config: Move server transport config into the relay module

This commit:
* creates feature/relay/transport_config.[ch],
* moves server transport config checks into them,
* exposes some code from src/app/config.c
  (we'll refactor it later in 29211), and
* adds thin wrappers to make the moved code compile.

No functional changes: the moved code is still enabled,
even if the relay module is disabled. (Some of the checks
are re-ordered, so the order of some warnings may change.)

Part of 32213.

2 files changed, 274 insertions, 0 deletions

diff --git a/src/feature/relay/transport_config.c b/src/feature/relay/transport_config.c
new file mode 100644
index 0000000000..b323f4299e
--- /dev/null
+++ b/src/feature/relay/transport_config.c
@@ -0,0 +1,247 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file transport_config.c
+ * @brief Code to interpret the user's configuration of Tor's server
+ *        pluggable transports.
+ **/
+
+#include "orconfig.h"
+#include "feature/relay/transport_config.h"
+
+#include "lib/encoding/confline.h"
+#include "lib/encoding/keyval.h"
+
+#include "lib/container/smartlist.h"
+
+/* Required for dirinfo_type_t in or_options_t */
+#include "core/or/or.h"
+#include "app/config/config.h"
+
+#include "feature/relay/ext_orport.h"
+#include "feature/relay/routermode.h"
+
+/* Copied from config.c, we will refactor later in 29211. */
+#define REJECT(arg) \
+  STMT_BEGIN *msg = tor_strdup(arg); return -1; STMT_END
+
+/** Given a ServerTransportListenAddr <b>line</b>, return its
+ *  <address:port> string. Return NULL if the line was not
+ *  well-formed.
+ *
+ *  If <b>transport</b> is set, return NULL if the line is not
+ *  referring to <b>transport</b>.
+ *
+ *  The returned string is allocated on the heap and it's the
+ *  responsibility of the caller to free it. */
+static char *
+get_bindaddr_from_transport_listen_line(const char *line,const char *transport)
+{
+  smartlist_t *items = NULL;
+  const char *parsed_transport = NULL;
+  char *addrport = NULL;
+  tor_addr_t addr;
+  uint16_t port = 0;
+
+  items = smartlist_new();
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+
+  if (smartlist_len(items) < 2) {
+    log_warn(LD_CONFIG,"Too few arguments on ServerTransportListenAddr line.");
+    goto err;
+  }
+
+  parsed_transport = smartlist_get(items, 0);
+  addrport = tor_strdup(smartlist_get(items, 1));
+
+  /* If 'transport' is given, check if it matches the one on the line */
+  if (transport && strcmp(transport, parsed_transport))
+    goto err;
+
+  /* Validate addrport */
+  if (tor_addr_port_parse(LOG_WARN, addrport, &addr, &port, -1)<0) {
+    log_warn(LD_CONFIG, "Error parsing ServerTransportListenAddr "
+             "address '%s'", addrport);
+    goto err;
+  }
+
+  goto done;
+
+ err:
+  tor_free(addrport);
+  addrport = NULL;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+
+  return addrport;
+}
+
+/** Given the name of a pluggable transport in <b>transport</b>, check
+ *  the configuration file to see if the user has explicitly asked for
+ *  it to listen on a specific port. Return a <address:port> string if
+ *  so, otherwise NULL. */
+char *
+get_transport_bindaddr_from_config(const char *transport)
+{
+  config_line_t *cl;
+  const or_options_t *options = get_options();
+
+  for (cl = options->ServerTransportListenAddr; cl; cl = cl->next) {
+    char *bindaddr =
+      get_bindaddr_from_transport_listen_line(cl->value, transport);
+    if (bindaddr)
+      return bindaddr;
+  }
+
+  return NULL;
+}
+
+/** Given a ServerTransportOptions <b>line</b>, return a smartlist
+ *  with the options. Return NULL if the line was not well-formed.
+ *
+ *  If <b>transport</b> is set, return NULL if the line is not
+ *  referring to <b>transport</b>.
+ *
+ *  The returned smartlist and its strings are allocated on the heap
+ *  and it's the responsibility of the caller to free it. */
+smartlist_t *
+get_options_from_transport_options_line(const char *line,const char *transport)
+{
+  smartlist_t *items = smartlist_new();
+  smartlist_t *options = smartlist_new();
+  const char *parsed_transport = NULL;
+
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+
+  if (smartlist_len(items) < 2) {
+    log_warn(LD_CONFIG,"Too few arguments on ServerTransportOptions line.");
+    goto err;
+  }
+
+  parsed_transport = smartlist_get(items, 0);
+  /* If 'transport' is given, check if it matches the one on the line */
+  if (transport && strcmp(transport, parsed_transport))
+    goto err;
+
+  SMARTLIST_FOREACH_BEGIN(items, const char *, option) {
+    if (option_sl_idx == 0) /* skip the transport field (first field)*/
+      continue;
+
+    /* validate that it's a k=v value */
