第三章 开发一个简单的HTTP模块

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

//当在配置块中出现mytest配置项的时候，就会调用此函数
//此函数用来注册请求到来的实际处理函数  下一个函数
static char *ngx_http_mytest_memory(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);

static char *ngx_http_mytest_file(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);

//请求到来且匹配到mytest项的时候实际处理函数
//这个函数在NGX_HTTP_CONTENT_PHASE阶段处理
static ngx_int_t ngx_http_mytest_handler_memory(ngx_http_request_t *r);

static ngx_int_t ngx_http_mytest_handler_file(ngx_http_request_t *r);


//配置项的数组
static ngx_command_t ngx_http_mytest_commands[] = {
    { 
        ngx_string("mytest"),
        NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_HTTP_LMT_CONF | NGX_CONF_NOARGS, 
        ngx_http_mytest_memory, 
        NGX_HTTP_LOC_CONF_OFFSET,
        0,
        NULL
    },

    {
        ngx_string("myfile"),
        NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_HTTP_LMT_CONF | NGX_CONF_NOARGS,
        ngx_http_mytest_file,
        NGX_HTTP_LOC_CONF_OFFSET,
        0,
        NULL
    },

    ngx_null_command
};

static ngx_http_module_t ngx_http_mytest_module_ctx = {
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

ngx_module_t ngx_http_mytest_module = {
    NGX_MODULE_V1,
    &ngx_http_mytest_module_ctx,
    ngx_http_mytest_commands,
    NGX_HTTP_MODULE,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NGX_MODULE_V1_PADDING
};

static char *ngx_http_mytest_memory(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_memory; 
    return NGX_CONF_OK;
}

static char *ngx_http_mytest_file(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_file;
    return NGX_CONF_OK;
}

/*
    struct ngx_file_s {
        ngx_fd_t fd;
        ngx_str_t name;
        ngx_file_info_t info; //typedef struct stat ngx_file_info_t
        off_t offset;
        off_t sys_offset;
        ngx_log_t *log;
        unsigned valid_info:1;
        unsigned directio:1;
    }
*/
//发送文件
static ngx_int_t ngx_http_mytest_handler_file(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;
    }

    ngx_str_t type = ngx_string("text/html");

    r->headers_out.status = NGX_HTTP_OK;

    r->headers_out.content_type = type;
    //这个缓冲区现在用来保存文件
    ngx_buf_t *b;
    //给ngx_buf_t分配内存
    b = ngx_palloc(r->pool, sizeof(ngx_buf_t));

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

    u_char *filename = (u_char *)"/usr/local/nginx/html/mytest.html";
    //是否是文件 标志位
    b->in_file = 1;
    //给文件结构体申请内存
    b->file = ngx_palloc(r->pool, sizeof(ngx_file_t));

    if(b->file == NULL) {
        return NGX_ERROR;
    }
    //打开文件
    //初始化ngx_file_s结构体
    b->file->fd = ngx_open_file(filename, NGX_FILE_RDONLY | NGX_FILE_NONBLOCK, NGX_FILE_OPEN, 0);

    b->file->log = r->connection->log;

    b->file->name.data = filename;

    b->file->name.len = sizeof(filename);
    //文件打开失败
    if(b->file->fd <= 0) {
        return NGX_HTTP_NOT_FOUND;
    }
    //info就是stat结构体
    if(ngx_file_info(filename, &b->file->info) == NGX_FILE_ERROR) { 
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    r->headers_out.content_length_n = b->file->info.st_size; 

    //发送响应头部
    rc = ngx_http_send_header(r);
    if(rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
        return rc;
    }

    //构造响应包体
    //文件发送起始偏移
    b->file_pos = 0;

    b->file_last = b->file->info.st_size; //pos == last 就停止发送

    b->last_buf = 1;

    //设置发送完毕之后关闭句柄的回调函数
    ngx_pool_cleanup_t *cln = ngx_pool_cleanup_add(r->pool, sizeof(ngx_pool_cleanup_file_t));

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

    cln->handler = ngx_pool_cleanup_file;

    ngx_pool_cleanup_file_t *clnf = cln->data;

    clnf->fd = b->file->fd;

    clnf->name = b->file->name.data;

    clnf->log = r->pool->log;

    //发送响应包体
    ngx_chain_t out;

    out.buf = b;

    out.next = NULL;

    return ngx_http_output_filter(r, &out);
}

/*
//这个函数定义在/core/ngx_palloc.c中
void ngx_pool_cleanup_file(void *data) {
    ngx_pool_cleanup_file_t *c = data;

    ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, c->log, 0, "file cleanup: fd:%d", c->fd);

    if(ngx_close_file(c->fd) == NGX_FILE_ERROR) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno, ngx_close_file_n "\"%s\" failed", c->name);
    }
}
*/

//此函数用于发送内存数据
static ngx_int_t ngx_http_mytest_handler_memory(ngx_http_request_t *r) {

    //方法只能是Get Head
    if(!(r->method & (NGX_HTTP_GET | NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }

    //丢弃http请求中请求包体，这样防止客户端发送超时
    ngx_int_t rc = ngx_http_discard_request_body(r);
    if(rc != NGX_OK) {
            return rc;
    }

    ngx_str_t type = ngx_string("text/plain");

    ngx_str_t response = ngx_string("Hello World!");
    //返回状态码
    r->headers_out.status = NGX_HTTP_OK;
    //设置响应包体长度
    r->headers_out.content_length_n = response.len;
    //设置响应头部Content_Type
    r->headers_out.content_type = type;

    //发送响应头部
    rc = ngx_http_send_header(r);
    if(rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
        return rc;
    }

    //构造响应包体
    ngx_buf_t *b;
    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->last_buf = 1;

    ngx_chain_t out;

    out.buf = b;

    out.next = NULL;

    return ngx_http_output_filter(r, &out);
}

上述代码文件命名为ngx_http_mytest_module.c ，同时放入任意目录，在目录中添加脚本，命名为config ，这个脚本必须为config ，脚本内容如下：

ngx_addon_name=ngx_http_mytest_module
HTTP_MODULES="$HTTP_MODULES ngx_http_mytest_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_mytest_module.c"

开始编译nginx，注意添加模块路径
./configure --add-module=/root/module

我上面的html 文件在/usr/local/nginx/html/mytest.html ，文件内容随便，一下是我的测试html文件内容：

<html>
<body>
《》《》《》《》《》《》《》
</body>
</html>

重新配置nginx.conf ，在server块中添加下面两个location

        location /myfile {
                myfile;
        }

        location /mytest {
                mytest;
        }

运行nginx，测试内容如下：