/*

这个小小的服务器主要的功能是用来练习在linux下的编程和熟悉与网络编程相关的知识。

这个服务器支持get和post两种请求方式。

支持cgi

支持图片、文档等等的静态内容。

完成于2016.8.2

*/

#include <arpa/inet.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <string.h>

#include <pthread.h>

#include <sys/stat.h>

#include <stdbool.h>

#include <fcntl.h>

#include <errno.h>

#define SERVER_STRING "Server: summerwind/0.1.0\r\n"

int start_up(int port);

void error_die(const char *msg);

void deal_request(void *server_sock);

int get_line(int,char *,int);

void uncompleted(int,char *);

void not_found(int,char *);

void deal_cgi(int,char *,char *,char *);

void deal_static(int,char *,int);

void send_head(int,char *);

int get_content(char *,int,int);

void get_mime(char *content_type,char *path);

void cgi_error(int);

void invalid_req(int);

int main(int argc,char **argv)

{

//服务器socket号

int server_sock;

int client_sock;

//端口号

int port;

int client_addr_len;

struct sockaddr_in client_addr;

pthread_t thread_id;

if(argc!=2){

perror("please run it like: ./tinyweb port");

exit(EXIT_FAILURE);

}

//把字符串类型端口号转为整型

port = atoi(argv[1]);

//初始化服务器socket号

server_sock=start_up(port);

client_addr_len=sizeof(client_addr);

//不断循环，不断接收客户端的链接请求

while(1){

//accept函数返回值，初始化客户socket号，以后获取客户端的内容和向客户端发送信息都

//通过这个端口号

client_sock = accept(server_sock,(struct sockaddr *)&client_addr,&client_addr_len);

if(client_sock == -1){

error_die("accept error\n");

}

//创建新的线程来为客户端服务，主要pthread_create这个函数的参数

if(pthread_create(&thread_id,NULL,(void *)deal_request,(void *)&client_sock)!=0)

error_die("pthread_create error\n");

}

close(server_sock);

return 0;

}

/*

这个函数主要是初始化服务器端的socket，以准备链接客户端

*/

int start_up(int port){

int sock_id;

struct sockaddr_in name;

//AF_INET表示ipv4,SOCK_STREAM表示有链接传输流，具体查看socket函数手册

if((sock_id=socket(AF_INET,SOCK_STREAM,0))==-1){

error_die("socket error\n");

}

memset(&name,0,sizeof(name));

//这是必须要设置的值

name.sin_family=AF_INET;

//使用这个函数把port转换为网络端存储形式

name.sin_port=htons(port);

//这个自动获取主机ip

name.sin_addr.s_addr=htonl(INADDR_ANY);

//把sock_id和sockaddr进行绑定

if(bind(sock_id,(struct sockaddr *)&name,sizeof(name))==-1){

error_die("bind error\n");

}

//启动监听

if(listen(sock_id,10)==-1){

error_die("listen error\n");

}

return sock_id;

}

//出错时在终端打印错误信息

void error_die(const char *msg)

{

perror(msg);

exit(EXIT_FAILURE);

}

/*

处理客户端发送过来的请求，主要是判断请求是get还是post方法

把 请求方法 url protocol 进行分离

并判断是请求静态内容还是cgi

分别调用deal_static和deal_cgi进行处理

*/

void deal_request(void *client_sock){

//客户端sock号

int cli_sock =*(int*)client_sock;

int charnum=0;

char buf[1024];

//请求方法

char method[10];

char url[255];

char protocol[50];

bool cgi=false;

//cgi程序的参数

char *query_string=NULL;

char *path=NULL;

//文件的各种信息，具体可以查看stat函数

struct stat st;

//读取一行

charnum=get_line(cli_sock,buf,sizeof(buf));

if(charnum==0){

error_die("get_line error\n");

}

//进行分离

if(EOF==sscanf(buf,"%[^ ] %[^ ] %[^ ]",method,url,protocol)){

error_die("sscanf error");

}

//method is not get and post

if((strcasecmp(method,"GET")!=0)&&(strcasecmp(method,"POST")!=0)){

uncompleted(cli_sock,method);

return;

}

if(strcasecmp(method,"POST")==0){

cgi=true;

}

if(strcasecmp(method,"GET")==0){

//找出？字符的位置

query_string=strchr(url,'?');

if(query_string){

cgi=true;

*query_string='\0';

query_string++;

}

//如果是get方法，后面的内容没有用，就丢弃

charnum=get_line(cli_sock,buf,sizeof(buf));

while((charnum>0)&&strcmp("\n",buf)){

//printf("%s",buf);

charnum=get_line(cli_sock,buf,sizeof(buf));

