commit de70eebc65d40d50f877b0f82df4d05ce670faa5 Author: Nick Mathewson nickm@torproject.org Date: Tue Apr 2 08:17:22 2019 -0400

Start on a command-parsing tool for controller commands.

There _is_ an underlying logic to these commands, but it isn't wholly uniform, given years of tweaks and changes. Fortunately I think there is a superset that will work.

This commit adds a parser for some of the most basic cases -- the ones currently handled by getargs_helper() and some of the object-taking ones. Soon will come initial tests; then I'll start using the parser.

After that, I'll expand the parser to handle the other cases that come up in the controller protocol. --- src/core/include.am | 1 + src/feature/control/control_cmd.c | 145 ++++++++++++++++++++++++++++-- src/feature/control/control_cmd.h | 39 ++++++++ src/feature/control/control_cmd_args_st.h | 44 +++++++++ 4 files changed, 221 insertions(+), 8 deletions(-)

diff --git a/src/core/include.am b/src/core/include.am index 982460172..b927f17a9 100644 --- a/src/core/include.am +++ b/src/core/include.am @@ -298,6 +298,7 @@ noinst_HEADERS += \ src/feature/control/control.h \ src/feature/control/control_auth.h \ src/feature/control/control_cmd.h \ + src/feature/control/control_cmd_args_st.h \ src/feature/control/control_connection_st.h \ src/feature/control/control_events.h \ src/feature/control/control_fmt.h \ diff --git a/src/feature/control/control_cmd.c b/src/feature/control/control_cmd.c index 930276b10..aa0bef513 100644 --- a/src/feature/control/control_cmd.c +++ b/src/feature/control/control_cmd.c @@ -45,6 +45,7 @@ #include "core/or/entry_connection_st.h" #include "core/or/origin_circuit_st.h" #include "core/or/socks_request_st.h" +#include "feature/control/control_cmd_args_st.h" #include "feature/control/control_connection_st.h" #include "feature/nodelist/node_st.h" #include "feature/nodelist/routerinfo_st.h" @@ -60,6 +61,87 @@ static int control_setconf_helper(control_connection_t *conn, uint32_t len, * finished authentication and is accepting commands. */ #define STATE_IS_OPEN(s) ((s) == CONTROL_CONN_STATE_OPEN)

+/** + * Release all storage held in <b>args</b> + **/ +void +control_cmd_args_free_(control_cmd_args_t *args) +{ + if (! args) + return; + + if (args->args) { + SMARTLIST_FOREACH(args->args, char *, c, tor_free(c)); + smartlist_free(args->args); + } + tor_free(args->object); + + tor_free(args); +} + +/** + * Helper: parse the arguments to a command according to <b>syntax</b>. On + * success, set *<b>error_out</b> to NULL and return a newly allocated + * control_cmd_args_t. On failure, set *<b>error_out</b> to newly allocated + * error string, and return NULL. + **/ +STATIC control_cmd_args_t * +control_cmd_parse_args(const char *command, + const control_cmd_syntax_t *syntax, + size_t body_len, + const char *body, + char **error_out) +{ + *error_out = NULL; + control_cmd_args_t *result = tor_malloc_zero(sizeof(control_cmd_args_t)); + const char *cmdline; + char *cmdline_alloc = NULL; + + result->command = command; + + const char *eol = memchr(body, '\n', body_len); + if (syntax->want_object) { + if (! eol || (eol+1) == body+body_len) { + *error_out = tor_strdup("Empty body"); + goto err; + } + cmdline_alloc = tor_memdup_nulterm(body, eol-body); + cmdline = cmdline_alloc; + ++eol; + result->object_len = read_escaped_data(eol, (body+body_len)-eol, + &result->object); + } else { + if (eol && (eol+1) != body+body_len) { + *error_out = tor_strdup("Unexpected body"); + goto err; + } + cmdline = body; + } + + result->args = smartlist_new(); + smartlist_split_string(result->args, cmdline, " ", + SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0); + size_t n_args = smartlist_len(result->args); + if (n_args < syntax->min_args) { + tor_asprintf(error_out, "Need at least %u argument(s)", + syntax->min_args); + goto err; + } else if (n_args > syntax->max_args) { + tor_asprintf(error_out, "Cannot accept more than %u argument(s)", + syntax->max_args); + goto err; + } + + tor_assert_nonfatal(*error_out == NULL); + goto done; + err: + tor_assert_nonfatal(*error_out != NULL); + control_cmd_args_free(result); + done: + tor_free(cmdline_alloc); + return result; +} + /** Called when we receive a SETCONF message: parse the body and try * to update our configuration. Reply with a DONE or ERROR message. * Modifies the contents of body.*/ @@ -2230,7 +2312,8 @@ handle_control_obsolete(control_connection_t *conn, **/ typedef enum handler_type_t { hnd_legacy, - hnd_legacy_mut + hnd_legacy_mut, + hnd_parsed, } handler_type_t;

/** @@ -2257,6 +2340,13 @@ typedef union handler_fn_t { int (*legacy_mut)(control_connection_t *conn, uint32_t arg_len, char *args); + + /** + * A "parsed" handler expects its arguments in a pre-parsed format, in + * an immutable control_cmd_args_t *object. + **/ + int (*parsed)(control_connection_t *conn, + const control_cmd_args_t *args); } handler_fn_t;

/** @@ -2279,6 +2369,10 @@ typedef struct control_cmd_def_t { * Zero or more CMD_FL_* flags, or'd together. */ unsigned flags; + /** + * For parsed command: a syntax description. + */ + const control_cmd_syntax_t *syntax; } control_cmd_def_t;

