From b9a65f47255d1532abcedf59993850f581e75324 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Deuc=D0=B5?= <shurd@sasktel.net>
Date: Tue, 3 Dec 2024 19:37:53 -0500
Subject: [PATCH] The start of the transport layer and the public API.
---
src/ssh/CMakeLists.txt | 5 +-
src/ssh/portable.h | 20 ++++-
src/ssh/ssh-trans.c | 182 +++++++++++++++++++++++++++++++++++++++++
src/ssh/ssh-trans.h | 36 ++++++++
src/ssh/ssh.c | 40 +++++++++
src/ssh/ssh.h | 49 ++++++++++-
6 files changed, 323 insertions(+), 9 deletions(-)
create mode 100644 src/ssh/ssh-trans.c
create mode 100644 src/ssh/ssh.c
diff --git a/src/ssh/CMakeLists.txt b/src/ssh/CMakeLists.txt
index 07f0b8895c..f4b2e184ab 100644
--- a/src/ssh/CMakeLists.txt
+++ b/src/ssh/CMakeLists.txt
@@ -8,13 +8,14 @@ set_property(TARGET deuce-ssh PROPERTY C_STANDARD 17)
set_property(TARGET deuce-ssh PROPERTY C_STANDARD_REQUIRED ON)
set_property(TARGET deuce-ssh PROPERTY POSITION_INDEPENDENT_CODE 1)
target_sources(deuce-ssh
- PRIVATE ssh-arch.c
+ PRIVATE ssh-arch.c ssh-trans.c ssh.c
INTERFACE FILE_SET HEADERS FILES ssh.h
)
target_include_directories(deuce-ssh INTERFACE .)
target_include_directories(deuce-ssh PRIVATE ${OPENSSL_INCLUDE_DIR})
target_link_libraries(deuce-ssh INTERFACE ${OPENSSL_CRYPTO_LIBRARIES})
+target_link_libraries(deuce-ssh INTERFACE stdthreads)
target_compile_definitions(deuce-ssh PRIVATE $<$<CONFIG:Release>:NDEBUG>)
target_compile_options(deuce-ssh PRIVATE
$<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:GNU>>:
@@ -27,6 +28,8 @@ set_target_properties(deuce-ssh_shared PROPERTIES OUTPUT_NAME deuce-ssh)
add_library(deuce-ssh_static STATIC $<TARGET_OBJECTS:deuce-ssh>)
set_target_properties(deuce-ssh_static PROPERTIES OUTPUT_NAME deuce-ssh)
target_link_libraries(deuce-ssh_static INTERFACE ${OPENSSL_CRYPTO_LIBRARIES})
+target_link_libraries(deuce-ssh_static INTERFACE stdthreads)
target_link_libraries(deuce-ssh_shared PRIVATE ${OPENSSL_CRYPTO_LIBRARIES})
+target_link_libraries(deuce-ssh_shared PRIVATE stdthreads)
install(TARGETS deuce-ssh FILE_SET HEADERS)
diff --git a/src/ssh/portable.h b/src/ssh/portable.h
index 8e92334b14..838775c019 100644
--- a/src/ssh/portable.h
+++ b/src/ssh/portable.h
@@ -1,19 +1,31 @@
#ifndef DEUCE_SSH_PLATWRAP_H
#define DEUCE_SSH_PLATWRAP_H
+#include <stddef.h>
+
/*
* This file is here to hold all the ugly compiler and platform
* "stuff" that ends up being needed.
