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view src/http/modules/ngx_http_userid_filter_module.c @ 6755:e2f13011343e stable-1.10

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HTTP/2: fixed the "http request count is zero" alert. When the stream is terminated the HEADERS frame can still wait in the output queue. This frame can't be removed and must be sent to the client anyway, since HTTP/2 uses stateful compression for headers. So in order to postpone closing and freeing memory of such stream the special close stream handler is set to the write event. After the HEADERS frame is sent the write event is called and the stream will be finally closed. Some events like receiving a RST_STREAM can trigger the read handler of such stream in closing state and cause unexpected processing that can result in another attempt to finalize the request. To prevent it the read handler is now set to ngx_http_empty_handler. Thanks to Amazon.
author Valentin Bartenev <vbart@nginx.com>
date Thu, 16 Jun 2016 20:55:11 +0300
parents 778ef9c3fd2d
children b3682580c1bd
line wrap: on
line source


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


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


#define NGX_HTTP_USERID_OFF   0
#define NGX_HTTP_USERID_LOG   1
#define NGX_HTTP_USERID_V1    2
#define NGX_HTTP_USERID_ON    3

/* 31 Dec 2037 23:55:55 GMT */
#define NGX_HTTP_USERID_MAX_EXPIRES  2145916555


typedef struct {
    ngx_uint_t  enable;

    ngx_int_t   service;

    ngx_str_t   name;
    ngx_str_t   domain;
    ngx_str_t   path;
    ngx_str_t   p3p;

    time_t      expires;

    u_char      mark;
} ngx_http_userid_conf_t;


typedef struct {
    uint32_t    uid_got[4];
    uint32_t    uid_set[4];
    ngx_str_t   cookie;
    ngx_uint_t  reset;
} ngx_http_userid_ctx_t;


static ngx_http_userid_ctx_t *ngx_http_userid_get_uid(ngx_http_request_t *r,
    ngx_http_userid_conf_t *conf);
static ngx_int_t ngx_http_userid_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, ngx_str_t *name, uint32_t *uid);
static ngx_int_t ngx_http_userid_set_uid(ngx_http_request_t *r,
    ngx_http_userid_ctx_t *ctx, ngx_http_userid_conf_t *conf);
static ngx_int_t ngx_http_userid_create_uid(ngx_http_request_t *r,
    ngx_http_userid_ctx_t *ctx, ngx_http_userid_conf_t *conf);

static ngx_int_t ngx_http_userid_add_variables(ngx_conf_t *cf);
static ngx_int_t ngx_http_userid_init(ngx_conf_t *cf);
static void *ngx_http_userid_create_conf(ngx_conf_t *cf);
static char *ngx_http_userid_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_http_userid_domain(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_userid_path(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_userid_expires(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_userid_p3p(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_userid_mark(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_http_userid_init_worker(ngx_cycle_t *cycle);



static uint32_t  start_value;
static uint32_t  sequencer_v1 = 1;
static uint32_t  sequencer_v2 = 0x03030302;


static u_char expires[] = "; expires=Thu, 31-Dec-37 23:55:55 GMT";


static ngx_http_output_header_filter_pt  ngx_http_next_header_filter;


static ngx_conf_enum_t  ngx_http_userid_state[] = {
    { ngx_string("off"), NGX_HTTP_USERID_OFF },
    { ngx_string("log"), NGX_HTTP_USERID_LOG },
    { ngx_string("v1"), NGX_HTTP_USERID_V1 },
    { ngx_string("on"), NGX_HTTP_USERID_ON },
    { ngx_null_string, 0 }
};


static ngx_conf_post_handler_pt  ngx_http_userid_domain_p =
    ngx_http_userid_domain;
static ngx_conf_post_handler_pt  ngx_http_userid_path_p = ngx_http_userid_path;
static ngx_conf_post_handler_pt  ngx_http_userid_p3p_p = ngx_http_userid_p3p;


static ngx_command_t  ngx_http_userid_commands[] = {

    { ngx_string("userid"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, enable),
      ngx_http_userid_state },

    { ngx_string("userid_service"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, service),
      NULL },

    { ngx_string("userid_name"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, name),
      NULL },

    { ngx_string("userid_domain"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, domain),
      &ngx_http_userid_domain_p },

    { ngx_string("userid_path"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, path),
      &ngx_http_userid_path_p },

    { ngx_string("userid_expires"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_http_userid_expires,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("userid_p3p"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_userid_conf_t, p3p),
      &ngx_http_userid_p3p_p },

