src/lib-imap/imap-parser.c

	imap-parser.c revision 69c0e4402662eb420853c11b8c27223a0bb8f0db
/* Copyright (C) 2002 Timo Sirainen */

#include "lib.h"
#include "iobuffer.h"
#include "imap-parser.h"

#define is_linebreak(c) \
    ((c) == '\r' || (c) == '\n')

typedef enum {
    ARG_PARSE_NONE = 0,
    ARG_PARSE_ATOM,
    ARG_PARSE_STRING,
    ARG_PARSE_LITERAL,
    ARG_PARSE_LITERAL_DATA
} ArgParseType;

struct _ImapParser {
    Pool pool;
    IOBuffer *inbuf, *outbuf;

    unsigned int pos;
    ImapArg *args;

    ArgParseType cur_type;
    size_t cur_pos;
    ImapArg *cur_arg;

    ImapArg *cur_list_arg; /* argument which contains current list */
    ImapArgList **cur_list; /* pointer where to append next list item */

        ImapParserFlags flags;
    int str_first_escape; /* ARG_PARSE_STRING: index to first '\' */
    uoff_t literal_size; /* ARG_PARSE_LITERAL: string size */
    unsigned int literal_skip_crlf:1;

    unsigned int inside_bracket:1;
    unsigned int eol:1;
    unsigned int error:1;
};

ImapParser *imap_parser_create(IOBuffer *inbuf, IOBuffer *outbuf)
{
    ImapParser *parser;

    parser = i_new(ImapParser, 1);
    parser->pool = pool_create("IMAP parser", 8192, FALSE);
    parser->inbuf = inbuf;
    parser->outbuf = outbuf;
    return parser;
}

void imap_parser_destroy(ImapParser *parser)
{
    pool_unref(parser->pool);
    i_free(parser);
}

void imap_parser_reset(ImapParser *parser)
{
    p_clear(parser->pool);

    parser->pos = 0;
    parser->args = NULL;

    parser->cur_type = ARG_PARSE_NONE;
    parser->cur_pos = 0;
    parser->cur_arg = NULL;

    parser->cur_list_arg = NULL;
    parser->cur_list = NULL;

    parser->eol = FALSE;
    parser->error = FALSE;
}

static int imap_parser_skip_whitespace(ImapParser *parser, char **data,
                       size_t *data_size)
{
    size_t i;

    for (i = parser->cur_pos; i < *data_size; i++) {
        if ((*data)[i] != ' ')
            break;
    }

        io_buffer_skip(parser->inbuf, i);
    parser->cur_pos = 0;

    *data += i;
    *data_size -= i;
    return *data_size > 0;
}

static ImapArg *imap_arg_create(ImapParser *parser)
{
    ImapArgList *list;

    /* create new argument into list */
    i_assert(parser->cur_list != NULL);

    list = p_new(parser->pool, ImapArgList, 1);
    *parser->cur_list = list;
    parser->cur_list = &list->next;

    return &list->arg;
}

static void imap_parser_open_list(ImapParser *parser)
{
    if (parser->cur_arg == NULL)
        parser->cur_arg = imap_arg_create(parser);

    parser->cur_arg->type = IMAP_ARG_LIST;
    parser->cur_list = &parser->cur_arg->data.list;
    parser->cur_list_arg = parser->cur_arg;

    parser->cur_type = ARG_PARSE_NONE;
    parser->cur_arg = NULL;
}

static int imap_parser_close_list(ImapParser *parser)
{
    ImapArgList **list;

    if (parser->cur_list_arg == NULL) {
        /* we're not inside list */
        parser->error = TRUE;
        return FALSE;
    }

    parser->cur_list_arg = parser->cur_list_arg->parent;
    if (parser->cur_list_arg == NULL) {
        /* end of argument */
        parser->cur_list = NULL;
        return TRUE;
    }

    /* skip to end of the upper list */
        list = &parser->cur_list_arg->data.list;
    while (*list != NULL)
        list = &(*list)->next;
    parser->cur_list = list;

    parser->cur_type = ARG_PARSE_NONE;
    parser->cur_arg = NULL;

    return TRUE;
}

static void imap_parser_save_arg(ImapParser *parser, char *data,
                 size_t lastpos)
{
    ImapArg *arg;

    arg = parser->cur_arg;
    if (arg == NULL)
        arg = imap_arg_create(parser);

    switch (parser->cur_type) {
    case ARG_PARSE_ATOM:
        if (lastpos == 3 && strncmp(data, "NIL", 3) == 0) {
            /* NIL argument */
            arg->type = IMAP_ARG_NIL;
        } else {
            /* simply save the string */
            arg->type = IMAP_ARG_ATOM;
            arg->data.str = p_strndup(parser->pool, data, lastpos);
        }
        break;
    case ARG_PARSE_STRING:
        /* data is quoted and may contain escapes. */
        arg->type = IMAP_ARG_STRING;
        arg->data.str = p_strndup(parser->pool, data+1, lastpos-1);

