Nginx的http_core模块

2021-05-09 Nginx Nginx 0 评论字数统计: 4.9k(字) 阅读时长: 28(分)

1、相关配置

核心模块配置如下
1
2
3
4
5
6
7
8
9
server {
    listen 80;
    location / {
        root html;
        index index.html;
    }
}
以上是http模块最核心的配置，一条listen指令，一条location指令，能够监听80端口，提供简单的web服务。

2、相关代码

首先看下解析server指令的代码

static char *
ngx_http_core_server(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
{
    char                        *rv;
    void                        *mconf;
    size_t                       len;
    u_char                      *p;
    ngx_uint_t                   i;
    ngx_conf_t                   pcf;
    ngx_http_module_t           *module;
    struct sockaddr_in          *sin;
    ngx_http_conf_ctx_t         *ctx, *http_ctx;
    ngx_http_listen_opt_t        lsopt;
    ngx_http_core_srv_conf_t    *cscf, **cscfp;
    ngx_http_core_main_conf_t   *cmcf;

    // 首先分配上下文内存
    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
    if (ctx == NULL) {
        return NGX_CONF_ERROR;
    }

    // 保存http模块main级别的conf
    http_ctx = cf->ctx;
    ctx->main_conf = http_ctx->main_conf;

    /* the server{}'s srv_conf */

    // 预分配保存server级别的内存
    ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
    if (ctx->srv_conf == NULL) {
        return NGX_CONF_ERROR;
    }

    /* the server{}'s loc_conf */

    // 预分配location级别的内存
    ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
    if (ctx->loc_conf == NULL) {
        return NGX_CONF_ERROR;
    }

    for (i = 0; cf->cycle->modules[i]; i++) {
        if (cf->cycle->modules[i]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[i]->ctx;

        // 调用每个模块create_srv_conf函数指针，创建server级别conf
        if (module->create_srv_conf) {
            mconf = module->create_srv_conf(cf);
            if (mconf == NULL) {
                return NGX_CONF_ERROR;
            }
            // 使用模块索引保存创建的server级别conf
            ctx->srv_conf[cf->cycle->modules[i]->ctx_index] = mconf;
        }

        // 调用每个模块create_loc_conf函数指针，创建location级别conf
        if (module->create_loc_conf) {
            mconf = module->create_loc_conf(cf);
            if (mconf == NULL) {
                return NGX_CONF_ERROR;
            }
            // 使用模块索引保存创建的location级别conf
            ctx->loc_conf[cf->cycle->modules[i]->ctx_index] = mconf;
        }
    }


    /* the server configuration context */

    cscf = ctx->srv_conf[ngx_http_core_module.ctx_index];
    cscf->ctx = ctx;

    //获取http的主配置
    cmcf = ctx->main_conf[ngx_http_core_module.ctx_index];

    // 创建servers数组
    cscfp = ngx_array_push(&cmcf->servers);
    if (cscfp == NULL) {
        return NGX_CONF_ERROR;
    }

    //保存cscfp
    *cscfp = cscf;


    /* parse inside server{} */

    pcf = *cf;
    cf->ctx = ctx;
    cf->cmd_type = NGX_HTTP_SRV_CONF;

    // 开始解析server块配置
    rv = ngx_conf_parse(cf, NULL);

    // 还原cf
    *cf = pcf;

    // 处理没有监听端口的情况, 默认80
    if (rv == NGX_CONF_OK && !cscf->listen) {
        ngx_memzero(&lsopt, sizeof(ngx_http_listen_opt_t));

        p = ngx_pcalloc(cf->pool, sizeof(struct sockaddr_in));
        if (p == NULL) {
            return NGX_CONF_ERROR;
        }

        lsopt.sockaddr = (struct sockaddr *) p;

        sin = (struct sockaddr_in *) p;

        sin->sin_family = AF_INET;
#if (NGX_WIN32)
        sin->sin_port = htons(80);
#else
        sin->sin_port = htons((getuid() == 0) ? 80 : 8000);
#endif
        sin->sin_addr.s_addr = INADDR_ANY;

        lsopt.socklen = sizeof(struct sockaddr_in);

        lsopt.backlog = NGX_LISTEN_BACKLOG;
        lsopt.rcvbuf = -1;
        lsopt.sndbuf = -1;
#if (NGX_HAVE_SETFIB)
        lsopt.setfib = -1;
#endif
#if (NGX_HAVE_TCP_FASTOPEN)
        lsopt.fastopen = -1;
#endif
        lsopt.wildcard = 1;

        len = NGX_INET_ADDRSTRLEN + sizeof(":65535") - 1;

        p = ngx_pnalloc(cf->pool, len);
        if (p == NULL) {
            return NGX_CONF_ERROR;
        }

        lsopt.addr_text.data = p;
        lsopt.addr_text.len = ngx_sock_ntop(lsopt.sockaddr, lsopt.socklen, p,
                                            len, 1);

