tinyhttpd 是一个不到 500 行的超轻量型 Http Server很适合初学者，帮助我们快速掌握unix socket编程 和 http请求流程。看完所有源码，真的感觉有很大收获，无论是 unix 的编程，还是 GET/POST 的 Web 处理流程，都清晰了不少。
直接从github下载
注释源码如下：
#include <stdio.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>
#define ISspace(x) isspace((int)(x))
#define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n"
// 从套接字监听HTTP请求
void accept_request(int);
// 返回错误请求代码
void bad_request(int);
// 读取服务器上的文件到套接字
void cat(int, FILE *);
// 执行cgi发生错误
void cannot_execute(int);
// 吧错误信息写到perror并退出
void error_die(const char *);
// 执行cgi
void execute_cgi(int, const char *, const char *, const char *);
// 读取一行套接字
int get_line(int, char *, int);
// 把http响应头写到套接字
void headers(int, const char *);
// 找不到文件
void not_found(int);
// 调用cat把吴福气文件返回客户端
void serve_file(int, const char *);
// 初始化http server
int startup(u_short *);
// 返回给浏览器表明收到的 HTTP 请求所用的 method 不被支持
void unimplemented(int);
/**********************************************************************/
/* 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(int client)
{
char buf[1024];
int numchars;
char method[255];
char url[255];
char path[512];
size_t i, j;
struct stat st;
int cgi = 0; /* becomes true if server decides this is a CGI
* program */
char *query_string = NULL;
/* 读取一行数据 */
numchars = get_line(client, buf, sizeof(buf));
printf("buf:%s\n", buf);
i = 0; j = 0;
/* 将数据 复制到method中，直到空格或长度超过 */
while (!ISspace(buf[j]) && (i < sizeof(method) - 1))
{
method[i] = buf[j];
i++; j++;
}
method[i] = '\0';
printf("method:%s\n", method);
/* 如果不是GET请求 或 POST请求 */
if (strcasecmp(method, "GET") && strcasecmp(method, "POST"))
{
/* 返回请求类型不支持到客户端 */
printf("uniplemented");
unimplemented(client);
return;
}
/*如果是POST请求 则执行cgi */
if (strcasecmp(method, "POST") == 0)
cgi = 1;
i = 0;
/* 转到下一个空格后的数据*/
/* 跳过空格 */
while (ISspace(buf[j]) && (j < sizeof(buf)))
j++;
/* 获取url */
while (!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf)))
{
url[i] = buf[j];
i++; j++;
}
url[i] = '\0';
if (strcasecmp(method, "GET") == 0)
{
query_string = url;
/* 获取url参数 */
while ((*query_string != '?') && (*query_string != '\0'))
query_string++;
/* 如果有参数 ，执行cgi*/
if (*query_string == '?')
{
cgi = 1;
/* 跳过？*/
*query_string = '\0';
query_string++;
}
}
/* 生成文件地址path */
sprintf(path, "htdocs%s", url);
printf("%s", path);
/* 如果url为 / 这访问 index.html*/
if (path[strlen(path) - 1] == '/')
strcat(path, "index.html");
/* 打开path文件*/
if (stat(path, &st) == -1) {
/* 打开文件失败 */
while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */
numchars = get_line(client, buf, sizeof(buf));
/* 返回403 错误 */
not_found(client);
}
else /* 打开文件成功 */
{
if ((st.st_mode & S_IFMT) == S_IFDIR)
strcat(path, "/index.html");
if ((st.st_mode & S_IXUSR) ||
(st.st_mode & S_IXGRP) ||
(st.st_mode & S_IXOTH) )
cgi = 1;
if (!cgi) /* 发送文件内容到客户端 */
serve_file(client, path);
else /* 执行cgi */
execute_cgi(client, path, method, query_string);
}
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);
}
/**********************************************************************/
/* Put the entire contents of a file out on a socket. This function
* is named after the UNIX "cat" command, because it might have been
* easier just to do something like pipe, fork, and exec("cat").
* Parameters: the client socket descriptor
* FILE pointer for the file to cat */
/**********************************************************************/
void cat(int client, FILE *resource)
{
char buf[1024];
/* 读取文件内容到buf */
fgets(buf, sizeof(buf), resource);
/* 读取玩所有内容并发送到客户端 */
while (!feof(resource))
{
send(client, buf, strlen(buf), 0);
fgets(buf, sizeof(buf), resource);
}
}
/**********************************************************************/
/* Inform the client that a CGI script could not be executed.
