#include <stdio.h>
#include <stdbool.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>
// 宏定义，是否是空格
#define ISspace(x) isspace((int)(x))
#define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n"
// 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
void accept_request(void *arg);
void bad_request(int);
void cat(int, FILE *);
void cannot_execute(int);
void
error_die(const char *);
void execute_cgi(int, const char *, const char *, const char *);
int get_line(int, char *, int);
// 返回http头
void headers(int, const char *);
void not_found(int);
void serve_file(int, const char *);
int startup(u_short *);
void unimplemented(int);
void normalize_path(char *path)
{
char *p = path;
char *q = path;
while (*p)
{
if (strncmp(p, "/../", 4) == 0)
{
p += 3;
while (q > path && *
--q != '/')
;
}
else if (strncmp(p, "/./", 3) == 0)
{
p += 2;
}
else if (strncmp(p, "//", 2) == 0)
{
p += 1;
}
else
{
*q++ = *p++;
}
}
*q = '\0';
}
/**********************************************************************/
/* A request has caused a call to accept() on the server port to
* return. Process the request appropriately.
* Parameters: the socket connected to the client */
/**********************************************************************/
void accept_request(void *arg)
{
int client = (intptr_t)arg;
char buf[1024];
char method[255];
char url[255];
char path[512];
struct stat st;
int cgi = 0;
char *query_string = NULL;
int numchars = get_line(client, buf, sizeof(buf));
size_t i = 0;
size_t j = 0;
while (!ISspace(buf[j]) && (i < sizeof(method)
- 1))
{
method[i] = buf[j];
i++;
j++;
}
method[i] = '\0';
/* 判断是Get还是Post，否则501 Not Implemented */
if (strcasecmp(method, "GET") && strcasecmp(method, "POST"))
{
unimplemented(client);
return;
}
/* 如果是POST，cgi置为1 */
if (strcasecmp(method, "POST") == 0)
{
cgi = 1;
}
i = 0;
while (ISspace(buf[j]) && (j < sizeof(buf)))
{
j++;
}
while (!ISspace(buf[j]) && (i < sizeof(url)
- 1) && (j < sizeof(buf)))
{
url[i] = buf[j];
i++;
j++;
}
url[i] = '\0';
/* 判断Get请求 */
if (strcasecmp(method, "GET") == 0)
{
query_string = url;
while ((*query_string != '?') && (*query_string != '\0'))
query_string++;
if (*query_string == '?')
{
cgi = 1;
*query_string = '\0';
query_string++;
}
}
// 路径
s
printf(path, "htdocs%s", url);
// 默认地址，解析到的路径如果为/，则自动加上index.html
if (path[strlen(path)
- 1] == '/')
strcat(path, "Index.html");
// 获得文件信息
if (stat(path, &st) ==
-1)
{
// 把所有http信息读出然后丢弃
while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */
numchars = get_line(client, buf, sizeof(buf));
// 没有找到
not_found(client);
}
else
{
if ((st.st_mode & S_IFMT) == S_IFDIR)
strcat(path, "/Index.html");
// 如果你的文件默认是有执行权限的，自动解析成cgi程序，如果有执行权限但是不能执行，会接受到报错信号
if ((st.st_mode & S_IXUSR) ||
(st.st_mode & S_IXGRP) ||
(st.st_mode & S_IXOTH))
cgi = 1;
if (!cgi)
// 接读取文件返回给请求的http客户端
serve_file(client, path);
else
// 执行cgi文件
execute_cgi(client, path, method, query_string);
}
// 执行完毕关闭socket
close(client);
}
/**********************************************************************/
/* Inform the client that a request it has made has a problem.
* Parameters: client socket */
/**********************************************************************/
void bad_request(int client)
{
char buf[1024];
s
printf(buf, "HTTP/1.0 400 BAD REQUEST\r\n");
send(client, buf, sizeof(buf), 0);
s
printf(buf, "Content
-type: text/html\r\n");
send(client, buf, sizeof(buf), 0);
s
printf(buf, "\r\n");
send(client, buf, sizeof(buf), 0);
s
printf(buf, "<P>Your browser sent a bad request, ");
send(client, buf, sizeof(buf), 0);
s
printf(buf, "such as a POST without a Content
-Length.\r\n");
send(client, buf, sizeof(buf), 0);
}
/*!
* @brief 将文件内容发送到网络客户端
*
* @param[in] client 客户端套接字描述符
* @param[in] resource 文件指针（指向要发送的文件）
*/
void cat(int client, FILE *resource)
{
char buf[1024];
size_t bytes_read;
while ((bytes_read = fread(buf, 1, sizeof(buf), resource)) > 0)
{
if (send(client, buf, bytes_read, 0) < bytes_read)
{
perror("send");
break;
}
}
}
/**********************************************************************/
/* Inform the client that a CGI script could not be executed.
