myhtml_worker.c
No OneTemporary
Actions

Size

13 KB

Referenced Files

None

Subscribers

None

myhtml_worker.c
View Options

	#include <stdlib.h>
	#include <stdbool.h>
	#include <stdio.h>
	#include <string.h>
	#include <stdarg.h>
	#include <unistd.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <errno.h>
	#include <ctype.h>

	#include "ei.h"
	#ifndef OTP_22_OR_NEWER
	# include "erl_interface.h"
	#endif

	#include <myhtml/myhtml.h>
	#include <myhtml/mynamespace.h>

	#include "tstack.h"

	#ifdef __GNUC__
	# define AFP(x, y) __attribute__((format (printf, x, y)))
	#else
	# define AFP(x, y)
	#endif

	#ifdef __GNUC__
	# define NORETURN __attribute__((noreturn))
	#else
	# define NORETURN
	#endif

	typedef struct _state_t {
	int fd;
	myhtml_t * myhtml;
	ei_cnode ec;
	bool looping;
	ei_x_buff buffer;
	} state_t;

	typedef enum parse_flags_e {
	FLAG_HTML_ATOMS = 1 << 0,
	FLAG_NIL_SELF_CLOSING = 1 << 1,
	FLAG_COMMENT_TUPLE3 = 1 << 2
	} parse_flags_t;

	static void handle_emsg(state_t * state, erlang_msg * emsg);
	static void handle_send(state_t * state, erlang_msg * emsg);
	static void err_term(ei_x_buff * response, const char * error_atom);
	static parse_flags_t decode_parse_flags(state_t * state, int arity);
	static void decode(state_t * state, ei_x_buff * response, const char * bin_data, size_t bin_size, parse_flags_t parse_flags);

	static void build_tree(ei_x_buff * response, myhtml_tree_t * tree, myhtml_tree_node_t * node, parse_flags_t parse_flags);
	static void prepare_node_attrs(ei_x_buff * response, myhtml_tree_node_t * node);

	static inline char * lowercase(char * c);

	static void panic(const char *fmt, ...) AFP(1, 2);
	static void panic(const char *fmt, ...) {
	char buf[4096];
	va_list va;

	va_start (va, fmt);
	vsnprintf (buf, sizeof buf, fmt, va);
	va_end (va);

	fprintf (stderr, "myhtml worker: error: %s\n", buf);
	exit (EXIT_FAILURE);
	}

	static void usage (void) NORETURN;
	static void usage (void) {
	fputs ("usage: myhtml_worker sname hostname cookie tname\n\n"
	" sname the short name you want this c-node to connect as\n"
	" hostname the hostname\n"
	" cookie the authentication cookie\n"
	" tname the target node short name to connect to\n", stderr);
	exit (EXIT_FAILURE);
	}

	int main(int argc, const char *argv[]) {
	#ifdef OTP_22_OR_NEWER
	// initialize erlang client library
	ei_init ();
	#else
	erl_init (NULL, -1);
	#endif

	if (argc != 5)
	usage ();

	const char *sname = argv[1];
	const char *hostname = argv[2];
	const char *cookie = argv[3];
	const char *tname = argv[4];

	char full_name[1024];
	char target_node[1024];

	snprintf (full_name, sizeof full_name, "%s@%s", sname, hostname);
	snprintf (target_node, sizeof target_node, "%s@%s", tname, hostname);

	struct in_addr addr;
	addr.s_addr = htonl(INADDR_ANY);

	// fd to erlang node
	state_t* state = calloc (1, sizeof(state_t));
	state->looping = true;
	ei_x_new (&state->buffer);

	// initialize this node
	printf ("initialising %s\n", full_name);
	if (ei_connect_xinit (&state->ec, hostname, sname, full_name, &addr, cookie, 0) == -1)
	panic ("ei_connect_xinit failed.");

	// connect to target node
	printf ("connecting to %s\n", target_node);
	if ((state->fd = ei_connect (&state->ec, target_node)) < 0)
	panic ("ei_connect failed.");

	state->myhtml = myhtml_create ();
	myhtml_init (state->myhtml, MyHTML_OPTIONS_DEFAULT, 1, 0);