}

}

//url的形式为：/aisi.jpg，而path是存取路径，把第一个/去掉，变为aisi.jpg

path=url+1;

//判断文件是否存在

if(stat(path,&st)==-1){

not_found(cli_sock,path);

}else{

//如果访问的是目录，默认为访问主页

if((st.st_mode&S_IFMT)==S_IFDIR){

sprintf(path,"index.html");

}

//查看是否有执行权限，如果有，就是cgi

if((st.st_mode&S_IXOTH)||(st.st_mode&S_IXUSR)||(st.st_mode&S_IXGRP)){

cgi=true;

}

//分别调用对应的处理函数

if(cgi){

deal_cgi(cli_sock,path,method,query_string);

}else{

deal_static(cli_sock,path,(int)st.st_size);

}

}

close(cli_sock);

}

//文件不存在时调用，向客户端发送文件不存在的信息

void not_found(int client_sock,char *path){

char buf[1024];

sprintf(buf,"HTTP/1.0 404 NOT FOUND\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,SERVER_STRING);

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"Content-Type:text/html\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"<html><title>Resource not found</title>\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"<body><h1>The resource of the path:\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"%s\n",path);

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"not found\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"</h1></body></html>");

send(client_sock,buf,strlen(buf),0);

}

//get a line

/*int get_line(int client_sock,char *buf){

int i=0;

int n=1;

char c='\0';

while(n>0&&c!='\n'){

n=recv(client_sock,&c,1,MSG_DONTWAIT);

if(c=='\r'){

n=recv(client_sock,&c,1,MSG_PEEK);

if(n&&c=='\n'){

n=recv(client_sock,&c,1,0);

}else{

c='\n';

}

}

buf[i++]=c;

}

return i;

}*/

//从sock读取内容，一次设置成读取一行

int get_line(int sock, char *buf, int size)

{

int i = 0;

char c = '\0';

int n;

while ((i < size - 1) && (c != '\n')){

n = recv(sock, &c, 1, 0);

/* DEBUG printf("%02X\n", c); */

if (n > 0){

if (c == '\r'){

n = recv(sock, &c, 1, MSG_PEEK);

/* DEBUG printf("%02X\n", c); */

if ((n > 0) && (c == '\n'))

recv(sock, &c, 1, 0);

else

c = '\n';

}

buf[i] = c;

i++;

} else

c = '\n';

}

buf[i] = '\0';

return(i);

}

//如果请求的方法不是get也不是post，返回错误信息

void uncompleted(int client_sock,char *method){

char buf[1024];

sprintf(buf,"HTTP/1.0 501 METHOD NOT COMPLETED\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"Content-Type:text/html\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"<html><title>METHOD NOT COMPLETED</title>\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"<body><p>This method :%s is not completed</p></body></html>\r\n",method);

send(client_sock,buf,strlen(buf),0);

}

/*

处理静态内容

*/

void deal_static(int client_sock,char *path,int file_size){

//send_head(client_sock,path);

//FILE *file=fopen(path,"r");

char *buf;

char file[file_size];

//对buf进行内存分配

buf = (char *)malloc(file_size);

//打开文件

int fd = open(path,O_RDONLY);

if(fd==-1){

not_found(client_sock,path);

}else{

//发送头部

send_head(client_sock,path);

//获取内容

get_content(buf,fd,file_size);

//给客户端发送文件内容

send(client_sock,buf,file_size,0);

}

//释放内容，这很重要

free(buf);

close(fd);

return;

}

/*

处理cgi的内容

*/

void deal_cgi(int client_sock,char *path,char *method,char *query_string){

int charnum=-1;

char buf[1024];

//请求的cgi的参数长度

int content_len=-1;

//也是参数长度

char con_len[10];

int cgi_output[2];

int cgi_input[2];

//进程号

pid_t pid;

//参数的内容

char content[255];

char c;

int status;

buf[0]='a';

buf[1]='\0';

//方法如果为post，不断读取剩下的内容并丢弃

if(strcasecmp(method,"POST")==0){

charnum=get_line(client_sock,buf,sizeof(buf));

while(charnum>0 && strcmp(buf,"\n")){

//找到content-length,获取参数内容的长度

buf[15]='\0';

if(strcmp(buf,"Content-Length:")==0){

content_len=atoi(&buf[16]);

}

charnum=get_line(client_sock,buf,sizeof(buf));

}

if(content_len==-1){

invalid_req(client_sock);

return;

}

}

//创建管道

if(pipe(cgi_output)==-1){

cgi_error(client_sock);

return;

