *dbuff, fr_pair_list_t *vps, fr_dns_ctx_t *pack
         *      Encode questions
         */
        slen = encode_record(&work_dbuff, &da_stack, vps, attr_dns_question, packet_ctx, packet + 4);
-       if (slen < 0) return slen - fr_dbuff_used(&work_dbuff);
+       if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
 
        /*
         *      Encode answers
         */
        slen = encode_record(&work_dbuff, &da_stack, vps, attr_dns_rr, packet_ctx, packet + 6);
-       if (slen < 0) return slen - fr_dbuff_used(&work_dbuff);
+       if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
 
        /*
         *      Encode NS records
         */
        slen = encode_record(&work_dbuff, &da_stack, vps, attr_dns_ns, packet_ctx, packet + 8);
-       if (slen < 0) return slen - fr_dbuff_used(&work_dbuff);
+       if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
 
        /*
         *      Encode additional records
         */
        slen = encode_record(&work_dbuff, &da_stack, vps, attr_dns_ar, packet_ctx, packet + 10);
-       if (slen < 0) return slen - fr_dbuff_used(&work_dbuff);
+       if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
 
        return fr_dbuff_set(dbuff, &work_dbuff);
 }

diff --git a/src/protocols/tacacs/encode.c b/src/protocols/tacacs/encode.c
index fa4d3b194e246773a8e225a6afb35044ab213f20..a841fc2bf073383410283196eb719e9a217469a1 100644 (file)
--- a/src/protocols/tacacs/encode.c
+++ b/src/protocols/tacacs/encode.c
@@ -220,7 +220,7 @@ static ssize_t tacacs_encode_body_arg_n(fr_dbuff_t *dbuff, uint8_t arg_cnt, uint
                        if (child_argc > (arg_cnt - i)) child_argc = arg_cnt = i;
 
                        slen = tacacs_encode_body_arg_n(&work_dbuff, child_argc, &arg_len[i], &vp->vp_group, vp->da);
-                       if (slen < 0) return slen - fr_dbuff_used(&work_dbuff);
+                       if (slen < 0) return FR_DBUFF_ERROR_OFFSET(slen, fr_dbuff_used(&work_dbuff));
 
                        i += child_argc;
                        continue;