Nginx的map模块

Nginx Nginx 评论

1、相关配置

geo模块配置指令如下：

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map $var1 $var2 {
	
}

详细用法参考nginx官方文档,此模块的功能是将$var1通过{}中的匹配条件生成$var2的值，支持正则表达式。

2、代码详解

2.1、首先来看看配置解析函数，负责解析map指令后的两个变量，并设置获取变量值的函数指针

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static char *
ngx_http_map_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_map_conf_t  *mcf = conf;

    char                              *rv;
    ngx_str_t                         *value, name;
    ngx_conf_t                         save;
    ngx_pool_t                        *pool;
    ngx_hash_init_t                    hash;
    ngx_http_map_ctx_t                *map;
    ngx_http_variable_t               *var;
    ngx_http_map_conf_ctx_t            ctx;
    ngx_http_compile_complex_value_t   ccv;
    //设置hash桶最大值
    if (mcf->hash_max_size == NGX_CONF_UNSET_UINT) {
        mcf->hash_max_size = 2048;
    }

    if (mcf->hash_bucket_size == NGX_CONF_UNSET_UINT) {
        mcf->hash_bucket_size = ngx_cacheline_size;

    } else {
        mcf->hash_bucket_size = ngx_align(mcf->hash_bucket_size,
                                          ngx_cacheline_size);
    }

    map = ngx_pcalloc(cf->pool, sizeof(ngx_http_map_ctx_t));
    if (map == NULL) {
        return NGX_CONF_ERROR;
    }

    value = cf->args->elts;

    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));

    ccv.cf = cf;
    ccv.value = &value[1];
    ccv.complex_value = &map->value;

    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    //解析第二个变量
    name = value[2];

    if (name.data[0] != '$') {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid variable name \"%V\"", &name);
        return NGX_CONF_ERROR;
    }

    //保存$符号后面的字符串
    name.len--;
    name.data++;

    // 把变量名添加到全局变量中
    var = ngx_http_add_variable(cf, &name, NGX_HTTP_VAR_CHANGEABLE);
    if (var == NULL) {
        return NGX_CONF_ERROR;
    }

    //设置获取此变量值的handler
    var->get_handler = ngx_http_map_variable;
    var->data = (uintptr_t) map;

    pool = ngx_create_pool(NGX_DEFAULT_POOL_SIZE, cf->log);
    if (pool == NULL) {
        return NGX_CONF_ERROR;
    }

    ctx.keys.pool = cf->pool;
    ctx.keys.temp_pool = pool;

    if (ngx_hash_keys_array_init(&ctx.keys, NGX_HASH_LARGE) != NGX_OK) {
        ngx_destroy_pool(pool);
        return NGX_CONF_ERROR;
    }

    ctx.values_hash = ngx_pcalloc(pool, sizeof(ngx_array_t) * ctx.keys.hsize);
    if (ctx.values_hash == NULL) {
        ngx_destroy_pool(pool);
        return NGX_CONF_ERROR;
    }

    // 初始化正则表达式
#if (NGX_PCRE)
    if (ngx_array_init(&ctx.regexes, cf->pool, 2, sizeof(ngx_http_map_regex_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NGX_CONF_ERROR;
    }
#endif

    ctx.default_value = NULL;
    ctx.cf = &save;
    ctx.hostnames = 0;
    ctx.no_cacheable = 0;

    save = *cf;
    cf->pool = pool;
    cf->ctx = &ctx;
    cf->handler = ngx_http_map;
    cf->handler_conf = conf;

    rv = ngx_conf_parse(cf, NULL);

