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《CSAPP》（第3版）答案（第十一章）
阅读量：4169 次
发布时间：2019-05-26

本文共 34412 字，大约阅读时间需要 114 分钟。

《CSAPP》（第3版）答案（第十一章）

P6

  • A
#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);void echo(int connfd);int main(int argc, char **argv){
     int listenfd, connfd;  char hostname[MAXLINE], port[MAXLINE];  socklen_t clientlen;  struct sockaddr_storage clientaddr;  /* Check command line args */  if (argc != 2) {
       fprintf(stderr, "usage: %s 
   
    \n", argv[0]);    exit(1);  }  listenfd = Open_listenfd(argv[1]);  while (1) {
       clientlen = sizeof(clientaddr);    connfd = Accept(listenfd, (SA *)&clientaddr, &clientlen); //line:netp:tiny:accept    Getnameinfo((SA *) &clientaddr, clientlen, hostname, MAXLINE,        port, MAXLINE, 0);    printf("Accepted connection from (%s, %s)\n", hostname, port);    echo(connfd);    Close(connfd);                                            //line:netp:tiny:close  }}void echo(int connfd) {
     size_t n;  char buf[MAXLINE];  rio_t rio;  Rio_readinitb(&rio, connfd);  while ((n = Rio_readlineb(&rio, buf, MAXLINE)) != 0) {
       if (strcmp(buf, "\r\n") == 0)      break;    Rio_writen(connfd, buf, n);  }}/* * doit - handle one HTTP request/response transaction */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);  if (!Rio_readlineb(&rio, buf, MAXLINE))  //line:netp:doit:readrequest    return;  printf("%s", buf);  sscanf(buf, "%s %s %s", method, uri, version);       //line:netp:doit:parserequest  if (strcasecmp(method, "GET")) {
                        //line:netp:doit:beginrequesterr    clienterror(fd, method, "501", "Not Implemented",        "Tiny does not implement this method");    return;  }                                                    //line:netp:doit:endrequesterr  read_requesthdrs(&rio);                              //line:netp:doit:readrequesthdrs  /* Parse URI from GET request */  is_static = parse_uri(uri, filename, cgiargs);       //line:netp:doit:staticcheck  if (stat(filename, &sbuf) < 0) {
                        //line:netp:doit:beginnotfound    clienterror(fd, filename, "404", "Not found",        "Tiny couldn't find this file");    return;  }                                                    //line:netp:doit:endnotfound  if (is_static) {
    /* Serve static content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)) {
    //line:netp:doit:readable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't read the file");      return;    }    serve_static(fd, filename, sbuf.st_size);        //line:netp:doit:servestatic  }  else {
    /* Serve dynamic content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {
    //line:netp:doit:executable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't run the CGI program");      return;    }    serve_dynamic(fd, filename, cgiargs);            //line:netp:doit:servedynamic  }}/* * read_requesthdrs - read HTTP request headers */void read_requesthdrs(rio_t *rp){
     char buf[MAXLINE];  Rio_readlineb(rp, buf, MAXLINE);  printf("%s", buf);  while(strcmp(buf, "\r\n")) {
             //line:netp:readhdrs:checkterm    Rio_readlineb(rp, buf, MAXLINE);    printf("%s", buf);  }  return;}/* * parse_uri - parse URI into filename and CGI args *             return 0 if dynamic content, 1 if static */int parse_uri(char *uri, char *filename, char *cgiargs){
     char *ptr;  if (!strstr(uri, "cgi-bin")) {
     /* Static content */ //line:netp:parseuri:isstatic    strcpy(cgiargs, "");                             //line:netp:parseuri:clearcgi    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert1    strcat(filename, uri);                           //line:netp:parseuri:endconvert1    if (uri[strlen(uri)-1] == '/')                   //line:netp:parseuri:slashcheck      strcat(filename, "home.html");               //line:netp:parseuri:appenddefault    return 1;  }  else {
     /* Dynamic content */                        //line:netp:parseuri:isdynamic    ptr = index(uri, '?');                           //line:netp:parseuri:beginextract    if (ptr) {
         strcpy(cgiargs, ptr+1);      *ptr = '\0';    }    else      strcpy(cgiargs, "");                         //line:netp:parseuri:endextract    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert2    strcat(filename, uri);                           //line:netp:parseuri:endconvert2    return 0;  }}/* * serve_static - copy a file back to the client */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);       //line:netp:servestatic:getfiletype  sprintf(buf, "HTTP/1.0 200 OK\r\n");    //line:netp:servestatic:beginserve  sprintf(buf, "%sServer: Tiny Web Server\r\n", buf);  sprintf(buf, "%sConnection: close\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));       //line:netp:servestatic:endserve  printf("Response headers:\n");  printf("%s", buf);  /* Send response body to client */  srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open  srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap  Close(srcfd);                           //line:netp:servestatic:close  Rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write  Munmap(srcp, filesize);                 //line:netp:servestatic:munmap}/* * 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, ".png"))    strcpy(filetype, "image/png");  else if (strstr(filename, ".jpg"))    strcpy(filetype, "image/jpeg");  else    strcpy(filetype, "text/plain");}/* * serve_dynamic - run a CGI program on behalf of the client */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 */ //line:netp:servedynamic:fork    /* Real server would set all CGI vars here */    setenv("QUERY_STRING", cgiargs, 1); //line:netp:servedynamic:setenv    Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */ //line:netp:servedynamic:dup2    Execve(filename, emptylist, environ); /* Run CGI program */ //line:netp:servedynamic:execve  }  Wait(NULL); /* Parent waits for and reaps child */ //line:netp:servedynamic:wait}/* * clienterror - returns an error message to the client */void clienterror(int fd, char *cause, char *errnum,    char *shortmsg, char *longmsg){
     char buf[MAXLINE], body[MAXBUF];  /* Build the HTTP response body */  sprintf(body, "
    Tiny Error");  sprintf(body, "%s\r\n", body);  sprintf(body, "%s%s: %s\r\n", body, errnum, shortmsg);  sprintf(body, "%s
    
