Check signature magic when starting delta job

Unsupported sig format can then be fatal if it happens during block
search

2 files changed, 13 insertions, 2 deletions

diff --git a/src/delta.c b/src/delta.c
index 2c52ca3..37a6aa5 100644
--- a/src/delta.c
+++ b/src/delta.c
@@ -465,6 +465,15 @@ rs_job_t *rs_delta_begin(rs_signature_t *sig)
                job->strong_sum_len);
         return NULL;
     }
+    
+    switch (job->signature->magic) {
+    case RS_BLAKE2_SIG_MAGIC:
+    case RS_MD4_SIG_MAGIC:
+        break;
+    default:
+        rs_error("Unknown signature algorithm %#x", job->signature->magic);
+        return NULL;
+    }
 
     return job;
 }
diff --git a/src/search.c b/src/search.c
index 98b3b78..43405bb 100644
--- a/src/search.c
+++ b/src/search.c
@@ -199,8 +199,10 @@ rs_search_for_block(rs_weak_sum_t weak_sum,
                 } else if (sig->magic == RS_MD4_SIG_MAGIC) {
                     rs_calc_md4_sum(inbuf, block_len, &strong_sum);
                 } else {
-                    rs_error("Unknown signature algorithm - this is a BUG");
-                    return 0; /* FIXME: Is this the best way to handle this? */
+                    /* Bad input data is checked in rs_delta_begin, so this
+                     * should never be reached. */
+                    rs_fatal("Unknown signature algorithm %#x", sig->magic);
+                    return 0;
                 }
                 got_strong = 1;
             }