* Parameter: the client socket descriptor. */
/**********************************************************************/
void cannot_execute(int client)
{
char buf[1024];
s
printf(buf, "HTTP/1.0 500 Internal Server
Error\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "Content
-type: text/html\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "<P>
Error prohibited CGI execution.\r\n");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
/*
Print out an
error message with
perror() (for
system errors; based
* on value of errno, which indicates
system call
errors) and exit the
* program indicating an
error. */
/**********************************************************************/
void
error_die(const char *sc)
{
perror(sc);
exit(1);
}
/**********************************************************************/
/* 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)
{
// 缓冲区
char buf[1024];
int cgi_output[2];
int cgi_input[2];
pid_t pid;
int status;
int i = 0;
char c;
int numchars = 1;
int content_length =
-1;
// 默认字符
buf[0] = 'A';
buf[1] = '\0';
// 忽略大小写比较字符串
if (strcasecmp(method, "GET") == 0)
{
while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */
{
numchars = get_line(client, buf, sizeof(buf));
}
}
else /* POST */
{
numchars = get_line(client, buf, sizeof(buf));
while ((numchars > 0) && strcmp("\n", buf))
{
// 如果是POST请求，就需要得到Content
-Length，Content
-Length：这个字符串一共长为15位，所以
// 取出头部一句后，将第16位设置结束符，进行比较
// 第16位置为结束
buf[15] = '\0';
if (strcasecmp(buf, "Content
-Length:") == 0)
// 内存从第17位开始就是长度，将17位开始的所有字符串转成整数就是content_length
content_length = atoi(&(buf[16]));
numchars = get_line(client, buf, sizeof(buf));
}
if (content_length ==
-1)
{
bad_request(client);
return;
}
}
s
printf(buf, "HTTP/1.0 200 OK\r\n");
send(client, buf, strlen(buf), 0);
// 建立output管道
if (pipe(cgi_output) < 0)
{
cannot_execute(client);
return;
}
// 建立input管道
if (pipe(cgi_input) < 0)
{
cannot_execute(client);
return;
}
if ((pid = fork()) < 0)
{
cannot_execute(client);
return;
}
if (pid == 0) /* child: CGI script */
{
char meth_env[255];
char query_env[255];
char length_env[255];
// 子进程输出重定向到output管道的1端
dup2(cgi_output[1], 1);
// 子进程输入重定向到input管道的0端
dup2(cgi_input[0], 0);
// 关闭无用管道口
close(cgi_output[0]);
close(cgi_input[1]);
// CGI环境变量
s
printf(meth_env, "REQUEST_METHOD=%s", method);
putenv(meth_env);
if (strcasecmp(method, "GET") == 0)
{
s
printf(query_env, "QUERY_STRING=%s", query_string);
putenv(query_env);
}
else
{ /* POST */
s
printf(length_env, "CONTENT_LENGTH=%d", content_length);
putenv(length_env);
}
// 替换执行path
execl(path, path, NULL);
// int m = execl(path, path, NULL);
// 如果path有问题，例如将html网页改成可执行的，但是执行后m为
-1
// 退出子进程，管道被破坏，但是父进程还在往里面写东西，触发Program received signal SIGPIPE, Broken pipe.
exit(0);
}
else
{ /* parent */
close(cgi_output[1]);
close(cgi_input[0]);
if (strcasecmp(method, "POST") == 0)
for (i = 0; i < content_length; i++)
{
recv(client, &c, 1, 0);
ssize_t bytes_written = write(cgi_input[1], &c, 1);
if (bytes_written <= 0)
{
// 错误处理
perror("Failed to write to CGI");
close(cgi_input[1]);
close(cgi_input[0]);
break;
}
}
// 从output管道读到子进程处理后的信息，然后send出去
while (read(cgi_output[0], &c, 1) > 0)
send(client, &c, 1, 0);
// 完成操作后关闭管道
close(cgi_output[0]);
close(cgi_input[1]);
// 等待子进程返回
waitpid(pid, &status, 0);
}
}
/**********************************************************************/
/* Get a line from a socket, whether the line ends in a newline,
* carriage return, or a CRLF combination. Terminates the string read
* with a null character. If no newline indicator is found before the
* end of the buffer, the string is terminated with a null. If any of
* the above three line terminators is read, the last character of the
* string will be a linefeed and the string will be terminated with a
* null character.
