From dc29cefb445a4fffef3148589a44911f4e132bcc Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Thu, 3 Oct 2024 23:02:58 +0200
Subject: [PATCH] Flock: converted HCS to the parser framework

---
 flock/ctl.c   | 295 +++++++++++++++-----------------------------------
 flock/flock.h |  10 +-
 2 files changed, 90 insertions(+), 215 deletions(-)

diff --git a/flock/ctl.c b/flock/ctl.c
index a50fda72..adba6f13 100644
--- a/flock/ctl.c
+++ b/flock/ctl.c
@@ -19,134 +19,55 @@
  *   - 4 with array of strings = run the given command inside the hypervisor
  */
 
-struct cbor_parser_context {
-  linpool *lp;
+struct hcs_parser_context {
+  struct cbor_parser_context *ctx;
   sock *sock;
 
-  PACKED enum {
-    CPE_TYPE = 0,
-    CPE_READ_INT,
-    CPE_COMPLETE_INT,
-    CPE_READ_BYTE,
-  } partial_state, partial_next;
-
-  byte type;
-  u64 value;
-  u64 partial_countdown;
-
   u64 bytes_consumed;
-
-  byte *target_buf;
-  uint target_len;
-
   u64 major_state;
 
-  const char *error;
-
-#define LOCAL_STACK_MAX_DEPTH 3
-  u64 stack_countdown[LOCAL_STACK_MAX_DEPTH];
-  uint stack_pos;
-
   /* Specific */
   union flock_machine_config cfg;
 };
 
-#define CBOR_PARSER_ERROR(...)	do {		\
-  ctx->error = lp_sprintf(ctx->lp, __VA_ARGS__);\
-  return -(ctx->bytes_consumed + pos + 1);	\
-} while (0)
-
-#define CBOR_PARSER_READ_INT(next)  do {		\
-  ctx->partial_state = CPE_READ_INT;			\
-  ctx->partial_countdown = (1 << (ctx->value - 24));	\
-  ctx->value = 0;					\
-  ctx->partial_next = next;				\
-} while (0)
-
-struct cbor_parser_context *
+struct hcs_parser_context *
 hcs_parser_init(sock *s)
 {
-  linpool *lp = lp_new(s->pool);
-  struct cbor_parser_context *ctx = lp_allocz(lp, sizeof *ctx);
+  struct cbor_parser_context *ctx = cbor_parser_new(s->pool, 4);
+  struct hcs_parser_context *htx = lp_allocz(ctx->lp, sizeof *htx);
 
-  ctx->lp = lp;
-  ctx->sock = s;
+  htx->ctx = ctx;
+  htx->sock = s;
 
-  ctx->type = 0xff;
-  ctx->stack_countdown[0] = 1;
-
-  return ctx;
+  return htx;
 }
 
+#define CBOR_PARSER_ERROR(...)	do {		\
+  ctx->error = lp_sprintf(ctx->lp, __VA_ARGS__);\
+  return -(htx->bytes_consumed + pos + 1);	\
+} while (0)
+
 s64
-hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
+hcs_parse(struct hcs_parser_context *htx, const byte *buf, s64 size)
 {
   ASSERT_DIE(size > 0);
+  struct cbor_parser_context *ctx = htx->ctx;
 
   for (int pos = 0; pos < size; pos++)
   {
-    const byte bp = buf[pos];
-    bool value_is_special = 0;
-    bool exit_stack = false;
-
-    switch (ctx->partial_state)
+    switch (cbor_parse_byte(ctx, buf[pos]))
     {
-      case CPE_TYPE:
-	/* Split the byte to type and value */
-	ctx->type = bp >> 5;
-	ctx->value = bp & 0x1f;
+      case CPR_ERROR:
+	/* Parser failure */
+	return -(htx->bytes_consumed + pos + 1);
 