%s: %s\r\n", body, longmsg, cause);  sprintf(body, "%s
    
    The Tiny Web server\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));}
  • B
GET / HTTP/1.1Host: localhost:5000User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/53.0Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8Accept-Language: en-US,en;q=0.5Accept-Encoding: gzip, deflateConnection: keep-alive
  • C
    HTTP 1.1
  • D

P7

#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;  char hostname[MAXLINE], port[MAXLINE];  socklen_t clientlen;  struct sockaddr_storage clientaddr;  /* Check command line args */  if (argc != 2) {
       fprintf(stderr, "usage: %s 
   
    \n", argv[0]);    exit(1);  }  listenfd = Open_listenfd(argv[1]);  while (1) {
       clientlen = sizeof(clientaddr);    connfd = Accept(listenfd, (SA *)&clientaddr, &clientlen); //line:netp:tiny:accept    Getnameinfo((SA *) &clientaddr, clientlen, hostname, MAXLINE,        port, MAXLINE, 0);    printf("Accepted connection from (%s, %s)\n", hostname, port);    doit(connfd);                                             //line:netp:tiny:doit    Close(connfd);                                            //line:netp:tiny:close  }}/* * doit - handle one HTTP request/response transaction */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);  if (!Rio_readlineb(&rio, buf, MAXLINE))  //line:netp:doit:readrequest    return;  printf("%s", buf);  sscanf(buf, "%s %s %s", method, uri, version);       //line:netp:doit:parserequest  if (strcasecmp(method, "GET")) {
                        //line:netp:doit:beginrequesterr    clienterror(fd, method, "501", "Not Implemented",        "Tiny does not implement this method");    return;  }                                                    //line:netp:doit:endrequesterr  read_requesthdrs(&rio);                              //line:netp:doit:readrequesthdrs  /* Parse URI from GET request */  is_static = parse_uri(uri, filename, cgiargs);       //line:netp:doit:staticcheck  if (stat(filename, &sbuf) < 0) {
                        //line:netp:doit:beginnotfound    clienterror(fd, filename, "404", "Not found",        "Tiny couldn't find this file");    return;  }                                                    //line:netp:doit:endnotfound  if (is_static) {
    /* Serve static content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)) {
    //line:netp:doit:readable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't read the file");      return;    }    serve_static(fd, filename, sbuf.st_size);        //line:netp:doit:servestatic  }  else {
    /* Serve dynamic content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {
    //line:netp:doit:executable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't run the CGI program");      return;    }    serve_dynamic(fd, filename, cgiargs);            //line:netp:doit:servedynamic  }}/* * read_requesthdrs - read HTTP request headers */void read_requesthdrs(rio_t *rp){
     char buf[MAXLINE];  Rio_readlineb(rp, buf, MAXLINE);  printf("%s", buf);  while(strcmp(buf, "\r\n")) {
             //line:netp:readhdrs:checkterm    Rio_readlineb(rp, buf, MAXLINE);    printf("%s", buf);  }  return;}/* * parse_uri - parse URI into filename and CGI args *             return 0 if dynamic content, 1 if static */int parse_uri(char *uri, char *filename, char *cgiargs){
     char *ptr;  if (!strstr(uri, "cgi-bin")) {
