/* Copyright (C) 2005 Timo Sirainen */

#include "lib.h"
#include "str.h"
#include "rfc822-parser.h"

/*
   atext        =       ALPHA / DIGIT / ; Any character except controls,
                        "!" / "#" /     ;  SP, and specials.
                        "$" / "%" /     ;  Used for atoms
                        "&" / "'" /
                        "*" / "+" /
                        "-" / "/" /
                        "=" / "?" /
                        "^" / "_" /
                        "`" / "{" /
                        "|" / "}" /
                        "~"

  MIME:

  token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
              or tspecials>
  tspecials :=  "(" / ")" / "<" / ">" / "@" /
                "," / ";" / ":" / "\" / <">
                "/" / "[" / "]" / "?" / "="

  So token is same as dot-atom, except stops also at '/', '?' and '='.
*/

/* atext chars are marked with 1, alpha and digits with 2,
   atext-but-mime-tspecials with 4 */
static unsigned char atext_chars[256] = {
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0-15 */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 16-31 */
	0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 4, /* 32-47 */
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 4, 0, 4, /* 48-63 */
	0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, /* 64-79 */
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 1, 1, /* 80-95 */
	1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, /* 96-111 */
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 0, /* 112-127 */

	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
};
#define IS_ATEXT(c) \
	(atext_chars[(int)(unsigned char)(c)] != 0)
#define IS_ATEXT_NON_TSPECIAL(c) \
	((atext_chars[(int)(unsigned char)(c)] & 3) != 0)

void rfc822_parser_init(struct rfc822_parser_context *ctx,
			const unsigned char *data, size_t size,
			string_t *last_comment)
{
	memset(ctx, 0, sizeof(*ctx));
	ctx->data = data;
	ctx->end = data + size;
	ctx->last_comment = last_comment;
}

int rfc822_skip_comment(struct rfc822_parser_context *ctx)
{
	const unsigned char *start;
	int level = 1;

	i_assert(*ctx->data == '(');

	if (ctx->last_comment != NULL)
		str_truncate(ctx->last_comment, 0);

	start = ++ctx->data;
	for (; ctx->data != ctx->end; ctx->data++) {
		switch (*ctx->data) {
		case '(':
			level++;
			break;
		case ')':
			if (--level == 0) {
				if (ctx->last_comment != NULL) {
					str_append_n(ctx->last_comment, start,
						     ctx->data - start);
				}
				ctx->data++;
				return ctx->data != ctx->end;
			}
			break;
		case '\\':
			if (ctx->last_comment != NULL) {
				str_append_n(ctx->last_comment, start,
					     ctx->data - start);
			}
			start = ctx->data + 1;

			ctx->data++;
			if (ctx->data == ctx->end)
				return -1;
			break;
		}
	}

	/* missing ')' */
	return -1;
}

int rfc822_skip_lwsp(struct rfc822_parser_context *ctx)
{
	for (; ctx->data != ctx->end;) {
		if (*ctx->data == ' ' || *ctx->data == '\t' ||
		    *ctx->data == '\r' || *ctx->data == '\n') {
                        ctx->data++;
			continue;
		}

		if (*ctx->data != '(')
			break;

		if (rfc822_skip_comment(ctx) < 0)
			return -1;
	}
	return ctx->data != ctx->end;
}

int rfc822_parse_atom(struct rfc822_parser_context *ctx, string_t *str)
{
	const unsigned char *start;

	/*
	   atom            = [CFWS] 1*atext [CFWS]
	   atext           =
	     ; Any character except controls, SP, and specials.
	*/
	for (start = ctx->data; ctx->data != ctx->end; ctx->data++) {
		if (IS_ATEXT(*ctx->data))
			continue;

		str_append_n(str, start, ctx->data - start);
		return rfc822_skip_lwsp(ctx);
	}

	str_append_n(str, start, ctx->data - start);
	return 0;
}

int rfc822_parse_dot_atom(struct rfc822_parser_context *ctx, string_t *str)
{
	const unsigned char *start;
	int ret;

	/*
	   dot-atom        = [CFWS] dot-atom-text [CFWS]
	   dot-atom-text   = 1*atext *("." 1*atext)

	   atext           =
	     ; Any character except controls, SP, and specials.