-	if (ctx->type == 7)
-	{
-	  if (ctx->value < 20)
-	    CBOR_PARSER_ERROR("Unknown simple value %u", ctx->value);
-	  else if (ctx->value < 24)
-	    ; /* false, true, null, undefined */
-	  else if (ctx->value < 28)
-	  {
-	    /* Need more data */
-	    CBOR_PARSER_READ_INT(CPE_COMPLETE_INT);
-	    break;
-	  }
-	  else if (ctx->value == 31)
-	    ; /* break-stop */
-	  else
-	    CBOR_PARSER_ERROR("Unknown simple value %u", ctx->value);
-	}
-	else
-	{
-	  if (ctx->value < 24)
-	    ; /* Immediate value, fall through */
-	  else if (ctx->value < 28)
-	  {
-	    /* Need more data */
-	    CBOR_PARSER_READ_INT(CPE_COMPLETE_INT);
-	    break;
-	  }
-	  else if ((ctx->value == 31) && (ctx->type >= 2) && (ctx->type <= 5))
-	    /* Indefinite length, fall through */
-	    value_is_special = 1;
-	  else
-	    CBOR_PARSER_ERROR("Garbled additional value %u for type %u", ctx->value, ctx->type);
-	}
-	/* fall through */
-
-      case CPE_READ_INT:
-	if (ctx->partial_state == CPE_READ_INT)
-	{
-	  /* Reading a network order integer */
-	  ctx->value <<= 8;
-	  ctx->value |= bp;
-	  if (--ctx->partial_countdown)
-	    break;
-	}
-	/* fall through */
-
-      case CPE_COMPLETE_INT:
-	/* TODO: exception for 7-31 end of long thing */
+      case CPR_MORE:
+	/* Need more bytes */
+	continue;
 
+      case CPR_MAJOR:
 	/* Check type acceptance */
-	switch (ctx->major_state)
+	switch (htx->major_state)
 	{
 	  case 0: /* toplevel */
 	    if (ctx->type != 5)
@@ -155,7 +76,7 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->value != 1)
 	      CBOR_PARSER_ERROR("Expected mapping of length 1, got %u", ctx->value);
 
-	    ctx->major_state = 1;
+	    htx->major_state = 1;
 	    break;
 
 	  case 1: /* inside toplevel mapping */
@@ -165,7 +86,7 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->value >= 5)
 	      CBOR_PARSER_ERROR("Command key too high, got %lu", ctx->value);
 
-	    ctx->major_state = ctx->value + 2;
+	    htx->major_state = ctx->value + 2;
 	    break;
 
 	  case 2: /* shutdown command: expected null */
@@ -175,21 +96,21 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    log(L_INFO "Requested shutdown via CLI");
 	    ev_send_loop(&main_birdloop, &poweroff_event);
 	    {
-	      struct cbor_writer *cw = cbor_init(ctx->sock->tbuf, ctx->sock->tbsize, ctx->lp);
+	      struct cbor_writer *cw = cbor_init(htx->sock->tbuf, htx->sock->tbsize, ctx->lp);
 	      cbor_open_block_with_length(cw, 1);
 	      cbor_add_int(cw, -1);
 	      cbor_add_string(cw, "OK");
-	      sk_send(ctx->sock, cw->pt);
+	      sk_send(htx->sock, cw->pt);
 	    }
 
-	    ctx->major_state = 1;
+	    htx->major_state = 1;
 	    break;
 
 	  case 3: /* telnet listener open */
 	    if ((ctx->type == 7) && (ctx->value == 22))
 	    {
-	      hexp_get_telnet(ctx->sock, NULL);
-	      ctx->major_state = 1;
+	      hexp_get_telnet(htx->sock, NULL);
+	      htx->major_state = 1;
 	      break;
 	    }
 
@@ -197,7 +118,7 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	      CBOR_PARSER_ERROR("Expected null or string, got %u-%u", ctx->type, ctx->value);
 
 	    ASSERT_DIE(!ctx->target_buf);
-	    ctx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    htx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
 	    ctx->target_len = ctx->value;
 
 	    break;
@@ -207,21 +128,21 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	      CBOR_PARSER_ERROR("Expected null, got %u-%u", ctx->type, ctx->value);
 
 	    log(L_INFO "Requested telnet close");
-	    ctx->major_state = 1;
+	    htx->major_state = 1;
 	    break;
 
 	  case 5: /* machine creation request */
 	    if (ctx->type != 5)
 	      CBOR_PARSER_ERROR("Expected mapping, got %u", ctx->type);
 
