Tinyhttpd学习
个人结合其他网站对Tinyhttpd的细读和学习
个人仓库:https://github.com/dopamine-joker/Mythhpd
项目github: https://github.com/EZLippi/Tinyhttpd
原项目官网:http://tinyhttpd.sourceforge.net
学习参考网站:https://www.cnblogs.com/nengm1988/p/7816618.html
1. 简介
Tinyhttpd 是J. David Blackstone在1999年写的一个不到 500 行的超轻量型 Http Server，比较适合初学者学习。
原作者:
代码语言：javascript复制This software is copyright 1999 by J. David Blackstone. Permission is granted to redistribute and modify this software under the terms of the GNU General Public License, available at http://www.gnu.org/ .
If you use this software or examine the code, I would appreciate knowing and would be overjoyed to hear about it at jdavidb@sourceforge.net .
This software is not production quality. It comes with no warranty of any kind, not even an implied warranty of fitness for a particular purpose. I am not responsible for the damage that will likely result if you use this software on your computer system.
I wrote this webserver for an assignment in my networking class in 1999. We were told that at a bare minimum the server had to serve pages, and told that we would get extra credit for doing "extras." Perl had introduced me to a whole lot of UNIX functionality (I learned sockets and fork from Perl!), and O'Reilly's lion book on UNIX system calls plus O'Reilly's books on CGI and writing web clients in Perl got me thinking and I realized I could make my webserver support CGI with little trouble.
Now, if you're a member of the Apache core group, you might not be impressed. But my professor was blown over. Try the color.cgi sample script and type in "chartreuse." Made me seem smarter than I am, at any rate. :)
Apache it's not. But I do hope that this program is a good educational tool for those interested in http/socket programming, as well as UNIX system calls. (There's some textbook uses of pipes, environment variables, forks, and so on.)
One last thing: if you look at my webserver or (are you out of mind?!?) use it, I would just be overjoyed to hear about it. Please email me. I probably won't really be releasing major updates, but if I help you learn something, I'd love to know!
Happy hacking!2. Tinyhttp运作流程
(参考博客的贴图):
具体文字流程也可在github项目找到,如下:
(1) 服务器启动，在指定端口或随机选取端口绑定 httpd 服务。
(2) 收到一个 HTTP 请求时（其实就是 listen 的端口 accpet 的时候），派生一个线程运行 accept_request 函数。
(3) 取出 HTTP 请求中的 method (GET 或 POST) 和 url,。对于 GET 方法，如果有携带参数，则 query_string 指针指向 url 中 ？ 后面的 GET 参数。
(4) 格式化 url 到 path 数组，表示浏览器请求的服务器文件路径，在 tinyhttpd 中服务器文件是在 htdocs 文件夹下。当 url 以 / 结尾，或 url 是个目录，则默认在 path 中加上 index.html，表示访问主页。
(5) 如果文件路径合法，对于无参数的 GET 请求，直接输出服务器文件到浏览器，即用 HTTP 格式写到套接字上，跳到（10）。其他情况（带参数 GET，POST 方式，url 为可执行文件），则调用 excute_cgi 函数执行 cgi 脚本。
(6) 读取整个 HTTP 请求并丢弃，如果是 POST 则找出 Content-Length. 把 HTTP 200 状态码写到套接字。
(7) 建立两个管道，cgi_input 和 cgi_output, 并 fork 一个进程。
(8) 在子进程中，把 STDOUT 重定向到 cgi_outputt 的写入端，把 STDIN 重定向到 cgi_input 的读取端，关闭 cgi_input 的写入端 和 cgi_output 的读取端，设置 request_method 的环境变量，GET 的话设置 query_string 的环境变量，POST 的话设置 content_length 的环境变量，这些环境变量都是为了给 cgi 脚本调用，接着用 execl 运行 cgi 程序。
(9) 在父进程中，关闭 cgi_input 的读取端 和 cgi_output 的写入端，如果 POST 的话，把 POST 数据写入 cgi_input，已被重定向到 STDIN，读取 cgi_output 的管道输出到客户端，该管道输入是 STDOUT。接着关闭所有管道，等待子进程结束。这一部分比较乱，见下图说明：
图 1 管道初始状态
图 2 管道最终状态
(10) 关闭与浏览器的连接，完成了一次 HTTP 请求与回应，因为 HTTP 是无连接的。
3. 注意
(1) 修改相关文件的权限
index.html必须不能有执行权限，否则代码中会将其当作cgi脚本处理。
代码语言：javascript复制if( (st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) ||(st.st_mode & S_IXOTH)){
//S_IXUSR 00100 owner has execute permission
//S_IXGRP 00010 group has execute permission