        // 添加端口到listening列表
        if (ngx_http_add_listen(cf, cscf, &lsopt) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    return rv;
}

接下来看看解析listen指令的函数, ngx_http_core_listen的实现

static char *
ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_srv_conf_t *cscf = conf;

    ngx_str_t              *value, size;
    ngx_url_t               u;
    ngx_uint_t              n;
    ngx_http_listen_opt_t   lsopt;

    cscf->listen = 1;

    value = cf->args->elts;

    // URL结构体内存空间置零
    ngx_memzero(&u, sizeof(ngx_url_t));

    u.url = value[1];
    u.listen = 1;
    u.default_port = 80;

    // 解析listen指令后的ip+port
    if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
        if (u.err) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "%s in \"%V\" of the \"listen\" directive",
                               u.err, &u.url);
        }

        return NGX_CONF_ERROR;
    }

    ngx_memzero(&lsopt, sizeof(ngx_http_listen_opt_t));

    lsopt.backlog = NGX_LISTEN_BACKLOG;
    lsopt.rcvbuf = -1;
    lsopt.sndbuf = -1;
#if (NGX_HAVE_SETFIB)
    lsopt.setfib = -1;
#endif
#if (NGX_HAVE_TCP_FASTOPEN)
    lsopt.fastopen = -1;
#endif
#if (NGX_HAVE_INET6)
    lsopt.ipv6only = 1;
#endif
    // 开始解析listen指令后的参数，第一个参数是listen，第二个参数是IP端口，所以n从2开始
    for (n = 2; n < cf->args->nelts; n++) {

        // 解析default server参数，并设置标志位
        if (ngx_strcmp(value[n].data, "default_server") == 0
            || ngx_strcmp(value[n].data, "default") == 0)
        {
            lsopt.default_server = 1;
            continue;
        }

        // 解析bind参数，并设置标志位
        if (ngx_strcmp(value[n].data, "bind") == 0) {
            lsopt.set = 1;
            lsopt.bind = 1;
            continue;
        }

#if (NGX_HAVE_SETFIB)
        if (ngx_strncmp(value[n].data, "setfib=", 7) == 0) {
            lsopt.setfib = ngx_atoi(value[n].data + 7, value[n].len - 7);
            lsopt.set = 1;
            lsopt.bind = 1;

            if (lsopt.setfib == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid setfib \"%V\"", &value[n]);
                return NGX_CONF_ERROR;
            }

            continue;
        }
#endif

#if (NGX_HAVE_TCP_FASTOPEN)
        // 解析fastopen参数，设置标志位和值
        if (ngx_strncmp(value[n].data, "fastopen=", 9) == 0) {
            lsopt.fastopen = ngx_atoi(value[n].data + 9, value[n].len - 9);
            lsopt.set = 1;
            lsopt.bind = 1;

            if (lsopt.fastopen == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid fastopen \"%V\"", &value[n]);
                return NGX_CONF_ERROR;
            }

            continue;
        }
#endif

        // 解析backlog参数，设置标志位和值
        if (ngx_strncmp(value[n].data, "backlog=", 8) == 0) {
            lsopt.backlog = ngx_atoi(value[n].data + 8, value[n].len - 8);
            lsopt.set = 1;
            lsopt.bind = 1;

            if (lsopt.backlog == NGX_ERROR || lsopt.backlog == 0) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid backlog \"%V\"", &value[n]);
                return NGX_CONF_ERROR;
            }

            continue;
        }

        // recv buf参数，设置标志位和值
        if (ngx_strncmp(value[n].data, "rcvbuf=", 7) == 0) {
            size.len = value[n].len - 7;
            size.data = value[n].data + 7;

            lsopt.rcvbuf = ngx_parse_size(&size);
            lsopt.set = 1;
            lsopt.bind = 1;

            if (lsopt.rcvbuf == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid rcvbuf \"%V\"", &value[n]);
                return NGX_CONF_ERROR;
            }

            continue;
        }

        // send buf参数，设置标志位和值
        if (ngx_strncmp(value[n].data, "sndbuf=", 7) == 0) {
            size.len = value[n].len - 7;
            size.data = value[n].data + 7;

            lsopt.sndbuf = ngx_parse_size(&size);
            lsopt.set = 1;
            lsopt.bind = 1;

            if (lsopt.sndbuf == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid sndbuf \"%V\"", &value[n]);
                return NGX_CONF_ERROR;
            }

            continue;
        }

        // 解析accept_filter参数，设置标志位
        if (ngx_strncmp(value[n].data, "accept_filter=", 14) == 0) {
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
            lsopt.accept_filter = (char *) &value[n].data[14];
            lsopt.set = 1;
            lsopt.bind = 1;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "accept filters \"%V\" are not supported "
                               "on this platform, ignored",
                               &value[n]);
#endif
            continue;
        }

