view src/event/quic/ngx_event_quic_tokens.c @ 9138:a90f79792b5d

QUIC: optimized ACK delay. Previously ACK was not generated if max_ack_delay was not yet expired and the number of unacknowledged ack-eliciting packets was less than two, as allowed by RFC 9000 13.2.1-13.2.2. However this only makes sense to avoid sending ACK-only packets, as explained by the RFC: On the other hand, reducing the frequency of packets that carry only acknowledgments reduces packet transmission and processing cost at both endpoints. Now ACK is delayed only if output frame queue is empty. Otherwise ACK is sent immediately, which significantly improves QUIC performance with certain tests.
author Roman Arutyunyan <arut@nginx.com>
date Thu, 27 Jul 2023 16:37:17 +0400
parents 77c1418916f7
children
line wrap: on
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/*
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_sha1.h>
#include <ngx_event_quic_connection.h>


static void ngx_quic_address_hash(struct sockaddr *sockaddr, socklen_t socklen,
    ngx_uint_t no_port, u_char buf[20]);


ngx_int_t
ngx_quic_new_sr_token(ngx_connection_t *c, ngx_str_t *cid, u_char *secret,
    u_char *token)
{
    ngx_str_t  tmp;

    tmp.data = secret;
    tmp.len = NGX_QUIC_SR_KEY_LEN;

    if (ngx_quic_derive_key(c->log, "sr_token_key", &tmp, cid, token,
                            NGX_QUIC_SR_TOKEN_LEN)
        != NGX_OK)
    {
        return NGX_ERROR;
    }

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
                   "quic stateless reset token %*xs",
                    (size_t) NGX_QUIC_SR_TOKEN_LEN, token);

    return NGX_OK;
}


ngx_int_t
ngx_quic_new_token(ngx_log_t *log, struct sockaddr *sockaddr,
    socklen_t socklen, u_char *key, ngx_str_t *token, ngx_str_t *odcid,
    time_t exp, ngx_uint_t is_retry)
{
    int                len, iv_len;
    u_char            *p, *iv;
    EVP_CIPHER_CTX    *ctx;
    const EVP_CIPHER  *cipher;

    u_char             in[NGX_QUIC_MAX_TOKEN_SIZE];

    ngx_quic_address_hash(sockaddr, socklen, !is_retry, in);

    p = in + 20;

    p = ngx_cpymem(p, &exp, sizeof(time_t));

    *p++ = is_retry ? 1 : 0;

    if (odcid) {
        *p++ = odcid->len;
        p = ngx_cpymem(p, odcid->data, odcid->len);

    } else {
        *p++ = 0;
    }

    len = p - in;

    cipher = EVP_aes_256_gcm();
    iv_len = NGX_QUIC_AES_256_GCM_IV_LEN;

    if ((size_t) (iv_len + len + NGX_QUIC_AES_256_GCM_TAG_LEN) > token->len) {
        ngx_log_error(NGX_LOG_ALERT, log, 0, "quic token buffer is too small");
        return NGX_ERROR;
    }

    ctx = EVP_CIPHER_CTX_new();
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    iv = token->data;

    if (RAND_bytes(iv, iv_len) <= 0
        || !EVP_EncryptInit_ex(ctx, cipher, NULL, key, iv))
    {
        EVP_CIPHER_CTX_free(ctx);
        return NGX_ERROR;
    }

    token->len = iv_len;

    if (EVP_EncryptUpdate(ctx, token->data + token->len, &len, in, len) != 1) {
        EVP_CIPHER_CTX_free(ctx);
        return NGX_ERROR;
    }

    token->len += len;

    if (EVP_EncryptFinal_ex(ctx, token->data + token->len, &len) <= 0) {
        EVP_CIPHER_CTX_free(ctx);
        return NGX_ERROR;
    }

    token->len += len;

    if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG,
                            NGX_QUIC_AES_256_GCM_TAG_LEN,
                            token->data + token->len)
        == 0)
    {
        EVP_CIPHER_CTX_free(ctx);
        return NGX_ERROR;
    }

    token->len += NGX_QUIC_AES_256_GCM_TAG_LEN;

    EVP_CIPHER_CTX_free(ctx);

