hs: Move get_lspecs_from_node to nodelist.c

Also:
* rename to node_get_link_specifier_smartlist
* rewrite to return a smartlist
* add link_specifier_smartlist_free

Part of 23576.

2 files changed, 101 insertions, 0 deletions

diff --git a/src/feature/nodelist/nodelist.c b/src/feature/nodelist/nodelist.c
index 9a27701803..32ee2677bb 100644
--- a/src/feature/nodelist/nodelist.c
+++ b/src/feature/nodelist/nodelist.c
@@ -1189,6 +1189,102 @@ node_get_rsa_id_digest(const node_t *node)
   return (const uint8_t*)node->identity;
 }
 
+/* Returns a new smartlist with all possible link specifiers from node:
+ *  - legacy ID is mandatory thus MUST be present in node;
+ *  - include ed25519 link specifier if present in the node, and the node
+ *    supports ed25519 link authentication, and:
+ *    - if direct_conn is true, its link versions are compatible with us,
+ *    - if direct_conn is false, regardless of its link versions;
+ *  - include IPv4 link specifier, if the primary address is not IPv4, log a
+ *    BUG() warning, and return an empty smartlist;
+ *  - include IPv6 link specifier if present in the node.
+ *
+ * If node is NULL, returns an empty smartlist.
+ *
+ * The smartlist must be freed using link_specifier_smartlist_free(). */
+smartlist_t *
+node_get_link_specifier_smartlist(const node_t *node, bool direct_conn)
+{
+  link_specifier_t *ls;
+  tor_addr_port_t ap;
+  smartlist_t *lspecs = smartlist_new();
+
+  if (!node)
+    return lspecs;
+
+  /* Get the relay's IPv4 address. */
+  node_get_prim_orport(node, &ap);
+
+  /* We expect the node's primary address to be a valid IPv4 address.
+   * This conforms to the protocol, which requires either an IPv4 or IPv6
+   * address (or both). */
+  if (BUG(!tor_addr_is_v4(&ap.addr)) ||
+      BUG(!tor_addr_port_is_valid_ap(&ap, 0))) {
+    return lspecs;
+  }
+
+  ls = link_specifier_new();
+  link_specifier_set_ls_type(ls, LS_IPV4);
+  link_specifier_set_un_ipv4_addr(ls, tor_addr_to_ipv4h(&ap.addr));
+  link_specifier_set_un_ipv4_port(ls, ap.port);
+  /* Four bytes IPv4 and two bytes port. */
+  link_specifier_set_ls_len(ls, sizeof(ap.addr.addr.in_addr) +
+                            sizeof(ap.port));
+  smartlist_add(lspecs, ls);
+
+  /* Legacy ID is mandatory and will always be present in node. */
+  ls = link_specifier_new();
+  link_specifier_set_ls_type(ls, LS_LEGACY_ID);
+  memcpy(link_specifier_getarray_un_legacy_id(ls), node->identity,
+         link_specifier_getlen_un_legacy_id(ls));
+  link_specifier_set_ls_len(ls, link_specifier_getlen_un_legacy_id(ls));
+  smartlist_add(lspecs, ls);
+
+  /* ed25519 ID is only included if the node has it, and the node declares a
+   protocol version that supports ed25519 link authentication.
+   If direct_conn is true, we also require that the node's link version is
+   compatible with us. (Otherwise, we will be sending the ed25519 key
+   to another tor, which may support different link versions.) */
+  if (!ed25519_public_key_is_zero(&node->ed25519_id) &&
+      node_supports_ed25519_link_authentication(node, direct_conn)) {
+    ls = link_specifier_new();
+    link_specifier_set_ls_type(ls, LS_ED25519_ID);
+    memcpy(link_specifier_getarray_un_ed25519_id(ls), &node->ed25519_id,
+           link_specifier_getlen_un_ed25519_id(ls));
+    link_specifier_set_ls_len(ls, link_specifier_getlen_un_ed25519_id(ls));
+    smartlist_add(lspecs, ls);
+  }
+
+  /* Check for IPv6. If so, include it as well. */
+  if (node_has_ipv6_orport(node)) {
+    ls = link_specifier_new();
+    node_get_pref_ipv6_orport(node, &ap);
+    link_specifier_set_ls_type(ls, LS_IPV6);
+    size_t addr_len = link_specifier_getlen_un_ipv6_addr(ls);
+    const uint8_t *in6_addr = tor_addr_to_in6_addr8(&ap.addr);
+    uint8_t *ipv6_array = link_specifier_getarray_un_ipv6_addr(ls);
+    memcpy(ipv6_array, in6_addr, addr_len);
+    link_specifier_set_un_ipv6_port(ls, ap.port);
+    /* Sixteen bytes IPv6 and two bytes port. */
+    link_specifier_set_ls_len(ls, addr_len + sizeof(ap.port));
+    smartlist_add(lspecs, ls);
+  }
+
+  return lspecs;
+}
+
+/* Free a link specifier list. */
+void
+link_specifier_smartlist_free_(smartlist_t *ls_list)
+{
+  if (!ls_list)
+    return;
+
+  SMARTLIST_FOREACH(ls_list, link_specifier_t *, lspec,
+                    link_specifier_free(lspec));
+  smartlist_free(ls_list);
+}
+
 /** Return the nickname of <b>node</b>, or NULL if we can't find one. */
 const char *
 node_get_nickname(const node_t *node)
diff --git a/src/feature/nodelist/nodelist.h b/src/feature/nodelist/nodelist.h
index 3420959618..a3d65347a8 100644
--- a/src/feature/nodelist/nodelist.h
+++ b/src/feature/nodelist/nodelist.h
@@ -77,6 +77,11 @@ int node_supports_v3_hsdir(const node_t *node);
 int node_supports_ed25519_hs_intro(const node_t *node);
 int node_supports_v3_rendezvous_point(const node_t *node);
 const uint8_t *node_get_rsa_id_digest(const node_t *node);
+smartlist_t *node_get_link_specifier_smartlist(const node_t *node,
+                                               bool direct_conn);
+void link_specifier_smartlist_free_(smartlist_t *ls_list);
+#define link_specifier_smartlist_free(ls_list) \
+  FREE_AND_NULL(smartlist_t, link_specifier_smartlist_free_, (ls_list))
 
 int node_has_ipv6_addr(const node_t *node);
 int node_has_ipv6_orport(const node_t *node);