-	    ctx->major_state = 501;
+	    htx->major_state = 501;
 	    break;
 
 	  case 6: /* machine shutdown request */
 	    if (ctx->type != 5)
 	      CBOR_PARSER_ERROR("Expecting mapping, got %u", ctx->type);
 
-	    ctx->major_state = 601;
+	    htx->major_state = 601;
 	    break;
 
 	  case 7: /* process spawner */
@@ -235,21 +156,21 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->value >= 5)
 	      CBOR_PARSER_ERROR("Command key too high, got %lu", ctx->value);
 
-	    ctx->major_state = ctx->value + 502;
+	    htx->major_state = ctx->value + 502;
 	    break;
 
 	  case 502: /* machine creation argument 0: name */
 	    if (ctx->type != 3)
 	      CBOR_PARSER_ERROR("Expected string, got %u", ctx->type);
 
-	    if (value_is_special)
+	    if (ctx->tflags & CPT_VARLEN)
 	      CBOR_PARSER_ERROR("Variable length string not supported yet");
 
-	    if (ctx->cfg.cf.name)
+	    if (htx->cfg.cf.name)
 	      CBOR_PARSER_ERROR("Duplicate argument 0 / name");
 
 	    ASSERT_DIE(!ctx->target_buf);
-	    ctx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    htx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
 	    ctx->target_len = ctx->value;
 	    break;
 
@@ -257,28 +178,28 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->type != 0)
 	      CBOR_PARSER_ERROR("Expected integer, got %u", ctx->type);
 
-	    if (ctx->cfg.cf.type)
-	      CBOR_PARSER_ERROR("Duplicate argument 1 / type, already have %d", ctx->cfg.cf.type);
+	    if (htx->cfg.cf.type)
+	      CBOR_PARSER_ERROR("Duplicate argument 1 / type, already have %d", htx->cfg.cf.type);
 
 	    if ((ctx->value < 1) && (ctx->value > 1) )
 	      CBOR_PARSER_ERROR("Unexpected type, got %lu", ctx->value);
 
-	    ctx->cfg.cf.type = ctx->value;
-	    ctx->major_state = 501;
+	    htx->cfg.cf.type = ctx->value;
+	    htx->major_state = 501;
 	    break;
 
 	  case 504: /* machine creation argument 2: workdir */
 	    if (ctx->type != 2)
 	      CBOR_PARSER_ERROR("Expected bytestring, got %u", ctx->type);
 
-	    if (value_is_special)
+	    if (ctx->tflags & CPT_VARLEN)
 	      CBOR_PARSER_ERROR("Variable length string not supported yet");
 
-	    if (ctx->cfg.container.workdir)
+	    if (htx->cfg.container.workdir)
 	      CBOR_PARSER_ERROR("Duplicate argument 2 / workdir");
 
 	    ASSERT_DIE(!ctx->target_buf);
-	    ctx->cfg.container.workdir = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    htx->cfg.container.workdir = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
 	    ctx->target_len = ctx->value;
 	    break;
 
@@ -286,14 +207,14 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->type != 2)
 	      CBOR_PARSER_ERROR("Expected bytestring, got %u", ctx->type);
 
-	    if (value_is_special)
+	    if (ctx->tflags & CPT_VARLEN)
 	      CBOR_PARSER_ERROR("Variable length string not supported yet");
 
-	    if (ctx->cfg.container.basedir)
+	    if (htx->cfg.container.basedir)
 	      CBOR_PARSER_ERROR("Duplicate argument 3 / basedir");
 
 	    ASSERT_DIE(!ctx->target_buf);
-	    ctx->cfg.container.basedir = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    htx->cfg.container.basedir = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
 	    ctx->target_len = ctx->value;
 	    break;
 