	// signal to stdout that we are ready
	printf ("%s ready\n", full_name);
	fflush (stdout);

	while (state->looping)
	{
	erlang_msg emsg;

	switch (ei_xreceive_msg (state->fd, &emsg, &state->buffer))
	{
	case ERL_TICK:
	break;
	case ERL_ERROR:
	panic ("ei_xreceive_msg: %s\n", strerror (erl_errno));
	break;
	default:
	handle_emsg (state, &emsg);
	break;
	}
	}

	// shutdown: free all state
	ei_x_free (&state->buffer);
	myhtml_destroy (state->myhtml);
	free (state);

	return EXIT_SUCCESS;
	}

	// handle an erlang_msg structure and call handle_send() if relevant
	static void handle_emsg (state_t * state, erlang_msg * emsg)
	{
	state->buffer.index = 0;

	switch (emsg->msgtype)
	{
	case ERL_REG_SEND:
	case ERL_SEND:
	handle_send (state, emsg);
	break;
	case ERL_LINK:
	case ERL_UNLINK:
	break;
	case ERL_EXIT:
	break;
	}
	}

	// handle ERL_SEND message type.
	// we expect a tuple with arity of 3 in state->buffer.
	// we expect the first argument to be an atom (`decode`),
	// the second argument to be the HTML payload, and the
	// third argument to be the argument list.
	// any other message: respond with an {error, unknown_call} tuple.
	static void handle_send (state_t * state, erlang_msg * emsg)
	{
	// response holds our response, prepare it
	ei_x_buff response;

	ei_x_new (&response);

	// check the protocol version, if it's unsupported, panic
	int version;
	if (ei_decode_version (state->buffer.buff, &state->buffer.index, &version) < 0)
	panic ("malformed message - bad version (%d).", version);

	// decode the tuple header, make sure we have an arity of 3.
	int arity;
	if (ei_decode_tuple_header (state->buffer.buff, &state->buffer.index, &arity) < 0 \|\| arity != 3)
	{
	err_term (&response, "badmatch");
	goto out;
	}

	// the tuple should begin with a `decode` atom.
	char atom[MAXATOMLEN];
	if (ei_decode_atom (state->buffer.buff, &state->buffer.index, atom) < 0)
	{
	err_term (&response, "badmatch");
	goto out;
	}

	if (strcmp (atom, "decode"))
	{
	err_term (&response, "unknown_call");
	goto out;
	}

	// the next argument should be a binary, allocate it dynamically.
	int bin_type, bin_size;
	if (ei_get_type (state->buffer.buff, &state->buffer.index, &bin_type, &bin_size) < 0)
	panic ("failed to decode binary size in message");

	// verify the type
	if (bin_type != ERL_BINARY_EXT)
	{
	err_term (&response, "badmatch");
	goto out;
	}

	// decode the binary
	char * bin_data = calloc (1, bin_size + 1);
	if (ei_decode_binary (state->buffer.buff, &state->buffer.index, bin_data, NULL) < 0)
	panic ("failed to decode binary in message");

	// next should be the options list
	if (ei_decode_list_header (state->buffer.buff, &state->buffer.index, &arity) < 0)
	panic ("failed to decode options list header in message");

	parse_flags_t parse_flags = decode_parse_flags (state, arity);
	decode (state, &response, bin_data, bin_size, parse_flags);

	free (bin_data);

	out:
	// send response
	ei_send (state->fd, &emsg->from, response.buff, response.buffsz);

	// free response
	ei_x_free (&response);

	return;
	}

	static void err_term (ei_x_buff * response, const char * error_atom)
	{
	response->index = 0;
	ei_x_encode_version (response);
	ei_x_encode_tuple_header (response, 2);
	ei_x_encode_atom (response, "error");
	ei_x_encode_atom (response, error_atom);
	}

	static parse_flags_t decode_parse_flags (state_t * state, int arity)
	{
	parse_flags_t parse_flags = 0;

	for (int i = 0; i < arity; i++)
	{
	char atom[MAXATOMLEN];

	if (ei_decode_atom (state->buffer.buff, &state->buffer.index, atom) < 0)
	continue;

	if (! strcmp ("html_atoms", atom))
	parse_flags \|= FLAG_HTML_ATOMS;
	else if (! strcmp ("nil_self_closing", atom))
	parse_flags \|= FLAG_NIL_SELF_CLOSING;
	else if (! strcmp ("comment_tuple3", atom))
	parse_flags \|= FLAG_COMMENT_TUPLE3;
	}

	return parse_flags;
	}

	static void decode (state_t * state, ei_x_buff * response, const char * bin_data, size_t bin_size, parse_flags_t parse_flags)
	{
	myhtml_tree_t * tree = myhtml_tree_create ();
	myhtml_tree_init (tree, state->myhtml);

