view src/mail/ngx_mail_parse.c @ 8797:1e2f4e9c8195 quic

QUIC: reworked migration handling. The quic connection now holds active, backup and probe paths instead of sockets. The number of migration paths is now limited and cannot be inflated by a bad client or an attacker. The client id is now associated with path rather than socket. This allows to simplify processing of output and connection ids handling. New migration abandons any previously started migrations. This allows to free consumed client ids and request new for use in future migrations and make progress in case when connection id limit is hit during migration. A path now can be revalidated without losing its state. The patch also fixes various issues with NAT rebinding case handling: - paths are now validated (previously, there was no validation and paths were left in limited state) - attempt to reuse id on different path is now again verified (this was broken in 40445fc7c403) - former path is now validated in case of apparent migration
author Vladimir Homutov <vl@nginx.com>
date Wed, 19 Jan 2022 22:39:24 +0300
parents b38728495e1a
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_mail.h>
#include <ngx_mail_pop3_module.h>
#include <ngx_mail_imap_module.h>
#include <ngx_mail_smtp_module.h>


ngx_int_t
ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c, c0, c1, c2, c3;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_command,
        sw_invalid,
        sw_spaces_before_argument,
        sw_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* POP3 command */
        case sw_start:
            s->cmd_start = p;
            state = sw_command;

            /* fall through */

        case sw_command:
            if (ch == ' ' || ch == CR || ch == LF) {
                c = s->cmd_start;

                if (p - c == 4) {

                    c0 = ngx_toupper(c[0]);
                    c1 = ngx_toupper(c[1]);
                    c2 = ngx_toupper(c[2]);
                    c3 = ngx_toupper(c[3]);

                    if (c0 == 'U' && c1 == 'S' && c2 == 'E' && c3 == 'R')
                    {
                        s->command = NGX_POP3_USER;

                    } else if (c0 == 'P' && c1 == 'A' && c2 == 'S' && c3 == 'S')
                    {
                        s->command = NGX_POP3_PASS;

                    } else if (c0 == 'A' && c1 == 'P' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_POP3_APOP;

                    } else if (c0 == 'Q' && c1 == 'U' && c2 == 'I' && c3 == 'T')
                    {
                        s->command = NGX_POP3_QUIT;

                    } else if (c0 == 'C' && c1 == 'A' && c2 == 'P' && c3 == 'A')
                    {
                        s->command = NGX_POP3_CAPA;

                    } else if (c0 == 'A' && c1 == 'U' && c2 == 'T' && c3 == 'H')
                    {
                        s->command = NGX_POP3_AUTH;

                    } else if (c0 == 'N' && c1 == 'O' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_POP3_NOOP;
#if (NGX_MAIL_SSL)
                    } else if (c0 == 'S' && c1 == 'T' && c2 == 'L' && c3 == 'S')
                    {
                        s->command = NGX_POP3_STLS;
#endif
                    } else {
                        goto invalid;
                    }

                } else {
                    goto invalid;
                }

                s->cmd.data = s->cmd_start;
                s->cmd.len = p - s->cmd_start;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_invalid:
            goto invalid;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            default:
                if (s->args.nelts <= 2) {
                    state = sw_argument;
                    s->arg_start = p;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            switch (ch) {

            case ' ':

                /*
                 * the space should be considered as part of the at username
                 * or password, but not of argument in other commands
                 */

                if (s->command == NGX_POP3_USER
                    || s->command == NGX_POP3_PASS)
                {
                    break;
                }

                /* fall through */

            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;
                s->arg_start = NULL;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;

            default:
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;
    s->state = (s->command != NGX_POP3_AUTH) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_invalid;

    /* skip invalid command till LF */

    for ( /* void */ ; p < s->buffer->last; p++) {
        if (*p == LF) {
            s->state = sw_start;
            s->buffer->pos = p + 1;
            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }
    }

    s->buffer->pos = p;

    return NGX_AGAIN;
}


ngx_int_t
ngx_mail_imap_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c, *dst, *src, *end;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_tag,
        sw_invalid,
        sw_spaces_before_command,
        sw_command,
        sw_spaces_before_argument,
        sw_argument,
        sw_backslash,
        sw_literal,
        sw_no_sync_literal_argument,
        sw_start_literal_argument,
        sw_literal_argument,
        sw_end_literal_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* IMAP tag */
        case sw_start:
            s->tag_start = p;
            state = sw_tag;

