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view src/http/v2/ngx_http_v2_table.c @ 7975:a7a77549265e

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HTTP/2: fixed sendfile() aio handling. With sendfile() in threads ("aio threads; sendfile on;"), client connection can block on writing, waiting for sendfile() to complete. In HTTP/2 this might result in the request hang, since an attempt to continue processing in thread event handler will call request's write event handler, which is usually stopped by ngx_http_v2_send_chain(): it does nothing if there are no additional data and stream->queued is set. Further, HTTP/2 resets stream's c->write->ready to 0 if writing blocks, so just fixing ngx_http_v2_send_chain() is not enough. Can be reproduced with test suite on Linux with: TEST_NGINX_GLOBALS_HTTP="aio threads; sendfile on;" prove h2*.t The following tests currently fail: h2_keepalive.t, h2_priority.t, h2_proxy_max_temp_file_size.t, h2.t, h2_trailers.t. Similarly, sendfile() with AIO preloading on FreeBSD can block as well, with similar results. This is, however, harder to reproduce, especially on modern FreeBSD systems, since sendfile() usually does not return EBUSY. Fix is to modify ngx_http_v2_send_chain() so it actually tries to send data to the main connection when called, and to make sure that c->write->ready is set by the relevant event handlers.
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 25 Nov 2021 22:02:10 +0300
parents 87e9e4aabf1b
children
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Valentin V. Bartenev
 */


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


#define NGX_HTTP_V2_TABLE_SIZE  4096


static ngx_int_t ngx_http_v2_table_account(ngx_http_v2_connection_t *h2c,
    size_t size);


static ngx_http_v2_header_t  ngx_http_v2_static_table[] = {
    { ngx_string(":authority"), ngx_string("") },
    { ngx_string(":method"), ngx_string("GET") },
    { ngx_string(":method"), ngx_string("POST") },
    { ngx_string(":path"), ngx_string("/") },
    { ngx_string(":path"), ngx_string("/index.html") },
    { ngx_string(":scheme"), ngx_string("http") },
    { ngx_string(":scheme"), ngx_string("https") },
    { ngx_string(":status"), ngx_string("200") },
    { ngx_string(":status"), ngx_string("204") },
    { ngx_string(":status"), ngx_string("206") },
    { ngx_string(":status"), ngx_string("304") },
    { ngx_string(":status"), ngx_string("400") },
    { ngx_string(":status"), ngx_string("404") },
    { ngx_string(":status"), ngx_string("500") },
    { ngx_string("accept-charset"), ngx_string("") },
    { ngx_string("accept-encoding"), ngx_string("gzip, deflate") },
    { ngx_string("accept-language"), ngx_string("") },
    { ngx_string("accept-ranges"), ngx_string("") },
    { ngx_string("accept"), ngx_string("") },
    { ngx_string("access-control-allow-origin"), ngx_string("") },
    { ngx_string("age"), ngx_string("") },
    { ngx_string("allow"), ngx_string("") },
    { ngx_string("authorization"), ngx_string("") },
    { ngx_string("cache-control"), ngx_string("") },
    { ngx_string("content-disposition"), ngx_string("") },
    { ngx_string("content-encoding"), ngx_string("") },
    { ngx_string("content-language"), ngx_string("") },
    { ngx_string("content-length"), ngx_string("") },
    { ngx_string("content-location"), ngx_string("") },
    { ngx_string("content-range"), ngx_string("") },
    { ngx_string("content-type"), ngx_string("") },
    { ngx_string("cookie"), ngx_string("") },
    { ngx_string("date"), ngx_string("") },
    { ngx_string("etag"), ngx_string("") },
    { ngx_string("expect"), ngx_string("") },
    { ngx_string("expires"), ngx_string("") },
    { ngx_string("from"), ngx_string("") },
    { ngx_string("host"), ngx_string("") },
    { ngx_string("if-match"), ngx_string("") },
    { ngx_string("if-modified-since"), ngx_string("") },
    { ngx_string("if-none-match"), ngx_string("") },
    { ngx_string("if-range"), ngx_string("") },
    { ngx_string("if-unmodified-since"), ngx_string("") },
    { ngx_string("last-modified"), ngx_string("") },
    { ngx_string("link"), ngx_string("") },
    { ngx_string("location"), ngx_string("") },
    { ngx_string("max-forwards"), ngx_string("") },
    { ngx_string("proxy-authenticate"), ngx_string("") },
    { ngx_string("proxy-authorization"), ngx_string("") },
    { ngx_string("range"), ngx_string("") },
    { ngx_string("referer"), ngx_string("") },
    { ngx_string("refresh"), ngx_string("") },
    { ngx_string("retry-after"), ngx_string("") },
    { ngx_string("server"), ngx_string("") },
    { ngx_string("set-cookie"), ngx_string("") },
    { ngx_string("strict-transport-security"), ngx_string("") },
    { ngx_string("transfer-encoding"), ngx_string("") },
    { ngx_string("user-agent"), ngx_string("") },
    { ngx_string("vary"), ngx_string("") },
    { ngx_string("via"), ngx_string("") },
    { ngx_string("www-authenticate"), ngx_string("") },
};