    { ngx_string("userid_mark"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_http_userid_mark,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_userid_filter_module_ctx = {
    ngx_http_userid_add_variables,         /* preconfiguration */
    ngx_http_userid_init,                  /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    NULL,                                  /* create server configuration */
    NULL,                                  /* merge server configuration */

    ngx_http_userid_create_conf,           /* create location configuration */
    ngx_http_userid_merge_conf             /* merge location configuration */
};


ngx_module_t  ngx_http_userid_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_userid_filter_module_ctx,    /* module context */
    ngx_http_userid_commands,              /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    ngx_http_userid_init_worker,           /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_str_t   ngx_http_userid_got = ngx_string("uid_got");
static ngx_str_t   ngx_http_userid_set = ngx_string("uid_set");
static ngx_str_t   ngx_http_userid_reset = ngx_string("uid_reset");
static ngx_uint_t  ngx_http_userid_reset_index;


static ngx_int_t
ngx_http_userid_filter(ngx_http_request_t *r)
{
    ngx_http_userid_ctx_t   *ctx;
    ngx_http_userid_conf_t  *conf;

    if (r != r->main) {
        return ngx_http_next_header_filter(r);
    }

    conf = ngx_http_get_module_loc_conf(r, ngx_http_userid_filter_module);

    if (conf->enable < NGX_HTTP_USERID_V1) {
        return ngx_http_next_header_filter(r);
    }

    ctx = ngx_http_userid_get_uid(r, conf);

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

    if (ngx_http_userid_set_uid(r, ctx, conf) == NGX_OK) {
        return ngx_http_next_header_filter(r);
    }

    return NGX_ERROR;
}


static ngx_int_t
ngx_http_userid_got_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_userid_ctx_t   *ctx;
    ngx_http_userid_conf_t  *conf;

    conf = ngx_http_get_module_loc_conf(r->main, ngx_http_userid_filter_module);

    if (conf->enable == NGX_HTTP_USERID_OFF) {
        v->not_found = 1;
        return NGX_OK;
    }

    ctx = ngx_http_userid_get_uid(r->main, conf);

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

    if (ctx->uid_got[3] != 0) {
        return ngx_http_userid_variable(r->main, v, &conf->name, ctx->uid_got);
    }

    v->not_found = 1;

    return NGX_OK;
}


static ngx_int_t
ngx_http_userid_set_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_userid_ctx_t   *ctx;
    ngx_http_userid_conf_t  *conf;

    conf = ngx_http_get_module_loc_conf(r->main, ngx_http_userid_filter_module);

    if (conf->enable < NGX_HTTP_USERID_V1) {
        v->not_found = 1;
        return NGX_OK;
    }

    ctx = ngx_http_userid_get_uid(r->main, conf);

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

    if (ngx_http_userid_create_uid(r->main, ctx, conf) != NGX_OK) {
        return NGX_ERROR;
    }

    if (ctx->uid_set[3] == 0) {
        v->not_found = 1;
        return NGX_OK;
    }

    return ngx_http_userid_variable(r->main, v, &conf->name, ctx->uid_set);
}


static ngx_http_userid_ctx_t *
ngx_http_userid_get_uid(ngx_http_request_t *r, ngx_http_userid_conf_t *conf)
{
    ngx_int_t                n;
    ngx_str_t                src, dst;
    ngx_table_elt_t        **cookies;
    ngx_http_userid_ctx_t   *ctx;

    ctx = ngx_http_get_module_ctx(r, ngx_http_userid_filter_module);

    if (ctx) {
        return ctx;
    }

    if (ctx == NULL) {
        ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_userid_ctx_t));
        if (ctx == NULL) {
            return NULL;
        }

        ngx_http_set_ctx(r, ctx, ngx_http_userid_filter_module);
    }

    n = ngx_http_parse_multi_header_lines(&r->headers_in.cookies, &conf->name,
                                          &ctx->cookie);
    if (n == NGX_DECLINED) {
        return ctx;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "uid cookie: \"%V\"", &ctx->cookie);

    if (ctx->cookie.len < 22) {
        cookies = r->headers_in.cookies.elts;
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "client sent too short userid cookie \"%V\"",
                      &cookies[n]->value);
        return ctx;
    }

    src = ctx->cookie;

    /*
     * we have to limit the encoded string to 22 characters because
     *  1) cookie may be marked by "userid_mark",
     *  2) and there are already the millions cookies with a garbage
     *     instead of the correct base64 trail "=="
     */

    src.len = 22;

    dst.data = (u_char *) ctx->uid_got;

    if (ngx_decode_base64(&dst, &src) == NGX_ERROR) {
        cookies = r->headers_in.cookies.elts;
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "client sent invalid userid cookie \"%V\"",
                      &cookies[n]->value);
        return ctx;
    }

    ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "uid: %08XD%08XD%08XD%08XD",
                   ctx->uid_got[0], ctx->uid_got[1],
                   ctx->uid_got[2], ctx->uid_got[3]);

    return ctx;
}


static ngx_int_t
ngx_http_userid_set_uid(ngx_http_request_t *r, ngx_http_userid_ctx_t *ctx,
    ngx_http_userid_conf_t *conf)
{
    u_char           *cookie, *p;
    size_t            len;
    ngx_str_t         src, dst;
    ngx_table_elt_t  *set_cookie, *p3p;

    if (ngx_http_userid_create_uid(r, ctx, conf) != NGX_OK) {
        return NGX_ERROR;
    }

    if (ctx->uid_set[3] == 0) {
        return NGX_OK;
    }

    len = conf->name.len + 1 + ngx_base64_encoded_length(16) + conf->path.len;

    if (conf->expires) {
        len += sizeof(expires) - 1 + 2;
    }

    if (conf->domain.len) {
        len += conf->domain.len;
    }

    cookie = ngx_pnalloc(r->pool, len);
    if (cookie == NULL) {
        return NGX_ERROR;
    }

    p = ngx_copy(cookie, conf->name.data, conf->name.len);
    *p++ = '=';

    if (ctx->uid_got[3] == 0 || ctx->reset) {
        src.len = 16;
        src.data = (u_char *) ctx->uid_set;
        dst.data = p;

        ngx_encode_base64(&dst, &src);

        p += dst.len;

        if (conf->mark) {
            *(p - 2) = conf->mark;
        }

    } else {
        p = ngx_cpymem(p, ctx->cookie.data, 22);
        *p++ = conf->mark;
        *p++ = '=';
    }

    if (conf->expires == NGX_HTTP_USERID_MAX_EXPIRES) {
        p = ngx_cpymem(p, expires, sizeof(expires) - 1);

    } else if (conf->expires) {
        p = ngx_cpymem(p, expires, sizeof("; expires=") - 1);
        p = ngx_http_cookie_time(p, ngx_time() + conf->expires);
    }

    p = ngx_copy(p, conf->domain.data, conf->domain.len);

    p = ngx_copy(p, conf->path.data, conf->path.len);

    set_cookie = ngx_list_push(&r->headers_out.headers);
    if (set_cookie == NULL) {
        return NGX_ERROR;
    }

    set_cookie->hash = 1;
    ngx_str_set(&set_cookie->key, "Set-Cookie");
    set_cookie->value.len = p - cookie;
    set_cookie->value.data = cookie;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "uid cookie: \"%V\"", &set_cookie->value);

    if (conf->p3p.len == 0) {
        return NGX_OK;
    }

    p3p = ngx_list_push(&r->headers_out.headers);
    if (p3p == NULL) {
        return NGX_ERROR;
    }

    p3p->hash = 1;
    ngx_str_set(&p3p->key, "P3P");
    p3p->value = conf->p3p;

    return NGX_OK;
}


static ngx_int_t
ngx_http_userid_create_uid(ngx_http_request_t *r, ngx_http_userid_ctx_t *ctx,
    ngx_http_userid_conf_t *conf)
{
    ngx_connection_t           *c;
    struct sockaddr_in         *sin;
    ngx_http_variable_value_t  *vv;
#if (NGX_HAVE_INET6)
    u_char                     *p;
    struct sockaddr_in6        *sin6;
#endif

    if (ctx->uid_set[3] != 0) {
        return NGX_OK;
    }

    if (ctx->uid_got[3] != 0) {

        vv = ngx_http_get_indexed_variable(r, ngx_http_userid_reset_index);

        if (vv->len == 0 || (vv->len == 1 && vv->data[0] == '0')) {

            if (conf->mark == '\0'
                || (ctx->cookie.len > 23
                    && ctx->cookie.data[22] == conf->mark
                    && ctx->cookie.data[23] == '='))
            {
                return NGX_OK;
            }

            ctx->uid_set[0] = ctx->uid_got[0];
            ctx->uid_set[1] = ctx->uid_got[1];
            ctx->uid_set[2] = ctx->uid_got[2];
            ctx->uid_set[3] = ctx->uid_got[3];

            return NGX_OK;