//S_IXOTH 00001 others have execute permission
cgi = 1;
}因此需要先将index.html的运行权限去除，使用命令 chmod 600 index.html
而脚本文件color.cgi需要有执行权限
(2) color.cgi修改
color.cgi使用perl编写的，对原项目的color.cgi中的代码中perl解释器路径进行更改。
若linux系统中的perl解释器路径与代码中的一致则不用修改
文件中第一行
代码语言：javascript复制#!/usr/local/bin/perl -Tw改为
代码语言：javascript复制#!/usr/bin/perl -Tw若perl脚本执行时没有找到相关模块则需手动安装
4. 食用流程
(1) 直接拷贝或者自行敲码
(2) 修改相关文件权限和perl代码（上面有写）
(3) 在项目目录下使用makefile构建
代码语言：javascript复制[root@localhost Myhttpd]# make clean
rm httpd
[root@localhost Myhttpd]# make
gcc -g -W -Wall -pthread -o httpd httpd.c(4) 运行
代码语言：javascript复制[root@localhost Myhttpd]# ./httpd
httpd running on port: 60555(5) 测试
1) POST
2) GET
5. 代码
个人在学习时加了一点注释
代码语言：javascript复制#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <ctype.h>
#include <strings.h>
#include <string.h>
#include <sys/stat.h>
#include <pthread.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <stdint.h>
#define ISspace(x) isspace((int)(x))
#define SERVER_STRING "Server: jdbhttpd/0.1.0rn"
#define STDIN 0
#define STDOUT 1
#define STDERR 2
void accept_request(void *arg);
void bad_request(int);
void cat(int, FILE *);
void cannot_execute(int);
void execute_cgi(int, const char *, const char *, const char *);
void headers(int, const char *);
int startup(u_short *);
int get_line(int, char *, int);
void unimplemented(int );
void error_die(const char *);
void not_found(int );
void serve_file(int , const char *);
// Http请求的信息
// GET请求
// GET / HTTP/1.1
// Host: 192.168.0.23:47310
// Connection: keep-alive
// Upgrade-Insecure-Requests: 1
// User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36
// Accept: text/html,application/xhtml xml,application/xml;q=0.9,image/webp,*/*; q = 0.8
// Accept - Encoding: gzip, deflate, sdch
// Accept - Language : zh - CN, zh; q = 0.8
// Cookie: __guid = 179317988.1576506943281708800.1510107225903.8862; monitor_count = 5
//
//
// POST请求
// POST / color1.cgi HTTP / 1.1
// Host: 192.168.0.23 : 47310
// Connection : keep - alive
// Content - Length : 10
// Cache - Control : max - age = 0
// Origin : http ://192.168.0.23:40786
// Upgrade - Insecure - Requests : 1
// User - Agent : Mozilla / 5.0 (Windows NT 6.1; WOW64) AppleWebKit / 537.36 (KHTML, like Gecko) Chrome / 55.0.2883.87 Safari / 537.36
// Content - Type : application / x - www - form - urlencoded
// Accept : text / html, application / xhtml xml, application / xml; q = 0.9, image / webp, */*;q=0.8
// Referer: http://192.168.0.23:47310/
// Accept-Encoding: gzip, deflate
// Accept-Language: zh-CN,zh;q=0.8
// Cookie: __guid=179317988.1576506943281708800.1510107225903.8862; monitor_count=281
// Form Data
// color=gray
void accept_request(void *arg){
int client = (intptr_t)arg;
char buf[1024]; //读取客户端发送的内容
char method[255]; //保存请求方法
char url[255]; //保存请求的url
char path[512]; //请求路径
size_t i,j;
struct stat st; //查询文件的数据结构
int cgi = 0; //是否调用cgi程序
char *query_string = NULL; //
int numchars = 1;
//读取http请求的第一行数据(request line),然后把请求方法存进method
//请求方法 URL 协议版本rn
numchars = get_line(client, buf, sizeof(buf));
i = 0; j = 0;
//根据上面的信息，首先到达第一个空格之前的都是请求方法
while(!ISspace(buf[j]) && (i < sizeof(method) -1) ){
method[i] = buf[j];
i ; j ;
}
method[i] = ' ';
//到这里，请求方法已经获取出来并保存在method中了
//如果不是get或者post请求
if(!strcasecmp(method, "GET") == 0 && !strcasecmp(method, "POST") == 0){
unimplemented(client);
return ;
}
//如果是POST，设置cgi=1
if(strcasecmp(method, "POST") == 0){
cgi = 1;
}
i = 0;
//跳过所有的空白字符，继续读取
while(ISspace(buf[j]) && (j < sizeof(buf))){
j ;
}
//把URL读出来保存到url数组中
