前言
nginx配置解析是在初始化ngx_cycle_t数据结构时，首先解析core模块，然后core模块依次解析自己的子模块。
配置解析过程
nginx调用ngx_conf_parse函数进行配置文件解析，下面是核心代码，函数首先打开配置文件，然后循环调用ngx_conf_read_token读取一行配置，解析出来保存在cf->args中，如果遇到";" 或者 "{", 在文件没有结束和错误情况下，则会回到ngx_conf_parse中，继续执行ngx_conf_handler函数。
char *
ngx_conf_parse(ngx_conf_t *cf, ngx_str_t *filename )
{
char *rv;
ngx_fd_t fd ;
ngx_int_t rc ;
ngx_buf_t buf ;
ngx_conf_file_t *prev, conf_file;
enum {
parse_file = 0 ,
parse_block ,
parse_param
} type ;
if (filename) {
/* 打开配置文件 */
fd = ngx_open_file(filename->data , NGX_FILE_RDONLY, NGX_FILE_OPEN, 0 );
if ( fd == NGX_INVALID_FILE ) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, ngx_errno ,
ngx_open_file_n " "%s" failed",
filename ->data);
return NGX_CONF_ERROR;
}
prev = cf-> conf_file;
cf ->conf_file = &conf_file ;
if ( ngx_fd_info(fd , & cf->conf_file->file .info) == NGX_FILE_ERROR) {
ngx_log_error (NGX_LOG_EMERG, cf->log , ngx_errno,
ngx_fd_info_n " "%s" failed", filename->data);
}
cf ->conf_file->buffer = &buf;
buf .start = ngx_alloc(NGX_CONF_BUFFER , cf-> log);
if ( buf.start == NULL ) {
goto failed;
}
buf .pos = buf.start ;
buf .last = buf.start ;
buf .end = buf.last + NGX_CONF_BUFFER;
buf .temporary = 1;
cf ->conf_file->file.fd = fd;
cf ->conf_file->file.name .len = filename->len ;
cf ->conf_file->file.name .data = filename->data ;
cf ->conf_file->file.offset = 0 ;
cf ->conf_file->file.log = cf-> log;
cf ->conf_file->line = 1;
type = parse_file;
} else if (cf->conf_file ->file. fd != NGX_INVALID_FILE ) {
type = parse_block;
} else {
type = parse_param;
}
for ( ;; ) {
rc = ngx_conf_read_token (cf);
/*
* ngx_conf_read_token() may return
*
* NGX_ERROR there is error
* NGX_OK the token terminated by ";" was found
* NGX_CONF_BLOCK_START the token terminated by "{" was found
* NGX_CONF_BLOCK_DONE the "}" was found
* NGX_CONF_FILE_DONE the configuration file is done
*/
if (rc == NGX_ERROR) {
goto done;
}
if (rc == NGX_CONF_BLOCK_DONE) {
if ( type != parse_block ) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0, "unexpected "}"");
goto failed;
}
goto done;
}
if (rc == NGX_CONF_FILE_DONE) {
if ( type == parse_block ) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"unexpected end of file, expecting "}"");
goto failed;
}
goto done;
}
if (rc == NGX_CONF_BLOCK_START) {
if ( type == parse_param ) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"block directives are not supported "
"in -g option");
goto failed;
}
}
/* rc == NGX_OK || rc == NGX_CONF_BLOCK_START */
if (cf-> handler) {
/*
* the custom handler, i.e., that is used in the http's
* "types { ... }" directive
*/
if ( rc == NGX_CONF_BLOCK_START ) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0, "unexpected "{"");
goto failed;
}
rv = (* cf->handler)(cf , NULL , cf-> handler_conf);
if ( rv == NGX_CONF_OK ) {
continue;
}
if ( rv == NGX_CONF_ERROR ) {
goto failed;
}