        /* remove the escapes */
        if (parser->str_first_escape >= 0) {
            /* -1 because we skipped the '"' prefix */
            string_remove_escapes(arg->data.str +
                          parser->str_first_escape-1);
        }
        break;
    case ARG_PARSE_LITERAL_DATA:
        if ((parser->flags & IMAP_PARSE_FLAG_LITERAL_SIZE) == 0) {
            /* simply save the string */
            arg->type = IMAP_ARG_STRING;
            arg->data.str = p_strndup(parser->pool, data, lastpos);
        } else {
            /* save literal size */
            arg->type = IMAP_ARG_LITERAL_SIZE;
            arg->data.literal_size = parser->literal_size;
        }
        break;
    default:
        i_assert(0);
    }

    parser->cur_arg = NULL;
        parser->cur_type = ARG_PARSE_NONE;
}

static int imap_parser_read_atom(ImapParser *parser, char *data,
                 size_t data_size)
{
    size_t i;

    /* read until we've found space, CR or LF. Data inside '[' and ']'
       characters are an exception though, allow spaces inside them. */
    for (i = parser->cur_pos; i < data_size; i++) {
        if (parser->inside_bracket) {
            if (data[i] == '[' || is_linebreak(data[i])) {
                /* a) nested '[' characters not allowed
                      (too much trouble and imap doesn't need)
                   b) missing ']' character */
                parser->error = TRUE;
                return FALSE;
            }

            if (data[i] == ']') {
                parser->inside_bracket = FALSE;
            }
        } else {
            if (data[i] == '[')
                parser->inside_bracket = TRUE;
            else if (data[i] == ' ' || data[i] == ')' ||
                 is_linebreak(data[i])) {
                imap_parser_save_arg(parser, data, i);
                break;
            }
        }
    }

    parser->cur_pos = i;
    return TRUE;
}

static int imap_parser_read_string(ImapParser *parser, char *data,
                   size_t data_size)
{
    size_t i;

    /* read until we've found non-escaped ", CR or LF */
    for (i = parser->cur_pos; i < data_size; i++) {
        if (data[i] == '"') {
            imap_parser_save_arg(parser, data, i);

            i++; /* skip the trailing '"' too */
            break;
        }

        if (data[i] == '\\') {
            if (i+1 == data_size) {
                /* known data ends with '\' - leave it to
                   next time as well if it happens to be \" */
                break;
            }

            /* save the first escaped char */
            if (parser->str_first_escape < 0)
                parser->str_first_escape = i;

            /* skip the escaped char */
            i++;
        }

        /* check linebreaks here, so escaping CR/LF isn't possible.
           string always ends with '"', so it's an error if we found
           a linebreak.. */
        if (is_linebreak(data[i])) {
            parser->error = TRUE;
            return FALSE;
        }
    }

    parser->cur_pos = i;
    return TRUE;
}

static int imap_parser_literal_end(ImapParser *parser)
{
    if ((parser->flags & IMAP_PARSE_FLAG_LITERAL_SIZE) == 0) {
        if (parser->literal_size > parser->inbuf->max_buffer_size) {
            /* too long string, abort. */
            parser->error = TRUE;
            return FALSE;
        }

        io_buffer_send(parser->outbuf, "+ OK\r\n", 6);
        io_buffer_send_flush(parser->outbuf);
    }

    parser->cur_type = ARG_PARSE_LITERAL_DATA;
    parser->literal_skip_crlf = TRUE;

    parser->cur_pos = 0;
    return TRUE;
}

static int imap_parser_read_literal(ImapParser *parser, char *data,
                    size_t data_size)
{
    size_t i, prev_size;

    /* expecting digits + "}" */
    for (i = parser->cur_pos; i < data_size; i++) {
        if (data[i] == '}') {
            io_buffer_skip(parser->inbuf, i+1);
            if (!imap_parser_literal_end(parser))
                return FALSE;
            break;
        }

        if (data[i] < '0' || data[i] > '9')
            return FALSE;

        prev_size = parser->literal_size;
        parser->literal_size = parser->literal_size*10 + (data[i]-'0');

        if (parser->literal_size < prev_size) {
            /* wrapped around, abort. */
            parser->error = TRUE;
            return FALSE;
        }
    }

    return TRUE;
}

static int imap_parser_read_literal_data(ImapParser *parser, char *data,
                     size_t data_size)
{
    if (parser->literal_skip_crlf) {
        /* skip \r\n or \n, anything else gives an error */
        if (*data == '\r') {
            if (data_size == 1)
                return TRUE;

            data++; data_size--;
            io_buffer_skip(parser->inbuf, 1);
        }

        if (*data != '\n')
            return FALSE;

        data++; data_size--;
        io_buffer_skip(parser->inbuf, 1);
        parser->literal_skip_crlf = FALSE;

        i_assert(parser->cur_pos == 0);
    }

    if ((parser->flags & IMAP_PARSE_FLAG_LITERAL_SIZE) == 0) {
        /* now we just wait until we've read enough data */
        if (data_size >= parser->literal_size) {
            imap_parser_save_arg(parser, data,
                         (size_t)parser->literal_size);
            parser->cur_pos = (size_t) parser->literal_size;
        }
    } else {
        /* we want to save only literal size, not the literal itself. */
        imap_parser_save_arg(parser, NULL, 0);
    }