@@ -304,74 +225,36 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    if (ctx->value >= 1)
 	      CBOR_PARSER_ERROR("Command key too high, got %lu", ctx->value);
 
-	    ctx->major_state = ctx->value + 602;
+	    htx->major_state = ctx->value + 602;
 	    break;
 
 	  case 602: /* machine creation argument 0: name */
 	    if (ctx->type != 3)
 	      CBOR_PARSER_ERROR("Expected string, got %u", ctx->type);
 
-	    if (value_is_special)
+	    if (ctx->tflags & CPT_VARLEN)
 	      CBOR_PARSER_ERROR("Variable length string not supported yet");
 
-	    if (ctx->cfg.cf.name)
+	    if (htx->cfg.cf.name)
 	      CBOR_PARSER_ERROR("Duplicate argument 0 / name");
 
 	    ASSERT_DIE(!ctx->target_buf);
-	    ctx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    htx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
 	    ctx->target_len = ctx->value;
 	    break;
 
 	  default:
 	    bug("invalid parser state");
 	}
-
-	/* Some types are completely parsed, some not yet */
-	switch (ctx->type)
-	{
-	  case 0:
-	  case 1:
-	  case 7:
-	    exit_stack = !--ctx->stack_countdown[ctx->stack_pos];
-	    ctx->partial_state = CPE_TYPE;
-	    break;
-
-	  case 2:
-	  case 3:
-	    ctx->partial_state = CPE_READ_BYTE;
-	    ctx->partial_countdown = ctx->value;
-	    ctx->target_buf = ctx->target_buf ?: lp_allocu(
-		ctx->lp, ctx->target_len = (ctx->target_len ?: ctx->value));
-	    break;
-
-	  case 4:
-	  case 5:
-	    if (++ctx->stack_pos >= LOCAL_STACK_MAX_DEPTH)
-	      CBOR_PARSER_ERROR("Stack too deep");
-
-	    /* set array/map size;
-	     * once for arrays, twice for maps;
-	     * ~0 for indefinite */
-	    ctx->stack_countdown[ctx->stack_pos] = value_is_special ? ~0ULL :
-	      (ctx->value * (ctx->type - 3));
-	    ctx->partial_state = CPE_TYPE;
-	    break;
-	}
-
 	break;
 
-      case CPE_READ_BYTE:
-	*ctx->target_buf = bp;
-	ctx->target_buf++;
-	if (--ctx->target_len)
-	  break;
-
-	/* Read completely! */
-	switch (ctx->major_state)
+      case CPR_STR_END:
+	/* Bytes read completely! */
+	switch (htx->major_state)
 	{
 	  case 3:
-	    hexp_get_telnet(ctx->sock, ctx->cfg.cf.name);
-	    ctx->major_state = 1;
+	    hexp_get_telnet(htx->sock, htx->cfg.cf.name);
+	    htx->major_state = 1;
 	    break;
 
 	  case 5:
@@ -381,103 +264,95 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	  case 502:
 	  case 504:
 	  case 505:
-	    ctx->major_state = 501;
+	    htx->major_state = 501;
 	    break;
 
 	  case 602:
-	    ctx->major_state = 601;
+	    htx->major_state = 601;
 	    break;
 
 	  default:
 	    bug("Unexpected state to end a (byte)string in");
 	  /* Code to run at the end of a (byte)string */
 	}
-
-	ctx->target_buf = NULL;
-	ctx->partial_state = CPE_TYPE;
-
-	exit_stack = !--ctx->stack_countdown[ctx->stack_pos];
+	break;
     }
 