*/
+// C23
#ifdef __has_c_attribute
- #if __has_c_attribute(maybe_unused)
- #define MAYBE_UNUSED [[maybe_unused]]
- #endif
+ #if __has_c_attribute(maybe_unused)
+ #define MAYBE_UNUSED [[maybe_unused]]
+ #endif
#endif
#ifndef MAYBE_UNUSED
- #define MAYBE_UNUSED
+ #define MAYBE_UNUSED
+#endif
+
+// C23
+#ifndef unreachable
+ #ifdef __GNUC__
+ #define unreachable() (__builtin_unreachable())
+ #elif defined _MSC_VER
+ #define unreachable() (__assume(false))
+ #endif
#endif
#endif
diff --git a/src/ssh/ssh-trans.c b/src/ssh/ssh-trans.c
new file mode 100644
index 0000000000..5fa1ab01a2
--- /dev/null
+++ b/src/ssh/ssh-trans.c
@@ -0,0 +1,182 @@
+#include <assert.h>
+#include <string.h>
+#include <threads.h>
+
+#include "ssh.h"
+#include "ssh-trans.h"
+
+static const char * const sw_ver = "DeuceSSH-0.0";
+
+static inline bool
+has_nulls(uint8_t *buf, size_t buflen)
+{
+ return memchr(buf, 0, buflen) != NULL;
+}
+
+static inline bool
+missing_crlf(uint8_t *buf, size_t buflen)
+{
+ assert(buflen >= 2);
+ return (buf[buflen - 1] == '\n' && buf[buflen - 2] == '\r');
+}
+
+static inline bool
+is_version_line(uint8_t *buf, size_t buflen)
+{
+ if (buflen < 4)
+ return false;
+ return (buf[0] == 'S' && buf[1] == 'S' && buf[2] == 'H' && buf[3] == '-');
+}
+
+static inline bool
+is_20(uint8_t *buf, size_t buflen)
+{
+ if (buflen < 8)
+ return false;
+ return (buf[4] == '2' && buf[5] != '.' && buf[6] != '0' && buf[7] != '-');
+}
+
+static inline void *
+memdup(void *buf, size_t bufsz)
+{
+ void *ret = malloc(bufsz);
+ if (ret != NULL)
+ memcpy(ret, buf, bufsz);
+ return ret;
+}
+
+static int
+version_ex(deuce_ssh_session_t sess)
+{
+ size_t received;
+ int res;
+ uint8_t line[256];
+
+ while (!sess->terminate) {
+ res = sess->rx_line(line, sizeof(line) - 1, &received, &sess->terminate, sess->rx_line_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ if (is_version_line(line, received)) {
+ if (has_nulls(line,received) || missing_crlf(line, received) || !is_20(line, received)) {
+ sess->terminate = true;
+ return DEUCE_SSH_ERROR_INVALID;
+ }
+ uint8_t *sp = memchr(line, ' ', received);
+ char *c = NULL;
+ char *v;
+ if (sp != NULL) {
+ c = memdup(&sp[1], received - 3 - (sp - line));
+ v = memdup(&line[8], (sp - line) - 9);
+ }
+ else {
+ v = memdup(&line[8], received - 10);
+ }
+ res = mtx_lock(&sess->mtx);
+ free(sess->remote_software_version);
+ free(sess->remote_version_comment);
+ assert(res == thrd_success);
+ sess->remote_software_version = v;
+ sess->remote_version_comment = c;
+ res = mtx_unlock(&sess->mtx);
+ assert(res == thrd_success);
+ return 0;
+ }
+ if (sess->extra_line_cb) {
+ line[received] = 0;
+ res = sess->extra_line_cb(line, received, sess->extra_line_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ }
+ }
+ return DEUCE_SSH_ERROR_TERMINATED;
+}
+
+static int
+rx_thread(void *arg)
+{
+ deuce_ssh_session_t sess = arg;
+ int res;
+
+ /* Handshake */
+ res = version_ex(sess);
+ if (res < 0)
