컴퓨터시스템설계 - 과제(8)      결과보고서

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과제 : tiny.c (Page 835)를 이용해 Web Server 프로그램을 실행시키고 내부동작을 분석하세요.

소스코드 분석

#include "csapp.h"

void doit(int fd);

void read_requesthdrs(rio_t *rp);

int parse_uri(char *uri, char *filename, char *cgiargs);

void serve_static(int fd, char *filename, int filesize);

void get_filetype(char *filename, char *filetype);

void serve_dynamic(int fd, char *filename, char *cgiargs);

void clienterror(int fd, char *cause, char *errnum,

char *shortmsg, char *longmsg);

int main(int argc, char **argv)

{

int listenfd, connfd, port, clientlen;

struct sockaddr_in clientaddr;

/* Check command line args */

if (argc != 2) {

fprintf(stderr, "usage: %s <port>\n", argv[0]);

exit(1);

}

port = atoi(argv[1]);

listenfd = Open_listenfd(port);

while (1) {

clientlen = sizeof(clientaddr);

connfd = Accept(listenfd, (SA *)&clientaddr, &clientlen);

doit(connfd);

Close(connfd);

}

}

/* $end tinymain */

/*

* doit - handle one HTTP request/response transaction

*/

/* $begin doit */

void doit(int fd)

{

int is_static;

struct stat sbuf;

char buf[MAXLINE], method[MAXLINE], uri[MAXLINE], version[MAXLINE];

char filename[MAXLINE], cgiargs[MAXLINE];

rio_t rio;

/* Read request line and headers */

Rio_readinitb(&rio, fd);

Rio_readlineb(&rio, buf, MAXLINE);

sscanf(buf, "%s %s %s", method, uri, version);

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

clienterror(fd, method, "501", "Not Implemented",

"Tiny does not implement this method");

return;

}

read_requesthdrs(&rio);

/* Parse URI from GET request */

is_static = parse_uri(uri, filename, cgiargs);

if (stat(filename, &sbuf) < 0) {

clienterror(fd, filename, "404", "Not found",

"Tiny couldn't find this file");

return;

}

if (is_static) { /* Serve static content */

if (!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)) {

clienterror(fd, filename, "403", "Forbidden",

"Tiny couldn't read the file");

return;

}

serve_static(fd, filename, sbuf.st_size);

}

else { /* Serve dynamic content */

if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {

clienterror(fd, filename, "403", "Forbidden",

"Tiny couldn't run the CGI program");

return;

}

serve_dynamic(fd, filename, cgiargs);

}

}

/* $end doit */

/*

* read_requesthdrs - read and parse HTTP request headers

*/

/* $begin read_requesthdrs */

void read_requesthdrs(rio_t *rp)

{

char buf[MAXLINE];

Rio_readlineb(rp, buf, MAXLINE);

printf("%s", buf);

while(strcmp(buf, "\r\n")) {

Rio_readlineb(rp, buf, MAXLINE);

printf("%s", buf);

}

return;

}

/* $end read_requesthdrs */

/*

* parse_uri - parse URI into filename and CGI args

*             return 0 if dynamic content, 1 if static

*/

/* $begin parse_uri */

int parse_uri(char *uri, char *filename, char *cgiargs)

{

char *ptr;

if (!strstr(uri, "cgi-bin")) {  /* Static content */

strcpy(cgiargs, "");

strcpy(filename, ".");

strcat(filename, uri);

if (uri[strlen(uri)-1] == '/')

strcat(filename, "home.html");

return 1;

}

else {  /* Dynamic content */

ptr = index(uri, '?');

if (ptr) {

strcpy(cgiargs, ptr+1);

*ptr = '\0';

}

else

strcpy(cgiargs, "");

strcpy(filename, ".");

strcat(filename, uri);

return 0;

}

}

/* $end parse_uri */

/*

* serve_static - copy a file back to the client

*/

/* $begin serve_static */

void serve_static(int fd, char *filename, int filesize)

{

int srcfd;

char *srcp, filetype[MAXLINE], buf[MAXBUF];

/* Send response headers to client */

get_filetype(filename, filetype);

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

sprintf(buf, "%sServer: Tiny Web Server\r\n", buf);

sprintf(buf, "%sContent-length: %d\r\n", buf, filesize);

sprintf(buf, "%sContent-type: %s\r\n\r\n", buf, filetype);

Rio_writen(fd, buf, strlen(buf));

/* Send response body to client */

srcfd = Open(filename, O_RDONLY, 0);

srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);

Close(srcfd);

Rio_writen(fd, srcp, filesize);

Munmap(srcp, filesize);

}

/*

* get_filetype - derive file type from file name

*/

void get_filetype(char *filename, char *filetype)

{

if (strstr(filename, ".html"))

strcpy(filetype, "text/html");

else if (strstr(filename, ".gif"))

strcpy(filetype, "image/gif");

else if (strstr(filename, ".jpg"))

strcpy(filetype, "image/jpeg");

else

strcpy(filetype, "text/plain");

}

/* $end serve_static */

/*

* serve_dynamic - run a CGI program on behalf of the client

*/

/* $begin serve_dynamic */

void serve_dynamic(int fd, char *filename, char *cgiargs)

{

char buf[MAXLINE], *emptylist[] = { NULL };

/* Return first part of HTTP response */

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

Rio_writen(fd, buf, strlen(buf));

sprintf(buf, "Server: Tiny Web Server\r\n");

Rio_writen(fd, buf, strlen(buf));

if (Fork() == 0) { /* child */

/* Real server would set all CGI vars here */

setenv("QUERY_STRING", cgiargs, 1);

Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */

Execve(filename, emptylist, environ); /* Run CGI program */

}

Wait(NULL); /* Parent waits for and reaps child */

}

/* $end serve_dynamic */

/*

* clienterror - returns an error message to the client

*/

/* $begin clienterror */

void clienterror(int fd, char *cause, char *errnum,

char *shortmsg, char *longmsg)

{

char buf[MAXLINE], body[MAXBUF];

/* Build the HTTP response body */

sprintf(body, "<html><title>Tiny Error</title>");

sprintf(body, "%s<body bgcolor=""ffffff"">\r\n", body);

sprintf(body, "%s%s: %s\r\n", body, errnum, shortmsg);

sprintf(body, "%s<p>%s: %s\r\n", body, longmsg, cause);

sprintf(body, "%s<hr><em>The Tiny Web server</em>\r\n", body);

/* Print the HTTP response */

sprintf(buf, "HTTP/1.0 %s %s\r\n", errnum, shortmsg);

Rio_writen(fd, buf, strlen(buf));

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

Rio_writen(fd, buf, strlen(buf));

sprintf(buf, "Content-length: %d\r\n\r\n", (int)strlen(body));

Rio_writen(fd, buf, strlen(buf));

Rio_writen(fd, body, strlen(body));

}

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