/** @@ -2287,16 +2381,27 @@ typedef struct control_cmd_def_t { */ #define CMD_FL_WIPE (1u<<0)

-/** - * Macro: declare a command with a one-line argument and a given set of - * flags. +#define SYNTAX_IGNORE { 0, UINT_MAX, false } + +/** Macro: declare a command with a one-line argument, a given set of flags, + * and a syntax definition. **/ -#define ONE_LINE(name, htype, flags) \ +#define ONE_LINE_(name, htype, flags, syntax) \ { #name, \ hnd_ ##htype, \ { .htype = handle_control_ ##name }, \ - flags \ + flags, \ + syntax, \ } + +/** Macro: declare a parsed command with a one-line argument, a given set of + * flags, and a syntax definition. + **/ +#define ONE_LINE(name, htype, flags) \ + ONE_LINE_(name, htype, flags, NULL) +#define ONE_LINE_PARSED(name, flags, syntax) \ + ONE_LINE_(name, parsed, flags, syntax) + /** * Macro: declare a command with a multi-line argument and a given set of * flags. @@ -2305,7 +2410,8 @@ typedef struct control_cmd_def_t { { "+"#name, \ hnd_ ##htype, \ { .htype = handle_control_ ##name }, \ - flags \ + flags, \ + NULL \ } /** * Macro: declare an obsolete command. (Obsolete commands give a different @@ -2315,7 +2421,8 @@ typedef struct control_cmd_def_t { { #name, \ hnd_legacy, \ { .legacy = handle_control_obsolete }, \ - 0 \ + 0, \ + NULL, \ }

/** @@ -2379,6 +2486,28 @@ handle_single_control_command(const control_cmd_def_t *def, if (def->handler.legacy_mut(conn, cmd_data_len, args)) rv = -1; break; + case hnd_parsed: { + control_cmd_args_t *parsed_args; + char *err=NULL; + tor_assert(def->syntax); + parsed_args = control_cmd_parse_args(conn->incoming_cmd, + def->syntax, + cmd_data_len, args, + &err); + if (!parsed_args) { + connection_printf_to_buf(conn, + "512 Bad arguments to %s: %s\r\n", + conn->incoming_cmd, err?err:""); + tor_free(err); + } else { + if (BUG(err)) + tor_free(err); + if (def->handler.parsed(conn, parsed_args)) + rv = 0; + control_cmd_args_free(parsed_args); + } + break; + } default: tor_assert_unreached(); } diff --git a/src/feature/control/control_cmd.h b/src/feature/control/control_cmd.h index a417e10da..1070a9edb 100644 --- a/src/feature/control/control_cmd.h +++ b/src/feature/control/control_cmd.h @@ -12,11 +12,19 @@ #ifndef TOR_CONTROL_CMD_H #define TOR_CONTROL_CMD_H

+#include "lib/malloc/malloc.h" + int handle_control_command(control_connection_t *conn, uint32_t cmd_data_len, char *args); void control_cmd_free_all(void);

+typedef struct control_cmd_args_t control_cmd_args_t; +void control_cmd_args_free_(control_cmd_args_t *args); + +#define control_cmd_args_free(v) \ + FREE_AND_NULL(control_cmd_args_t, control_cmd_args_free_, (v)) + #ifdef CONTROL_CMD_PRIVATE #include "lib/crypt_ops/crypto_ed25519.h"

@@ -39,6 +47,37 @@ STATIC int add_onion_helper_keyarg(const char *arg, int discard_pk, STATIC rend_authorized_client_t *add_onion_helper_clientauth(const char *arg, int *created, char **err_msg_out);

+/** + * Definition for the syntax of a controller command, as parsed by + * control_cmd_parse_args. + * + * WORK IN PROGRESS: This structure is going to get more complex as this + * branch goes on. + **/ +typedef struct control_cmd_syntax_t { + /** + * Lowest number of positional arguments that this command accepts. + * 0 for "it's okay not to have positional arguments." + **/ + unsigned int min_args; + /** + * Highest number of positional arguments that this command accepts. + * UINT_MAX for no limit. + **/ + unsigned int max_args; + /** + * True iff this command wants to be followed by a multiline object. + **/ + bool want_object; +} control_cmd_syntax_t; + +STATIC control_cmd_args_t *control_cmd_parse_args( + const char *command, + const control_cmd_syntax_t *syntax, + size_t body_len, + const char *body, + char **error_out); + #endif /* defined(CONTROL_CMD_PRIVATE) */

#ifdef CONTROL_MODULE_PRIVATE diff --git a/src/feature/control/control_cmd_args_st.h b/src/feature/control/control_cmd_args_st.h new file mode 100644 index 000000000..9ecc5d750 --- /dev/null +++ b/src/feature/control/control_cmd_args_st.h @@ -0,0 +1,44 @@ +/* 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 control_cmd_args_st.h + * \brief Definition for control_cmd_args_t + **/ + +#ifndef TOR_CONTROL_CMD_ST_H +#define TOR_CONTROL_CMD_ST_H + +struct smartlist_t; +struct config_line_t; + +/** + * Parsed arguments for a control command. + * + * WORK IN PROGRESS: This structure is going to get more complex as this + * branch goes on. + **/ +struct control_cmd_args_t { + /** + * The command itself, as provided by the controller. Not owned by this + * structure. + **/ + const char *command; + /** + * Positional arguments to the command. + **/ + struct smartlist_t *args; + /** + * Number of bytes in <b>object</b>; 0 if <b>object</b> is not set. + **/ + size_t object_len; + /** + * A multiline object passed with this command. + **/ + char *object; +}; + +#endif /* !defined(TOR_CONTROL_CMD_ST_H) */