### http static module[](http://tengine.taobao.org/book/chapter_03.html#http-static-module "永久链接至标题") 从某种程度上来说,此模块可以算的上是“最正宗的”,“最古老”的content handler。因为本模块的作用就是读取磁盘上的静态文件,并把文件内容作为产生的输出。在Web技术发展的早期,只有静态页面,没有服务端脚本来动态生成HTML的时候。恐怕开发个Web服务器的时候,第一个要开发就是这样一个content handler。 http static module的代码位于src/http/modules/ngx_http_static_module.c中,总共只有两百多行近三百行。可以说是非常短小。 我们首先来看一下该模块的模块上下文的定义。 [](http:// "点击提交Issue,反馈你的意见...") ngx_http_module_t ngx_http_static_module_ctx = { NULL, /* preconfiguration */ ngx_http_static_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; 是非常的简洁吧,连任何与配置相关的函数都没有。对了,因为该模块没有提供任何配置指令。大家想想也就知道了,这个模块做的事情实在是太简单了,也确实没什么好配置的。唯一需要调用的函数是一个ngx_http_static_init函数。好了,来看一下这个函数都干了写什么。 [](http:// "点击提交Issue,反馈你的意见...") static ngx_int_t ngx_http_static_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_static_handler; return NGX_OK; } 仅仅是挂载这个handler到NGX_HTTP_CONTENT_PHASE处理阶段。简单吧? 下面我们就看一下这个模块最核心的处理逻辑所在的ngx_http_static_handler函数。该函数大概占了这个模块代码量的百分之八九十。 [](http:// "点击提交Issue,反馈你的意见...") static ngx_int_t ngx_http_static_handler(ngx_http_request_t *r) { u_char *last, *location; size_t root, len; ngx_str_t path; ngx_int_t rc; ngx_uint_t level; ngx_log_t *log; ngx_buf_t *b; ngx_chain_t out; ngx_open_file_info_t of; ngx_http_core_loc_conf_t *clcf; if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD|NGX_HTTP_POST))) { return NGX_HTTP_NOT_ALLOWED; } if (r->uri.data[r->uri.len - 1] == '/') { return NGX_DECLINED; } log = r->connection->log; /* * ngx_http_map_uri_to_path() allocates memory for terminating '\0' * so we do not need to reserve memory for '/' for possible redirect */ last = ngx_http_map_uri_to_path(r, &path, &root, 0); if (last == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } path.len = last - path.data; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http filename: \"%s\"", path.data); clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); ngx_memzero(&of, sizeof(ngx_open_file_info_t)); of.read_ahead = clcf->read_ahead; of.directio = clcf->directio; of.valid = clcf->open_file_cache_valid; of.min_uses = clcf->open_file_cache_min_uses; of.errors = clcf->open_file_cache_errors; of.events = clcf->open_file_cache_events; if (ngx_http_set_disable_symlinks(r, clcf, &path, &of) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool) != NGX_OK) { switch (of.err) { case 0: return NGX_HTTP_INTERNAL_SERVER_ERROR; case NGX_ENOENT: case NGX_ENOTDIR: case NGX_ENAMETOOLONG: level = NGX_LOG_ERR; rc = NGX_HTTP_NOT_FOUND; break; case NGX_EACCES: #if (NGX_HAVE_OPENAT) case NGX_EMLINK: case NGX_ELOOP: #endif level = NGX_LOG_ERR; rc = NGX_HTTP_FORBIDDEN; break; default: level = NGX_LOG_CRIT; rc = NGX_HTTP_INTERNAL_SERVER_ERROR; break; } if (rc != NGX_HTTP_NOT_FOUND || clcf->log_not_found) { ngx_log_error(level, log, of.err, "%s \"%s\" failed", of.failed, path.data); } return rc; } r->root_tested = !r->error_page; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http static fd: %d", of.fd); if (of.is_dir) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, log, 0, "http dir"); ngx_http_clear_location(r); r->headers_out.location = ngx_palloc(r->pool, sizeof(ngx_table_elt_t)); if (r->headers_out.location == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } len = r->uri.len + 1; if (!clcf->alias && clcf->root_lengths == NULL && r->args.len == 0) { location = path.data + clcf->root.len; *last = '/'; } else { if (r->args.len) { len += r->args.len + 1; } location = ngx_pnalloc(r->pool, len); if (location == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } last = ngx_copy(location, r->uri.data, r->uri.len); *last = '/'; if (r->args.len) { *++last = '?'; ngx_memcpy(++last, r->args.data, r->args.len); } } /* * we do not need to set the r->headers_out.location->hash and * r->headers_out.location->key fields */ r->headers_out.location->value.len = len; r->headers_out.location->value.data = location; return NGX_HTTP_MOVED_PERMANENTLY; } #if !(NGX_WIN32) /* the not regular files are probably Unix specific */ if (!of.is_file) { ngx_log_error(NGX_LOG_CRIT, log, 0, "\"%s\" is not a regular file", path.data); return NGX_HTTP_NOT_FOUND; } #endif if (r->method & NGX_HTTP_POST) { return NGX_HTTP_NOT_ALLOWED; } rc = ngx_http_discard_request_body(r); if (rc != NGX_OK) { return rc; } log->action = "sending response to client"; r->headers_out.status = NGX_HTTP_OK; r->headers_out.content_length_n = of.size; r->headers_out.last_modified_time = of.mtime; if (ngx_http_set_content_type(r) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (r != r->main && of.size == 0) { return ngx_http_send_header(r); } r->allow_ranges = 1; /* we need to allocate all before the header would be sent */ b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t)); if (b == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } b->file = ngx_pcalloc(r->pool, sizeof(ngx_file_t)); if (b->file == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } rc = ngx_http_send_header(r); if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) { return rc; } b->file_pos = 0; b->file_last = of.size; b->in_file = b->file_last ? 1: 0; b->last_buf = (r == r->main) ? 1: 0; b->last_in_chain = 1; b->file->fd = of.fd; b->file->name = path; b->file->log = log; b->file->directio = of.is_directio; out.buf = b; out.next = NULL; return ngx_http_output_filter(r, &out); } 首先是检查客户端的http请求类型(r->method),如果请求类型为NGX_HTTP_GET|NGX_HTTP_HEAD|NGX_HTTP_POST,则继续进行处理,否则一律返回NGX_HTTP_NOT_ALLOWED从而拒绝客户端的发起的请求。 其次是检查请求的url的结尾字符是不是斜杠‘/’,如果是说明请求的不是一个文件,给后续的handler去处理,比如后续的ngx_http_autoindex_handler(如果是请求的是一个目录下面,可以列出这个目录的文件),或者是ngx_http_index_handler(如果请求的路径下面有个默认的index文件,直接返回index文件的内容)。 然后接下来调用了一个ngx_http_map_uri_to_path函数,该函数的作用是把请求的http协议的路径转化成一个文件系统的路径。 然后根据转化出来的具体路径,去打开文件,打开文件的时候做了2种检查,一种是,如果请求的文件是个symbol link,根据配置,是否允许符号链接,不允许返回错误。还有一个检查是,如果请求的是一个名称,是一个目录的名字,也返回错误。如果都没有错误,就读取文件,返回内容。其实说返回内容可能不是特别准确,比较准确的说法是,把产生的内容传递给后续的filter去处理。