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0, rv );
goto failed;
}
rc = ngx_conf_handler (cf, rc);
if (rc == NGX_ERROR) {
goto failed;
}
}
failed:
rc = NGX_ERROR ;
done:
if (filename) {
if ( cf->conf_file->buffer ->start) {
ngx_free (cf-> conf_file->buffer ->start);
}
if ( ngx_close_file(fd ) == NGX_FILE_ERROR) {
ngx_log_error (NGX_LOG_ALERT, cf->log , ngx_errno,
ngx_close_file_n " %s failed",
filename ->data);
return NGX_CONF_ERROR;
}
cf ->conf_file = prev;
}
if (rc == NGX_ERROR) {
return NGX_CONF_ERROR;
}
return NGX_CONF_OK ;
}
ngx_conf_handler函数如下，函数会遍历所有模块，并匹配配置命令key，取出配置上下文指针，执行相应的set函数。
static ngx_int_t
ngx_conf_handler(ngx_conf_t *cf, ngx_int_t last)
{
char *rv;
void *conf, **confp;
ngx_uint_t i , found;
ngx_str_t *name;
ngx_command_t *cmd;
name = cf ->args-> elts;
found = 0;
/*遍历所有模块，并比较模块中所有配置的key值*/
for (i = 0 ; ngx_modules[i]; i ++) {
cmd = ngx_modules[i]->commands ;
if ( cmd == NULL) {
continue;
}
for ( /* void */ ; cmd->name .len; cmd++) {
if ( name->len != cmd-> name.len ) {
continue;
}
/*比较命令key值是否和配置的一致*/
if ( ngx_strcmp(name ->data, cmd->name .data) != 0) {
continue;
}
found = 1 ;
/*过滤掉非指定模块，进入ngx_conf_parse前，会指定module_type值，解析指定模块*/
if ( ngx_modules[i ]->type != NGX_CONF_MODULE
&& ngx_modules[i]->type != cf-> module_type)
{
continue;
}
/*判断解析的配置命令类型是否和指定的类型一致，cmd_type在进入ngx_conf_parse前指定*/
if (!( cmd->type & cf-> cmd_type)) {
continue;
}
if (!( cmd->type & NGX_CONF_BLOCK) && last != NGX_OK) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"directive "%s" is not terminated by ";"",
name ->data);
return NGX_ERROR;
}
if (( cmd->type & NGX_CONF_BLOCK) && last != NGX_CONF_BLOCK_START) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"directive "%s" has no opening "{"",
name ->data);
return NGX_ERROR;
}
/*判断配置参数个数是否正确*/
if (!( cmd->type & NGX_CONF_ANY)) {
if ( cmd->type & NGX_CONF_FLAG) {
if ( cf->args->nelts != 2 ) {
goto invalid;
}
} else if (cmd ->type & NGX_CONF_1MORE) {
if ( cf->args->nelts < 2 ) {
goto invalid;
}
} else if (cmd ->type & NGX_CONF_2MORE) {
if ( cf->args->nelts < 3 ) {
goto invalid;
}
} else if (cf ->args-> nelts > NGX_CONF_MAX_ARGS ) {
goto invalid;
} else if (!(cmd ->type & argument_number[cf ->args-> nelts - 1 ]))
{
goto invalid;
}
}
/* 获取指定配置上下文的指针，*/
conf = NULL ;
if ( cmd->type & NGX_DIRECT_CONF) {
/*
*取ngx_core_module模块配置ngx_core_conf_t指针，由于该模块结构中直接配置了create_conf回调函数，已经分配过内存，直接使用
*/
conf = (( void **) cf->ctx )[ngx_modules[i]->index ];
} else if (cmd ->type & NGX_MAIN_CONF) {
/*
*假设cmd->name值是http，即正在解析http{}块，(((void **) cf->ctx)[ngx_modules[i]->index]取出的是ngx_http_module模块配置ngx_http_conf_ctx_t的指针，
*由于配置还未进行内存分配，因此这里取了指针的地址，以备后面ngx_http_block对其进行内存分配
*/
conf = &((( void **) cf->ctx )[ngx_modules[i]->index ]);
} else if (cf ->ctx) {
/*
*假设cmd->name值是location，并出现在server{}第一层中，即解析server { location{} }块，首先confp取出的是ngx_http_conf_ctx_t中srv_conf指针值，
*conf则取出当前模块对应的http配置指针
*/