while(!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf))){
url[i] = buf[j];
i ; j ;
}
url[i] = ' ';
//如果是get请求
if(strcasecmp(method, "GET") == 0){
//指针指向url
query_string = url;
//去遍历这个url,跳过字符?前面所有的字符
//如果遍历完没找到字符?则退出
while((*query_string != '?') && (*query_string != ' ')){
query_string ;
}
//退出循环后检查当前字符是?吗
if(*query_string == '?'){
cgi = 1;
//在字符?处分隔
*query_string = ' ';
query_string ;
}
}
//？号前的路径
sprintf(path, "htdocs%s", url);
//如果path数组最后一个字符是/的话，则拼接上一个index.html
if(path[strlen(path) - 1] == '/'){
strcat(path, "index.html");
}
//在系统上查看这个文件是否存在
if(stat(path, &st) == -1){
//如果不存在，则读取完http后面全部的内容(head)并忽略
while((numchars > 0) && strcmp("n", buf)){
numchars = get_line(client, buf, sizeof(buf));
}
//返回值找不到的response
not_found(client);
} else{ //如果存在
//判断请求的文件类型
if((st.st_mode & S_IFMT) == S_IFDIR){
//如果是目录，就在path后接/index.html
strcat(path, "/index.html");
}
if( (st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) ||(st.st_mode & S_IXOTH)){
//S_IXUSR 00100 owner has execute permission
//S_IXGRP 00010 group has execute permission
//S_IXOTH 00001 others have execute permission
//如果是可执行文件，无论是属于用户/组/其他 这三种类型的，将cgi置1
cgi = 1;
}
if(!cgi){
//如果不需要cgi的，html页面，直接发送
serve_file(client, path);
} else{
//如果需要cgi调用的
execute_cgi(client, path, method, query_string);
}
}
close(client);
printf("close client!n");
}
/**********************************************************************/
/* Execute a CGI script. Will need to set environment variables as
* appropriate.
* Parameters: client socket descriptor
* path to the CGI script */
/**********************************************************************/
void execute_cgi(int client, const char *path, const char *method, const char *query_string){
char buf[1024]; //缓冲区
int cgi_output[2]; //管道，用于进程交换数据
int cgi_input[2];
pid_t pid; //进程id
int status;
int i;
char c;
int numchars = 1;
int content_length = -1;
//往buf中填东西保证能进入下面的while
buf[0] = 'A';
buf[1] = ' ';
//如果是GET方法，则忽略请求剩下的内容
if (strcasecmp(method, "GET") == 0) {
while ((numchars > 0) && strcmp("n", buf)){ /* read & discard headers */
numchars = get_line(client, buf, sizeof(buf));
}
} else if (strcasecmp(method, "POST") == 0){ //POST请求
numchars = get_line(client, buf, sizeof(buf));
//这里要对header一行一行读取
//因为只是POST数据部分长度的请求头数据行为 Content-Length: XX
//数字部分刚好对应下标16
while ((numchars > 0) && strcmp("n", buf)){
buf[15] = ' ';
//如果读取到指示数据长度的那一行
if (strcasecmp(buf, "Content-Length:") == 0)
content_length = atoi(&(buf[16]));
numchars = get_line(client, buf, sizeof(buf));
}
//如果请求头中找不到指示数据长度的参数，则报错返回
if (content_length == -1) {
bad_request(client);
return;
}
} else{/*HEAD or other*/
}
//表示成功
sprintf(buf, "HTTP/1.0 200 OKrn");
send(client, buf, strlen(buf), 0);
//创建两个管道,用于两个进程的通信
if(pipe(cgi_output) < 0){
cannot_execute(client);
return;
}
if(pipe(cgi_input) < 0){
cannot_execute(client);
return;
}
// fork后管道都复制了一份，都是一样的
// 子进程关闭2个无用的端口，避免浪费
// ×<------------------------->1 output
// 0<-------------------------->× input
// 父进程关闭2个无用的端口，避免浪费
// 0<-------------------------->× output
// ×<------------------------->1 input
// 此时父子进程已经可以通信
//创建子进程，fork()从此处开始有两个进程执行相同代码
if( (pid = fork()) < 0){
cannot_execute(client);
return ;
}
if(pid == 0){ //子进程执行cgi脚本
char meth_env[255];
char query_env[255];
char length_env[255];
//将子进程的输出由标准输出重定向到 cgi_ouput 的管道写端上，1是stdout
dup2(cgi_output[1], 1);
//将子进程的输出由标准输入重定向到 cgi_ouput 的管道读端上，0是stdin
dup2(cgi_input[0], 0);
//关闭 cgi_ouput 管道的读端与cgi_input 管道的写端
close(cgi_output[0]);
close(cgi_input[1]);
//构造CGI环境变量
