Use K/V parser to handle LOG messages for pluggable transports.

This patch changes the LOG pluggable transport message to use the recent
K/V parser that landed in Tor. This allows PT's to specify the log
severity level as well as the message. A mapping between the PT log
severity levels and Tor's log serverity level is provided.

See: https://bugs.torproject.org/28846

4 files changed, 83 insertions, 12 deletions

diff --git a/src/feature/client/transports.c b/src/feature/client/transports.c
index de53fe3469..6a3479a470 100644
--- a/src/feature/client/transports.c
+++ b/src/feature/client/transports.c
@@ -101,6 +101,8 @@
 #include "core/or/connection_or.h"
 #include "feature/relay/ext_orport.h"
 #include "feature/control/control.h"
+#include "lib/encoding/confline.h"
+#include "lib/encoding/kvline.h"
 
 #include "lib/process/process.h"
 #include "lib/process/env.h"
@@ -1144,22 +1146,63 @@ parse_log_line(const char *line, managed_proxy_t *mp)
   tor_assert(line);
   tor_assert(mp);
 
+  config_line_t *values = NULL;
+  char *log_message = NULL;
+
   if (strlen(line) < (strlen(PROTO_LOG) + 1)) {
     log_warn(LD_PT, "Managed proxy sent us a %s line "
                     "with missing argument.", PROTO_LOG);
     goto done;
   }
 
-  const char *message = line + strlen(PROTO_LOG) + 1;
+  const char *data = line + strlen(PROTO_LOG) + 1;
+  values = kvline_parse(data, KV_QUOTED);
+
+  if (! values) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote an invalid LOG message: %s",
+             mp->argv[0], data);
+    goto done;
+  }
+
+  const config_line_t *severity = config_line_find(values, "SEVERITY");
+  const config_line_t *message = config_line_find(values, "MESSAGE");
+
+  /* Check if we got a message. */
+  if (! message) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote a LOG line without "
+                    "MESSAGE: %s", mp->argv[0], data);
+    goto done;
+  }
+
+  /* Check if severity is there and whether it's valid. */
+  if (! severity) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote a LOG line without "
+                    "SEVERITY: %s", mp->argv[0], data);
+    goto done;
+  }
 
-  log_info(LD_PT, "Managed proxy \"%s\" says: %s",
-           mp->argv[0], message);
+  int log_severity = managed_proxy_severity_parse(severity->value);
+
+  if (log_severity == -1) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote a LOG line with an "
+                    "invalid severity level: %s",
+                    mp->argv[0], severity->value);
+    goto done;
+  }
+
+  tor_log(log_severity, LD_PT, "Managed proxy \"%s\": %s",
+          mp->argv[0], message->value);
+
+  /* Prepend the PT name. */
+  config_line_prepend(&values, "PT", mp->argv[0]);
+  log_message = kvline_encode(values, KV_QUOTED);
 
   /* Emit control port event. */
-  control_event_pt_log(mp->argv[0], message);
+  control_event_pt_log(log_message);
 
  done:
-  return;
+  config_free_lines(values);
+  tor_free(log_message);
 }
 
 /** Return a newly allocated string that tor should place in
@@ -1779,3 +1822,30 @@ managed_proxy_exit_callback(process_t *process, process_exit_code_t exit_code)
 
   return true;
 }
+
+/** Returns a valid integer log severity level from <b>severity</b> that
+ * is compatible with Tor's logging functions. Returns <b>-1</b> on
+ * error. */
+STATIC int
+managed_proxy_severity_parse(const char *severity)
+{
+  tor_assert(severity);
+
+  /* Slightly different than log.c's parse_log_level :-( */
+  if (! strcmp(severity, "debug"))
+    return LOG_DEBUG;
+
+  if (! strcmp(severity, "info"))
+    return LOG_INFO;
+
+  if (! strcmp(severity, "notice"))
+    return LOG_NOTICE;
+
+  if (! strcmp(severity, "warning"))
+    return LOG_WARN;
+
+  if (! strcmp(severity, "error"))
+    return LOG_ERR;
+
+  return -1;
+}
diff --git a/src/feature/client/transports.h b/src/feature/client/transports.h
index a3994a0099..b8d1bb0081 100644
--- a/src/feature/client/transports.h
+++ b/src/feature/client/transports.h
@@ -147,6 +147,8 @@ STATIC void managed_proxy_stdout_callback(process_t *, const char *, size_t);
 STATIC void managed_proxy_stderr_callback(process_t *, const char *, size_t);
 STATIC bool managed_proxy_exit_callback(process_t *, process_exit_code_t);
 
+STATIC int managed_proxy_severity_parse(const char *);
+
 #endif /* defined(PT_PRIVATE) */
 
 #endif /* !defined(TOR_TRANSPORTS_H) */
diff --git a/src/feature/control/control.c b/src/feature/control/control.c
index 7fae3b7a1b..849f11707e 100644
--- a/src/feature/control/control.c
+++ b/src/feature/control/control.c
@@ -7033,15 +7033,14 @@ control_event_transport_launched(const char *mode, const char *transport_name,
                      mode, transport_name, fmt_addr(addr), port);
 }
 
-/** A pluggable transport called <b>pt_name</b> has emitted a log
- * message found in <b>message</b>. */
+/** A pluggable transport called <b>pt_name</b> has emitted a log message
+ * found in <b>message</b> at <b>severity</b> log level. */
 void
-control_event_pt_log(const char *pt_name, const char *message)
+control_event_pt_log(const char *log)
 {
   send_control_event(EVENT_PT_LOG,
-                     "650 PT_LOG %s %s\r\n",
-                     pt_name,
-                     message);
+                     "650 PT_LOG %s\r\n",
+                     log);
 }
 
 /** Convert rendezvous auth type to string for HS_DESC control events
diff --git a/src/feature/control/control.h b/src/feature/control/control.h
index a1609b0f06..b3a2707672 100644
--- a/src/feature/control/control.h
+++ b/src/feature/control/control.h
@@ -207,7 +207,7 @@ void control_event_clients_seen(const char *controller_str);
 void control_event_transport_launched(const char *mode,
                                       const char *transport_name,
                                       tor_addr_t *addr, uint16_t port);
-void control_event_pt_log(const char *pt_name, const char *message);
+void control_event_pt_log(const char *log);
 const char *rend_auth_type_to_string(rend_auth_type_t auth_type);
 MOCK_DECL(const char *, node_describe_longname_by_id,(const char *id_digest));
 void control_event_hs_descriptor_requested(const char *onion_address,