     /* Static content */ //line:netp:parseuri:isstatic    strcpy(cgiargs, "");                             //line:netp:parseuri:clearcgi    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert1    strcat(filename, uri);                           //line:netp:parseuri:endconvert1    if (uri[strlen(uri)-1] == '/')                   //line:netp:parseuri:slashcheck      strcat(filename, "home.html");               //line:netp:parseuri:appenddefault    return 1;  }  else {
     /* Dynamic content */                        //line:netp:parseuri:isdynamic    ptr = index(uri, '?');                           //line:netp:parseuri:beginextract    if (ptr) {
         strcpy(cgiargs, ptr+1);      *ptr = '\0';    }    else      strcpy(cgiargs, "");                         //line:netp:parseuri:endextract    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert2    strcat(filename, uri);                           //line:netp:parseuri:endconvert2    return 0;  }}/* * serve_static - copy a file back to the client */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);       //line:netp:servestatic:getfiletype  sprintf(buf, "HTTP/1.0 200 OK\r\n");    //line:netp:servestatic:beginserve  sprintf(buf, "%sServer: Tiny Web Server\r\n", buf);  sprintf(buf, "%sConnection: close\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));       //line:netp:servestatic:endserve  printf("Response headers:\n");  printf("%s", buf);  /* Send response body to client */  srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open  srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap  Close(srcfd);                           //line:netp:servestatic:close  Rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write  Munmap(srcp, filesize);                 //line:netp:servestatic:munmap}/* * 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, ".png"))    strcpy(filetype, "image/png");  else if (strstr(filename, ".jpg"))    strcpy(filetype, "image/jpeg");  else if (strstr(filename, ".mpeg"))    strcpy(filetype, "video/mpeg");  else    strcpy(filetype, "text/plain");}/* * serve_dynamic - run a CGI program on behalf of the client */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 */ //line:netp:servedynamic:fork    /* Real server would set all CGI vars here */    setenv("QUERY_STRING", cgiargs, 1); //line:netp:servedynamic:setenv    Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */ //line:netp:servedynamic:dup2    Execve(filename, emptylist, environ); /* Run CGI program */ //line:netp:servedynamic:execve  }  Wait(NULL); /* Parent waits for and reaps child */ //line:netp:servedynamic:wait}/* * clienterror - returns an error message to the client */void clienterror(int fd, char *cause, char *errnum,    char *shortmsg, char *longmsg){
     char buf[MAXLINE], body[MAXBUF];  /* Build the HTTP response body */  sprintf(body, "
    Tiny Error");  sprintf(body, "%s\r\n", body);  sprintf(body, "%s%s: %s\r\n", body, errnum, shortmsg);  sprintf(body, "%s
    
%s: %s\r\n", body, longmsg, cause);  sprintf(body, "%s
    
    The Tiny Web server\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));}

以上是源代码。如果不知道怎么跑关注私信我，我把整个工程文件夹发过去。

P8

#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);void sigchild_handler(int sig);int main(int argc, char **argv){
     int listenfd, connfd;  char hostname[MAXLINE], port[MAXLINE];  socklen_t clientlen;  struct sockaddr_storage clientaddr;  /* Check command line args */  if (argc != 2) {
       fprintf(stderr, "usage: %s 
   
