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/1.1Host: www.baidu.comUser-Agent: curl/7.54.0Accept: */*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 \r\n",
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\r\n",
item->key,
item->value
);
item = item->next;
}
} // output body
if(response->body != NULL) { fprintf(stream, "\r\n%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\r\nContent-Length: 3\r\n\r\n111"; 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/1.1the 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 50000void initString(char * c, int length) { int i = 0; while(i < length) {
*(c + i) = '\0';
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 !\n";
client_len = sizeof(client_address);
client_sockfd = accept(server_sockfd,
(struct sockaddr *)&client_address, &client_len);
read(client_sockfd, &ch, MAXREQUESTLEN); printf("%s\n", 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！
原文出处：https://www.cnblogs.com/chens-smile/p/9498340.html
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