        // deferred 参数
        if (ngx_strcmp(value[n].data, "deferred") == 0) {
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
            lsopt.deferred_accept = 1;
            lsopt.set = 1;
            lsopt.bind = 1;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "the deferred accept is not supported "
                               "on this platform, ignored");
#endif
            continue;
        }

        // 解析ipv6参数，设置标志位
        if (ngx_strncmp(value[n].data, "ipv6only=o", 10) == 0) {
#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
            if (ngx_strcmp(&value[n].data[10], "n") == 0) {
                lsopt.ipv6only = 1;

            } else if (ngx_strcmp(&value[n].data[10], "ff") == 0) {
                lsopt.ipv6only = 0;

            } else {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid ipv6only flags \"%s\"",
                                   &value[n].data[9]);
                return NGX_CONF_ERROR;
            }

            lsopt.set = 1;
            lsopt.bind = 1;

            continue;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "ipv6only is not supported "
                               "on this platform");
            return NGX_CONF_ERROR;
#endif
        }

        // reuseport 参数，设置标志位
        if (ngx_strcmp(value[n].data, "reuseport") == 0) {
#if (NGX_HAVE_REUSEPORT)
            lsopt.reuseport = 1;
            lsopt.set = 1;
            lsopt.bind = 1;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "reuseport is not supported "
                               "on this platform, ignored");
#endif
            continue;
        }

        // 解析ssl参数，设置标志位
        if (ngx_strcmp(value[n].data, "ssl") == 0) {
#if (NGX_HTTP_SSL)
            lsopt.ssl = 1;
            continue;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "the \"ssl\" parameter requires "
                               "ngx_http_ssl_module");
            return NGX_CONF_ERROR;
#endif
        }

        // 解析http2参数，设置标志位
        if (ngx_strcmp(value[n].data, "http2") == 0) {
#if (NGX_HTTP_V2)
            lsopt.http2 = 1;
            continue;
#else
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "the \"http2\" parameter requires "
                               "ngx_http_v2_module");
            return NGX_CONF_ERROR;
#endif
        }

        // 解析spdy参数
        if (ngx_strcmp(value[n].data, "spdy") == 0) {
            ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                               "invalid parameter \"spdy\": "
                               "ngx_http_spdy_module was superseded "
                               "by ngx_http_v2_module");
            continue;
        }

        // 解析so_keepalive，设置标志位
        if (ngx_strncmp(value[n].data, "so_keepalive=", 13) == 0) {

            if (ngx_strcmp(&value[n].data[13], "on") == 0) {
                lsopt.so_keepalive = 1;

            } else if (ngx_strcmp(&value[n].data[13], "off") == 0) {
                lsopt.so_keepalive = 2;

            } else {

#if (NGX_HAVE_KEEPALIVE_TUNABLE)
                u_char     *p, *end;
                ngx_str_t   s;

                end = value[n].data + value[n].len;
                s.data = value[n].data + 13;

                p = ngx_strlchr(s.data, end, ':');
                if (p == NULL) {
                    p = end;
                }

                if (p > s.data) {
                    s.len = p - s.data;

                    lsopt.tcp_keepidle = ngx_parse_time(&s, 1);
                    if (lsopt.tcp_keepidle == (time_t) NGX_ERROR) {
                        goto invalid_so_keepalive;
                    }
                }

                s.data = (p < end) ? (p + 1) : end;

                p = ngx_strlchr(s.data, end, ':');
                if (p == NULL) {
                    p = end;
                }

                if (p > s.data) {
                    s.len = p - s.data;

                    lsopt.tcp_keepintvl = ngx_parse_time(&s, 1);
                    if (lsopt.tcp_keepintvl == (time_t) NGX_ERROR) {
                        goto invalid_so_keepalive;
                    }
                }

                s.data = (p < end) ? (p + 1) : end;

                if (s.data < end) {
                    s.len = end - s.data;

                    lsopt.tcp_keepcnt = ngx_atoi(s.data, s.len);
                    if (lsopt.tcp_keepcnt == NGX_ERROR) {
                        goto invalid_so_keepalive;
                    }
                }

                if (lsopt.tcp_keepidle == 0 && lsopt.tcp_keepintvl == 0
                    && lsopt.tcp_keepcnt == 0)
                {
                    goto invalid_so_keepalive;
                }

                lsopt.so_keepalive = 1;