    *cf = save;

    if (rv != NGX_CONF_OK) {
        ngx_destroy_pool(pool);
        return rv;
    }

    if (ctx.no_cacheable) {
        var->flags |= NGX_HTTP_VAR_NOCACHEABLE;
    }

    map->default_value = ctx.default_value ? ctx.default_value:
                                             &ngx_http_variable_null_value;

    map->hostnames = ctx.hostnames;

    hash.key = ngx_hash_key_lc;
    hash.max_size = mcf->hash_max_size;
    hash.bucket_size = mcf->hash_bucket_size;
    hash.name = "map_hash";
    hash.pool = cf->pool;

    if (ctx.keys.keys.nelts) {
        hash.hash = &map->map.hash.hash;
        hash.temp_pool = NULL;

        if (ngx_hash_init(&hash, ctx.keys.keys.elts, ctx.keys.keys.nelts)
            != NGX_OK)
        {
            ngx_destroy_pool(pool);
            return NGX_CONF_ERROR;
        }
    }

    if (ctx.keys.dns_wc_head.nelts) {

        ngx_qsort(ctx.keys.dns_wc_head.elts,
                  (size_t) ctx.keys.dns_wc_head.nelts,
                  sizeof(ngx_hash_key_t), ngx_http_map_cmp_dns_wildcards);

        hash.hash = NULL;
        hash.temp_pool = pool;

        if (ngx_hash_wildcard_init(&hash, ctx.keys.dns_wc_head.elts,
                                   ctx.keys.dns_wc_head.nelts)
            != NGX_OK)
        {
            ngx_destroy_pool(pool);
            return NGX_CONF_ERROR;
        }

        map->map.hash.wc_head = (ngx_hash_wildcard_t *) hash.hash;
    }

    if (ctx.keys.dns_wc_tail.nelts) {

        ngx_qsort(ctx.keys.dns_wc_tail.elts,
                  (size_t) ctx.keys.dns_wc_tail.nelts,
                  sizeof(ngx_hash_key_t), ngx_http_map_cmp_dns_wildcards);

        hash.hash = NULL;
        hash.temp_pool = pool;

        if (ngx_hash_wildcard_init(&hash, ctx.keys.dns_wc_tail.elts,
                                   ctx.keys.dns_wc_tail.nelts)
            != NGX_OK)
        {
            ngx_destroy_pool(pool);
            return NGX_CONF_ERROR;
        }

        map->map.hash.wc_tail = (ngx_hash_wildcard_t *) hash.hash;
    }

#if (NGX_PCRE)

    if (ctx.regexes.nelts) {
        map->map.regex = ctx.regexes.elts;
        map->map.nregex = ctx.regexes.nelts;
    }

#endif

    ngx_destroy_pool(pool);

    return rv;
}


2.2、解析map块中的内容

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static char *
ngx_http_map(ngx_conf_t *cf, ngx_command_t *dummy, void *conf)
{
    u_char                            *data;
    size_t                             len;
    ngx_int_t                          rv;
    ngx_str_t                         *value, v;
    ngx_uint_t                         i, key;
    ngx_http_map_conf_ctx_t           *ctx;
    ngx_http_complex_value_t           cv, *cvp;
    ngx_http_variable_value_t         *var, **vp;
    ngx_http_compile_complex_value_t   ccv;

    ctx = cf->ctx;

    value = cf->args->elts;

    if (cf->args->nelts == 1
        && ngx_strcmp(value[0].data, "hostnames") == 0)
    {
        ctx->hostnames = 1;
        return NGX_CONF_OK;
    }

    if (cf->args->nelts == 1
        && ngx_strcmp(value[0].data, "volatile") == 0)
    {
        ctx->no_cacheable = 1;
        return NGX_CONF_OK;
    }

    if (cf->args->nelts != 2) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid number of the map parameters");
        return NGX_CONF_ERROR;
    }

    if (ngx_strcmp(value[0].data, "include") == 0) {
        return ngx_conf_include(cf, dummy, conf);
    }

    key = 0;

    for (i = 0; i < value[1].len; i++) {
        key = ngx_hash(key, value[1].data[i]);
    }

    key %= ctx->keys.hsize;

    vp = ctx->values_hash[key].elts;

    if (vp) {
        for (i = 0; i < ctx->values_hash[key].nelts; i++) {

            if (vp[i]->valid) {
                data = vp[i]->data;
                len = vp[i]->len;

