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view src/http/v3/ngx_http_v3_parse.c @ 8549:d70a38acaea0 quic

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HTTP/3: skip unknown frames on request stream. As per HTTP/3 draft 29, section 4.1: Frames of unknown types (Section 9), including reserved frames (Section 7.2.8) MAY be sent on a request or push stream before, after, or interleaved with other frames described in this section. Also, trailers frame is now used as an indication of the request body end.
author Roman Arutyunyan <arut@nginx.com>
date Mon, 24 Aug 2020 09:56:36 +0300
parents 0596fe1aee16
children 234e9d89ff7f
line wrap: on
line source


/*
 * Copyright (C) Roman Arutyunyan
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


static ngx_int_t ngx_http_v3_parse_lookup(ngx_connection_t *c,
    ngx_uint_t dynamic, ngx_uint_t index, ngx_str_t *name, ngx_str_t *value);


ngx_int_t
ngx_http_v3_parse_varlen_int(ngx_connection_t *c,
    ngx_http_v3_parse_varlen_int_t *st, u_char ch)
{
    enum {
        sw_start = 0,
        sw_length_2,
        sw_length_3,
        sw_length_4,
        sw_length_5,
        sw_length_6,
        sw_length_7,
        sw_length_8
    };

    switch (st->state) {

    case sw_start:

        st->value = ch;
        if (st->value & 0xc0) {
            st->state = sw_length_2;
            break;
        }

        goto done;

    case sw_length_2:

        st->value = (st->value << 8) + ch;
        if ((st->value & 0xc000) == 0x4000) {
            st->value &= 0x3fff;
            goto done;
        }

        st->state = sw_length_3;
        break;

    case sw_length_4:

        st->value = (st->value << 8) + ch;
        if ((st->value & 0xc0000000) == 0x80000000) {
            st->value &= 0x3fffffff;
            goto done;
        }

        st->state = sw_length_5;
        break;

    case sw_length_3:
    case sw_length_5:
    case sw_length_6:
    case sw_length_7:

        st->value = (st->value << 8) + ch;
        st->state++;
        break;

    case sw_length_8:

        st->value = (st->value << 8) + ch;
        st->value &= 0x3fffffffffffffff;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse varlen int %uL", st->value);

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_prefix_int(ngx_connection_t *c,
    ngx_http_v3_parse_prefix_int_t *st, ngx_uint_t prefix, u_char ch)
{
    ngx_uint_t  mask;
    enum {
        sw_start = 0,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        mask = (1 << prefix) - 1;
        st->value = ch & mask;

        if (st->value != mask) {
            goto done;
        }

        st->shift = 0;
        st->state = sw_value;
        break;

    case sw_value:

        st->value += (uint64_t) (ch & 0x7f) << st->shift;

        if (st->shift == 56
            && ((ch & 0x80) || (st->value & 0xc000000000000000)))
        {
            ngx_log_error(NGX_LOG_INFO, c->log, 0,
                          "client exceeded integer size limit");
            return NGX_HTTP_V3_ERR_EXCESSIVE_LOAD;
        }

        if (ch & 0x80) {
            st->shift += 7;
            break;
        }

        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse prefix int %uL", st->value);

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_headers(ngx_connection_t *c, ngx_http_v3_parse_headers_t *st,
    u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_type,
        sw_length,
        sw_skip,
        sw_prefix,
        sw_verify,
        sw_header_rep,
        sw_done
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse headers");

        st->state = sw_type;

        /* fall through */

    case sw_type:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->type = st->vlint.value;
        st->state = sw_length;
        break;

    case sw_length:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->length = st->vlint.value;

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse headers type:%ui, len:%ui",
                       st->type, st->length);

        if (st->type != NGX_HTTP_V3_FRAME_HEADERS) {
            st->state = st->length > 0 ? sw_skip : sw_type;
            break;
        }

        st->state = sw_prefix;
        break;

    case sw_skip:

        if (--st->length == 0) {
            st->state = sw_type;
        }

        break;

    case sw_prefix:

        if (st->length-- == 0) {
            return NGX_HTTP_V3_ERR_FRAME_ERROR;
        }

        rc = ngx_http_v3_parse_header_block_prefix(c, &st->prefix, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        if (st->length == 0) {
            return NGX_HTTP_V3_ERR_FRAME_ERROR;
        }

        st->state = sw_verify;
        break;

    case sw_verify:

        rc = ngx_http_v3_check_insert_count(c, st->prefix.insert_count);
        if (rc != NGX_OK) {
            return rc;
        }

        st->state = sw_header_rep;

