Review: VTun client core (vtun/, include/vtesse/, tests)

include/vtesse/version.h

@@ -0,0 +1,7 @@
+#ifndef VTESSE_VERSION_H
+#define VTESSE_VERSION_H
+
+/* MAJOR.MM. Bumping it in a push to main publishes release vMAJOR.MM (CI). */
+#define VTESSE_VERSION "1.00"
+
+#endif

include/vtesse/vtun_client.h

@@ -0,0 +1,55 @@
+/*
+ * VTun client (TCP transport, type tun / ether, no compression/encryption).
+ *
+ * Non-blocking, single-threaded, no global state. Exposes tunnel_ops_t.
+ * Name resolution uses getaddrinfo() and may block briefly at connect time.
+ */
+#ifndef VTESSE_VTUN_CLIENT_H
+#define VTESSE_VTUN_CLIENT_H
+
+#include <stdint.h>
+
+#include "netcore/tunnel.h"
+#include "vtesse/vtun_proto.h"
+
+enum vt_auth {
+    VT_AUTH_XOR = 0        /* servers built without OpenSSL */
+};
+
+typedef struct vt_cfg {
+    const char *host;
+    uint16_t    port;
+    const char *session;
+    const char *password;
+    int         auth;                   /* enum vt_auth */
+
+    /* Optional tuning; 0 selects the default. */
+    int handshake_timeout_ms;           /* per step, default 15000 (CHAL step >= 10000) */
+    int ka_interval_ms;                 /* own ECHO_REQ period, default 10000 */
+    int ka_count;                       /* dead after ka_count * interval silence, default 5 */
+    int data_delay_ms;                  /* OK FLAGS -> TUNNEL_EV_UP delay, default 500 */
+    int reconnect_min_ms;               /* default 1000 */
+    int reconnect_max_ms;               /* default 30000 */
+    int out_buffer_size;                /* default 65536 */
+    int no_reconnect;                   /* 1: report FAILED instead of retrying */
+} vt_cfg_t;
+
+typedef struct vt vt_t;
+
+/* Copies the configuration. Returns NULL and sets *err on invalid config / OOM. */
+vt_t *vt_create(const vt_cfg_t *cfg, int *err);
+void  vt_destroy(vt_t *vt);
+
+/* Start connecting (first attempt happens immediately). */
+int   vt_start(vt_t *vt);
+
+/* Tunnel interface. */
+const tunnel_ops_t *vt_tunnel_ops(void);
+tunnel_t vt_tunnel(vt_t *vt);
+
+/* Diagnostics. */
+const char       *vt_greeting(const vt_t *vt);     /* last server greeting, "" if none */
+const vt_flags_t *vt_session_flags(const vt_t *vt); /* flags of the last session */
+int               vt_is_up(const vt_t *vt);
+
+#endif

include/vtesse/vtun_proto.h

@@ -0,0 +1,73 @@
+/*
+ * VTun wire format helpers (verified against VTun 3.0.2).
+ * Pure functions, no I/O, explicit byte order.
+ */
+#ifndef VTESSE_VTUN_PROTO_H
+#define VTESSE_VTUN_PROTO_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define VT_MESG_SIZE        50      /* every control message, NUL padded */
+#define VT_CHAL_SIZE        16
+#define VT_CHAL_TEXT_SIZE   (VT_CHAL_SIZE * 2 + 3)  /* "<" + 32 + ">" + NUL */
+#define VT_FRAME_SIZE       2048    /* max payload we send */
+#define VT_FRAME_OVERHEAD   100     /* receivers accept up to SIZE + OVERHEAD */
+#define VT_FRAME_MAX_RX     (VT_FRAME_SIZE + VT_FRAME_OVERHEAD)
+#define VT_FSIZE_MASK       0x0fff
+#define VT_FLAGS_MASK       0xf000
+#define VT_CONN_CLOSE       0x1000
+#define VT_ECHO_REQ         0x2000
+#define VT_ECHO_REP         0x4000
+#define VT_BAD_FRAME        0x8000  /* never on the wire in 3.0.2 */
+#define VT_SESSION_MAX      42      /* "HOST: " + name + "\n" must fit 49 bytes */
+
+/* Session names: 1..42 printable characters, no space, ':', control chars. */
+int vt_session_name_valid(const char *name);
+
+/* Build "<prefix><arg>\n" padded with NUL to 50 bytes. -1 if longer than 49. */
+int vt_mesg_build(uint8_t out[VT_MESG_SIZE], const char *prefix, const char *arg);
+
+/* Challenge text "<" + 32 chars 'a'..'p' + ">" <-> 16 bytes. */
+void vt_chal_encode(const uint8_t chal[VT_CHAL_SIZE], char out[VT_CHAL_TEXT_SIZE]);
+/* Finds '<' in msg; requires exactly 32 chars 'a'..'p' followed by '>'. 0 on success. */
+int  vt_chal_decode(const char *msg, uint8_t chal[VT_CHAL_SIZE]);
+
+/* XOR challenge response (servers built without OpenSSL). pwd must be non-empty. */
+void vt_chal_xor(uint8_t chal[VT_CHAL_SIZE], const char *pwd);
+
+typedef struct vt_flags {
+    char transport;     /* 'T' or 'U', 0 if absent */
+    char type;          /* 'u' tun, 'e' ether, 't' tty, 'p' pipe, 0 if absent */
+    int  keepalive;
+    int  shaper;        /* S<n>, 0 if absent */
+    int  zlib;          /* C<n> present */
+    int  lzo;           /* L<n> present */
+    int  zlevel;
+    int  encrypt;       /* E or E<n> present */
+    int  cipher;        /* 0 = legacy */
+} vt_flags_t;
+
+/* Parse "OK FLAGS: <...>". Same grammar as VTun cf2bf: unknown characters,
+ * a missing number after C/L/S or a missing '>' are errors. 0 on success. */
+int vt_flags_parse(const char *msg, vt_flags_t *f);
+
+/* Policy check: TCP, type tun or ether, no compression, no encryption.
+ * Returns TUNNEL_OK or a TUNNEL_ERR_* code. */
+int vt_flags_check(const vt_flags_t *f);
+
+/* Format flags back as "<...>" in VTun server order (for logs/tests). */
+void vt_flags_format(const vt_flags_t *f, char *out, size_t size);
+
+static inline void vt_hdr_put(uint8_t b[2], uint16_t v)
+{
+    b[0] = (uint8_t)(v >> 8);
+    b[1] = (uint8_t)v;
+}
+
+static inline uint16_t vt_hdr_get(const uint8_t b[2])
+{
+    return (uint16_t)((b[0] << 8) | b[1]);
+}
+
+#endif