	// parse tree
	mystatus_t status = myhtml_parse (tree, MyENCODING_UTF_8, bin_data, bin_size);
	if (status != MyHTML_STATUS_OK)
	{
	err_term (response, "myhtml_parse_failed");
	return;
	}

	// build tree
	myhtml_tree_node_t * root = myhtml_tree_get_document (tree);
	build_tree (response, tree, root->child, parse_flags);
	myhtml_tree_destroy (tree);
	}

	// a tag is sent as a tuple:
	// - a string or atom for the tag name
	// - an attribute list
	// - a children list
	// in this function, we prepare the atom and complete attribute list
	static void prepare_tag_header (ei_x_buff * response, const char * tag_string, myhtml_tree_node_t * node, parse_flags_t parse_flags)
	{
	myhtml_tag_id_t tag_id = myhtml_node_tag_id (node);
	myhtml_namespace_t tag_ns = myhtml_node_namespace (node);

	ei_x_encode_tuple_header (response, 3);

	if (! (parse_flags & FLAG_HTML_ATOMS) \|\| (tag_id == MyHTML_TAG__UNDEF \|\| tag_id == MyHTML_TAG_LAST_ENTRY \|\| tag_ns != MyHTML_NAMESPACE_HTML))
	ei_x_encode_binary (response, tag_string, strlen (tag_string));
	else
	ei_x_encode_atom (response, tag_string);

	prepare_node_attrs (response, node);
	}

	// prepare an attribute node
	static void prepare_node_attrs(ei_x_buff * response, myhtml_tree_node_t * node)
	{
	myhtml_tree_attr_t * attr;

	for (attr = myhtml_node_attribute_first (node); attr != NULL; attr = myhtml_attribute_next (attr))
	{
	size_t attr_name_len;
	const char *attr_name = myhtml_attribute_key (attr, &attr_name_len);
	size_t attr_value_len;
	const char *attr_value = myhtml_attribute_value (attr, &attr_value_len);

	/* guard against poisoned attribute nodes */
	if (! attr_name_len)
	continue;

	ei_x_encode_list_header (response, 1);
	ei_x_encode_tuple_header (response, 2);
	ei_x_encode_binary (response, attr_name, attr_name_len);

	if (attr_value_len)
	ei_x_encode_binary (response, attr_value, attr_value_len);
	else
	ei_x_encode_binary (response, attr_name, attr_name_len);
	}

	ei_x_encode_empty_list (response);
	}

	// dump a comment node
	static void prepare_comment (ei_x_buff * response, const char * node_comment, size_t comment_len, parse_flags_t parse_flags)
	{
	ei_x_encode_tuple_header (response, parse_flags & FLAG_COMMENT_TUPLE3 ? 3 : 2);
	ei_x_encode_atom (response, "comment");

	if (parse_flags & FLAG_COMMENT_TUPLE3)
	ei_x_encode_list_header (response, 0);

	ei_x_encode_binary (response, node_comment, comment_len);
	}

	#ifdef DEBUG_LIST_MANIP

	#define EMIT_LIST_HDR \
	printf ("list hdr for node %p\n", current_node); \
	fflush (stdout); \
	ei_x_encode_list_header (response, 1)

	#define EMIT_EMPTY_LIST_HDR \
	printf ("list empty for node %p\n", current_node); \
	fflush (stdout); \
	ei_x_encode_list_header (response, 0)

	#define EMIT_LIST_TAIL \
	printf ("list tail for node %p\n", current_node); \
	fflush (stdout); \
	ei_x_encode_empty_list (response)

	#else

	#define EMIT_LIST_HDR ei_x_encode_list_header (response, 1)
	#define EMIT_EMPTY_LIST_HDR ei_x_encode_list_header (response, 0)
	#define EMIT_LIST_TAIL ei_x_encode_empty_list (response)