sprintf(meth_env, "REQUEST_METHOD=%s", method);
//将环境变量加入子进程的运行环境中
putenv(meth_env);
//根据http请求的方法，构造存储不同的环境变量
if(strcasecmp(method, "GET") == 0){
sprintf(query_env, "QUERY_STRING=%s", query_string);
putenv(query_env);
} else{ //POST
sprintf(length_env, "CONTENT_LENGTH=%d", content_length);
putenv(length_env);
}
//替换执行path
execl(path, path, NULL);
exit(0);
} else{ //父进程
close(cgi_output[1]); //父进程关闭cgi_output管道的写端和cgi_input管道的读端
close(cgi_input[0]);
//如果是 POST 方法的话就继续读 body 的内容，并写到 cgi_input 管道里让子进程去读
if(strcasecmp(method, "POST") == 0){
for(i = 0; i < content_length; i ){
//把post请求的数据(color=xxx)写入input管道中，供子进程读取使用
recv(client, &c, 1, 0);
write(cgi_input[1], &c, 1);
}
}
//将output管道读取的信息写给客户端，这里是对应的html
while (read(cgi_output[0], &c, 1) > 0){
send(client, &c, 1, 0);
}
close(cgi_output[0]); //关闭管道
close(cgi_input[1]);
waitpid(pid, &status, 0); //等待子进程的退出
}
// printf("end cgin");
}
/**********************************************************************/
/* Inform the client that a request it has made has a problem.
* Parameters: client socket */
/**********************************************************************/
void bad_request(int client){
char buf[1024];
sprintf(buf, "HTTP/1.0 400 BAD REQUESTrn");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "Content-type: text/html;rn");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "rn");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "<P>Your browser sent a bad request, ");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "such as a POST without a Content-Length.rn");
send(client, buf, sizeof(buf), 0);
}
/**********************************************************************/
/* Inform the client that a CGI script could not be executed.
* Parameter: the client socket descriptor. */
/**********************************************************************/
void cannot_execute(int client){
char buf[1024];
sprintf(buf, "HTTP/1.0 500 Internal Server Errorrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-type: text/htmlrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<P>Error prohibited CGI execution.rn");
send(client, buf, strlen(buf), 0);
}
void serve_file(int client, const char *filename){
FILE *resource = NULL;
int numchars = 1;
char buf[1024];
//保证buf里面有东西，能进入while循环
buf[0] = 'A';
buf[1] = ' ';
//忽略http请求后面的所有内容
while((numchars > 0) && strcmp("n", buf)){
numchars = get_line(client, buf, sizeof(buf));
}
//打开文件
resource = fopen(filename, "r");
if(resource == NULL){ //打开失败
not_found(client);
} else{ //打开成功
//打开成功后，把文件的信息封装成response的头部(header)并返回
headers(client, filename);
cat(client, resource);
}
}
/**********************************************************************/
/* Return the informational HTTP headers about a file. */
/* Parameters: the socket to print the headers on
* the name of the file */
/**********************************************************************/
void headers(int client, const char *filename){
char buf[1024];
//伪装手法，避免编译器因为没使用这个变量而发出警告
(void)filename; /* could use filename to determine file type */
strcpy(buf, "HTTP/1.0 200 OKrn");
send(client, buf, strlen(buf), 0);
strcpy(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/htmlrn");
send(client, buf, strlen(buf), 0);
strcpy(buf, "rn");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
/* Put the entire contents of a file out on a socket. This function
* is named after the UNIX "cat" command, because it might have been
* easier just to do something like pipe, fork, and exec("cat").