#else

                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "the \"so_keepalive\" parameter accepts "
                                   "only \"on\" or \"off\" on this platform");
                return NGX_CONF_ERROR;

#endif
            }

            lsopt.set = 1;
            lsopt.bind = 1;

            continue;

#if (NGX_HAVE_KEEPALIVE_TUNABLE)
        invalid_so_keepalive:

            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid so_keepalive value: \"%s\"",
                               &value[n].data[13]);
            return NGX_CONF_ERROR;
#endif
        }

        // 解析pp协议参数，开启pp协议标志位
        if (ngx_strcmp(value[n].data, "proxy_protocol") == 0) {
            lsopt.proxy_protocol = 1;
            continue;
        }

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[n]);
        return NGX_CONF_ERROR;
    }

    // 处理监听端口
    for (n = 0; n < u.naddrs; n++) {
        lsopt.sockaddr = u.addrs[n].sockaddr;
        lsopt.socklen = u.addrs[n].socklen;
        lsopt.addr_text = u.addrs[n].name;
        // 获取通配符关键字
        lsopt.wildcard = ngx_inet_wildcard(lsopt.sockaddr);

        // 将端口放入全局端口列表中
        if (ngx_http_add_listen(cf, cscf, &lsopt) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    return NGX_CONF_OK;
}

接下来看看解析location指令的函数, ngx_http_core_location的实现

static char *
ngx_http_core_location(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
{
    char                      *rv;
    u_char                    *mod;
    size_t                     len;
    ngx_str_t                 *value, *name;
    ngx_uint_t                 i;
    ngx_conf_t                 save;
    ngx_http_module_t         *module;
    ngx_http_conf_ctx_t       *ctx, *pctx;
    ngx_http_core_loc_conf_t  *clcf, *pclcf;

    // 首先申请保存配置的内存
    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
    if (ctx == NULL) {
        return NGX_CONF_ERROR;
    }

    // 设置main级别和server级别配置
    pctx = cf->ctx;
    ctx->main_conf = pctx->main_conf;
    ctx->srv_conf = pctx->srv_conf;

    ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
    if (ctx->loc_conf == NULL) {
        return NGX_CONF_ERROR;
    }

    // 遍历http模块，调用创建location级别配置函数
    for (i = 0; cf->cycle->modules[i]; i++) {
        // 跳过非http模块
        if (cf->cycle->modules[i]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[i]->ctx;

        if (module->create_loc_conf) {
            ctx->loc_conf[cf->cycle->modules[i]->ctx_index] =
                                                   module->create_loc_conf(cf);
            if (ctx->loc_conf[cf->cycle->modules[i]->ctx_index] == NULL) {
                return NGX_CONF_ERROR;
            }
        }
    }

    // 取出core模块的location级别配置
    clcf = ctx->loc_conf[ngx_http_core_module.ctx_index];
    clcf->loc_conf = ctx->loc_conf;

    value = cf->args->elts;

    // 处理location指令后的参数，比如/ ~ = 以及其他正则表达式
    if (cf->args->nelts == 3) {

        len = value[1].len;
        mod = value[1].data;
        name = &value[2];

        if (len == 1 && mod[0] == '=') {

            clcf->name = *name;
            clcf->exact_match = 1;

        } else if (len == 2 && mod[0] == '^' && mod[1] == '~') {

            clcf->name = *name;
            clcf->noregex = 1;

        } else if (len == 1 && mod[0] == '~') {

            if (ngx_http_core_regex_location(cf, clcf, name, 0) != NGX_OK) {
                return NGX_CONF_ERROR;
            }

        } else if (len == 2 && mod[0] == '~' && mod[1] == '*') {

            if (ngx_http_core_regex_location(cf, clcf, name, 1) != NGX_OK) {
                return NGX_CONF_ERROR;
            }

        } else {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid location modifier \"%V\"", &value[1]);
            return NGX_CONF_ERROR;
        }

    } else {

        name = &value[1];

        if (name->data[0] == '=') {

            clcf->name.len = name->len - 1;
            clcf->name.data = name->data + 1;
            clcf->exact_match = 1;

        } else if (name->data[0] == '^' && name->data[1] == '~') {

            clcf->name.len = name->len - 2;
            clcf->name.data = name->data + 2;
            clcf->noregex = 1;

        } else if (name->data[0] == '~') {

            name->len--;
            name->data++;

            if (name->data[0] == '*') {

                name->len--;
                name->data++;

                // 处理正则表达式
                if (ngx_http_core_regex_location(cf, clcf, name, 1) != NGX_OK) {
                    return NGX_CONF_ERROR;
                }

            } else {
                if (ngx_http_core_regex_location(cf, clcf, name, 0) != NGX_OK) {
                    return NGX_CONF_ERROR;
                }
            }