    \n", argv[0]);    exit(1);  }  if (Signal(SIGCHLD, sigchild_handler) == SIG_ERR)    unix_error("signal child handler error");  listenfd = Open_listenfd(argv[1]);  while (1) {
       clientlen = sizeof(clientaddr);    connfd = Accept(listenfd, (SA *)&clientaddr, &clientlen); //line:netp:tiny:accept    Getnameinfo((SA *) &clientaddr, clientlen, hostname, MAXLINE,        port, MAXLINE, 0);    printf("Accepted connection from (%s, %s)\n", hostname, port);    doit(connfd);                                             //line:netp:tiny:doit    Close(connfd);                                            //line:netp:tiny:close  }}void sigchild_handler(int sig) {
     int old_errno = errno;  int status;  pid_t pid;  while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
     }  errno = old_errno;}/* * doit - handle one HTTP request/response transaction */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);  if (!Rio_readlineb(&rio, buf, MAXLINE))  //line:netp:doit:readrequest    return;  printf("%s", buf);  sscanf(buf, "%s %s %s", method, uri, version);       //line:netp:doit:parserequest  if (strcasecmp(method, "GET")) {
                        //line:netp:doit:beginrequesterr    clienterror(fd, method, "501", "Not Implemented",        "Tiny does not implement this method");    return;  }                                                    //line:netp:doit:endrequesterr  read_requesthdrs(&rio);                              //line:netp:doit:readrequesthdrs  /* Parse URI from GET request */  is_static = parse_uri(uri, filename, cgiargs);       //line:netp:doit:staticcheck  if (stat(filename, &sbuf) < 0) {
                        //line:netp:doit:beginnotfound    clienterror(fd, filename, "404", "Not found",        "Tiny couldn't find this file");    return;  }                                                    //line:netp:doit:endnotfound  if (is_static) {
    /* Serve static content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)) {
    //line:netp:doit:readable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't read the file");      return;    }    serve_static(fd, filename, sbuf.st_size);        //line:netp:doit:servestatic  }  else {
    /* Serve dynamic content */    if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {
    //line:netp:doit:executable      clienterror(fd, filename, "403", "Forbidden",          "Tiny couldn't run the CGI program");      return;    }    serve_dynamic(fd, filename, cgiargs);            //line:netp:doit:servedynamic  }}/* * read_requesthdrs - read HTTP request headers */void read_requesthdrs(rio_t *rp){
     char buf[MAXLINE];  Rio_readlineb(rp, buf, MAXLINE);  printf("%s", buf);  while(strcmp(buf, "\r\n")) {
             //line:netp:readhdrs:checkterm    Rio_readlineb(rp, buf, MAXLINE);    printf("%s", buf);  }  return;}/* * parse_uri - parse URI into filename and CGI args *             return 0 if dynamic content, 1 if static */int parse_uri(char *uri, char *filename, char *cgiargs){
     char *ptr;  if (!strstr(uri, "cgi-bin")) {
     /* Static content */ //line:netp:parseuri:isstatic    strcpy(cgiargs, "");                             //line:netp:parseuri:clearcgi    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert1    strcat(filename, uri);                           //line:netp:parseuri:endconvert1    if (uri[strlen(uri)-1] == '/')                   //line:netp:parseuri:slashcheck      strcat(filename, "home.html");               //line:netp:parseuri:appenddefault    return 1;  }  else {
     /* Dynamic content */                        //line:netp:parseuri:isdynamic    ptr = index(uri, '?');                           //line:netp:parseuri:beginextract    if (ptr) {
         strcpy(cgiargs, ptr+1);      *ptr = '\0';    }    else      strcpy(cgiargs, "");                         //line:netp:parseuri:endextract    strcpy(filename, ".");                           //line:netp:parseuri:beginconvert2    strcat(filename, uri);                           //line:netp:parseuri:endconvert2    return 0;  }}/* * serve_static - copy a file back to the client */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);       //line:netp:servestatic:getfiletype  sprintf(buf, "HTTP/1.0 200 OK\r\n");    //line:netp:servestatic:beginserve  sprintf(buf, "%sServer: Tiny Web Server\r\n", buf);  sprintf(buf, "%sConnection: close\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));       //line:netp:servestatic:endserve  printf("Response headers:\n");  printf("%s", buf);  /* Send response body to client */  srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open  srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap  Close(srcfd);                           //line:netp:servestatic:close  Rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write  Munmap(srcp, filesize);                 //line:netp:servestatic:munmap}/* * 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, ".png"))    strcpy(filetype, "image/png");  else if (strstr(filename, ".jpg"))    strcpy(filetype, "image/jpeg");  else    strcpy(filetype, "text/plain");}/* * serve_dynamic - run a CGI program on behalf of the client */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 */ //line:netp:servedynamic:fork    /* Real server would set all CGI vars here */    setenv("QUERY_STRING", cgiargs, 1); //line:netp:servedynamic:setenv    Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */ //line:netp:servedynamic:dup2    Execve(filename, emptylist, environ); /* Run CGI program */ //line:netp:servedynamic:execve  }}/* * clienterror - returns an error message to the client */void clienterror(int fd, char *cause, char *errnum,    char *shortmsg, char *longmsg){
     char buf[MAXLINE], body[MAXBUF];  /* Build the HTTP response body */  sprintf(body, "
    Tiny Error");  sprintf(body, "%s\r\n", body);  sprintf(body, "%s%s: %s\r\n", body, errnum, shortmsg);  sprintf(body, "%s
    
