hs: Implement a helper to repurpose a circuit

When we repurpose a hidden service circuit, we need to clean up from the HS
circuit map and any HS related data structured contained in the circuit.

This commit adds an helper function that does it when repurposing a hidden
service circuit.

Fixes #29034

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/feature/hs/hs_circuit.c b/src/feature/hs/hs_circuit.c
index e3873d2f18..2e59a357b3 100644
--- a/src/feature/hs/hs_circuit.c
+++ b/src/feature/hs/hs_circuit.c
@@ -24,6 +24,7 @@
 #include "feature/nodelist/describe.h"
 #include "feature/nodelist/nodelist.h"
 #include "feature/rend/rendservice.h"
+#include "feature/rend/rendcommon.h"
 #include "feature/stats/rephist.h"
 #include "lib/crypt_ops/crypto_dh.h"
 #include "lib/crypt_ops/crypto_rand.h"
@@ -1269,3 +1270,33 @@ hs_circ_cleanup(circuit_t *circ)
     hs_circuitmap_remove_circuit(circ);
   }
 }
+
+/* The given circuit will be repurposed so take the appropriate actions. A
+ * cleanup from the HS maps and of all HS related structures is done.
+ *
+ * Once this function returns, the circuit can be safely repurposed. */
+void
+hs_circ_repurpose(circuit_t *circ)
+{
+  origin_circuit_t *origin_circ;
+
+  tor_assert(circ);
+
+  /* Only repurposing an origin circuit is possible for HS. */
+  if (!CIRCUIT_IS_ORIGIN(circ)) {
+    return;
+  }
+  origin_circ = TO_ORIGIN_CIRCUIT(circ);
+
+  /* First, cleanup the circuit from the HS maps. */
+  hs_circ_cleanup(circ);
+
+  /* Depending on the version, different cleanup is done. */
+  if (origin_circ->rend_data) {
+    /* v2. */
+    rend_circ_cleanup(origin_circ);
+  } else if (origin_circ->hs_ident) {
+    /* v3. */
+    hs_ident_circuit_free(origin_circ->hs_ident);
+  }
+}