            } else {
                cvp = (ngx_http_complex_value_t *) vp[i]->data;
                data = cvp->value.data;
                len = cvp->value.len;
            }

            if (value[1].len != len) {
                continue;
            }

            if (ngx_strncmp(value[1].data, data, len) == 0) {
                var = vp[i];
                goto found;
            }
        }

    } else {
        if (ngx_array_init(&ctx->values_hash[key], cf->pool, 4,
                           sizeof(ngx_http_variable_value_t *))
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }
    }

    var = ngx_palloc(ctx->keys.pool, sizeof(ngx_http_variable_value_t));
    if (var == NULL) {
        return NGX_CONF_ERROR;
    }

    v.len = value[1].len;
    v.data = ngx_pstrdup(ctx->keys.pool, &value[1]);
    if (v.data == NULL) {
        return NGX_CONF_ERROR;
    }

    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));

    ccv.cf = ctx->cf;
    ccv.value = &v;
    ccv.complex_value = &cv;

    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    if (cv.lengths != NULL) {
        cvp = ngx_palloc(ctx->keys.pool, sizeof(ngx_http_complex_value_t));
        if (cvp == NULL) {
            return NGX_CONF_ERROR;
        }

        *cvp = cv;

        var->len = 0;
        var->data = (u_char *) cvp;
        var->valid = 0;

    } else {
        var->len = v.len;
        var->data = v.data;
        var->valid = 1;
    }

    var->no_cacheable = 0;
    var->not_found = 0;

    vp = ngx_array_push(&ctx->values_hash[key]);
    if (vp == NULL) {
        return NGX_CONF_ERROR;
    }

    *vp = var;

found:

    if (ngx_strcmp(value[0].data, "default") == 0) {

        if (ctx->default_value) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "duplicate default map parameter");
            return NGX_CONF_ERROR;
        }

        ctx->default_value = var;

        return NGX_CONF_OK;
    }

#if (NGX_PCRE)

    if (value[0].len && value[0].data[0] == '~') {
        ngx_regex_compile_t    rc;
        ngx_http_map_regex_t  *regex;
        u_char                 errstr[NGX_MAX_CONF_ERRSTR];

        regex = ngx_array_push(&ctx->regexes);
        if (regex == NULL) {
            return NGX_CONF_ERROR;
        }

        value[0].len--;
        value[0].data++;

        ngx_memzero(&rc, sizeof(ngx_regex_compile_t));

        if (value[0].data[0] == '*') {
            value[0].len--;
            value[0].data++;
            rc.options = NGX_REGEX_CASELESS;
        }

        rc.pattern = value[0];
        rc.err.len = NGX_MAX_CONF_ERRSTR;
        rc.err.data = errstr;

        regex->regex = ngx_http_regex_compile(ctx->cf, &rc);
        if (regex->regex == NULL) {
            return NGX_CONF_ERROR;
        }

        regex->value = var;

        return NGX_CONF_OK;
    }

#endif

    if (value[0].len && value[0].data[0] == '\\') {
        value[0].len--;
        value[0].data++;
    }

    rv = ngx_hash_add_key(&ctx->keys, &value[0], var,
                          (ctx->hostnames) ? NGX_HASH_WILDCARD_KEY : 0);

    if (rv == NGX_OK) {
        return NGX_CONF_OK;
    }

    if (rv == NGX_DECLINED) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid hostname or wildcard \"%V\"", &value[0]);
    }

    if (rv == NGX_BUSY) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "conflicting parameter \"%V\"", &value[0]);
    }

    return NGX_CONF_ERROR;
}s

3、总结

map模块生成的变量遵循nginx的变量规则，获取变量值的方式也与nginx其他变量类似

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