        /* fall through */

    case sw_header_rep:

        rc = ngx_http_v3_parse_header_rep(c, &st->header_rep, st->prefix.base,
                                          ch);

        if (--st->length == 0 && rc == NGX_AGAIN) {
            return NGX_HTTP_V3_ERR_FRAME_ERROR;
        }

        if (rc != NGX_DONE) {
            return rc;
        }

        if (st->length == 0) {
            goto done;
        }

        return NGX_OK;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse headers done");

    if (st->prefix.insert_count > 0) {
        if (ngx_http_v3_client_ack_header(c, c->qs->id) != NGX_OK) {
            return NGX_ERROR;
        }
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_block_prefix(ngx_connection_t *c,
    ngx_http_v3_parse_header_block_prefix_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_req_insert_count,
        sw_delta_base,
        sw_read_delta_base
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse header block prefix");

        st->state = sw_req_insert_count;

        /* fall through */

    case sw_req_insert_count:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 8, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->insert_count = st->pint.value;
        st->state = sw_delta_base;
        break;

    case sw_delta_base:

        st->sign = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_delta_base;

        /* fall through */

    case sw_read_delta_base:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->delta_base = st->pint.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    rc = ngx_http_v3_decode_insert_count(c, &st->insert_count);
    if (rc != NGX_OK) {
        return rc;
    }

    if (st->sign) {
        st->base = st->insert_count - st->delta_base - 1;
    } else {
        st->base = st->insert_count + st->delta_base;
    }

    ngx_log_debug4(NGX_LOG_DEBUG_HTTP, c->log, 0,
                  "http3 parse header block prefix done "
                  "insert_count:%ui, sign:%ui, delta_base:%ui, base:%ui",
                  st->insert_count, st->sign, st->delta_base, st->base);

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_rep(ngx_connection_t *c,
    ngx_http_v3_parse_header_rep_t *st, ngx_uint_t base, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_header_ri,
        sw_header_lri,
        sw_header_l,
        sw_header_pbi,
        sw_header_lpbi
    };

    if (st->state == sw_start) {

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse header representation");

        ngx_memzero(&st->header, sizeof(ngx_http_v3_parse_header_t));

        st->header.base = base;

        if (ch & 0x80) {
            /* Indexed Header Field */

            st->state = sw_header_ri;

        } else if (ch & 0x40) {
            /* Literal Header Field With Name Reference */

            st->state = sw_header_lri;

        } else if (ch & 0x20) {
            /* Literal Header Field Without Name Reference */

            st->state = sw_header_l;

        } else if (ch & 0x10) {
            /* Indexed Header Field With Post-Base Index */

            st->state = sw_header_pbi;

        } else {
            /* Literal Header Field With Post-Base Name Reference */

            st->state = sw_header_lpbi;
        }
    }

    switch (st->state) {

    case sw_header_ri:
        rc = ngx_http_v3_parse_header_ri(c, &st->header, ch);
        break;

    case sw_header_lri:
        rc = ngx_http_v3_parse_header_lri(c, &st->header, ch);
        break;

    case sw_header_l:
        rc = ngx_http_v3_parse_header_l(c, &st->header, ch);
        break;

    case sw_header_pbi:
        rc = ngx_http_v3_parse_header_pbi(c, &st->header, ch);
        break;

    case sw_header_lpbi:
        rc = ngx_http_v3_parse_header_lpbi(c, &st->header, ch);
        break;

    default:
        rc = NGX_OK;
    }

    if (rc != NGX_DONE) {
        return rc;
    }

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header representation done");

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_literal(ngx_connection_t *c, ngx_http_v3_parse_literal_t *st,
    u_char ch)
{
    ngx_uint_t               n;
    ngx_http_v3_srv_conf_t  *h3scf;
    enum {
        sw_start = 0,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse literal huff:%ui, len:%ui",
                       st->huffman, st->length);

        n = st->length;

        h3scf = ngx_http_v3_get_module_srv_conf(c, ngx_http_v3_module);

        if (n > h3scf->max_field_size) {
            ngx_log_error(NGX_LOG_INFO, c->log, 0,
                          "client exceeded http3_max_field_size limit");
            return NGX_HTTP_V3_ERR_EXCESSIVE_LOAD;
        }

        if (st->huffman) {
            n = n * 8 / 5;
            st->huffstate = 0;
        }

        st->last = ngx_pnalloc(c->pool, n + 1);
        if (st->last == NULL) {
            return NGX_ERROR;
        }

        st->value.data = st->last;
        st->state = sw_value;