}

//创建管道

if(pipe(cgi_input)==-1){

cgi_error(client_sock);

return;

}

//fork一个新的进程处理cgi

if((pid=fork())==-1){

cgi_error(client_sock);

return;

}

sprintf(buf,"HTTP/1.0 200 OK\r\n");

send(client_sock,buf,strlen(buf),0);

//子进程

if(pid==0){

//把cgi_input的输出端重定向为stdin

dup2(cgi_input[0],0);

//把客户sock重定向为stdout

dup2(client_sock,1);

//分别关闭不使用的两个管道端口

close(cgi_input[1]);

close(cgi_output[0]);

//设置环境变量，在cgi程序中可以获取

setenv("REQUEST_METHOD",method,1);

if(strcasecmp(method,"GET")==0)

setenv("QUERY_STRING",query_string,1);

else

setenv("CONTENT_LENGTH",con_len,1);

//使用exec系列函数调用cgi程序

execl(path,path,NULL);

exit(0);

}

else

{

close(cgi_input[0]);

close(cgi_output[1]);

if(strcasecmp(method,"POST")==0){

//读取参数的内容，输出到管道中，cgi程序可以在管道中获取

recv(client_sock,content,content_len,0);

write(cgi_input[1],content,content_len);

}

//while(read(cgi_output[0],&c,1)>0)

//send(client_sock,&c,1,0);

close(cgi_output[0]);

close(cgi_input[1]);

waitpid(pid,&status,0);

}

}

//管道或者fork不成功

void cgi_error(int client_sock){

char buf[1024];

sprintf(buf,"HTTP/1.0 501 CGI EXEC ERROR\r\n");

sprintf(buf,"%sContent-Type:text/html\r\n\r\n",buf);

sprintf(buf,"%s<html><title>cgi error</title>\r\n",buf);

sprintf(buf,"%s<body><p>cgi exec error\r\n",buf);

sprintf(buf,"%s<p>maybe pipe or fork\r\n",buf);

sprintf(buf,"%s</body></html>\r\n",buf);

send(client_sock,buf,strlen(buf),0);

}

//post方法没有content-length

void invalid_req(int client_sock){

char buf[1024];

sprintf(buf,"HTTP/1.0 400 INVALID REQUEST\r\n");

sprintf(buf,"%sContent-Type:text/html\r\n\r\n",buf);

sprintf(buf,"%s<html><title>bad request</title>\r\n",buf);

sprintf(buf,"%s<body><p>this post method does not has content length",buf);

sprintf(buf,"%s</p></body></html>\r\n",buf);

send(client_sock,buf,strlen(buf),0);

}

//获取文件的内容

int get_content(char *usrbuf,int fd,int file_size){

/*char buf[1024];

//fgets(buf,sizeof(buf),file);

while(read(fd,buf,sizeof(buf))){

//fgets(buf,sizeof(buf),file);

send(client_sock,buf,strlen(buf),0);

}*/

int nleft = file_size;

int nread;

char *bufp=usrbuf;

while (nleft > 0) {

if ((nread = read(fd, bufp, nleft)) < 0) {

if (errno == EINTR) /* interrupted by sig handler return */

nread = 0; /* and call read() again */

else

return -1; /* errno set by read() */

}else if (nread == 0)

break; /* EOF */

nleft -= nread;

bufp += nread;

}

return(file_size-nleft);

}

//发送头部

void send_head(int client_sock,char *path){

char content_type[30];

get_mime(content_type,path);

char buf[1024];

sprintf(buf,"HTTP/1.0 200 OK\r\n");

send(client_sock,buf,strlen(buf),0);

sprintf(buf,SERVER_STRING);

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"Content-Type:%s\r\n",content_type);

send(client_sock,buf,strlen(buf),0);

sprintf(buf,"\r\n");

send(client_sock,buf,strlen(buf),0);

}

//获取mime类型

void get_mime(char *content_type,char *path){

char *index=strchr(path,'.');

if((strcasecmp(index,".jpeg")==0)||(strcasecmp(index,".jpg")==0))

strcpy(content_type,"image/jpeg");

else if(strcasecmp(index,".pdf")==0)

strcpy(content_type,"application/pdf");

else if(strcasecmp(index,".mp4")==0)

strcpy(content_type,"video/mp4");

else if(strcasecmp(index,".gif")==0)

strcpy(content_type,"image/gif");

else if(strcasecmp(index,".html")==0)

strcpy(content_type,"text/html");

else

strcpy(content_type,"text/plain");

printf("content-type:%s\n",content_type);

return;

//return content_type;

}