+    if (!string_is_key_value(LOG_WARN, option)) {
+      log_warn(LD_CONFIG, "%s is not a k=v value.", escaped(option));
+      goto err;
+    }
+
+    /* add it to the options smartlist */
+    smartlist_add_strdup(options, option);
+    log_debug(LD_CONFIG, "Added %s to the list of options", escaped(option));
+  } SMARTLIST_FOREACH_END(option);
+
+  goto done;
+
+ err:
+  SMARTLIST_FOREACH(options, char*, s, tor_free(s));
+  smartlist_free(options);
+  options = NULL;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+
+  return options;
+}
+
+/** Given the name of a pluggable transport in <b>transport</b>, check
+ *  the configuration file to see if the user has asked us to pass any
+ *  parameters to the pluggable transport. Return a smartlist
+ *  containing the parameters, otherwise NULL. */
+smartlist_t *
+get_options_for_server_transport(const char *transport)
+{
+  config_line_t *cl;
+  const or_options_t *options = get_options();
+
+  for (cl = options->ServerTransportOptions; cl; cl = cl->next) {
+    smartlist_t *options_sl =
+      get_options_from_transport_options_line(cl->value, transport);
+    if (options_sl)
+      return options_sl;
+  }
+
+  return NULL;
+}
+
+/**
+ * Legacy validation/normalization function for the server transport options.
+ * Uses old_options as the previous options.
+ *
+ * Returns 0 on success, returns -1 and sets *msg to a newly allocated string
+ * on error.
+ */
+int
+options_validate_server_transport(const or_options_t *old_options,
+                                  or_options_t *options,
+                                  char **msg)
+{
+  (void)old_options;
+
+  if (BUG(!options))
+    return -1;
+
+  if (BUG(!msg))
+    return -1;
+
+  config_line_t *cl;
+
+  for (cl = options->ServerTransportPlugin; cl; cl = cl->next) {
+    if (parse_transport_line(options, cl->value, 1, 1) < 0)
+      REJECT("Invalid server transport line. See logs for details.");
+  }
+
+  if (options->ServerTransportPlugin && !server_mode(options)) {
+    log_notice(LD_GENERAL, "Tor is not configured as a relay but you specified"
+               " a ServerTransportPlugin line (%s). The ServerTransportPlugin "
+               "line will be ignored.",
+               escaped(options->ServerTransportPlugin->value));
+  }
+
+  for (cl = options->ServerTransportListenAddr; cl; cl = cl->next) {
+    /** If get_bindaddr_from_transport_listen_line() fails with
+        'transport' being NULL, it means that something went wrong
+        while parsing the ServerTransportListenAddr line. */
+    char *bindaddr = get_bindaddr_from_transport_listen_line(cl->value, NULL);
+    if (!bindaddr)
+      REJECT("ServerTransportListenAddr did not parse. See logs for details.");
+    tor_free(bindaddr);
+  }
+
+  if (options->ServerTransportListenAddr && !options->ServerTransportPlugin) {
+    log_notice(LD_GENERAL, "You need at least a single managed-proxy to "
+               "specify a transport listen address. The "
+               "ServerTransportListenAddr line will be ignored.");
+  }
+
+  for (cl = options->ServerTransportOptions; cl; cl = cl->next) {
+    /** If get_options_from_transport_options_line() fails with
+        'transport' being NULL, it means that something went wrong
+        while parsing the ServerTransportOptions line. */
+    smartlist_t *options_sl =
+      get_options_from_transport_options_line(cl->value, NULL);
+    if (!options_sl)
+      REJECT("ServerTransportOptions did not parse. See logs for details.");
+
+    SMARTLIST_FOREACH(options_sl, char *, cp, tor_free(cp));
+    smartlist_free(options_sl);
+  }
+
+  return 0;
+}
diff --git a/src/feature/relay/transport_config.h b/src/feature/relay/transport_config.h
new file mode 100644
index 0000000000..6ef1bc4020
--- /dev/null
+++ b/src/feature/relay/transport_config.h
@@ -0,0 +1,27 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file transport_config.h
+ * @brief Header for feature/relay/transport_config.c
+ **/
+
+#ifndef TOR_FEATURE_RELAY_TRANSPORT_CONFIG_H
+#define TOR_FEATURE_RELAY_TRANSPORT_CONFIG_H
+
+typedef struct or_options_t or_options_t;
+typedef struct smartlist_t smartlist_t;
+
+char *get_transport_bindaddr_from_config(const char *transport);
+smartlist_t *get_options_from_transport_options_line(const char *line,
+                                                     const char *transport);
+smartlist_t *get_options_for_server_transport(const char *transport);
+
+int options_validate_server_transport(const or_options_t *old_options,
+                                      or_options_t *options,
+                                      char **msg);
+
+#endif /* !defined(TOR_FEATURE_RELAY_TRANSPORT_CONFIG_H) */