%s: %s\r\n", body, longmsg, cause);  sprintf(body, "%s
    
    The Tiny Web server\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));}

P9

@@ -152,12 +152,12 @@   printf("Response headers:\n");   printf("%s", buf); -  /* Send response body to client */   srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open-  srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap+  srcp = (char*)Malloc(filesize);+  Rio_readn(srcfd, srcp, filesize);   Close(srcfd);                           //line:netp:servestatic:close   Rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write-  Munmap(srcp, filesize);                 //line:netp:servestatic:munmap+  free(srcp); }

P10

  • A
   Tiny Server
   
  
    
first number: 
  
    
second number:
  • B
@@ -1,5 +1,5 @@ /*- * adder.c - a minimal CGI program that adds two numbers together+ * form-adder.c - a minimal CGI program that adds two numbers together  */ #include "../csapp.h" @@ -12,10 +12,8 @@   if ((buf = getenv("QUERY_STRING")) != NULL) {
        p = strchr(buf, '&');     *p = '\0';-    strcpy(arg1, buf);-    strcpy(arg2, p+1);-    n1 = atoi(arg1);-    n2 = atoi(arg2);+    sscanf(buf, "first=%d", &n1);+    sscanf(p+1, "second=%d", &n2);   }    /* Make the response body */