            /* fall through */

        case sw_tag:
            switch (ch) {
            case ' ':
                s->tag.len = p - s->tag_start + 1;
                s->tag.data = s->tag_start;
                state = sw_spaces_before_command;
                break;
            case CR:
            case LF:
                goto invalid;
            default:
                if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')
                    && (ch < '0' || ch > '9') && ch != '-' && ch != '.'
                    && ch != '_')
                {
                    goto invalid;
                }
                if (p - s->tag_start > 31) {
                    goto invalid;
                }
                break;
            }
            break;

        case sw_invalid:
            goto invalid;

        case sw_spaces_before_command:
            switch (ch) {
            case ' ':
                break;
            case CR:
            case LF:
                goto invalid;
            default:
                s->cmd_start = p;
                state = sw_command;
                break;
            }
            break;

        case sw_command:
            if (ch == ' ' || ch == CR || ch == LF) {

                c = s->cmd_start;

                switch (p - c) {

                case 4:
                    if ((c[0] == 'N' || c[0] == 'n')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'O'|| c[2] == 'o')
                        && (c[3] == 'P'|| c[3] == 'p'))
                    {
                        s->command = NGX_IMAP_NOOP;

                    } else {
                        goto invalid;
                    }
                    break;

                case 5:
                    if ((c[0] == 'L'|| c[0] == 'l')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'G'|| c[2] == 'g')
                        && (c[3] == 'I'|| c[3] == 'i')
                        && (c[4] == 'N'|| c[4] == 'n'))
                    {
                        s->command = NGX_IMAP_LOGIN;

                    } else {
                        goto invalid;
                    }
                    break;

                case 6:
                    if ((c[0] == 'L'|| c[0] == 'l')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'G'|| c[2] == 'g')
                        && (c[3] == 'O'|| c[3] == 'o')
                        && (c[4] == 'U'|| c[4] == 'u')
                        && (c[5] == 'T'|| c[5] == 't'))
                    {
                        s->command = NGX_IMAP_LOGOUT;

                    } else {
                        goto invalid;
                    }
                    break;

#if (NGX_MAIL_SSL)
                case 8:
                    if ((c[0] == 'S'|| c[0] == 's')
                        && (c[1] == 'T'|| c[1] == 't')
                        && (c[2] == 'A'|| c[2] == 'a')
                        && (c[3] == 'R'|| c[3] == 'r')
                        && (c[4] == 'T'|| c[4] == 't')
                        && (c[5] == 'T'|| c[5] == 't')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'S'|| c[7] == 's'))
                    {
                        s->command = NGX_IMAP_STARTTLS;

                    } else {
                        goto invalid;
                    }
                    break;
#endif

                case 10:
                    if ((c[0] == 'C'|| c[0] == 'c')
                        && (c[1] == 'A'|| c[1] == 'a')
                        && (c[2] == 'P'|| c[2] == 'p')
                        && (c[3] == 'A'|| c[3] == 'a')
                        && (c[4] == 'B'|| c[4] == 'b')
                        && (c[5] == 'I'|| c[5] == 'i')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'I'|| c[7] == 'i')
                        && (c[8] == 'T'|| c[8] == 't')
                        && (c[9] == 'Y'|| c[9] == 'y'))
                    {
                        s->command = NGX_IMAP_CAPABILITY;

                    } else {
                        goto invalid;
                    }
                    break;

                case 12:
                    if ((c[0] == 'A'|| c[0] == 'a')
                        && (c[1] == 'U'|| c[1] == 'u')
                        && (c[2] == 'T'|| c[2] == 't')
                        && (c[3] == 'H'|| c[3] == 'h')
                        && (c[4] == 'E'|| c[4] == 'e')
                        && (c[5] == 'N'|| c[5] == 'n')
                        && (c[6] == 'T'|| c[6] == 't')
                        && (c[7] == 'I'|| c[7] == 'i')
                        && (c[8] == 'C'|| c[8] == 'c')
                        && (c[9] == 'A'|| c[9] == 'a')
                        && (c[10] == 'T'|| c[10] == 't')
                        && (c[11] == 'E'|| c[11] == 'e'))
                    {
                        s->command = NGX_IMAP_AUTHENTICATE;

