/*!
* *************************************************************************************************
* @copyright(c) 2008-2025 Shenzhen TP-LINK Technologies Co.Ltd.
*
* @file http.c
* @brief
*
* @author huyushuai
* @version 1.0.0
* @date 2025-08-08
* *************************************************************************************************
*/
/**************************************************************************************************/
/* INCLUDE_FILES */
/**************************************************************************************************/
#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>
#include <errno.h>
#include <signal.h>
#include <stdatomic.h>
#include <sys/wait.h>
/**************************************************************************************************/
/* DEFINES */
/**************************************************************************************************/
#define ISspace(x) isspace((int)(x))
#define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n"
#define MAX_PROCESSES 100 // 最大子进程数量限制
#define DOCUMENT_ROOT "htdocs"
/**************************************************************************************************/
/* LOCAL_PROTOTYPES */
/**************************************************************************************************/
void accept_request(int client_sock);
void bad_request(int client);
void cat(int, FILE *);
void can
not_execute(int);
void error_die(const char *);
void execute_cgi(int, const char *, const char *, const char *);
int get_line(int, char *, int);
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);
const char *get_content_type(const char *
path);
void handle_sig
pipe(int sig);
/**************************************************************************************************/
/* LOCAL_FUNCTIONS */
/**************************************************************************************************/
/*!
* @brief 路径规范函数
*
* @param[in]
path 文件路径
*/
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';
}
/*!
* @brief 忽略SIG
PIPE信号处理
*
* @param[in] sig SIG
PIPE信号
*/
void handle_sig
pipe(int sig)
{
}
/*!
* @brief
*
* @param[in] ctx Comment
*/
void accept_request(int client_sock) {
int client = client_sock;
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';
// 只支持GET和POST方法
if (strcasecmp(method, "GET") && strcasecmp(method, "POST"))
{
unimplemented(client);
close(client);
return;
}
// POST请求启用CGI
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';
// 处理GET查询参数
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++;
}
}
// 构建安全路径
if (strlen(url) == 0 || strstr(url, "..") != NULL)
{
bad_request(client);
close(client);
return;
}
snprintf(
path, sizeof(
path), "%s%s", DOCUMENT_ROOT, url);
normalize_
path(
path);
// 确保路径在文档根目录内
if (strncmp(
path, DOCUMENT_ROOT, strlen(DOCUMENT_ROOT)) != 0)
{
not_found(client);
close(client);
return;
}
if (
path[strlen(
path) - 1] == '/')
{
strncat(
path, "index.html", sizeof(
path) - strlen(
path) - 1);
}
if (stat(
path, &st) == -1)
{
while ((numchars > 0) && strcmp("\n", buf) != 0)
{
numchars = get_line(client, buf, sizeof(buf));
}
not_found(client);
}
else
{
if (S_ISDIR(st.st_mode))
{
strncat(
path, "/index.html", sizeof(
path) - strlen(
path) - 1);
stat(
path, &st);
}
if ((st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) || (st.st_mode & S_IXOTH))
{
cgi = 1;
}
if (!cgi)
{
serve_file(client,
path);
}
else
{
execute_cgi(client,
path, method, query_string);
}
}
/* 清理资源 */
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];
sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "Content-type: text/html\r\n");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "\r\n");
send(client, buf, sizeof(buf), 0);
sprintf(buf, "<P>Your browser sent a bad request, ");
send(client, buf, sizeof(buf), 0);
sprintf(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 can
not_execute(int client)
{
char buf[1024];
sprintf(buf, "HTTP/1.0 500 Internal Server Error\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-type: text/html\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
sprintf(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))
{
buf[15] = '\0';
if (strcasecmp(buf, "Content-Length:") == 0)
{
content_length = atoi(&(buf[16]));
}
numchars = get_line(client, buf, sizeof(buf));
}
if (content_length == -1)
{
bad_request(client);
return;
}
}
sprintf(buf, "HTTP/1.0 200 OK\r\n");
send(client, buf, strlen(buf), 0);
/* 建立output管道 */
if (
pipe(cgi_output) < 0)
{
can
not_execute(client);
return;
}
/* 建立input管道 */
if (
pipe(cgi_input) < 0)
{
can
not_execute(client);
return;
}
if ((pid = fork()) < 0)
{
can
not_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
sprintf(meth_env, "REQUEST_METHOD=%s", method);
putenv(meth_env);
if (strcasecmp(method, "GET") == 0)
{
sprintf(query_env, "QUERY_STRING=%s", query_string);
putenv(query_env);
}
else
{ /* POST */
sprintf(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 SIG
PIPE,
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)
{
perror("Failed to
write to CGI");
close(cgi_input[1]);
close(cgi_input[0]);
break;
}
}
}
while (read(cgi_output[0], &c, 1) > 0)
{
send(client, &c, 1, 0);
}
close(cgi_output[0]);
close(cgi_input[1]);
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
/*!
