Extract addr-policy parsing code.

1 files changed, 218 insertions, 0 deletions

diff --git a/src/feature/dirparse/policy_parse.c b/src/feature/dirparse/policy_parse.c
new file mode 100644
index 0000000000..e102a62282
--- /dev/null
+++ b/src/feature/dirparse/policy_parse.c
@@ -0,0 +1,218 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file policy_parse.c
+ * \brief Code to parse address policies.
+ **/
+
+#define  EXPOSE_ROUTERDESC_TOKEN_TABLE
+
+#include "core/or/or.h"
+
+#include "core/or/policies.h"
+#include "feature/dirparse/parsecommon.h"
+#include "feature/dirparse/policy_parse.h"
+#include "feature/dirparse/routerparse.h"
+#include "feature/dirparse/unparseable.h"
+#include "lib/memarea/memarea.h"
+
+#include "core/or/addr_policy_st.h"
+
+static addr_policy_t *router_parse_addr_policy_private(directory_token_t *tok);
+
+/** Parse the addr policy in the string <b>s</b> and return it.  If
+ * assume_action is nonnegative, then insert its action (ADDR_POLICY_ACCEPT or
+ * ADDR_POLICY_REJECT) for items that specify no action.
+ *
+ * Returns NULL on policy errors.
+ *
+ * Set *<b>malformed_list</b> to true if the entire policy list should be
+ * discarded. Otherwise, set it to false, and only this item should be ignored
+ * on error - the rest of the policy list can continue to be processed and
+ * used.
+ *
+ * The addr_policy_t returned by this function can have its address set to
+ * AF_UNSPEC for '*'.  Use policy_expand_unspec() to turn this into a pair
+ * of AF_INET and AF_INET6 items.
+ */
+MOCK_IMPL(addr_policy_t *,
+router_parse_addr_policy_item_from_string,(const char *s, int assume_action,
+                                           int *malformed_list))
+{
+  directory_token_t *tok = NULL;
+  const char *cp, *eos;
+  /* Longest possible policy is
+   * "accept6 [ffff:ffff:..255]/128:10000-65535",
+   * which contains a max-length IPv6 address, plus 26 characters.
+   * But note that there can be an arbitrary amount of space between the
+   * accept and the address:mask/port element.
+   * We don't need to multiply TOR_ADDR_BUF_LEN by 2, as there is only one
+   * IPv6 address. But making the buffer shorter might cause valid long lines,
+   * which parsed in previous versions, to fail to parse in new versions.
+   * (These lines would have to have excessive amounts of whitespace.) */
+  char line[TOR_ADDR_BUF_LEN*2 + 32];
+  addr_policy_t *r;
+  memarea_t *area = NULL;
+
+  tor_assert(malformed_list);
+  *malformed_list = 0;
+
+  s = eat_whitespace(s);
+  /* We can only do assume_action on []-quoted IPv6, as "a" (accept)
+   * and ":" (port separator) are ambiguous */
+  if ((*s == '*' || *s == '[' || TOR_ISDIGIT(*s)) && assume_action >= 0) {
+    if (tor_snprintf(line, sizeof(line), "%s %s",
+               assume_action == ADDR_POLICY_ACCEPT?"accept":"reject", s)<0) {
+      log_warn(LD_DIR, "Policy %s is too long.", escaped(s));
+      return NULL;
+    }
+    cp = line;
+    tor_strlower(line);
+  } else { /* assume an already well-formed address policy line */
+    cp = s;
+  }
+
+  eos = cp + strlen(cp);
+  area = memarea_new();
+  tok = get_next_token(area, &cp, eos, routerdesc_token_table);
+  if (tok->tp == ERR_) {
+    log_warn(LD_DIR, "Error reading address policy: %s", tok->error);
+    goto err;
+  }
+  if (tok->tp != K_ACCEPT && tok->tp != K_ACCEPT6 &&
+      tok->tp != K_REJECT && tok->tp != K_REJECT6) {
+    log_warn(LD_DIR, "Expected 'accept' or 'reject'.");
+    goto err;
+  }
+
+  /* Use the extended interpretation of accept/reject *,
+   * expanding it into an IPv4 wildcard and an IPv6 wildcard.
+   * Also permit *4 and *6 for IPv4 and IPv6 only wildcards. */
+  r = router_parse_addr_policy(tok, TAPMP_EXTENDED_STAR);
+  if (!r) {
+    goto err;
+  }
+
+  /* Ensure that accept6/reject6 fields are followed by IPv6 addresses.
+   * AF_UNSPEC addresses are only permitted on the accept/reject field type.