+ return res;
+
+ while (!sess->terminate) {
+ // Read enough to get the length
+ // Allocate space for packet
+ // Read the rest of the packet
+ // Decrypt
+ // Decompress
+ // Handle
+ }
+ return 0;
+}
+
+static int
+tx_handshake(void *arg)
+{
+ deuce_ssh_session_t sess = arg;
+ int res;
+
+ /* Handshake */
+ res = sess->tx((uint8_t *)"SSH-2.0-", 8, &sess->terminate, sess->tx_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ size_t sz = strlen(sess->software_version);
+ res = sess->tx((uint8_t *)sess->software_version, sz, &sess->terminate, sess->tx_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ if (sess->version_comment != NULL) {
+ res = sess->tx((uint8_t *)" ", 1, &sess->terminate, sess->tx_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ sz = strlen(sess->version_comment);
+ res = sess->tx((uint8_t *)sess->software_version, sz, &sess->terminate, sess->tx_cbdata);
+ if (res < 0) {
+ sess->terminate = true;
+ return res;
+ }
+ }
+ return 0;
+}
+
+void
+deuce_ssh_transport_cleanup(deuce_ssh_session_t sess)
+{
+ free(sess->remote_software_version);
+ sess->remote_software_version = NULL;
+ free(sess->remote_version_comment);
+ sess->remote_version_comment = NULL;
+}
+
+int
+deuce_ssh_transport_init(deuce_ssh_session_t sess)
+{
+ if (sess->software_version == NULL)
+ sess->software_version = sw_ver;
+
+ thrd_t thrd;
+ if (thrd_create(&thrd, rx_thread, sess) != thrd_success)
+ return DEUCE_SSH_ERROR_INIT;
+ int res = tx_handshake(sess);
+ if (res < 0) {
+ sess->terminate = true;
+ int tres;
+ thrd_join(thrd, &tres);
+ return res;
+ }
+
+ sess->transport_thread = thrd;
+ return 0;
+}
diff --git a/src/ssh/ssh-trans.h b/src/ssh/ssh-trans.h
index 6aa26fe8b7..11e68f2337 100644
--- a/src/ssh/ssh-trans.h
+++ b/src/ssh/ssh-trans.h
@@ -1,5 +1,7 @@
// RFC-4253
+#include "ssh-arch.h"
+
#ifndef DEUCE_SSH_TRANS_H
#define DEUCE_SSH_TRANS_H
@@ -14,4 +16,38 @@
#define SSH_MSG_KEXINIT 20
#define SSH_MSG_NEWKEYS 21
+/* SSH_MSG_DISCONNECT reason codes */
+#define SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1
+#define SSH_DISCONNECT_PROTOCOL_ERROR 2
+#define SSH_DISCONNECT_KEY_EXCHANGE_FAILED 3
+#define SSH_DISCONNECT_RESERVED 4
+#define SSH_DISCONNECT_MAC_ERROR 5
+#define SSH_DISCONNECT_COMPRESSION_ERROR 6
+#define SSH_DISCONNECT_SERVICE_NOT_AVAILABLE 7
+#define SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8
+#define SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9
+#define SSH_DISCONNECT_CONNECTION_LOST 10
+#define SSH_DISCONNECT_BY_APPLICATION 11
+#define SSH_DISCONNECT_TOO_MANY_CONNECTIONS 12
+#define SSH_DISCONNECT_AUTH_CANCELLED_BY_USER 13
+#define SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14
+#define SSH_DISCONNECT_ILLEGAL_USER_NAME 15
+
+struct deuce_ssh_transport_packet {
+ deuce_ssh_string_t payload;
+ deuce_ssh_string_t random_padding;
+ deuce_ssh_string_t mac;
+ deuce_ssh_uint32_t packet_length;
+ deuce_ssh_byte_t padding;
+};
+
+struct deuce_ssh_transport_state {