        } else {
            ctx->reset = 1;

            if (vv->len == 3 && ngx_strncmp(vv->data, "log", 3) == 0) {
                ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
                        "userid cookie \"%V=%08XD%08XD%08XD%08XD\" was reset",
                        &conf->name, ctx->uid_got[0], ctx->uid_got[1],
                        ctx->uid_got[2], ctx->uid_got[3]);
            }
        }
    }

    /*
     * TODO: in the threaded mode the sequencers should be in TLS and their
     * ranges should be divided between threads
     */

    if (conf->enable == NGX_HTTP_USERID_V1) {
        if (conf->service == NGX_CONF_UNSET) {
            ctx->uid_set[0] = 0;
        } else {
            ctx->uid_set[0] = conf->service;
        }
        ctx->uid_set[1] = (uint32_t) ngx_time();
        ctx->uid_set[2] = start_value;
        ctx->uid_set[3] = sequencer_v1;
        sequencer_v1 += 0x100;

    } else {
        if (conf->service == NGX_CONF_UNSET) {

            c = r->connection;

            if (ngx_connection_local_sockaddr(c, NULL, 0) != NGX_OK) {
                return NGX_ERROR;
            }

            switch (c->local_sockaddr->sa_family) {

#if (NGX_HAVE_INET6)
            case AF_INET6:
                sin6 = (struct sockaddr_in6 *) c->local_sockaddr;

                p = (u_char *) &ctx->uid_set[0];

                *p++ = sin6->sin6_addr.s6_addr[12];
                *p++ = sin6->sin6_addr.s6_addr[13];
                *p++ = sin6->sin6_addr.s6_addr[14];
                *p = sin6->sin6_addr.s6_addr[15];

                break;
#endif
            default: /* AF_INET */
                sin = (struct sockaddr_in *) c->local_sockaddr;
                ctx->uid_set[0] = sin->sin_addr.s_addr;
                break;
            }

        } else {
            ctx->uid_set[0] = htonl(conf->service);
        }

        ctx->uid_set[1] = htonl((uint32_t) ngx_time());
        ctx->uid_set[2] = htonl(start_value);
        ctx->uid_set[3] = htonl(sequencer_v2);
        sequencer_v2 += 0x100;
        if (sequencer_v2 < 0x03030302) {
            sequencer_v2 = 0x03030302;
        }
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_userid_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v,
    ngx_str_t *name, uint32_t *uid)
{
    v->len = name->len + sizeof("=00001111222233334444555566667777") - 1;
    v->data = ngx_pnalloc(r->pool, v->len);
    if (v->data == NULL) {
        return NGX_ERROR;
    }

    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;

    ngx_sprintf(v->data, "%V=%08XD%08XD%08XD%08XD",
                name, uid[0], uid[1], uid[2], uid[3]);

    return NGX_OK;
}


static ngx_int_t
ngx_http_userid_reset_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    *v = ngx_http_variable_null_value;

    return NGX_OK;
}


static ngx_int_t
ngx_http_userid_add_variables(ngx_conf_t *cf)
{
    ngx_int_t             n;
    ngx_http_variable_t  *var;

    var = ngx_http_add_variable(cf, &ngx_http_userid_got, 0);
    if (var == NULL) {
        return NGX_ERROR;
    }

    var->get_handler = ngx_http_userid_got_variable;

    var = ngx_http_add_variable(cf, &ngx_http_userid_set, 0);
    if (var == NULL) {
        return NGX_ERROR;
    }

    var->get_handler = ngx_http_userid_set_variable;

    var = ngx_http_add_variable(cf, &ngx_http_userid_reset,
                                NGX_HTTP_VAR_CHANGEABLE);
    if (var == NULL) {
        return NGX_ERROR;
    }

    var->get_handler = ngx_http_userid_reset_variable;

    n = ngx_http_get_variable_index(cf, &ngx_http_userid_reset);
    if (n == NGX_ERROR) {
        return NGX_ERROR;
    }

    ngx_http_userid_reset_index = n;

    return NGX_OK;
}


static void *
ngx_http_userid_create_conf(ngx_conf_t *cf)
{
    ngx_http_userid_conf_t  *conf;