+   * Unlike descriptors, torrcs exit policy accept/reject can be followed by
+   * either an IPv4 or IPv6 address. */
+  if ((tok->tp == K_ACCEPT6 || tok->tp == K_REJECT6) &&
+       tor_addr_family(&r->addr) != AF_INET6) {
+    /* This is a non-fatal error, just ignore this one entry. */
+    *malformed_list = 0;
+    log_warn(LD_DIR, "IPv4 address '%s' with accept6/reject6 field type in "
+             "exit policy. Ignoring, but continuing to parse rules. (Use "
+             "accept/reject with IPv4 addresses.)",
+             tok->n_args == 1 ? tok->args[0] : "");
+    addr_policy_free(r);
+    r = NULL;
+    goto done;
+  }
+
+  goto done;
+ err:
+  *malformed_list = 1;
+  r = NULL;
+ done:
+  token_clear(tok);
+  if (area) {
+    DUMP_AREA(area, "policy item");
+    memarea_drop_all(area);
+  }
+  return r;
+}
+
+/** Given a K_ACCEPT[6] or K_REJECT[6] token and a router, create and return
+ * a new exit_policy_t corresponding to the token. If TAPMP_EXTENDED_STAR
+ * is set in fmt_flags, K_ACCEPT6 and K_REJECT6 tokens followed by *
+ * expand to IPv6-only policies, otherwise they expand to IPv4 and IPv6
+ * policies */
+addr_policy_t *
+router_parse_addr_policy(directory_token_t *tok, unsigned fmt_flags)
+{
+  addr_policy_t newe;
+  char *arg;
+
+  tor_assert(tok->tp == K_REJECT || tok->tp == K_REJECT6 ||
+             tok->tp == K_ACCEPT || tok->tp == K_ACCEPT6);
+
+  if (tok->n_args != 1)
+    return NULL;
+  arg = tok->args[0];
+
+  if (!strcmpstart(arg,"private"))
+    return router_parse_addr_policy_private(tok);
+
+  memset(&newe, 0, sizeof(newe));
+
+  if (tok->tp == K_REJECT || tok->tp == K_REJECT6)
+    newe.policy_type = ADDR_POLICY_REJECT;
+  else
+    newe.policy_type = ADDR_POLICY_ACCEPT;
+
+  /* accept6/reject6 * produces an IPv6 wildcard address only.
+   * (accept/reject * produces rules for IPv4 and IPv6 wildcard addresses.) */
+  if ((fmt_flags & TAPMP_EXTENDED_STAR)
+      && (tok->tp == K_ACCEPT6 || tok->tp == K_REJECT6)) {
+    fmt_flags |= TAPMP_STAR_IPV6_ONLY;
+  }
+
+  if (tor_addr_parse_mask_ports(arg, fmt_flags, &newe.addr, &newe.maskbits,
+                                &newe.prt_min, &newe.prt_max) < 0) {
+    log_warn(LD_DIR,"Couldn't parse line %s. Dropping", escaped(arg));
+    return NULL;
+  }
+
+  return addr_policy_get_canonical_entry(&newe);
+}
+
+/** Parse an exit policy line of the format "accept[6]/reject[6] private:...".
+ * This didn't exist until Tor 0.1.1.15, so nobody should generate it in
+ * router descriptors until earlier versions are obsolete.
+ *
+ * accept/reject and accept6/reject6 private all produce rules for both
+ * IPv4 and IPv6 addresses.
+ */
+static addr_policy_t *
+router_parse_addr_policy_private(directory_token_t *tok)
+{
+  const char *arg;
+  uint16_t port_min, port_max;
+  addr_policy_t result;
+
+  arg = tok->args[0];
+  if (strcmpstart(arg, "private"))
+    return NULL;
+
+  arg += strlen("private");
+  arg = (char*) eat_whitespace(arg);
+  if (!arg || *arg != ':')
+    return NULL;
+
+  if (parse_port_range(arg+1, &port_min, &port_max)<0)
+    return NULL;
+
+  memset(&result, 0, sizeof(result));
+  if (tok->tp == K_REJECT || tok->tp == K_REJECT6)
+    result.policy_type = ADDR_POLICY_REJECT;
+  else
+    result.policy_type = ADDR_POLICY_ACCEPT;
+  result.is_private = 1;
+  result.prt_min = port_min;
+  result.prt_max = port_max;
+
+  if (tok->tp == K_ACCEPT6 || tok->tp == K_REJECT6) {
+    log_warn(LD_GENERAL,
+             "'%s' expands into rules which apply to all private IPv4 and "
+             "IPv6 addresses. (Use accept/reject private:* for IPv4 and "
+             "IPv6.)", tok->n_args == 1 ? tok->args[0] : "");
+  }
+
+  return addr_policy_get_canonical_entry(&result);
+}
+