        /* fall through */

    case sw_value:

        if (st->huffman) {
            if (ngx_http_v2_huff_decode(&st->huffstate, &ch, 1, &st->last,
                                        st->length == 1, c->log)
                != NGX_OK)
            {
                return NGX_ERROR;
            }

        } else {
            *st->last++ = ch;
        }

        if (--st->length) {
            break;
        }

        st->value.len = st->last - st->value.data;
        *st->last = '\0';
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse literal done \"%V\"", &st->value);

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_ri(ngx_connection_t *c, ngx_http_v3_parse_header_t *st,
    u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_index
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse header ri");

        st->dynamic = (ch & 0x40) ? 0 : 1;
        st->state = sw_index;

        /* fall through */

    case sw_index:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 6, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->index = st->pint.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header ri done %s%ui]",
                   st->dynamic ? "dynamic[-" : "static[", st->index);

    if (st->dynamic) {
        st->index = st->base - st->index - 1;
    }

    rc = ngx_http_v3_parse_lookup(c, st->dynamic, st->index, &st->name,
                                  &st->value);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_lri(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_index,
        sw_value_len,
        sw_read_value_len,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse header lri");

        st->dynamic = (ch & 0x10) ? 0 : 1;
        st->state = sw_index;

        /* fall through */

    case sw_index:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 4, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->index = st->pint.value;
        st->state = sw_value_len;
        break;

    case sw_value_len:

        st->literal.huffman = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_value_len;

        /* fall through */

    case sw_read_value_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            goto done;
        }

        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->value = st->literal.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header lri done %s%ui] \"%V\"",
                   st->dynamic ? "dynamic[-" : "static[",
                   st->index, &st->value);

    if (st->dynamic) {
        st->index = st->base - st->index - 1;
    }

    rc = ngx_http_v3_parse_lookup(c, st->dynamic, st->index, &st->name, NULL);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_l(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_name_len,
        sw_name,
        sw_value_len,
        sw_read_value_len,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse header l");

        st->literal.huffman = (ch & 0x08) ? 1 : 0;
        st->state = sw_name_len;

        /* fall through */

    case sw_name_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 3, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            return NGX_ERROR;
        }

        st->state = sw_name;
        break;

    case sw_name:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->name = st->literal.value;
        st->state = sw_value_len;
        break;

    case sw_value_len:

        st->literal.huffman = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_value_len;

        /* fall through */

    case sw_read_value_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            goto done;
        }

        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->value = st->literal.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header l done \"%V\" \"%V\"",
                   &st->name, &st->value);

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_pbi(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_index
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse header pbi");

        st->state = sw_index;

        /* fall through */

    case sw_index:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 4, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->index = st->pint.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header pbi done dynamic[+%ui]", st->index);

    rc = ngx_http_v3_parse_lookup(c, 1, st->base + st->index, &st->name,
                                  &st->value);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_lpbi(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_index,
        sw_value_len,
        sw_read_value_len,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse header lpbi");

        st->state = sw_index;

        /* fall through */

    case sw_index:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 3, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->index = st->pint.value;
        st->state = sw_value_len;
        break;

    case sw_value_len:

        st->literal.huffman = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_value_len;

        /* fall through */

    case sw_read_value_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            goto done;
        }

        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->value = st->literal.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header lpbi done dynamic[+%ui] \"%V\"",
                   st->index, &st->value);

    rc = ngx_http_v3_parse_lookup(c, 1, st->base + st->index, &st->name, NULL);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


static ngx_int_t
ngx_http_v3_parse_lookup(ngx_connection_t *c, ngx_uint_t dynamic,
    ngx_uint_t index, ngx_str_t *name, ngx_str_t *value)
{
    u_char  *p;

    if (!dynamic) {
        if (ngx_http_v3_lookup_static(c, index, name, value) != NGX_OK) {
            return NGX_HTTP_V3_ERR_DECOMPRESSION_FAILED;
        }

        return NGX_OK;
    }

    if (ngx_http_v3_lookup(c, index, name, value) != NGX_OK) {
        return NGX_HTTP_V3_ERR_DECOMPRESSION_FAILED;
    }

    if (name) {
        p = ngx_pnalloc(c->pool, name->len + 1);
        if (p == NULL) {
            return NGX_ERROR;
        }

        ngx_memcpy(p, name->data, name->len);
        p[name->len] = '\0';
        name->data = p;
    }

    if (value) {
        p = ngx_pnalloc(c->pool, value->len + 1);
        if (p == NULL) {
            return NGX_ERROR;
        }

        ngx_memcpy(p, value->data, value->len);
        p[value->len] = '\0';
        value->data = p;
    }

    return NGX_OK;
}


ngx_int_t
ngx_http_v3_parse_control(ngx_connection_t *c, void *data, u_char ch)
{
    ngx_http_v3_parse_control_t *st = data;