confp = *( void **) ((char *) cf->ctx + cmd-> conf);
if ( confp) {
conf = confp[ ngx_modules[i ]->ctx_index];
}
}
/*配置的set函数*/
rv = cmd-> set(cf , cmd, conf);
if ( rv == NGX_CONF_OK ) {
return NGX_OK;
}
if ( rv == NGX_CONF_ERROR ) {
return NGX_ERROR;
}
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
""%s" directive %s" , name-> data, rv );
return NGX_ERROR;
}
}
if (found) {
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
""%s" directive is not allowed here" , name->data);
return NGX_ERROR;
}
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"unknown directive "%s"" , name-> data);
return NGX_ERROR ;
invalid:
ngx_conf_log_error (NGX_LOG_EMERG, cf, 0,
"invalid number of arguments in "%s" directive",
name ->data);
return NGX_ERROR ;
}
下面我们假设配置读取的是http{}块，则set函数即为ngx_http_block，函数首先给ngx_http_conf_ctx_t配置分配内存，然后递归调用ngx_conf_parse开始解析所有NGX_HTTP_MODULE模块中main_conf字段，解析中如果遇到location{}或者server{}块，则调用相应的set函数进行解析，整个http{}块共享同一个main_conf。如果一个字段可以同时出现在main_conf，srv_conf中，则这个字段会保存在srv_conf中，如果一个字段可以同时出现在main_conf，srv_conf，loc_conf中，则此配置必定保存在loc_conf中。配置的合并其实就是对那些可以出现在多个层的字段，如果内层没有赋值，则由外层向内层赋值过程。
static char *
ngx_http_block(ngx_conf_t *cf, ngx_command_t *cmd , void *conf)
{
char *rv;
ngx_uint_t mi , m, s;
ngx_conf_t pcf ;
ngx_http_module_t *module;
ngx_http_conf_ctx_t *ctx;
ngx_http_core_loc_conf_t *clcf;
ngx_http_core_srv_conf_t **cscfp;
ngx_http_core_main_conf_t *cmcf;
/*ngx_http_ctx_t分配内存*/
ctx = ngx_pcalloc (cf-> pool, sizeof(ngx_http_conf_ctx_t ));
if (ctx == NULL) {
return NGX_CONF_ERROR;
}
/*conf指针即ngx_conf_handler中取出的ngx_http_ctx_t指针的地址，将分配的内存赋值，相当于(((void **) cf->ctx)[ngx_modules[i]->index]) = ctx*/
*(ngx_http_conf_ctx_t **) conf = ctx;
/*设置HTTP模块相关配置的索引地址*/
ngx_http_max_module = 0 ;
for (m = 0 ; ngx_modules[m]; m ++) {
if ( ngx_modules[m ]->type != NGX_HTTP_MODULE) {
continue;
}
ngx_modules [m]-> ctx_index = ngx_http_max_module ++;
}
/* main_conf整个http{}块共享同一个main_conf */
ctx->main_conf = ngx_pcalloc(cf->pool ,
sizeof(void *) * ngx_http_max_module );
if (ctx-> main_conf == NULL) {
return NGX_CONF_ERROR;
}
/*
* http{}块没有srv_conf，合并时使用
*/
ctx->srv_conf = ngx_pcalloc(cf->pool , sizeof (void *) * ngx_http_max_module);
if (ctx-> srv_conf == NULL) {
return NGX_CONF_ERROR;
}
/*
* http{}没有loc_conf，合并时使用
*/
ctx->loc_conf = ngx_pcalloc(cf->pool , sizeof (void *) * ngx_http_max_module);
if (ctx-> loc_conf == NULL) {
return NGX_CONF_ERROR;
}
/*
* create the main_conf's, the null srv_conf's, and the null loc_conf's
* of the all http modules
*/
for (m = 0 ; ngx_modules[m]; m ++) {
if ( ngx_modules[m ]->type != NGX_HTTP_MODULE) {
continue;
}
module = ngx_modules[m]->ctx ;
mi = ngx_modules[m]->ctx_index ;
if ( module->create_main_conf ) {
ctx ->main_conf[mi] = module->create_main_conf(cf );
if ( ctx->main_conf [mi] == NULL) {
return NGX_CONF_ERROR;
}
}
if ( module->create_srv_conf ) {
ctx ->srv_conf[mi] = module->create_srv_conf(cf );