        } else {

            // 保存clcf的name
            clcf->name = *name;

            if (name->data[0] == '@') {
                clcf->named = 1;
            }
        }
    }

    // 设置location级别的配置
    pclcf = pctx->loc_conf[ngx_http_core_module.ctx_index];

    // 判断是否微location类型配置
    if (cf->cmd_type == NGX_HTTP_LOC_CONF) {

        /* nested location */

#if 0
        clcf->prev_location = pclcf;
#endif

        if (pclcf->exact_match) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "location \"%V\" cannot be inside "
                               "the exact location \"%V\"",
                               &clcf->name, &pclcf->name);
            return NGX_CONF_ERROR;
        }

        if (pclcf->named) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "location \"%V\" cannot be inside "
                               "the named location \"%V\"",
                               &clcf->name, &pclcf->name);
            return NGX_CONF_ERROR;
        }

        if (clcf->named) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "named location \"%V\" can be "
                               "on the server level only",
                               &clcf->name);
            return NGX_CONF_ERROR;
        }

        len = pclcf->name.len;

#if (NGX_PCRE)
        if (clcf->regex == NULL
            && ngx_filename_cmp(clcf->name.data, pclcf->name.data, len) != 0)
#else
        if (ngx_filename_cmp(clcf->name.data, pclcf->name.data, len) != 0)
#endif
        {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "location \"%V\" is outside location \"%V\"",
                               &clcf->name, &pclcf->name);
            return NGX_CONF_ERROR;
        }
    }

    // 添加location
    if (ngx_http_add_location(cf, &pclcf->locations, clcf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    // 保持cf结构体
    save = *cf;
    cf->ctx = ctx;
    cf->cmd_type = NGX_HTTP_LOC_CONF;

    // 解析location里面的指令
    rv = ngx_conf_parse(cf, NULL);

    // 恢复原来的配置
    *cf = save;

    return rv;
}

接下来看看root指令解析函数，ngx_http_core_root的实现


static char *
ngx_http_core_root(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t *clcf = conf;

    ngx_str_t                  *value;
    ngx_int_t                   alias;
    ngx_uint_t                  n;
    ngx_http_script_compile_t   sc;

    alias = (cmd->name.len == sizeof("alias") - 1) ? 1 : 0;

    if (clcf->root.data) {

        if ((clcf->alias != 0) == alias) {
            return "is duplicate";
        }

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "\"%V\" directive is duplicate, "
                           "\"%s\" directive was specified earlier",
                           &cmd->name, clcf->alias ? "alias" : "root");

        return NGX_CONF_ERROR;
    }

    if (clcf->named && alias) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the \"alias\" directive cannot be used "
                           "inside the named location");

        return NGX_CONF_ERROR;
    }

    value = cf->args->elts;

    // 处理第一个参数
    if (ngx_strstr(value[1].data, "$document_root")
        || ngx_strstr(value[1].data, "${document_root}"))
    {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the $document_root variable cannot be used "
                           "in the \"%V\" directive",
                           &cmd->name);

        return NGX_CONF_ERROR;
    }

    if (ngx_strstr(value[1].data, "$realpath_root")
        || ngx_strstr(value[1].data, "${realpath_root}"))
    {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the $realpath_root variable cannot be used "
                           "in the \"%V\" directive",
                           &cmd->name);

        return NGX_CONF_ERROR;
    }

    clcf->alias = alias ? clcf->name.len : 0;
    clcf->root = value[1];

    if (!alias && clcf->root.len > 0
        && clcf->root.data[clcf->root.len - 1] == '/')
    {
        clcf->root.len--;
    }

    if (clcf->root.data[0] != '$') {
        if (ngx_conf_full_name(cf->cycle, &clcf->root, 0) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    // 统计变量数量
    n = ngx_http_script_variables_count(&clcf->root);

    // 结构体置空
    ngx_memzero(&sc, sizeof(ngx_http_script_compile_t));
    sc.variables = n;

#if (NGX_PCRE)
    if (alias && clcf->regex) {
        clcf->alias = NGX_MAX_SIZE_T_VALUE;
        n = 1;
    }
#endif

    //处理变量
    if (n) {
        sc.cf = cf;
        sc.source = &clcf->root;
        sc.lengths = &clcf->root_lengths;
        sc.values = &clcf->root_values;
        sc.complete_lengths = 1;
        sc.complete_values = 1;

        if (ngx_http_script_compile(&sc) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    return NGX_CONF_OK;
}