	   For RFC-822 compatibility allow LWSP around '.'
	*/
	for (start = ctx->data; ctx->data != ctx->end; ctx->data++) {
		if (IS_ATEXT(*ctx->data))
			continue;

		str_append_n(str, start, ctx->data - start);

		if ((ret = rfc822_skip_lwsp(ctx)) <= 0)
			return ret;

		if (*ctx->data != '.')
			return 1;

		ctx->data++;
		str_append_c(str, '.');

		if ((ret = rfc822_skip_lwsp(ctx)) <= 0)
			return ret;
		start = ctx->data;
	}

	str_append_n(str, start, ctx->data - start);
	return 0;
}

int rfc822_parse_mime_token(struct rfc822_parser_context *ctx, string_t *str)
{
	const unsigned char *start;

	for (start = ctx->data; ctx->data != ctx->end; ctx->data++) {
		if (IS_ATEXT_NON_TSPECIAL(*ctx->data) || *ctx->data == '.')
			continue;

		str_append_n(str, start, ctx->data - start);
		return rfc822_skip_lwsp(ctx);
	}

	str_append_n(str, start, ctx->data - start);
	return 0;
}

int rfc822_parse_quoted_string(struct rfc822_parser_context *ctx, string_t *str)
{
	const unsigned char *start;

	i_assert(*ctx->data == '"');
	ctx->data++;

	for (start = ctx->data; ctx->data != ctx->end; ctx->data++) {
		if (*ctx->data == '"') {
			str_append_n(str, start, ctx->data - start);
			ctx->data++;
			return rfc822_skip_lwsp(ctx);
		}

		if (*ctx->data != '\\')
			continue;

		ctx->data++;
		if (ctx->data == ctx->end)
			return -1;

		str_append_n(str, start, ctx->data - start);
		start = ctx->data;
	}

	/* missing '"' */
	return -1;
}

int rfc822_parse_phrase(struct rfc822_parser_context *ctx, string_t *str)
{
	int ret;

	for (;;) {
		if (*ctx->data == '"')
			ret = rfc822_parse_quoted_string(ctx, str);
		else
			ret = rfc822_parse_atom(ctx, str);
		if (ret <= 0)
			return ret;

		if (!IS_ATEXT(*ctx->data) && *ctx->data != '"')
			break;
		str_append_c(str, ' ');
	}
	return rfc822_skip_lwsp(ctx);
}

static int
rfc822_parse_domain_literal(struct rfc822_parser_context *ctx, string_t *str)
{
	const unsigned char *start;

	/*
	   domain-literal  = [CFWS] "[" *([FWS] dcontent) [FWS] "]" [CFWS]
	   dcontent        = dtext / quoted-pair
	   dtext           = NO-WS-CTL /     ; Non white space controls
			     %d33-90 /       ; The rest of the US-ASCII
			     %d94-126        ;  characters not including "[",
					     ;  "]", or "\"
	*/
	i_assert(*ctx->data == '[');

	for (start = ctx->data; ctx->data != ctx->end; ctx->data++) {
		if (*ctx->data == '\\') {
			ctx->data++;
			if (ctx->data == ctx->end)
				break;
		} else if (*ctx->data == ']') {
			ctx->data++;
			str_append_n(str, start, ctx->data - start);
			return ctx->data != ctx->end;
		}
	}

	/* missing ']' */
	return -1;
}

int rfc822_parse_domain(struct rfc822_parser_context *ctx, string_t *str)
{
	/*
	   domain          = dot-atom / domain-literal / obs-domain
	   domain-literal  = [CFWS] "[" *([FWS] dcontent) [FWS] "]" [CFWS]
	   obs-domain      = atom *("." atom)
	*/
	i_assert(*ctx->data == '@');
	ctx->data++;

	if (rfc822_skip_lwsp(ctx) <= 0)
		return -1;

	if (*ctx->data == '[') {
		if (rfc822_parse_domain_literal(ctx, str) < 0)
			return -1;
	} else {
		if (rfc822_parse_dot_atom(ctx, str) < 0)
			return -1;
	}

	return ctx->data != ctx->end;
}