     /* End of array or map */
-    while (exit_stack)
+    while (cbor_parse_block_end(ctx))
     {
-      switch (ctx->major_state)
+      switch (htx->major_state)
       {
 	/* Code to run at the end of the mapping */
 	case 0: /* toplevel item ended */
-	  ctx->major_state = ~0ULL;
+	  htx->major_state = ~0ULL;
 	  return pos + 1;
 
 	case 1:
-	  ctx->major_state = 0;
+	  htx->major_state = 0;
 	  break;
 
 	case 5:
 	  /* Finalize the command to exec in hypervisor */
 	  CBOR_PARSER_ERROR("NOT IMPLEMENTED YET");
-	  ctx->major_state = 1;
+	  htx->major_state = 1;
 	  break;
 
 	case 501:
-	  if (!ctx->cfg.cf.type)
+	  if (!htx->cfg.cf.type)
 	    CBOR_PARSER_ERROR("Machine type not specified");
 
-	  if (!ctx->cfg.cf.name)
+	  if (!htx->cfg.cf.name)
 	    CBOR_PARSER_ERROR("Machine name not specified");
 
-	  if (!ctx->cfg.container.workdir)
+	  if (!htx->cfg.container.workdir)
 	    CBOR_PARSER_ERROR("Machine workdir not specified");
 
-	  if (!ctx->cfg.container.basedir)
+	  if (!htx->cfg.container.basedir)
 	    CBOR_PARSER_ERROR("Machine basedir not specified");
 
 	  hypervisor_container_request(
-	      ctx->sock,
-	      ctx->cfg.cf.name,
-	      ctx->cfg.container.basedir,
-	      ctx->cfg.container.workdir);
+	      htx->sock,
+	      htx->cfg.cf.name,
+	      htx->cfg.container.basedir,
+	      htx->cfg.container.workdir);
 
-	  ctx->major_state = 1;
+	  htx->major_state = 1;
 	  break;
 
 	case 601:
-	  if (!ctx->cfg.cf.name)
+	  if (!htx->cfg.cf.name)
 	    CBOR_PARSER_ERROR("Machine name not specified");
 
-	  hypervisor_container_shutdown(ctx->sock, ctx->cfg.cf.name);
+	  hypervisor_container_shutdown(htx->sock, htx->cfg.cf.name);
 
-	  ctx->major_state = 1;
+	  htx->major_state = 1;
 	  break;
 
 	default:
 	  bug("Unexpected state to end a mapping in");
       }
-
-      /* Check exit from the next item */
-      ASSERT_DIE(ctx->stack_pos);
-      exit_stack = !--ctx->stack_countdown[--ctx->stack_pos];
     }
   }
 
-  ctx->bytes_consumed += size;
+  htx->bytes_consumed += size;
   return size;
 }
 
 bool
-hcs_complete(struct cbor_parser_context *ctx)
+hcs_complete(struct hcs_parser_context *htx)
 {
-  return ctx->major_state == ~0ULL;
+  return htx->major_state == ~0ULL;
 }
 
 const char *
-hcs_error(struct cbor_parser_context *ctx)
+hcs_error(struct hcs_parser_context *htx)
 {
-  return ctx->error;
+  return htx->ctx->error;
 }
 
 void
-hcs_parser_cleanup(struct cbor_parser_context *ctx)
+hcs_parser_cleanup(struct hcs_parser_context *htx)
 {
-  rfree(ctx->lp);
+  cbor_parser_free(htx->ctx);
 }
diff --git a/flock/flock.h b/flock/flock.h
index 1abb6c58..d2041ccc 100644
--- a/flock/flock.h
+++ b/flock/flock.h
@@ -22,11 +22,11 @@ struct flock_config {
 
 extern struct flock_config flock_config;
 
-struct cbor_parser_context *hcs_parser_init(sock *s);
-s64 hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size);
-void hcs_parser_cleanup(struct cbor_parser_context *ctx);
-const char *hcs_error(struct cbor_parser_context *ctx);
-bool hcs_complete(struct cbor_parser_context *ctx);
+struct hcs_parser_context *hcs_parser_init(sock *s);
+s64 hcs_parse(struct hcs_parser_context *ctx, const byte *buf, s64 size);
+void hcs_parser_cleanup(struct hcs_parser_context *ctx);
+const char *hcs_error(struct hcs_parser_context *ctx);
+bool hcs_complete(struct hcs_parser_context *ctx);
 
 void hexp_get_telnet(sock *, const char *name);