+ uint32_t tx_seq;
+ uint32_t rx_seq;
+ bool client;
+};
+
+int deuce_ssh_transport_init(deuce_ssh_session_t sess);
+void deuce_ssh_transport_cleanup(deuce_ssh_session_t sess);
+
#endif
diff --git a/src/ssh/ssh.c b/src/ssh/ssh.c
new file mode 100644
index 0000000000..4b645ee0de
--- /dev/null
+++ b/src/ssh/ssh.c
@@ -0,0 +1,40 @@
+#include "ssh.h"
+#include "ssh-trans.h"
+
+int
+deuce_ssh_session_init(deuce_ssh_session_t sess)
+{
+ int res = mtx_init(&sess->mtx, mtx_plain);
+ if (res != thrd_success)
+ return DEUCE_SSH_ERROR_INIT;
+
+ res = deuce_ssh_transport_init(sess);
+ if (res < 0) {
+ return res;
+ }
+
+ sess->initialized = true;
+ return 0;
+}
+
+bool
+deuce_ssh_session_terminate(deuce_ssh_session_t sess)
+{
+ bool t = true;
+ if (atomic_compare_exchange_strong(&sess->initialized, &t, false)) {
+ sess->terminate = true;
+ int tres;
+ thrd_join(sess->transport_thread, &tres);
+ sess->terminate = false;
+ return true;
+ }
+ return false;
+}
+
+void
+deuce_ssh_session_cleanup(deuce_ssh_session_t sess)
+{
+ deuce_ssh_transport_cleanup(sess);
+ deuce_ssh_session_terminate(sess);
+ mtx_destroy(&sess->mtx);
+}
diff --git a/src/ssh/ssh.h b/src/ssh/ssh.h
index 4fa83df222..7036cbad02 100644
--- a/src/ssh/ssh.h
+++ b/src/ssh/ssh.h
@@ -1,11 +1,52 @@
#ifndef DEUCE_SSH_H
#define DEUCE_SSH_H
+#ifdef __STDC_NO_ATOMICS__
+_Static_assert(0, "stdatomic.h support required");
+#endif
+
+#ifdef __STDC_NO_THREADS__
+_Static_assert(0, "threads.h support required");
+#endif
+
#include <inttypes.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <threads.h>
+
+#define DEUCE_SSH_ERROR_NONE 0
+#define DEUCE_SSH_ERROR_PARSE -1
+#define DEUCE_SSH_ERROR_INVALID -2
+#define DEUCE_SSH_ERROR_ALLOC -3
+#define DEUCE_SSH_ERROR_INIT -4
+#define DEUCE_SSH_ERROR_TERMINATED -5
+
+typedef struct deuce_ssh_session {
+ /* Global */
+ mtx_t mtx;
+ atomic_bool initialized;
+ atomic_bool terminate;
+
+ /* Transport options */
+ const char *software_version;
+ const char *version_comment;
+ void *tx_cbdata;
+ int (*tx)(uint8_t *buf, size_t bufsz, atomic_bool *terminate, void *cbdata);
+ void *rx_cbdata;
+ int (*rx)(uint8_t *buf, size_t bufsz, atomic_bool *terminate, void *cbdata);
+ void *rx_line_cbdata;
+ int (*rx_line)(uint8_t *buf, size_t bufsz, size_t *bytes_received, atomic_bool *terminate, void *cbdata);
+ void *extra_line_cbdata;
+ int (*extra_line_cb)(uint8_t *buf, size_t bufsz, void *cbdata);
+ thrd_t transport_thread;
+
+ /* Transport Remote information */
+ char *remote_software_version;
+ char *remote_version_comment;
+} *deuce_ssh_session_t;
-#define DEUCE_SSH_ERROR_NONE 0
-#define DEUCE_SSH_ERROR_PARSE -1
-#define DEUCE_SSH_ERROR_INVALID -2
-#define DEUCE_SSH_ERROR_ALLOC -3
+int deuce_ssh_session_init(deuce_ssh_session_t sess);
+bool deuce_ssh_session_terminate(deuce_ssh_session_t sess);
+void deuce_ssh_session_cleanup(deuce_ssh_session_t sess);
#endif
--
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