#define NGX_HTTP_V2_STATIC_TABLE_ENTRIES                                      \
    (sizeof(ngx_http_v2_static_table)                                         \
     / sizeof(ngx_http_v2_header_t))


ngx_str_t *
ngx_http_v2_get_static_name(ngx_uint_t index)
{
    return &ngx_http_v2_static_table[index - 1].name;
}


ngx_str_t *
ngx_http_v2_get_static_value(ngx_uint_t index)
{
    return &ngx_http_v2_static_table[index - 1].value;
}


ngx_int_t
ngx_http_v2_get_indexed_header(ngx_http_v2_connection_t *h2c, ngx_uint_t index,
    ngx_uint_t name_only)
{
    u_char                *p;
    size_t                 rest;
    ngx_http_v2_header_t  *entry;

    if (index == 0) {
        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
                      "client sent invalid hpack table index 0");
        return NGX_ERROR;
    }

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
                   "http2 get indexed %s: %ui",
                   name_only ? "name" : "header", index);

    index--;

    if (index < NGX_HTTP_V2_STATIC_TABLE_ENTRIES) {
        h2c->state.header = ngx_http_v2_static_table[index];
        return NGX_OK;
    }

    index -= NGX_HTTP_V2_STATIC_TABLE_ENTRIES;

    if (index < h2c->hpack.added - h2c->hpack.deleted) {
        index = (h2c->hpack.added - index - 1) % h2c->hpack.allocated;
        entry = h2c->hpack.entries[index];

        p = ngx_pnalloc(h2c->state.pool, entry->name.len + 1);
        if (p == NULL) {
            return NGX_ERROR;
        }

        h2c->state.header.name.len = entry->name.len;
        h2c->state.header.name.data = p;

        rest = h2c->hpack.storage + NGX_HTTP_V2_TABLE_SIZE - entry->name.data;

        if (entry->name.len > rest) {
            p = ngx_cpymem(p, entry->name.data, rest);
            p = ngx_cpymem(p, h2c->hpack.storage, entry->name.len - rest);

        } else {
            p = ngx_cpymem(p, entry->name.data, entry->name.len);
        }

        *p = '\0';

        if (name_only) {
            return NGX_OK;
        }

        p = ngx_pnalloc(h2c->state.pool, entry->value.len + 1);
        if (p == NULL) {
            return NGX_ERROR;
        }

        h2c->state.header.value.len = entry->value.len;
        h2c->state.header.value.data = p;

        rest = h2c->hpack.storage + NGX_HTTP_V2_TABLE_SIZE - entry->value.data;

        if (entry->value.len > rest) {
            p = ngx_cpymem(p, entry->value.data, rest);
            p = ngx_cpymem(p, h2c->hpack.storage, entry->value.len - rest);

        } else {
            p = ngx_cpymem(p, entry->value.data, entry->value.len);
        }

        *p = '\0';

        return NGX_OK;
    }

    ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
                  "client sent out of bound hpack table index: %ui", index);

    return NGX_ERROR;
}


ngx_int_t
ngx_http_v2_add_header(ngx_http_v2_connection_t *h2c,
    ngx_http_v2_header_t *header)
{
    size_t                 avail;
    ngx_uint_t             index;
    ngx_http_v2_header_t  *entry, **entries;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
                   "http2 table add: \"%V: %V\"",
                   &header->name, &header->value);

    if (h2c->hpack.entries == NULL) {
        h2c->hpack.allocated = 64;
        h2c->hpack.size = NGX_HTTP_V2_TABLE_SIZE;
        h2c->hpack.free = NGX_HTTP_V2_TABLE_SIZE;

        h2c->hpack.entries = ngx_palloc(h2c->connection->pool,
                                        sizeof(ngx_http_v2_header_t *)
                                        * h2c->hpack.allocated);
        if (h2c->hpack.entries == NULL) {
            return NGX_ERROR;
        }

        h2c->hpack.storage = ngx_palloc(h2c->connection->pool,
                                        h2c->hpack.free);
        if (h2c->hpack.storage == NULL) {
            return NGX_ERROR;
        }

        h2c->hpack.pos = h2c->hpack.storage;
    }

    if (ngx_http_v2_table_account(h2c, header->name.len + header->value.len)
        != NGX_OK)
    {
        return NGX_OK;
    }

    if (h2c->hpack.reused == h2c->hpack.deleted) {
        entry = ngx_palloc(h2c->connection->pool, sizeof(ngx_http_v2_header_t));
        if (entry == NULL) {
            return NGX_ERROR;
        }