接下来看看type指令解析函数, ngx_http_core_type的实现

static char *
ngx_http_core_type(ngx_conf_t *cf, ngx_command_t *dummy, void *conf)
{
    ngx_http_core_loc_conf_t *clcf = conf;

    ngx_str_t       *value, *content_type, *old;
    ngx_uint_t       i, n, hash;
    ngx_hash_key_t  *type;

    value = cf->args->elts;
    // 解析第一个参数，判断是否为include
    if (ngx_strcmp(value[0].data, "include") == 0) {
        if (cf->args->nelts != 2) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid number of arguments"
                               " in \"include\" directive");
            return NGX_CONF_ERROR;
        }

        return ngx_conf_include(cf, dummy, conf);
    }

    //申请保存content_type的内存
    content_type = ngx_palloc(cf->pool, sizeof(ngx_str_t));
    if (content_type == NULL) {
        return NGX_CONF_ERROR;
    }

    // 取content_type的值
    *content_type = value[0];

    for (i = 1; i < cf->args->nelts; i++) {

        hash = ngx_hash_strlow(value[i].data, value[i].data, value[i].len);

        type = clcf->types->elts;
        for (n = 0; n < clcf->types->nelts; n++) {
            if (ngx_strcmp(value[i].data, type[n].key.data) == 0) {
                old = type[n].value;
                type[n].value = content_type;

                ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                                   "duplicate extension \"%V\", "
                                   "content type: \"%V\", "
                                   "previous content type: \"%V\"",
                                   &value[i], content_type, old);
                goto next;
            }
        }

        // 从types中取出一个元素
        type = ngx_array_push(clcf->types);
        if (type == NULL) {
            return NGX_CONF_ERROR;
        }

        //保存
        type->key = value[i];
        type->key_hash = hash;
        type->value = content_type;

    next:
        continue;
    }

    return NGX_CONF_OK;
}

接下来看看server_name指令的解析函数, ngx_http_core_server_name的实现

static char *
ngx_http_core_server_name(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_srv_conf_t *cscf = conf;

    u_char                   ch;
    ngx_str_t               *value;
    ngx_uint_t               i;
    ngx_http_server_name_t  *sn;

    // 取参数
    value = cf->args->elts;

    // 遍历参数个数
    for (i = 1; i < cf->args->nelts; i++) {

        ch = value[i].data[0];

        // 判断是否为通配符
        if ((ch == '*' && (value[i].len < 3 || value[i].data[1] != '.'))
            || (ch == '.' && value[i].len < 2))
        {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "server name \"%V\" is invalid", &value[i]);
            return NGX_CONF_ERROR;
        }

        // 判断server_name中是否含有/
        if (ngx_strchr(value[i].data, '/')) {
            ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                               "server name \"%V\" has suspicious symbols",
                               &value[i]);
        }

        // 取一个server_name的元素
        sn = ngx_array_push(&cscf->server_names);
        if (sn == NULL) {
            return NGX_CONF_ERROR;
        }

#if (NGX_PCRE)
        sn->regex = NULL;
#endif
        // 保存server块配置结构体
        sn->server = cscf;

        // 判断server_name参数是否为主机名称，如果是，则使用cycle->hostname，否则server_name的值就是value的值
        if (ngx_strcasecmp(value[i].data, (u_char *) "$hostname") == 0) {
            sn->name = cf->cycle->hostname;

        } else {
            sn->name = value[i];
        }

        // 处理server_name转小写
        if (value[i].data[0] != '~') {
            ngx_strlow(sn->name.data, sn->name.data, sn->name.len);
            continue;
        }

#if (NGX_PCRE)
        // 处理正则表达式
        {
        u_char               *p;
        ngx_regex_compile_t   rc;
        u_char                errstr[NGX_MAX_CONF_ERRSTR];

        if (value[i].len == 1) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "empty regex in server name \"%V\"", &value[i]);
            return NGX_CONF_ERROR;
        }

        // 跳过第一个符号
        value[i].len--;
        value[i].data++;

        ngx_memzero(&rc, sizeof(ngx_regex_compile_t));

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

        for (p = value[i].data; p < value[i].data + value[i].len; p++) {
            if (*p >= 'A' && *p <= 'Z') {
                rc.options = NGX_REGEX_CASELESS;
                break;
            }
        }

        // 编译正则表达式
        sn->regex = ngx_http_regex_compile(cf, &rc);
        if (sn->regex == NULL) {
            return NGX_CONF_ERROR;
        }

        sn->name = value[i];
        cscf->captures = (rc.captures > 0);
        }
#else
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "using regex \"%V\" "
                           "requires PCRE library", &value[i]);

        return NGX_CONF_ERROR;
#endif
    }

    return NGX_CONF_OK;
}

接下来看看error_page指令的解析函数, ngx_http_core_error_page的实现

ngx_http_core_error_page(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t *clcf = conf;

    u_char                            *p;
    ngx_int_t                          overwrite;
    ngx_str_t                         *value, uri, args;
    ngx_uint_t                         i, n;
    ngx_http_err_page_t               *err;
    ngx_http_complex_value_t           cv;
    ngx_http_compile_complex_value_t   ccv;

    if (clcf->error_pages == NULL) {
        clcf->error_pages = ngx_array_create(cf->pool, 4,
                                             sizeof(ngx_http_err_page_t));
        if (clcf->error_pages == NULL) {
            return NGX_CONF_ERROR;
        }
    }

    value = cf->args->elts;

    i = cf->args->nelts - 2;