P11

tiny.c更改：

@@ -7,9 +7,9 @@ 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 serve_static(int fd, char *filename, int filesize, char *method); void get_filetype(char *filename, char *filetype);-void serve_dynamic(int fd, char *filename, char *cgiargs);+void serve_dynamic(int fd, char *filename, char *cgiargs, char *method); void clienterror(int fd, char *cause, char *errnum,     char *shortmsg, char *longmsg); @@ -55,7 +55,7 @@     return;   printf("%s", buf);   sscanf(buf, "%s %s %s", method, uri, version);       //line:netp:doit:parserequest-  if (strcasecmp(method, "GET")) {
                        //line:netp:doit:beginrequesterr+  if (!(strcasecmp(method, "GET") == 0 || strcasecmp(method, "HEAD") == 0)) {
        clienterror(fd, method, "501", "Not Implemented",         "Tiny does not implement this method");     return;@@ -76,7 +76,7 @@           "Tiny couldn't read the file");       return;     }-    serve_static(fd, filename, sbuf.st_size);        //line:netp:doit:servestatic+    serve_static(fd, filename, sbuf.st_size, method);        //line:netp:doit:servestatic   }   else {
    /* Serve dynamic content */     if (!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)) {
    //line:netp:doit:executable@@ -84,7 +84,7 @@           "Tiny couldn't run the CGI program");       return;     }-    serve_dynamic(fd, filename, cgiargs);            //line:netp:doit:servedynamic+    serve_dynamic(fd, filename, cgiargs, method);            //line:netp:doit:servedynamic   } } @@ -136,7 +136,7 @@ /*  * serve_static - copy a file back to the client  */-void serve_static(int fd, char *filename, int filesize)+void serve_static(int fd, char *filename, int filesize, char *method) {
      int srcfd;   char *srcp, filetype[MAXLINE], buf[MAXBUF];@@ -152,6 +152,9 @@   printf("Response headers:\n");   printf("%s", buf); +  if (strcasecmp(method, "HEAD") == 0)+    return;+   /* Send response body to client */   srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open   srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap@@ -180,7 +183,7 @@ /*  * serve_dynamic - run a CGI program on behalf of the client  */-void serve_dynamic(int fd, char *filename, char *cgiargs)+void serve_dynamic(int fd, char *filename, char *cgiargs, char *method) {
      char buf[MAXLINE], *emptylist[] = {
    NULL }; @@ -193,6 +196,7 @@   if (Fork() == 0) {
    /* Child */ //line:netp:servedynamic:fork     /* Real server would set all CGI vars here */     setenv("QUERY_STRING", cgiargs, 1); //line:netp:servedynamic:setenv+    setenv("REQUEST_METHOD", method, 1);     Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */ //line:netp:servedynamic:dup2     Execve(filename, emptylist, environ); /* Run CGI program */ //line:netp:servedynamic:execve   }

addr.c更改：

@@ -1,10 +1,10 @@ /*- * adder.c - a minimal CGI program that adds two numbers together+ * head-adder.c - a minimal CGI program that adds two numbers together  */ #include "../csapp.h"  int main(void) {
   -  char *buf, *p;+  char *buf, *p, *method;   char arg1[MAXLINE], arg2[MAXLINE], content[MAXLINE];   int n1=0, n2=0; @@ -18,6 +18,8 @@     n2 = atoi(arg2);   } +  method = getenv("REQUEST_METHOD");+   /* Make the response body */   sprintf(content, "Welcome to add.com: ");   sprintf(content, "%sTHE Internet addition portal.\r\n
", content);@@ -29,7 +31,10 @@   printf("Connection: close\r\n");   printf("Content-length: %d\r\n", (int)strlen(content));   printf("Content-type: text/html\r\n\r\n");-  printf("%s", content);++  if (strcasecmp(method, "HEAD") != 0)+    printf("%s", content);+   fflush(stdout);    exit(0);

P12

tiny.c

@@ -5,7 +5,7 @@ #include "csapp.h"  void doit(int fd);-void read_requesthdrs(rio_t *rp);+int read_requesthdrs(rio_t *rp, char *method); 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);@@ -55,12 +55,14 @@     return;   printf("%s", buf);   sscanf(buf, "%s %s %s", method, uri, version);       //line:netp:doit:parserequest-  if (strcasecmp(method, "GET")) {
                        //line:netp:doit:beginrequesterr+  if (!(strcasecmp(method, "GET") == 0 || strcasecmp(method, "POST") == 0)) {
        clienterror(fd, method, "501", "Not Implemented",         "Tiny does not implement this method");     return;   }                                                    //line:netp:doit:endrequesterr-  read_requesthdrs(&rio);                              //line:netp:doit:readrequesthdrs+  int param_len = read_requesthdrs(&rio, method);++  Rio_readnb(&rio, buf, param_len);    /* Parse URI from GET request */   is_static = parse_uri(uri, filename, cgiargs);       //line:netp:doit:staticcheck@@ -84,24 +86,29 @@           "Tiny couldn't run the CGI program");       return;     }-    serve_dynamic(fd, filename, cgiargs);            //line:netp:doit:servedynamic+    if (strcasecmp(method, "GET") == 0)+      serve_dynamic(fd, filename, cgiargs);+    else+      serve_dynamic(fd, filename, buf);   } }  /*  * read_requesthdrs - read HTTP request headers  */-void read_requesthdrs(rio_t *rp)+int read_requesthdrs(rio_t *rp, char *method) {
      char buf[MAXLINE];+  int len = 0; -  Rio_readlineb(rp, buf, MAXLINE);-  printf("%s", buf);-  while(strcmp(buf, "\r\n")) {
             //line:netp:readhdrs:checkterm+  do {
        Rio_readlineb(rp, buf, MAXLINE);     printf("%s", buf);-  }-  return;+    if (strcasecmp(method, "POST") == 0 && strncasecmp(buf, "Content-Length:", 15) == 0)+      sscanf(buf, "Content-Length: %d", &len);+  } while(strcmp(buf, "\r\n"));++  return len;