    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_first_type,
        sw_type,
        sw_length,
        sw_cancel_push,
        sw_settings,
        sw_max_push_id,
        sw_skip
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse control");

        st->state = sw_first_type;

        /* fall through */

    case sw_first_type:
    case sw_type:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->type = st->vlint.value;

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse frame type:%ui", st->type);

        if (st->state == sw_first_type
            && st->type != NGX_HTTP_V3_FRAME_SETTINGS)
        {
            return NGX_HTTP_V3_ERR_MISSING_SETTINGS;
        }

        st->state = sw_length;
        break;

    case sw_length:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse frame len:%uL", st->vlint.value);

        st->length = st->vlint.value;
        if (st->length == 0) {
            st->state = sw_type;
            break;
        }

        switch (st->type) {

        case NGX_HTTP_V3_FRAME_CANCEL_PUSH:
            st->state = sw_cancel_push;
            break;

        case NGX_HTTP_V3_FRAME_SETTINGS:
            st->state = sw_settings;
            break;

        case NGX_HTTP_V3_FRAME_MAX_PUSH_ID:
            st->state = sw_max_push_id;
            break;

        default:
            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                           "http3 parse skip unknown frame");
            st->state = sw_skip;
        }

        break;

    case sw_cancel_push:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);

        if (--st->length == 0 && rc == NGX_AGAIN) {
            return NGX_HTTP_V3_ERR_FRAME_ERROR;
        }

        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_cancel_push(c, st->vlint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        st->state = sw_type;
        break;

    case sw_settings:

        rc = ngx_http_v3_parse_settings(c, &st->settings, ch);

        if (--st->length == 0 && rc == NGX_AGAIN) {
            return NGX_HTTP_V3_ERR_SETTINGS_ERROR;
        }

        if (rc != NGX_DONE) {
            return rc;
        }

        if (st->length == 0) {
            st->state = sw_type;
        }

        break;

    case sw_max_push_id:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);

        if (--st->length == 0 && rc == NGX_AGAIN) {
            return NGX_HTTP_V3_ERR_FRAME_ERROR;
        }

        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_set_max_push_id(c, st->vlint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        st->state = sw_type;
        break;

    case sw_skip:

        if (--st->length == 0) {
            st->state = sw_type;
        }

        break;
    }

    return NGX_AGAIN;
}


ngx_int_t
ngx_http_v3_parse_settings(ngx_connection_t *c,
    ngx_http_v3_parse_settings_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_id,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse settings");

        st->state = sw_id;

        /* fall through */

    case sw_id:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->id = st->vlint.value;
        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        if (ngx_http_v3_set_param(c, st->id, st->vlint.value) != NGX_OK) {
            return NGX_HTTP_V3_ERR_SETTINGS_ERROR;
        }

        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse settings done");

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_encoder(ngx_connection_t *c, void *data, u_char ch)
{
    ngx_http_v3_parse_encoder_t *st = data;

    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_inr,
        sw_iwnr,
        sw_capacity,
        sw_duplicate
    };

    if (st->state == sw_start) {

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse encoder instruction");

        if (ch & 0x80) {
            /* Insert With Name Reference */

            st->state = sw_inr;

        } else if (ch & 0x40) {
            /*  Insert Without Name Reference */

            st->state = sw_iwnr;

        } else if (ch & 0x20) {
            /*  Set Dynamic Table Capacity */

            st->state = sw_capacity;

        } else {
            /* Duplicate */

            st->state = sw_duplicate;
        }
    }

    switch (st->state) {

    case sw_inr:

        rc = ngx_http_v3_parse_header_inr(c, &st->header, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        goto done;

    case sw_iwnr:

        rc = ngx_http_v3_parse_header_iwnr(c, &st->header, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        goto done;

    case sw_capacity:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 5, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_set_capacity(c, st->pint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        goto done;

    case sw_duplicate:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 5, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_duplicate(c, st->pint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse encoder instruction done");

    st->state = sw_start;
    return NGX_AGAIN;
}


ngx_int_t
ngx_http_v3_parse_header_inr(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_name_index,
        sw_value_len,
        sw_read_value_len,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse header inr");

        st->dynamic = (ch & 0x40) ? 0 : 1;
        st->state = sw_name_index;