* Parameters: the client socket descriptor
* FILE pointer for the file to cat */
/**********************************************************************/
void cat(int client, FILE *resource){
char buf[1024];
//从文件文件描述符中读取指定内容
fgets(buf, sizeof(buf), resource);
while (!feof(resource)){
send(client, buf, strlen(buf), 0);
fgets(buf, sizeof(buf), resource);
}
}
/**********************************************************************/
/* Inform the client that the requested web method has not been
* implemented.
* Parameter: the client socket */
/**********************************************************************/
void unimplemented(int client){
char buf[1024];
sprintf(buf, "HTTP/1.0 501 Method Not Implementedrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/htmlrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<HTML><HEAD><TITLE>Method Not Implementedrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</TITLE></HEAD>rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<BODY><P>HTTP request method not supported.rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</BODY></HTML>rn");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
/* Give a client a 404 not found status message. */
/**********************************************************************/
void not_found(int client){
char buf[1024];
sprintf(buf, "HTTP/1.0 404 NOT FOUNDrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/htmlrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<HTML><TITLE>Not Found</TITLE>rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<BODY><P>The server could not fulfillrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "your request because the resource specifiedrn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "is unavailable or nonexistent.rn");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</BODY></HTML>rn");
send(client, buf, strlen(buf), 0);
}
//读取http请求
int get_line(int sock, char *buf, int size){
int i = 0;
char c = ' ';
int n;
while ((i < size - 1) && (c != 'n')){
n = recv(sock, &c, 1, 0);
/* DEBUG printf("Xn", c); */
if (n > 0){
if (c == 'r'){
n = recv(sock, &c, 1, MSG_PEEK);
/* DEBUG printf("Xn", c); */
if ((n > 0) && (c == 'n'))
recv(sock, &c, 1, 0);
else
c = 'n';
}
buf[i] = c;
i ;
}
else
c = 'n';
}
buf[i] = ' ';
return(i);
}
int startup(u_short *port){
int httpd = 0;
struct sockaddr_in name;
httpd = socket(AF_INET, SOCK_STREAM, 0);
if(httpd == -1){
error_die("socket");
}
//套接字数据结构初始化
memset(&name, 0, sizeof(name));
name.sin_family = AF_INET;
name.sin_port = htons(*port);
name.sin_addr.s_addr = htonl(INADDR_ANY);
// 设置套接字选项避免地址使用错误
// int on=1;
// if((setsockopt(httpd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on)))<0) {
// error_die("setsockopt failed");
// exit(EXIT_FAILURE);
// }
//将数据结构和创建的httpd套接字绑定
if(bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0){
error_die("bind");
}
//如果端口没有设置，提供个随机端口
if (*port == 0) { /* if dynamically allocating a port */
socklen_t namelen = sizeof(name);
if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1)
error_die("getsockname");
*port = ntohs(name.sin_port);
}
//绑定后开始监听
if(listen(httpd, 5) < 0){
error_die("listen");
}
// printf("start up OK!n");
return httpd;
}
void error_die(const char *sc){
//包含于<stdio.h>,基于当前的 errno 值，在标准错误上产生一条错误消息。参考《TLPI》P49
perror(sc);
exit(1);
}
int main(void){
int server_sock = -1; //服务器的sock文件描述符
u_short port = 0;
int client_sock = -1; //客户端的sock文件描述符
struct sockaddr_in client_name; //客户端套接字标签数据结构
char client_ip[64]; //客户端的ip
socklen_t client_name_len = sizeof(client_name);
pthread_t newthread;
server_sock = startup(&port); //获得监听sock文件描述符
printf("httpd running on port: %dn", port);
while(1){
//等待客户端连接
client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len);
printf("client ip : %st port : %dn",
inet_ntop(AF_INET, &client_name.sin_addr.s_addr,client_ip,sizeof(client_ip)),
ntohs(client_name.sin_port));
if(client_sock == -1)
error_die("accept");
//accept_request(client_sock);
//每次收到请求，创建一个线程来处理接受到的请求
//把client_sock转成地址作为参数传入pthread_create
if (pthread_create(&newthread, NULL, (void *)accept_request, (void *)(intptr_t)client_sock) != 0)
perror("pthread_create");
}
close(server_sock);
return 0;
}6. 相关
涉及到的有 socket通信， 多进程，多线程(pthread)，进程管道通信，http中GET,POST相关数据格式等
