从零手写实现 nginx-21-modules 模块

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

// 模块的 context 结构体
typedef struct {
    ngx_str_t test_str;
} ngx_http_mytest_conf_t;

// 解析配置项的回调函数
static char *ngx_http_mytest(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) {
    ngx_http_core_loc_conf_t *clcf;
    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_mytest_handler;

    // 获取配置项参数
    ngx_str_t *value = cf->args->elts;
    ngx_http_mytest_conf_t *lcf = conf;
    lcf->test_str = value[1];

    return NGX_CONF_OK;
}

// 模块处理请求的回调函数
static ngx_int_t ngx_http_mytest_handler(ngx_http_request_t *r) {
    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }

    ngx_int_t rc = ngx_http_discard_request_body(r);
    if (rc != NGX_OK) {
        return rc;
    }

    // 设置响应头
    ngx_str_t *test_str = ...; // 从配置中获取字符串
    ngx_table_elt_t *h = ngx_list_push(&r->headers_out.headers);
    if (h == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    h->key = ngx_http_mytest_header_name;
    h->value = *test_str;
    h->hash = 1; // 计算hash值

    // 发送响应
    ngx_int_t status = NGX_HTTP_OK;
    ngx_str_t response = ngx_http_mytest_response;
    ngx_buf_t *b = ngx_create_temp_buf(r.pool, response.len);
    if (b == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    ngx_memcpy(b->pos, response.data, response.len);
    b->last = b->pos + response.len;
    b->memory = 1;
    b->last_buf = 1;

    r->headers_out.status = status;
    r->headers_out.content_length_n = response.len;
    r->headers_out.content_type_len = sizeof("text/plain") - 1;
    ngx_str_set(&r->headers_out.content_type, "text/plain");

    return ngx_http_send_header(r) == NGX_ERROR
        ? NGX_HTTP_INTERNAL_SERVER_ERROR
        : ngx_http_output_filter(r, b);
}

// 模块的定义
ngx_module_t ngx_http_mytest_module = {
    ..., // 模块的各种方法
    ngx_http_mytest_create_conf, // 创建配置结构体的方法
    ngx_http_mytest_init_conf // 初始化配置结构体的方法
};

// 配置指令结构体
static ngx_command_t ngx_http_