        /* fall through */

    case sw_name_index:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 6, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->index = st->pint.value;
        st->state = sw_value_len;
        break;

    case sw_value_len:

        st->literal.huffman = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_value_len;

        /* fall through */

    case sw_read_value_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            goto done;
        }

        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->value = st->literal.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header inr done %s[%ui] \"%V\"",
                   st->dynamic ? "dynamic" : "static",
                   st->index, &st->value);

    rc = ngx_http_v3_ref_insert(c, st->dynamic, st->index, &st->value);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_header_iwnr(ngx_connection_t *c,
    ngx_http_v3_parse_header_t *st, u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_name_len,
        sw_name,
        sw_value_len,
        sw_read_value_len,
        sw_value
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse header iwnr");

        st->literal.huffman = (ch & 0x20) ? 1 : 0;
        st->state = sw_name_len;

        /* fall through */

    case sw_name_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 5, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            return NGX_ERROR;
        }

        st->state = sw_name;
        break;

    case sw_name:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->name = st->literal.value;
        st->state = sw_value_len;
        break;

    case sw_value_len:

        st->literal.huffman = (ch & 0x80) ? 1 : 0;
        st->state = sw_read_value_len;

        /* fall through */

    case sw_read_value_len:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->literal.length = st->pint.value;
        if (st->literal.length == 0) {
            goto done;
        }

        st->state = sw_value;
        break;

    case sw_value:

        rc = ngx_http_v3_parse_literal(c, &st->literal, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->value = st->literal.value;
        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse header iwnr done \"%V\":\"%V\"",
                   &st->name, &st->value);

    rc = ngx_http_v3_insert(c, &st->name, &st->value);
    if (rc != NGX_OK) {
        return rc;
    }

    st->state = sw_start;
    return NGX_DONE;
}


ngx_int_t
ngx_http_v3_parse_decoder(ngx_connection_t *c, void *data, u_char ch)
{
    ngx_http_v3_parse_decoder_t *st = data;

    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_ack_header,
        sw_cancel_stream,
        sw_inc_insert_count
    };

    if (st->state == sw_start) {

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse decoder instruction");

        if (ch & 0x80) {
            /* Header Acknowledgement */

            st->state = sw_ack_header;

        } else if (ch & 0x40) {
            /*  Stream Cancellation */

            st->state = sw_cancel_stream;

        }  else {
            /*  Insert Count Increment */

            st->state = sw_inc_insert_count;
        }
    }

    switch (st->state) {

    case sw_ack_header:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 7, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_ack_header(c, st->pint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        goto done;

    case sw_cancel_stream:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 6, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_cancel_stream(c, st->pint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        goto done;

    case sw_inc_insert_count:

        rc = ngx_http_v3_parse_prefix_int(c, &st->pint, 6, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        rc = ngx_http_v3_inc_insert_count(c, st->pint.value);
        if (rc != NGX_OK) {
            return rc;
        }

        goto done;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http3 parse decoder instruction done");

    st->state = sw_start;
    return NGX_AGAIN;
}


ngx_int_t
ngx_http_v3_parse_data(ngx_connection_t *c, ngx_http_v3_parse_data_t *st,
    u_char ch)
{
    ngx_int_t  rc;
    enum {
        sw_start = 0,
        sw_type,
        sw_length,
        sw_skip
    };

    switch (st->state) {

    case sw_start:

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse data");

        st->state = sw_type;

        /* fall through */

    case sw_type:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->type = st->vlint.value;

        if (st->type == NGX_HTTP_V3_FRAME_HEADERS) {
            /* trailers */
            goto done;
        }

        st->state = sw_length;
        break;

    case sw_length:

        rc = ngx_http_v3_parse_varlen_int(c, &st->vlint, ch);
        if (rc != NGX_DONE) {
            return rc;
        }

        st->length = st->vlint.value;

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http3 parse data type:%ui, len:%ui",
                       st->type, st->length);

        if (st->type != NGX_HTTP_V3_FRAME_DATA && st->length > 0) {
            st->state = sw_skip;
            break;
        }

        st->state = sw_type;
        return NGX_OK;

    case sw_skip:

        if (--st->length == 0) {
            st->state = sw_type;
        }

        break;
    }

    return NGX_AGAIN;

done:

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 parse data done");

    st->state = sw_start;
    return NGX_DONE;
}