从零开始一个http服务器（三)
代码地址 ： https://github.com/flamedancer/cserver
git checkout step3
运行：
gcc request.h request.c response.h response.c main.c tools/utils.c tools/utils.h && ./a.out
测试:
浏览器打开 http://127.0.0.1:9734/
response 构造
- 观察response结构
- 定义并返回response
- 测试
观察response结构
上一节,我们成功解析了http的request，但是我们在浏览器访问我们的地址http://127.0.0.1:9734/ 还是无法正常显示。这是因为我们没有给浏览器返回它能读懂的信息。这一节我们的目标是让浏览器正确的显示信息。什么样的才是浏览器能读懂的信息呢？不妨我们用telnet来模拟向百度主页发一个http request,来看看百度主页返回的是什么信息。
伪造一个http request的字符串，注意 headers 中的 Host 代表我们要访问的主机地址。
GET / HTTP/1.1
Host: www.baidu.com
User-Agent: curl/7.54.0
Accept: */*
Content-Type: application/x-www-form-urlencode
再用telnet连接www.baidu.com 并指定80端口（80为http默认端口，telnet默认端口为23）, telnet www.baidu.com 80
复制黏贴上面我们构造的字符串回车后，你应该能看到如下类似的返回结果：
Trying 119.75.216.20...
Connected to www.a.shifen.com.
Escape character is '^]'.
GET / HTTP/1.1
Host: www.baidu.com
User-Agent: curl/7.54.0
Accept: */*
Content-Type: application/x-www-form-urlencode
HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform
Connection: Keep-Alive
Content-Length: 2381
Content-Type: text/html
Date: Sat, 18 Aug 2018 02:12:08 GMT
Etag: "588604c8-94d"
Last-Modified: Mon, 23 Jan 2017 13:27:36 GMT
Pragma: no-cache
Server: bfe/1.0.8.18
Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/
<!DOCTYPE html>
<!--STATUS OK--><html> ...</html>
Connection closed by foreign host.
从HTTP/1.1 200 OK开始就是百度放回给我们的结果。让人惊喜的是这种结构和request很类型，除了第一行外。仔细看看:
- 第一行为 http版本号 response返回码 response返回结果描述
- 第二行开始为headers
- 空行后，接body
定义并返回response
根据response的结构有的信息定义我们的结构体.
/* response.h
*/
#include <stdio.h>
#include "tools/utils.h"
#include "request.h"
struct http_response {
char * version;
char * code; // 状态返回码
char * desc; // 返回描述
struct Map * headers;
char * body;
};
void initHttpResponse(struct http_response * response);
void doResponse(
struct http_request * request,
FILE * stream
);
void outputToFile(
struct http_response * response,
FILE * stream
);
构造我们的response数据, 我们每次都返回相同的数据.
/* response.c
*/
#include <stdio.h> /* fprintf NULL */
#include <string.h> /* strlen */
#include "response.h"
#include "request.h"
#include "tools/utils.h"
void initHttpResponse(struct http_response * response) {
response->version = NULL;
response->code = NULL;
response->desc = NULL;
response->headers = NULL;
response->body = NULL;
}
void doResponse(struct http_request * request, FILE * stream) {
struct http_response responseInstance;
struct http_response * response = &responseInstance;
initHttpResponse(response);
response->version = "HTTP/1.1";
response->code = "200";
response->desc = "OK";
char * content = "<html>hello everyone</html>";
char content_len[25];
sprintf(content_len, "%lu", strlen(content));
struct Item * item = newItem(
"Content-Length",
content_len
);
struct Map map_instance;
initMap(&map_instance);
response->headers = &map_instance;
mapPush(response->headers, item);
response->body = content;
outputToFile(response, stream);
// clean
releaseMap(request->headers);
}
void outputToFile(struct http_response * response, FILE * stream) {
// output version code desc
int r = fprintf(stream, "%s %s %s
",
response->version,
response->code,
response->desc
);
// output headers
struct Map* map = response->headers;
struct List* list;
struct Item* item;
int print_item_cnt = 0;
for(int i=0; i<map->table_len; i++) {
list = map->table[i];
if(list == NULL) {
continue;
}
item = list->start;
while(item != NULL) {
fprintf(stream, "%s: %s
",
item->key,
item->value
);
item = item->next;
}
}
// output body
if(response->body != NULL) {
fprintf(stream, "
%s", response->body);
}
}
写一个测试用例，将本应向客服端发送的数据输出到stdout
/* test/responseTest.c
test cmd:
gcc ../request.h ../request.c ../response.h ../response.c ../tools/utils.h ../tools/utils.c responseTest.c && ./a.out
*/
#include <stdio.h>
#include "../request.h"
#include "../response.h"
int main() {
struct http_request request;
char data[] = "POST / HTTP/1.1
Content-Length: 3
111";
struct Map headers;
request.headers = &headers;
parse_request(&request, data);
doResponse(&request, stdout);
}
cd 到 test 目录
运行： gcc ../request.h ../request.c ../response.h ../response.c ../tools/utils.h ../tools/utils.c responseTest.c && ./a.out
可以看到正确的输出：
---------------------------
method is: POST
url is: /
http version is: HTTP/1.1
the headers are :
{'Content-Length': ' 3'}
body is 111
---------------------------
HTTP/1.1 200 OK
Content-Length: 27
<html>hello everyone</html>
现在修改main函数，加上我们的reponse处理逻辑
/**
run cmd:
gcc request.h request.c response.h response.c main.c tools/utils.c tools/utils.h && ./a.out
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netinet/in.h>
#include <stdlib.h>
#include "request.h"
#include "response.h"
#define MAXREQUESTLEN 50000
void initString(char * c, int length) {
int i = 0;
while(i < length) {
*(c + i) = ' ';
i++;
}
}
int main() {
int server_sockfd, client_sockfd;
socklen_t server_len, client_len;
struct sockaddr_in server_address;
struct sockaddr_in client_address;
server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
server_address.sin_port = htons(9734);
server_len = sizeof(server_address);
bind(server_sockfd, (struct sockaddr *)&server_address, server_len);
listen(server_sockfd, 5);
while(1) {
char ch[MAXREQUESTLEN];
initString(ch, MAXREQUESTLEN);
// char send_str[] = "hello world !
";
client_len = sizeof(client_address);
client_sockfd = accept(server_sockfd,
(struct sockaddr *)&client_address, &client_len);
read(client_sockfd, &ch, MAXREQUESTLEN);
printf("%s
", ch);
struct http_request request;
struct Map headers;
request.headers = &headers;
parse_request(&request, ch);
FILE* fp = fdopen(client_sockfd, "w+");
doResponse(&request, fp);
fflush(fp);
fclose(fp);
// write(client_sockfd, &send_str, sizeof(send_str)/sizeof(send_str[0]));
}
}
测试
启动我们的server gcc request.h request.c response.h response.c main.c tools/utils.c tools/utils.h && ./a.out
再在浏览器访问我们的服务器地址 http://127.0.0.1:9734/
现在浏览器能识别我们的返回结果了！