if ( ctx->srv_conf [mi] == NULL) {
return NGX_CONF_ERROR;
}
}
if ( module->create_loc_conf ) {
ctx ->loc_conf[mi] = module->create_loc_conf(cf );
if ( ctx->loc_conf [mi] == NULL) {
return NGX_CONF_ERROR;
}
}
}
/*
*保存原来上下文配置，cf->ctx赋值为ngx_http_ctx_t指针，后面要开始递归解析http{}块，在后面的我们会看到很多这样的操作
*/
pcf = *cf;
cf->ctx = ctx;
for (m = 0 ; ngx_modules[m]; m ++) {
if ( ngx_modules[m ]->type != NGX_HTTP_MODULE) {
continue;
}
module = ngx_modules[m]->ctx ;
if ( module->preconfiguration ) {
if ( module->preconfiguration (cf) != NGX_OK) {
return NGX_CONF_ERROR;
}
}
}
/*
*module_type和cmd_type赋值，进入ngx_conf_parse后解析NGX_HTTP_MODULE模块，并且NGX_HTTP_MAIN_CONF类型的配置
*/
cf->module_type = NGX_HTTP_MODULE;
cf->cmd_type = NGX_HTTP_MAIN_CONF;
rv = ngx_conf_parse (cf, NULL);
if (rv != NGX_CONF_OK) {
goto failed;
}
/*
* 上面解析完成后，所有的server{}列表保存在cmcf->servers中，然后开始合并server{}块，合并server{}块时，同时会开始合并location{}块
*/
cmcf = ctx ->main_conf[ngx_http_core_module.ctx_index ];
cscfp = cmcf ->servers.elts;
for (m = 0 ; ngx_modules[m]; m ++) {
if ( ngx_modules[m ]->type != NGX_HTTP_MODULE) {
continue;
}
module = ngx_modules[m]->ctx ;
mi = ngx_modules[m]->ctx_index ;
/* init http{} main_conf's */
if ( module->init_main_conf ) {
rv = module->init_main_conf(cf , ctx-> main_conf[mi ]);
if ( rv != NGX_CONF_OK ) {
goto failed;
}
}
rv = ngx_http_merge_servers(cf, cmcf , module, mi);
if ( rv != NGX_CONF_OK ) {
goto failed;
}
}
/* 创建location节点树, 把location链表转换成三叉树, 利于用户根据请求url取出相应的配置 */
for (s = 0 ; s < cmcf->servers .nelts; s++) {
clcf = cscfp[ s]->ctx->loc_conf [ngx_http_core_module.ctx_index];
if ( ngx_http_init_locations(cf , cscfp[ s], clcf) != NGX_OK) {
return NGX_CONF_ERROR;
}
if ( ngx_http_init_static_location_trees(cf , clcf) != NGX_OK) {
return NGX_CONF_ERROR;
}
}
if (ngx_http_init_phases(cf, cmcf ) != NGX_OK) {
return NGX_CONF_ERROR;
}
if (ngx_http_init_headers_in_hash(cf, cmcf ) != NGX_OK) {
return NGX_CONF_ERROR;
}
for (m = 0 ; ngx_modules[m]; m ++) {
if ( ngx_modules[m ]->type != NGX_HTTP_MODULE) {
continue;
}
module = ngx_modules[m]->ctx ;
if ( module->postconfiguration ) {
if ( module->postconfiguration (cf) != NGX_OK) {
return NGX_CONF_ERROR;
}
}
}
if (ngx_http_variables_init_vars(cf) != NGX_OK) {
return NGX_CONF_ERROR;
}
/*
* http{}'s cf->ctx was needed while the configuration merging
* and in postconfiguration process
*/
*cf = pcf;
if (ngx_http_init_phase_handlers(cf, cmcf ) != NGX_OK) {
return NGX_CONF_ERROR;
}
/* optimize the lists of ports, addresses and server names */
if (ngx_http_optimize_servers(cf, cmcf , cmcf-> ports) != NGX_OK) {
return NGX_CONF_ERROR;
}
return NGX_CONF_OK ;
failed:
*cf = pcf;
return rv ;
}
http模块解析完成后, 所有的server配置都会保存在cmcf->servers数组中, 每个server下的location会组成一个三叉树, 保存在相对应的server中ngx_http_core_loc_conf_t中static_locations. 服务器接收一个url请求后, 通过相应的地址和端口找到server配置, 通过三叉树找到相匹配的ngx_http_core_loc_conf_t配置, 进而获取到正确的配置信息.