                    } else {
                        goto invalid;
                    }
                    break;

                default:
                    goto invalid;
                }

                s->cmd.data = s->cmd_start;
                s->cmd.len = p - s->cmd_start;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            case '"':
                if (s->args.nelts <= 2) {
                    s->quoted = 1;
                    s->arg_start = p + 1;
                    state = sw_argument;
                    break;
                }
                goto invalid;
            case '{':
                if (s->args.nelts <= 2) {
                    state = sw_literal;
                    break;
                }
                goto invalid;
            default:
                if (s->args.nelts <= 2) {
                    s->arg_start = p;
                    state = sw_argument;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            if (ch == ' ' && s->quoted) {
                break;
            }

            switch (ch) {
            case '"':
                if (!s->quoted) {
                    break;
                }
                s->quoted = 0;
                /* fall through */
            case ' ':
            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;

                if (s->backslash) {
                    dst = s->arg_start;
                    end = p;

                    for (src = dst; src < end; dst++) {
                        *dst = *src;
                        if (*src++ == '\\') {
                            *dst = *src++;
                        }
                    }

                    arg->len = dst - s->arg_start;
                    s->backslash = 0;
                }

                s->arg_start = NULL;

                switch (ch) {
                case '"':
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            case '\\':
                if (s->quoted) {
                    s->backslash = 1;
                    state = sw_backslash;
                }
                break;
            }
            break;

        case sw_backslash:
            switch (ch) {
            case CR:
            case LF:
                goto invalid;
            default:
                state = sw_argument;
            }
            break;

        case sw_literal:
            if (ch >= '0' && ch <= '9') {
                s->literal_len = s->literal_len * 10 + (ch - '0');
                break;
            }
            if (ch == '}') {
                state = sw_start_literal_argument;
                break;
            }
            if (ch == '+') {
                state = sw_no_sync_literal_argument;
                break;
            }
            goto invalid;

        case sw_no_sync_literal_argument:
            if (ch == '}') {
                s->no_sync_literal = 1;
                state = sw_start_literal_argument;
                break;
            }
            goto invalid;

        case sw_start_literal_argument:
            switch (ch) {
            case CR:
                break;
            case LF:
                s->buffer->pos = p + 1;
                s->arg_start = p + 1;
                if (s->no_sync_literal == 0) {
                    s->state = sw_literal_argument;
                    return NGX_IMAP_NEXT;
                }
                state = sw_literal_argument;
                s->no_sync_literal = 0;
                break;
            default:
                goto invalid;
            }
            break;

        case sw_literal_argument:
            if (s->literal_len && --s->literal_len) {
                break;
            }

            arg = ngx_array_push(&s->args);
            if (arg == NULL) {
                return NGX_ERROR;
            }
            arg->len = p + 1 - s->arg_start;
            arg->data = s->arg_start;
            s->arg_start = NULL;
            state = sw_end_literal_argument;

            break;

        case sw_end_literal_argument:
            switch (ch) {
            case '{':
                if (s->args.nelts <= 2) {
                    state = sw_literal;
                    break;
                }
                goto invalid;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            default:
                state = sw_spaces_before_argument;
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;
    s->state = (s->command != NGX_IMAP_AUTHENTICATE) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_invalid;
    s->quoted = 0;
    s->backslash = 0;
    s->no_sync_literal = 0;
    s->literal_len = 0;

    /* skip invalid command till LF */

    for ( /* void */ ; p < s->buffer->last; p++) {
        if (*p == LF) {
            s->state = sw_start;
            s->buffer->pos = p + 1;

            /* detect non-synchronizing literals */

            if ((size_t) (p - s->buffer->start) > sizeof("{1+}") - 1) {
                p--;

                if (*p == CR) {
                    p--;
                }

                if (*p == '}' && *(p - 1) == '+') {
                    s->quit = 1;
                }
            }

            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }
    }

    s->buffer->pos = p;

    return NGX_AGAIN;
}


ngx_int_t
ngx_mail_smtp_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c, c0, c1, c2, c3;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_command,
        sw_invalid,
        sw_spaces_before_argument,
        sw_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* SMTP command */
        case sw_start:
            s->cmd_start = p;
            state = sw_command;

            /* fall through */

        case sw_command:
            if (ch == ' ' || ch == CR || ch == LF) {
                c = s->cmd_start;

                if (p - c == 4) {

                    c0 = ngx_toupper(c[0]);
                    c1 = ngx_toupper(c[1]);
                    c2 = ngx_toupper(c[2]);
                    c3 = ngx_toupper(c[3]);

                    if (c0 == 'H' && c1 == 'E' && c2 == 'L' && c3 == 'O')
                    {
                        s->command = NGX_SMTP_HELO;