* Parameters: the socket descriptor
* the buffer to save the data in
* the size of the buffer
* Returns: the number of bytes stored (excluding null) */
/**********************************************************************/
// 得到一行数据,只要发现c为\n,就认为是一行结束，如果读到\r,再用MSG_PEEK的方式读入一个字符，如果是\n，从socket用读出
// 如果是下个字符则不处理，将c置为\n，结束。如果读到的数据为0中断，或者小于0，也视为结束，c置为\n
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')
{
// 偷窥一个字节，如果是\n就读走
n = recv(sock, &c, 1, MSG_PEEK);
/* DEBUG
printf("%02X\n", c); */
if ((n > 0) && (c == '\n'))
recv(sock, &c, 1, 0);
else
// 不是\n（读到下一行的字符）或者没读到，置c为\n 跳出循环,完成一行读取
c = '\n';
}
buf[i] = c;
i++;
}
else
c = '\n';
}
buf[i] = '\0';
return (i);
}
/**********************************************************************/
/* Return the informational HTTP headers about a file. */
/* Parameters: the socket to
print the headers on
* the name of the file */
/**********************************************************************/
// 加入http的headers
const char *get_content_type(const char *path)
{
const char *ext = strrchr(path, '.');
if (ext)
{
if (strcasecmp(ext, ".css") == 0)
return "text/css";
if (strcasecmp(ext, ".js") == 0)
return "application/javascript";
if (strcasecmp(ext, ".png") == 0)
return "image/png";
if (strcasecmp(ext, ".jpg") == 0 || strcasecmp(ext, ".jpeg") == 0)
return "image/jpeg";
if (strcasecmp(ext, ".gif") == 0)
return "image/gif";
if (strcasecmp(ext, ".ico") == 0)
return "image/x
-icon";
if (strcasecmp(ext, ".svg") == 0)
return "image/svg+xml";
if (strcasecmp(ext, ".woff") == 0)
return "font/woff";
if (strcasecmp(ext, ".woff2") == 0)
return "font/woff2";
}
return "text/html";
}
/*!
* @brief
*
* @param[in] client Comment
* @param[in] filename Comment
*/
void headers(int client, const char *filename)
{
char buf[1024];
const char *content_type = get_content_type(filename);
s
printf(buf, "HTTP/1.0 200 OK\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
s
printf(buf, "Content
-Type: %s\r\n", content_type);
send(client, buf, strlen(buf), 0);
s
printf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
}
/*!
* @brief
*
* @param[in] client Comment
*/
void not_found(int client)
{
char buf[1024];
s
printf(buf, "HTTP/1.0 404 NOT FOUND\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
s
printf(buf, "Content
-Type: text/html\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "<HTML><TITLE>Not Found</TITLE>\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "<BODY><P>The server could not fulfill\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "your request because the resource specified\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "is unavailable or nonexistent.\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "</BODY></HTML>\r\n");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
/* Send a regular file to the client. Use headers, and report
*
errors to client if they occur.
* Parameters: a pointer to a file structure produced from the socket
* file descriptor
* the name of the file to serve */
/**********************************************************************/
/*!
* @brief 如果不是CGI文件，直接读取文件返回给请求的http客户端
*
* @param[in] client Comment
* @param[in] filename Comment
*/
void serve_file(int client, const char *filename)
{
FILE *resource = NULL;
int numchars = 1;
char buf[1024];
// 默认字符
buf[0] = 'A';
buf[1] = '\0';
while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */
{
numchars = get_line(client, buf, sizeof(buf));
}
resource = fopen(filename, "rb");
printf("Serving file: %s\n", filename);
if (resource == NULL)
{
not_found(client);
}
else
{
headers(client, filename);
cat(client, resource);
}
fclose(resource);
}
/**********************************************************************/
/* This function starts the process of listening for web connections
* on a specified port. If the port is 0, then dynamically allocate a
* port and modify the original port variable to reflect the actual
* port.
* Parameters: pointer to variable containing the port to connect on
* Returns: the socket */
/**********************************************************************/
int startup(u_short *port)
{
int httpd = 0;
struct sockaddr_in name;
httpd = socket(PF_INET, SOCK_STREAM, 0);
if (httpd ==
-1)
{
error_die("socket");
}
memset(&name, 0, sizeof(name));
name.sin_family = AF_INET;
name.sin_port = htons(*port);
name.sin_addr.s_addr = htonl(INADDR_ANY);
// 绑定socket
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);
}
// 监听
if (listen(httpd, 5) < 0)
error_die("listen");
return (httpd);
}
/**********************************************************************/
/* Inform the client that the requested web method has not been
* implemented.
* Parameter: the client socket */
/**********************************************************************/
// 如果方法没有实现，就返回此信息
void unimplemented(int client)
{
char buf[1024];
s
printf(buf, "HTTP/1.0 501 Method Not Implemented\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
s
printf(buf, "Content
-Type: text/html\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "<HTML><HEAD><TITLE>Method Not Implemented\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "</TITLE></HEAD>\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "<BODY><P>HTTP request method not supported.\r\n");
send(client, buf, strlen(buf), 0);
s
printf(buf, "</BODY></HTML>\r\n");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
int main(void)
{
int server_sock =
-1;
u_short port = 80;
int client_sock =
-1;
struct sockaddr_in client_name;
// 这边要为socklen_t类型
socklen_t client_name_len = sizeof(client_name);
pthread_t newthread;
server_sock = startup(&port);
printf("httpd running on port %d\n", port);
while (1)
{
client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len);
if (client_sock ==
-1)
{
error_die("accept");
}
// 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);
}
实现以多进程方式实现web server功能(必修)
本文介绍了perror函数的使用方法，该函数用于打印系统错误信息到标准错误输出。它依赖于全局变量errno来获取错误码，并通过sys_errlist数组来显示对应的错误信息。
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