    return TRUE;
}

/* Returns TRUE if argument was fully processed. Also returns TRUE if
   an argument inside a list was processed. */
static int imap_parser_read_arg(ImapParser *parser, ImapArg *root_arg)
{
    char *data;
    size_t data_size;

    data = (char *) io_buffer_get_data(parser->inbuf, &data_size);
    if (data_size == 0)
        return FALSE;

    if (parser->cur_arg == NULL && parser->cur_list == NULL) {
        /* beginning to parse a new argument */
        parser->cur_arg = root_arg;
    }

    while (parser->cur_type == ARG_PARSE_NONE) {
        /* we haven't started parsing yet */
        if (!imap_parser_skip_whitespace(parser, &data, &data_size))
            return FALSE;
        i_assert(parser->cur_pos == 0);

        switch (data[0]) {
        case '\r':
        case '\n':
            /* unexpected end of line */
            parser->eol = TRUE;
            return FALSE;
        case '"':
            parser->cur_type = ARG_PARSE_STRING;
            parser->str_first_escape = -1;
            break;
        case '{':
            parser->cur_type = ARG_PARSE_LITERAL;
            parser->literal_size = 0;
            break;
        case '(':
            imap_parser_open_list(parser);
            break;
        case ')':
            if (!imap_parser_close_list(parser))
                return FALSE;

            if (parser->cur_list_arg == NULL) {
                /* end of argument */
                parser->cur_pos++;
                return TRUE;
            }
            break;
        default:
            parser->cur_type = ARG_PARSE_ATOM;
                        parser->inside_bracket = FALSE;
            break;
        }

        parser->cur_pos++;
    }

    i_assert(data_size > 0);

    switch (parser->cur_type) {
    case ARG_PARSE_ATOM:
        if (!imap_parser_read_atom(parser, data, data_size))
            return FALSE;
        break;
    case ARG_PARSE_STRING:
        if (!imap_parser_read_string(parser, data, data_size))
            return FALSE;
        break;
    case ARG_PARSE_LITERAL:
        if (!imap_parser_read_literal(parser, data, data_size))
            return FALSE;

        /* pass through to parsing data. since inbuf->skip was
           modified, we need to get the data start position again. */
        data = (char *) io_buffer_get_data(parser->inbuf, &data_size);
    case ARG_PARSE_LITERAL_DATA:
        imap_parser_read_literal_data(parser, data, data_size);
        break;
    default:
        i_assert(0);
    }

    /* NOTE: data and data_size are invalid here, the functions above
       may have changed them. */

    return parser->cur_type == ARG_PARSE_NONE;
}

int imap_parser_read_args(ImapParser *parser, unsigned int count,
              ImapParserFlags flags, ImapArg **args)
{
    unsigned int args_size;

    parser->flags = flags;

    args_size = 0;
    while (count == 0 || parser->pos < count) {
        if (parser->pos >= args_size) {
            args_size = nearest_power(parser->pos);
            if (args_size < 8) args_size = 8;

            parser->args =
                p_realloc_min(parser->pool, parser->args,
                          args_size * sizeof(ImapArg));
        }

        if (!imap_parser_read_arg(parser, &parser->args[parser->pos]))
            break;

        /* jump to next argument, unless we're processing a list */
        if (parser->cur_list == NULL)
            parser->pos++;
    }

    if (parser->pos >= count || parser->eol) {
        /* all arguments read / end of line */
        *args = parser->args;
        return count == 0 || parser->pos < count ? parser->pos : count;
    } else if (parser->error) {
        /* error, abort */
        *args = NULL;
        return -1;
    } else {
        /* need more data */
        *args = NULL;
        return -2;
    }
}

const char *imap_parser_read_word(ImapParser *parser)
{
    char *data;
    size_t i, data_size;

    /* get the beginning of data in input buffer */
    data = (char *) io_buffer_get_data(parser->inbuf, &data_size);

    for (i = 0; i < data_size; i++) {
        if (data[i] == ' ' || data[i] == '\r' || data[i] == '\n')
            break;
    }

    if (i < data_size) {
        io_buffer_skip(parser->inbuf, i + (data[i] == ' ' ? 1 : 0));
        return p_strndup(parser->pool, data, i);
    } else {
        return NULL;
    }
}

const char *imap_parser_read_line(ImapParser *parser)
{
    char *data;
    size_t i, data_size;

    /* get the beginning of data in input buffer */
    data = (char *) io_buffer_get_data(parser->inbuf, &data_size);

    for (i = 0; i < data_size; i++) {
        if (data[i] == '\r' || data[i] == '\n')
            break;
    }

    if (i < data_size) {
        io_buffer_skip(parser->inbuf, i);
        return p_strndup(parser->pool, data, i);
    } else {
        return NULL;
    }
}

const char *imap_arg_string(ImapArg *arg)
{
    switch (arg->type) {
    case IMAP_ARG_NIL:
        return "";

    case IMAP_ARG_ATOM:
    case IMAP_ARG_STRING:
        return arg->data.str;

    default:
        return NULL;
    }
}