	#endif

	static void build_tree (ei_x_buff * response, myhtml_tree_t * tree, myhtml_tree_node_t * node, parse_flags_t parse_flags)
	{
	myhtml_tree_node_t * current_node = node;

	tstack stack;
	tstack_init (&stack, 30);

	// ok we're going to send an actual response so start encoding it
	response->index = 0;
	ei_x_encode_version (response);

	while (current_node != NULL)
	{
	myhtml_tag_id_t tag_id = myhtml_node_tag_id (current_node);
	myhtml_namespace_t tag_ns = myhtml_node_namespace (current_node);

	if (tag_id == MyHTML_TAG__TEXT)
	{
	size_t text_len;
	const char * node_text = myhtml_node_text (current_node, &text_len);

	EMIT_LIST_HDR;
	ei_x_encode_binary (response, node_text, text_len);
	}
	else if (tag_id == MyHTML_TAG__COMMENT)
	{
	size_t comment_len;
	const char* node_comment = myhtml_node_text (current_node, &comment_len);

	EMIT_LIST_HDR;
	prepare_comment (response, node_comment, comment_len, parse_flags);
	}
	else
	{
	// get name of tag
	size_t tag_name_len;
	const char *tag_name = myhtml_tag_name_by_id (tree, tag_id, &tag_name_len);
	// get namespace of tag
	size_t tag_ns_len;
	const char *tag_ns_name_ptr = myhtml_namespace_name_by_id (tag_ns, &tag_ns_len);
	char buffer [tag_ns_len + tag_name_len + 2];
	char *tag_string = buffer;

	if (tag_ns != MyHTML_NAMESPACE_HTML)
	{
	// tag_ns_name_ptr is unmodifyable, copy it in our tag_ns_buffer to make it modifyable.
	// +1 because myhtml uses strlen for length returned, which doesn't include the null-byte
	// https://github.com/lexborisov/myhtml/blob/0ade0e564a87f46fd21693a7d8c8d1fa09ffb6b6/source/myhtml/mynamespace.c#L80
	char tag_ns_buffer[tag_ns_len + 1];
	strncpy (tag_ns_buffer, tag_ns_name_ptr, sizeof tag_ns_buffer);
	lowercase (tag_ns_buffer);

	snprintf (tag_string, sizeof buffer, "%s:%s", tag_ns_buffer, tag_name);
	}
	else
	{
	// strncpy length does not contain null, so blank the buffer before copying
	// and limit the copy length to buffer size minus one for safety.
	memset (tag_string, '\0', sizeof buffer);
	strncpy (tag_string, tag_name, sizeof buffer - 1);
	}

	if (response->index > 1)
	{
	EMIT_LIST_HDR;
	}

	prepare_tag_header (response, tag_string, current_node, parse_flags);

	if (current_node->child)
	{
	tstack_push (&stack, current_node);
	current_node = current_node->child;

	continue;
	}
	else
	{
	if (parse_flags & FLAG_NIL_SELF_CLOSING && (myhtml_node_is_close_self(current_node) \|\| myhtml_node_is_void_element(current_node)))
	{
	#ifdef DEBUG_LIST_MANIP
	printf ("self-closing tag %s emit nil?\n", tag_string); fflush (stdout);
	#endif
	ei_x_encode_atom (response, "nil");
	}
	else
	{
	EMIT_EMPTY_LIST_HDR;
	}
	}
	}

	if (current_node->next)
	current_node = current_node->next;
	else
	{
	while (! current_node->next && stack.used != 0)
	{
	EMIT_LIST_TAIL;
	current_node = tstack_pop (&stack);
	}

	if (current_node->next)
	current_node = current_node->next;
	}

	// are we at root?
	if (current_node == node)
	break;
	}

	tstack_free (&stack);
	}

	static inline char * lowercase(char* c)
	{
	char * p = c;

	while (*p)
	{
	p = tolower ((unsigned char) p);
	p++;
	}

	return c;
	}

File Metadata

Mime Type: text/x-c
Expires: Fri, Jul 18, 12:02 PM (1 d, 2 h)
Storage Engine: blob
Storage Format: Raw Data
Storage Handle: 261670
Default Alt Text: myhtml_worker.c (13 KB)

myhtml_worker.cNo OneTemporaryActions

myhtml_worker.cView Options

File Metadata

Event Timeline

myhtml_worker.c
No OneTemporary
Actions

myhtml_worker.c
View Options