    // 解析重定向的code
    if (value[i].data[0] == '=') {
        if (i == 1) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid value \"%V\"", &value[i]);
            return NGX_CONF_ERROR;
        }

        if (value[i].len > 1) {
            overwrite = ngx_atoi(&value[i].data[1], value[i].len - 1);

            if (overwrite == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid value \"%V\"", &value[i]);
                return NGX_CONF_ERROR;
            }

        } else {
            overwrite = 0;
        }

        n = 2;

    } else {
        overwrite = -1;
        n = 1;
    }

    uri = value[cf->args->nelts - 1];

    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));

    ccv.cf = cf;
    ccv.value = &uri;
    ccv.complex_value = &cv;
    // 解析uri变量
    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    ngx_str_null(&args);
    // 解析uri及参数
    if (cv.lengths == NULL && uri.len && uri.data[0] == '/') {
        //搜索查询参数起点
        p = (u_char *) ngx_strchr(uri.data, '?');

        if (p) {
            cv.value.len = p - uri.data;
            cv.value.data = uri.data;
            p++;
            args.len = (uri.data + uri.len) - p;
            args.data = p;
        }
    }

    // 开始从第一个参数解析需要重定向的code
    for (i = 1; i < cf->args->nelts - n; i++) {
        err = ngx_array_push(clcf->error_pages);
        if (err == NULL) {
            return NGX_CONF_ERROR;
        }
        // 解析数字code
        err->status = ngx_atoi(value[i].data, value[i].len);
        // 如果解析出错或者是499，则直接返回错误
        if (err->status == NGX_ERROR || err->status == 499) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid value \"%V\"", &value[i]);
            return NGX_CONF_ERROR;
        }
        // status范围300-599之间
        if (err->status < 300 || err->status > 599) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "value \"%V\" must be between 300 and 599",
                               &value[i]);
            return NGX_CONF_ERROR;
        }

        err->overwrite = overwrite;

        if (overwrite == -1) {
            switch (err->status) {
                case NGX_HTTP_TO_HTTPS:
                case NGX_HTTPS_CERT_ERROR:
                case NGX_HTTPS_NO_CERT:
                case NGX_HTTP_REQUEST_HEADER_TOO_LARGE:
                    err->overwrite = NGX_HTTP_BAD_REQUEST;
            }
        }

        err->value = cv;
        err->args = args;
    }

    return NGX_CONF_OK;
}

error_page主要用于内部重定向，在special response的时候处理相关逻辑

ngx_int_t
ngx_http_special_response_handler(ngx_http_request_t *r, ngx_int_t error)
{
    ngx_uint_t                 i, err;
    ngx_http_err_page_t       *err_page;
    ngx_http_core_loc_conf_t  *clcf;

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http special response: %i, \"%V?%V\"",
                   error, &r->uri, &r->args);

    r->err_status = error;

    if (r->keepalive) {
        switch (error) {
            case NGX_HTTP_BAD_REQUEST:
            case NGX_HTTP_REQUEST_ENTITY_TOO_LARGE:
            case NGX_HTTP_REQUEST_URI_TOO_LARGE:
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
            case NGX_HTTP_INTERNAL_SERVER_ERROR:
            case NGX_HTTP_NOT_IMPLEMENTED:
                r->keepalive = 0;
        }
    }

    if (r->lingering_close) {
        switch (error) {
            case NGX_HTTP_BAD_REQUEST:
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
                r->lingering_close = 0;
        }
    }
    // content-length置为0
    r->headers_out.content_type.len = 0;

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
    // 这里对error_page以及uri_changes判断
    if (!r->error_page && clcf->error_pages && r->uri_changes != 0) {
        
        if (clcf->recursive_error_pages == 0) {
            r->error_page = 1;
        }

        err_page = clcf->error_pages->elts;
        // 找到对应code
        for (i = 0; i < clcf->error_pages->nelts; i++) {
            if (err_page[i].status == error) {
                // 直接调用error_page逻辑
                return ngx_http_send_error_page(r, &err_page[i]);
            }
        }
    }

    r->expect_tested = 1;

    if (ngx_http_discard_request_body(r) != NGX_OK) {
        r->keepalive = 0;
    }

    if (clcf->msie_refresh
        && r->headers_in.msie
        && (error == NGX_HTTP_MOVED_PERMANENTLY
            || error == NGX_HTTP_MOVED_TEMPORARILY))
    {
        return ngx_http_send_refresh(r);
    }

    if (error == NGX_HTTP_CREATED) {
        /* 201 */
        err = 0;