* @brief 从socket中获取一行数据
*
* @param[in] sock socket
* @param[in] buf 用于保存数据的缓冲区
* @param[in] size 缓冲区的大小
* @return int 存储的字节数
*/
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);
if (n > 0)
{
if (c == '\r')
{
n = recv(sock, &c, 1, MSG_PEEK);
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);
}
/*!
* @brief 根据文件路径的扩展名返回对应的 MIME 类型
*
* @param[in]
path 路径字符串
* @return const char*
*/
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 发送HTTP响应头
*
* @param[in] client 客户端
* @param[in] filename 文件名
*/
void headers(int client, const char *filename)
{
char buf[1024];
const char *content_type = get_content_type(filename);
sprintf(buf, "HTTP/1.0 200 OK\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: %s\r\n", content_type);
send(client, buf, strlen(buf), 0);
sprintf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
}
/*!
* @brief 404
*
* @param[in] client 客户端
*/
void
not_found(int client)
{
char buf[1024];
sprintf(buf, "HTTP/1.0 404
NOT FOUND\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/html\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<HTML><TITLE>
Not Found</TITLE>\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<BODY><P>The server
could not fulfill\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "your request because the resource specified\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "is unavailable or nonexistent.\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</BODY></HTML>\r\n");
send(client, buf, strlen(buf), 0);
}
/*!
* @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 客户端
* @param[in] filename 文件名
*/
void serve_file(int client, const char *filename)
{
FILE *resource = NULL;
int numchars = 1;
char buf[1024];
buf[0] = 'A';
buf[1] = '\0';
while ((numchars > 0) && strcmp("\n", buf))
{
numchars = get_line(client, buf, sizeof(buf));
}
resource = fopen(filename, "rb");
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);
if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0)
{
error_die("bind");
}
if (*port == 0)
{
socklen_t namelen = sizeof(name);
if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1)
{
error_die("getsockname");
}
*port = ntohs(name.sin_port);
}
if (listen(httpd, 5) < 0)
{
error_die("listen");
}
return (httpd);
}
/*!
* @brief 没有实现请求
*
* @param[in] client 客户端
*/
void unimplemented(int client)
{
char buf[1024];
sprintf(buf, "HTTP/1.0 501 Method
Not Implemented\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/html\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<HTML><HEAD><TITLE>Method
Not Implemented\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</TITLE></HEAD>\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "<BODY><P>HTTP request method
not supported.\r\n");
send(client, buf, strlen(buf), 0);
sprintf(buf, "</BODY></HTML>\r\n");
send(client, buf, strlen(buf), 0);
}
int main(void) {
int server_sock = -1;
u_short port = 80; // 使用8080端口避免权限问题
struct sockaddr_in client_name;
socklen_t client_name_len = sizeof(client_name);
// 设置信号处理
signal(SIG
PIPE, handle_sig
pipe);
server_sock = startup(&port);
printf("HTTP server running on port %d\n", port);
while (1)
{
int client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len);
if (client_sock == -1)
{
perror("accept failed");
continue;
}
pid_t pid = fork();
if (pid < 0)
{
perror("fork failed");
close(client_sock);
}
else if (0 == pid)
{
close(server_sock);
accept_request(client_sock);
exit(EXIT_SUCCESS);
}
else
{
close(client_sock);
}
}
close(server_sock);
return 0;
}
实现以IO多路复用方式实现web server功能(必修)
要求尽可能少的修改代码，并列出要添加或者删除的部分
本文解决了一个在Ubuntu 12.04中遇到的问题，即登录时出现'couldnotwritebytesbrokenpipe'错误，并且在tt2终端下执行ls命令失败。问题原因在于/etc/profile文件中的PATH变量被误写为$PAHT。
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