post-addr

@@ -1,5 +1,5 @@ /*- * adder.c - a minimal CGI program that adds two numbers together+ * post-adder.c - a minimal CGI program that adds two numbers together  */ #include "../csapp.h" @@ -12,10 +12,8 @@   if ((buf = getenv("QUERY_STRING")) != NULL) {
        p = strchr(buf, '&');     *p = '\0';-    strcpy(arg1, buf);-    strcpy(arg2, p+1);-    n1 = atoi(arg1);-    n2 = atoi(arg2);+    sscanf(buf, "first=%d", &n1);+    sscanf(p+1, "second=%d", &n2);   }

P13

@@ -13,6 +13,17 @@ void clienterror(int fd, char *cause, char *errnum,     char *shortmsg, char *longmsg); +// improved rio written+void Im_rio_writen(int fd, void *usrbuf, size_t n) {
   +  if (rio_writen(fd, usrbuf, n) != n) {
   +    if (errno == EPIPE)+      fprintf(stderr, "EPIPE error");++    fprintf(stderr, "%s ", strerror(errno));+    unix_error("client side has ended connection");+  }+}+ int main(int argc, char **argv) {
      int listenfd, connfd;@@ -26,6 +37,9 @@     exit(1);   } +  if (Signal(SIGPIPE, SIG_IGN) == SIG_ERR)+    unix_error("mask signal pipe error");+   listenfd = Open_listenfd(argv[1]);   while (1) {
        clientlen = sizeof(clientaddr);@@ -148,7 +162,7 @@   sprintf(buf, "%sConnection: close\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));       //line:netp:servestatic:endserve+  Im_rio_writen(fd, buf, strlen(buf));       //line:netp:servestatic:endserve   printf("Response headers:\n");   printf("%s", buf); @@ -156,7 +170,7 @@   srcfd = Open(filename, O_RDONLY, 0);    //line:netp:servestatic:open   srcp = Mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);//line:netp:servestatic:mmap   Close(srcfd);                           //line:netp:servestatic:close-  Rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write+  Im_rio_writen(fd, srcp, filesize);         //line:netp:servestatic:write   Munmap(srcp, filesize);                 //line:netp:servestatic:munmap } @@ -186,11 +200,13 @@    /* Return first part of HTTP response */   sprintf(buf, "HTTP/1.0 200 OK\r\n");-  Rio_writen(fd, buf, strlen(buf));+  Im_rio_writen(fd, buf, strlen(buf));   sprintf(buf, "Server: Tiny Web Server\r\n");-  Rio_writen(fd, buf, strlen(buf));+  Im_rio_writen(fd, buf, strlen(buf));    if (Fork() == 0) {
    /* Child */ //line:netp:servedynamic:fork+    if (Signal(SIGPIPE, SIG_DFL) == SIG_ERR)+      unix_error("unmask signal pipe error");     /* Real server would set all CGI vars here */     setenv("QUERY_STRING", cgiargs, 1); //line:netp:servedynamic:setenv     Dup2(fd, STDOUT_FILENO);         /* Redirect stdout to client */ //line:netp:servedynamic:dup2@@ -216,10 +232,10 @@    /* Print the HTTP response */   sprintf(buf, "HTTP/1.0 %s %s\r\n", errnum, shortmsg);-  Rio_writen(fd, buf, strlen(buf));+  Im_rio_writen(fd, buf, strlen(buf));   sprintf(buf, "Content-type: text/html\r\n");-  Rio_writen(fd, buf, strlen(buf));+  Im_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));+  Im_rio_writen(fd, buf, strlen(buf));+  Im_rio_writen(fd, body, strlen(body)); }

第十一章 完

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