    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_userid_conf_t));
    if (conf == NULL) {
        return NULL;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     conf->name = { 0, NULL };
     *     conf->domain = { 0, NULL };
     *     conf->path = { 0, NULL };
     *     conf->p3p = { 0, NULL };
     */

    conf->enable = NGX_CONF_UNSET_UINT;
    conf->service = NGX_CONF_UNSET;
    conf->expires = NGX_CONF_UNSET;
    conf->mark = (u_char) '\xFF';

    return conf;
}


static char *
ngx_http_userid_merge_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_userid_conf_t *prev = parent;
    ngx_http_userid_conf_t *conf = child;

    ngx_conf_merge_uint_value(conf->enable, prev->enable,
                              NGX_HTTP_USERID_OFF);

    ngx_conf_merge_str_value(conf->name, prev->name, "uid");
    ngx_conf_merge_str_value(conf->domain, prev->domain, "");
    ngx_conf_merge_str_value(conf->path, prev->path, "; path=/");
    ngx_conf_merge_str_value(conf->p3p, prev->p3p, "");

    ngx_conf_merge_value(conf->service, prev->service, NGX_CONF_UNSET);
    ngx_conf_merge_sec_value(conf->expires, prev->expires, 0);

    if (conf->mark == (u_char) '\xFF') {
        if (prev->mark == (u_char) '\xFF') {
            conf->mark = '\0';
        } else {
            conf->mark = prev->mark;
        }
    }

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_userid_init(ngx_conf_t *cf)
{
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter = ngx_http_userid_filter;

    return NGX_OK;
}


static char *
ngx_http_userid_domain(ngx_conf_t *cf, void *post, void *data)
{
    ngx_str_t  *domain = data;

    u_char  *p, *new;

    if (ngx_strcmp(domain->data, "none") == 0) {
        ngx_str_set(domain, "");
        return NGX_CONF_OK;
    }

    new = ngx_pnalloc(cf->pool, sizeof("; domain=") - 1 + domain->len);
    if (new == NULL) {
        return NGX_CONF_ERROR;
    }

    p = ngx_cpymem(new, "; domain=", sizeof("; domain=") - 1);
    ngx_memcpy(p, domain->data, domain->len);

    domain->len += sizeof("; domain=") - 1;
    domain->data = new;

    return NGX_CONF_OK;
}


static char *
ngx_http_userid_path(ngx_conf_t *cf, void *post, void *data)
{
    ngx_str_t  *path = data;

    u_char  *p, *new;

    new = ngx_pnalloc(cf->pool, sizeof("; path=") - 1 + path->len);
    if (new == NULL) {
        return NGX_CONF_ERROR;
    }

    p = ngx_cpymem(new, "; path=", sizeof("; path=") - 1);
    ngx_memcpy(p, path->data, path->len);

    path->len += sizeof("; path=") - 1;
    path->data = new;

    return NGX_CONF_OK;
}


static char *
ngx_http_userid_expires(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_userid_conf_t *ucf = conf;

    ngx_str_t  *value;

    if (ucf->expires != NGX_CONF_UNSET) {
        return "is duplicate";
    }

    value = cf->args->elts;

    if (ngx_strcmp(value[1].data, "max") == 0) {
        ucf->expires = NGX_HTTP_USERID_MAX_EXPIRES;
        return NGX_CONF_OK;
    }

    if (ngx_strcmp(value[1].data, "off") == 0) {
        ucf->expires = 0;
        return NGX_CONF_OK;
    }

    ucf->expires = ngx_parse_time(&value[1], 1);
    if (ucf->expires == (time_t) NGX_ERROR) {
        return "invalid value";
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_userid_p3p(ngx_conf_t *cf, void *post, void *data)
{
    ngx_str_t  *p3p = data;

    if (ngx_strcmp(p3p->data, "none") == 0) {
        ngx_str_set(p3p, "");
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_userid_mark(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_userid_conf_t *ucf = conf;

    ngx_str_t  *value;

    if (ucf->mark != (u_char) '\xFF') {
        return "is duplicate";
    }

    value = cf->args->elts;

    if (ngx_strcmp(value[1].data, "off") == 0) {
        ucf->mark = '\0';
        return NGX_CONF_OK;
    }

    if (value[1].len != 1
        || !((value[1].data[0] >= '0' && value[1].data[0] <= '9')
              || (value[1].data[0] >= 'A' && value[1].data[0] <= 'Z')
              || (value[1].data[0] >= 'a' && value[1].data[0] <= 'z')
              || value[1].data[0] == '='))
    {
        return "value must be \"off\" or a single letter, digit or \"=\"";
    }

    ucf->mark = value[1].data[0];

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_userid_init_worker(ngx_cycle_t *cycle)
{
    struct timeval  tp;

    ngx_gettimeofday(&tp);

    /* use the most significant usec part that fits to 16 bits */
    start_value = ((tp.tv_usec / 20) << 16) | ngx_pid;

    return NGX_OK;
}