                    } else if (c0 == 'E' && c1 == 'H' && c2 == 'L' && c3 == 'O')
                    {
                        s->command = NGX_SMTP_EHLO;

                    } else if (c0 == 'Q' && c1 == 'U' && c2 == 'I' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_QUIT;

                    } else if (c0 == 'A' && c1 == 'U' && c2 == 'T' && c3 == 'H')
                    {
                        s->command = NGX_SMTP_AUTH;

                    } else if (c0 == 'N' && c1 == 'O' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_SMTP_NOOP;

                    } else if (c0 == 'M' && c1 == 'A' && c2 == 'I' && c3 == 'L')
                    {
                        s->command = NGX_SMTP_MAIL;

                    } else if (c0 == 'R' && c1 == 'S' && c2 == 'E' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_RSET;

                    } else if (c0 == 'R' && c1 == 'C' && c2 == 'P' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_RCPT;

                    } else if (c0 == 'V' && c1 == 'R' && c2 == 'F' && c3 == 'Y')
                    {
                        s->command = NGX_SMTP_VRFY;

                    } else if (c0 == 'E' && c1 == 'X' && c2 == 'P' && c3 == 'N')
                    {
                        s->command = NGX_SMTP_EXPN;

                    } else if (c0 == 'H' && c1 == 'E' && c2 == 'L' && c3 == 'P')
                    {
                        s->command = NGX_SMTP_HELP;

                    } else {
                        goto invalid;
                    }
#if (NGX_MAIL_SSL)
                } else if (p - c == 8) {

                    if ((c[0] == 'S'|| c[0] == 's')
                        && (c[1] == 'T'|| c[1] == 't')
                        && (c[2] == 'A'|| c[2] == 'a')
                        && (c[3] == 'R'|| c[3] == 'r')
                        && (c[4] == 'T'|| c[4] == 't')
                        && (c[5] == 'T'|| c[5] == 't')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'S'|| c[7] == 's'))
                    {
                        s->command = NGX_SMTP_STARTTLS;

                    } else {
                        goto invalid;
                    }
#endif
                } else {
                    goto invalid;
                }

                s->cmd.data = s->cmd_start;
                s->cmd.len = p - s->cmd_start;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_invalid:
            goto invalid;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            default:
                if (s->args.nelts <= 10) {
                    state = sw_argument;
                    s->arg_start = p;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            switch (ch) {
            case ' ':
            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;
                s->arg_start = NULL;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;

            default:
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;
    s->state = (s->command != NGX_SMTP_AUTH) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_invalid;

    /* skip invalid command till LF */

    for ( /* void */ ; p < s->buffer->last; p++) {
        if (*p == LF) {
            s->state = sw_start;
            s->buffer->pos = p + 1;
            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }
    }

    s->buffer->pos = p;

    return NGX_AGAIN;
}


ngx_int_t
ngx_mail_auth_parse(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_str_t                 *arg;

#if (NGX_MAIL_SSL)
    if (ngx_mail_starttls_only(s, c)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }
#endif

    if (s->args.nelts == 0) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    arg = s->args.elts;

    if (arg[0].len == 5) {

        if (ngx_strncasecmp(arg[0].data, (u_char *) "LOGIN", 5) == 0) {

            if (s->args.nelts == 1) {
                return NGX_MAIL_AUTH_LOGIN;
            }

            if (s->args.nelts == 2) {
                return NGX_MAIL_AUTH_LOGIN_USERNAME;
            }

            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }

        if (ngx_strncasecmp(arg[0].data, (u_char *) "PLAIN", 5) == 0) {

            if (s->args.nelts == 1) {
                return NGX_MAIL_AUTH_PLAIN;
            }

            if (s->args.nelts == 2) {
                return ngx_mail_auth_plain(s, c, 1);
            }
        }

        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    if (arg[0].len == 8) {

        if (ngx_strncasecmp(arg[0].data, (u_char *) "CRAM-MD5", 8) == 0) {

            if (s->args.nelts != 1) {
                return NGX_MAIL_PARSE_INVALID_COMMAND;
            }

            return NGX_MAIL_AUTH_CRAM_MD5;
        }

        if (ngx_strncasecmp(arg[0].data, (u_char *) "EXTERNAL", 8) == 0) {

            if (s->args.nelts == 1) {
                return NGX_MAIL_AUTH_EXTERNAL;
            }

            if (s->args.nelts == 2) {
                return ngx_mail_auth_external(s, c, 1);
            }
        }

        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}