    } else {
        entry = h2c->hpack.entries[h2c->hpack.reused++ % h2c->hpack.allocated];
    }

    avail = h2c->hpack.storage + NGX_HTTP_V2_TABLE_SIZE - h2c->hpack.pos;

    entry->name.len = header->name.len;
    entry->name.data = h2c->hpack.pos;

    if (avail >= header->name.len) {
        h2c->hpack.pos = ngx_cpymem(h2c->hpack.pos, header->name.data,
                                    header->name.len);
    } else {
        ngx_memcpy(h2c->hpack.pos, header->name.data, avail);
        h2c->hpack.pos = ngx_cpymem(h2c->hpack.storage,
                                    header->name.data + avail,
                                    header->name.len - avail);
        avail = NGX_HTTP_V2_TABLE_SIZE;
    }

    avail -= header->name.len;

    entry->value.len = header->value.len;
    entry->value.data = h2c->hpack.pos;

    if (avail >= header->value.len) {
        h2c->hpack.pos = ngx_cpymem(h2c->hpack.pos, header->value.data,
                                    header->value.len);
    } else {
        ngx_memcpy(h2c->hpack.pos, header->value.data, avail);
        h2c->hpack.pos = ngx_cpymem(h2c->hpack.storage,
                                    header->value.data + avail,
                                    header->value.len - avail);
    }

    if (h2c->hpack.allocated == h2c->hpack.added - h2c->hpack.deleted) {

        entries = ngx_palloc(h2c->connection->pool,
                             sizeof(ngx_http_v2_header_t *)
                             * (h2c->hpack.allocated + 64));
        if (entries == NULL) {
            return NGX_ERROR;
        }

        index = h2c->hpack.deleted % h2c->hpack.allocated;

        ngx_memcpy(entries, &h2c->hpack.entries[index],
                   (h2c->hpack.allocated - index)
                   * sizeof(ngx_http_v2_header_t *));

        ngx_memcpy(&entries[h2c->hpack.allocated - index], h2c->hpack.entries,
                   index * sizeof(ngx_http_v2_header_t *));

        (void) ngx_pfree(h2c->connection->pool, h2c->hpack.entries);

        h2c->hpack.entries = entries;

        h2c->hpack.added = h2c->hpack.allocated;
        h2c->hpack.deleted = 0;
        h2c->hpack.reused = 0;
        h2c->hpack.allocated += 64;
    }

    h2c->hpack.entries[h2c->hpack.added++ % h2c->hpack.allocated] = entry;

    return NGX_OK;
}


static ngx_int_t
ngx_http_v2_table_account(ngx_http_v2_connection_t *h2c, size_t size)
{
    ngx_http_v2_header_t  *entry;

    size += 32;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
                   "http2 table account: %uz free:%uz",
                   size, h2c->hpack.free);

    if (size <= h2c->hpack.free) {
        h2c->hpack.free -= size;
        return NGX_OK;
    }

    if (size > h2c->hpack.size) {
        h2c->hpack.deleted = h2c->hpack.added;
        h2c->hpack.free = h2c->hpack.size;
        return NGX_DECLINED;
    }

    do {
        entry = h2c->hpack.entries[h2c->hpack.deleted++ % h2c->hpack.allocated];
        h2c->hpack.free += 32 + entry->name.len + entry->value.len;
    } while (size > h2c->hpack.free);

    h2c->hpack.free -= size;

    return NGX_OK;
}


ngx_int_t
ngx_http_v2_table_size(ngx_http_v2_connection_t *h2c, size_t size)
{
    ssize_t                needed;
    ngx_http_v2_header_t  *entry;

    if (size > NGX_HTTP_V2_TABLE_SIZE) {
        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
                      "client sent invalid table size update: %uz", size);

        return NGX_ERROR;
    }

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
                   "http2 new hpack table size: %uz was:%uz",
                   size, h2c->hpack.size);

    needed = h2c->hpack.size - size;

    while (needed > (ssize_t) h2c->hpack.free) {
        entry = h2c->hpack.entries[h2c->hpack.deleted++ % h2c->hpack.allocated];
        h2c->hpack.free += 32 + entry->name.len + entry->value.len;
    }

    h2c->hpack.size = size;
    h2c->hpack.free -= needed;

    return NGX_OK;
}