    } else if (error == NGX_HTTP_NO_CONTENT) {
        /* 204 */
        err = 0;

    } else if (error >= NGX_HTTP_MOVED_PERMANENTLY
               && error < NGX_HTTP_LAST_3XX)
    {
        /* 3XX */
        err = error - NGX_HTTP_MOVED_PERMANENTLY + NGX_HTTP_OFF_3XX;

    } else if (error >= NGX_HTTP_BAD_REQUEST
               && error < NGX_HTTP_LAST_4XX)
    {
        /* 4XX */
        err = error - NGX_HTTP_BAD_REQUEST + NGX_HTTP_OFF_4XX;

    } else if (error >= NGX_HTTP_NGINX_CODES
               && error < NGX_HTTP_LAST_5XX)
    {
        /* 49X, 5XX */
        err = error - NGX_HTTP_NGINX_CODES + NGX_HTTP_OFF_5XX;
        switch (error) {
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
            case NGX_HTTP_REQUEST_HEADER_TOO_LARGE:
                r->err_status = NGX_HTTP_BAD_REQUEST;
        }

    } else {
        /* unknown code, zero body */
        err = 0;
    }

    return ngx_http_send_special_response(r, clcf, err);
}

接下来看下ngx_http_send_error_page的函数实现

static ngx_int_t
ngx_http_send_error_page(ngx_http_request_t *r, ngx_http_err_page_t *err_page)
{
    ngx_int_t                  overwrite;
    ngx_str_t                  uri, args;
    ngx_table_elt_t           *location;
    ngx_http_core_loc_conf_t  *clcf;

    overwrite = err_page->overwrite;

    if (overwrite && overwrite != NGX_HTTP_OK) {
        r->expect_tested = 1;
    }

    // 如果配置了code，则将error_code置为配置的code
    if (overwrite >= 0) {
        r->err_status = overwrite;
    }

    // 处理url中的变量
    if (ngx_http_complex_value(r, &err_page->value, &uri) != NGX_OK) {
        return NGX_ERROR;
    }

    // 如果url是/开始
    if (uri.len && uri.data[0] == '/') {

        if (err_page->value.lengths) {
            ngx_http_split_args(r, &uri, &args);

        } else {
            args = err_page->args;
        }

        if (r->method != NGX_HTTP_HEAD) {
            r->method = NGX_HTTP_GET;
            r->method_name = ngx_http_core_get_method;
        }

        return ngx_http_internal_redirect(r, &uri, &args);
    }

    // 跳转到name的location
    if (uri.len && uri.data[0] == '@') {
        return ngx_http_named_location(r, &uri);
    }

    r->expect_tested = 1;

    if (ngx_http_discard_request_body(r) != NGX_OK) {
        r->keepalive = 0;
    }

    // 从headers中取一个元素，用作重定向
    location = ngx_list_push(&r->headers_out.headers);

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

    if (overwrite != NGX_HTTP_MOVED_PERMANENTLY
        && overwrite != NGX_HTTP_MOVED_TEMPORARILY
        && overwrite != NGX_HTTP_SEE_OTHER
        && overwrite != NGX_HTTP_TEMPORARY_REDIRECT
        && overwrite != NGX_HTTP_PERMANENT_REDIRECT)
    {
        r->err_status = NGX_HTTP_MOVED_TEMPORARILY;
    }

    location->hash = 1;
    ngx_str_set(&location->key, "Location");
    location->value = uri;

    ngx_http_clear_location(r);

    r->headers_out.location = location;

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (clcf->msie_refresh && r->headers_in.msie) {
        return ngx_http_send_refresh(r);
    }

    return ngx_http_send_special_response(r, clcf, r->err_status
                                                   - NGX_HTTP_MOVED_PERMANENTLY
                                                   + NGX_HTTP_OFF_3XX);
}

本文链接： https://weeweetan.github.io/2021/05/09/Nginx的http-core模块/
版权声明： 本博客所有文章除特别声明外，均采用 CC BY 4.0 CN协议许可协议。转载请注明出处！

weeweetanBackend Developer

初级程序猿，之前主要涉及数据备份相关领域，现在研究CDN方向。业余时间也喜欢锻炼下，目前参过一次半程马拉松，四次全程马拉松，半马最好成绩99分钟，全马最好成绩3小时47分钟。