#ifdef NGX_QUIC_DEBUG_PACKETS
    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, log, 0,
                   "quic new token len:%uz %xV", token->len, token);
#endif

    return NGX_OK;
}


static void
ngx_quic_address_hash(struct sockaddr *sockaddr, socklen_t socklen,
    ngx_uint_t no_port, u_char buf[20])
{
    size_t                len;
    u_char               *data;
    ngx_sha1_t            sha1;
    struct sockaddr_in   *sin;
#if (NGX_HAVE_INET6)
    struct sockaddr_in6  *sin6;
#endif

    len = (size_t) socklen;
    data = (u_char *) sockaddr;

    if (no_port) {
        switch (sockaddr->sa_family) {

#if (NGX_HAVE_INET6)
        case AF_INET6:
            sin6 = (struct sockaddr_in6 *) sockaddr;

            len = sizeof(struct in6_addr);
            data = sin6->sin6_addr.s6_addr;

            break;
#endif

        case AF_INET:
            sin = (struct sockaddr_in *) sockaddr;

            len = sizeof(in_addr_t);
            data = (u_char *) &sin->sin_addr;

            break;
        }
    }

    ngx_sha1_init(&sha1);
    ngx_sha1_update(&sha1, data, len);
    ngx_sha1_final(buf, &sha1);
}


ngx_int_t
ngx_quic_validate_token(ngx_connection_t *c, u_char *key,
    ngx_quic_header_t *pkt)
{
    int                len, tlen, iv_len;
    u_char            *iv, *p;
    time_t             now, exp;
    size_t             total;
    ngx_str_t          odcid;
    EVP_CIPHER_CTX    *ctx;
    const EVP_CIPHER  *cipher;

    u_char             addr_hash[20];
    u_char             tdec[NGX_QUIC_MAX_TOKEN_SIZE];

#if NGX_SUPPRESS_WARN
    ngx_str_null(&odcid);
#endif

    /* Retry token or NEW_TOKEN in a previous connection */

    cipher = EVP_aes_256_gcm();
    iv = pkt->token.data;
    iv_len = NGX_QUIC_AES_256_GCM_IV_LEN;

    /* sanity checks */

    if (pkt->token.len < (size_t) iv_len + NGX_QUIC_AES_256_GCM_TAG_LEN) {
        goto garbage;
    }

    if (pkt->token.len > (size_t) iv_len + NGX_QUIC_MAX_TOKEN_SIZE
                         + NGX_QUIC_AES_256_GCM_TAG_LEN)
    {
        goto garbage;
    }

    ctx = EVP_CIPHER_CTX_new();
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    if (!EVP_DecryptInit_ex(ctx, cipher, NULL, key, iv)) {
        EVP_CIPHER_CTX_free(ctx);
        return NGX_ERROR;
    }

    p = pkt->token.data + iv_len;
    len = pkt->token.len - iv_len - NGX_QUIC_AES_256_GCM_TAG_LEN;

    if (EVP_DecryptUpdate(ctx, tdec, &tlen, p, len) != 1) {
        EVP_CIPHER_CTX_free(ctx);
        goto garbage;
    }
    total = tlen;

    if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
                            NGX_QUIC_AES_256_GCM_TAG_LEN, p + len)
        == 0)
    {
        EVP_CIPHER_CTX_free(ctx);
        goto garbage;
    }

    if (EVP_DecryptFinal_ex(ctx, tdec + tlen, &tlen) <= 0) {
        EVP_CIPHER_CTX_free(ctx);
        goto garbage;
    }
    total += tlen;

    EVP_CIPHER_CTX_free(ctx);

    if (total < (20 + sizeof(time_t) + 2)) {
        goto garbage;
    }

    p = tdec + 20;

    ngx_memcpy(&exp, p, sizeof(time_t));
    p += sizeof(time_t);

    pkt->retried = (*p++ == 1);

    ngx_quic_address_hash(c->sockaddr, c->socklen, !pkt->retried, addr_hash);

    if (ngx_memcmp(tdec, addr_hash, 20) != 0) {
        goto bad_token;
    }

    odcid.len = *p++;
    if (odcid.len) {
        if (odcid.len > NGX_QUIC_MAX_CID_LEN) {
            goto bad_token;
        }

        if ((size_t)(tdec + total - p) < odcid.len) {
            goto bad_token;
        }

        odcid.data = p;
    }

    now = ngx_time();

    if (now > exp) {
        ngx_log_error(NGX_LOG_INFO, c->log, 0, "quic expired token");
        return NGX_DECLINED;
    }

    if (odcid.len) {
        pkt->odcid.len = odcid.len;
        pkt->odcid.data = pkt->odcid_buf;
        ngx_memcpy(pkt->odcid.data, odcid.data, odcid.len);

    } else {
        pkt->odcid = pkt->dcid;
    }

    pkt->validated = 1;

    return NGX_OK;

garbage:

    ngx_log_error(NGX_LOG_INFO, c->log, 0, "quic garbage token");

    return NGX_ABORT;

bad_token:

    ngx_log_error(NGX_LOG_INFO, c->log, 0, "quic invalid token");

    return NGX_DECLINED;
}