《CSAPP》（第3版）答案（第十一章）

《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 <port>\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, "<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));
}

• B

GET / HTTP/1.1
Host: localhost:5000
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/53.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive

• C
  HTTP 1.1
• D
  rfc

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 <port>\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, "<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));
}

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 <port>\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, "<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));
}

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

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Tiny Server</title>
</head>
<body>
<form action="/cgi-bin/form-adder" method="GET">
  <p>first number: <input type="text" name="first"/></p>
  <p>second number: <input type="text" name="second"/></p>
  <input type="submit" value="Submit"/>
</form>
</body>
</html>

• 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<p>", 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