* Parameter: the client socket descriptor. */
/**********************************************************************/
void cannot_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)
{
/* 打印错误信息 */
perror(sc);
exit(1);
}
/**********************************************************************/
/*CGI(Common Gateway Interface 通用网关接口)
* 作用：
* 提取用户提交的表单信息
* 处理表单信息
* 输出，返回html响应*/
/* 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)
{
char buf[1024];
int cgi_output[2];
int cgi_input[2];
pid_t pid;
int status;
int i;
char c;
int numchars = 1;
int content_length = -1;
buf[0] = 'A'; buf[1] = '\0';
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);
if (pipe(cgi_output) < 0)
{
cannot_execute(client);
return;
}
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];
dup2(cgi_output[1], 1);
dup2(cgi_input[0], 0);
close(cgi_output[0]);
close(cgi_input[1]);
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);
}
execl(path, path, NULL);
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);
write(cgi_input[1], &c, 1);
}
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) */
/**********************************************************************/
int get_line(int sock, char *buf, int size)
{
int i = 0;
char c = '\0';
int n;
/* 循环读取直到长度超过size或者读到了行末 */
while ((i < size - 1) && (c != '\n'))
{
/* 获取客户端发送的数据 （获取 1 个字符存放在c中)，
* flag = 0 从tcp buffer 中复制数据并将它从tcp buffer,
* 中移除*/
n = recv(sock, &c, 1, 0);
/* DEBUG printf("%02X\n", c); */
if (n > 0)/* 读取到了数据 */
{
if (c == '\r')/*如果是行末 读取下一行 */
{
/* msg_peek 仅把tcp buffer中的数据督导buf中，
* 并不会把读取的数据从tcpbuffer中移除，再次
* 调用时任然读取到的时这个数据 */
n = recv(sock, &c, 1, MSG_PEEK);
/* DEBUG printf("%02X\n", c); */
if ((n > 0) && (c == '\n'))
/* 如果接收到的是 \r\n则将\n从tcp buffer中移除 */
recv(sock, &c, 1, 0);
else
c = '\n';
}
buf[i] = c;
i++;
}
else
c = '\n';
}
buf[i] = '\0';
/* 返回读取到的个数 */
return(i);
}
/**********************************************************************/
/* Return the informational HTTP headers about a file. */
/* Parameters: the socket to print the headers on
* the name of the file */
/**********************************************************************/
void headers(int client, const char *filename)
{
char buf[1024];
(void)filename; /* could use filename to determine file type */
strcpy(buf, "HTTP/1.0 200 OK\r\n");
send(client, buf, strlen(buf), 0);
strcpy(buf, SERVER_STRING);
send(client, buf, strlen(buf), 0);
sprintf(buf, "Content-Type: text/html\r\n");
send(client, buf, strlen(buf), 0);
strcpy(buf, "\r\n");
send(client, buf, strlen(buf), 0);
}
/**********************************************************************/
/* Give a client a 404 not found status message. */
/**********************************************************************/
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);
}
/**********************************************************************/
/* 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 */
/**********************************************************************/
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)) /* read & discard headers */
numchars = get_line(client, buf, sizeof(buf));
resource = fopen(filename, "r");
if (resource == NULL)
not_found(client);
else
{
/* 向客户端发送 header和内容*/
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; /* 文件描述符*/
struct sockaddr_in name;
httpd = socket(PF_INET, SOCK_STREAM, 0);
/* 出错处理 */
if (httpd == -1)
error_die("socket");
/* 清0 */
memset(&name, 0, sizeof(name));
name.sin_family = AF_INET;
name.sin_port = htons(*port);
name.sin_addr.s_addr = htonl(INADDR_ANY); /* 全网 */
if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0)
error_die("bind");
if (*port == 0) /* 如果端口为0 则申请一个临时端口 */
{
int 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);
}
/**********************************************************************/
/* Inform the client that the requested web method has not been
* implemented.
* Parameter: the client socket */
/**********************************************************************/
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(int argc, char argv[])
{
int server_sock = -1;
u_short port = 0;
int client_sock = -1;
struct sockaddr_in client_name;
int client_name_len = sizeof(client_name);
pthread_t newthread;
server_sock = startup(&port);
printf("httpd running on port %d\n", port);
while (1)
{
/* 开始阻塞接受 */
client_sock = accept(server_sock,
(struct sockaddr *)&client_name,
&client_name_len);
if (client_sock == -1)
error_die("accept");
/* 收到客户端连接，创建一个线程处理连接 */
if (pthread_create(&newthread , NULL, accept_request, client_sock) != 0)
perror("pthread_create");
}
close(server_sock);
return(0);
}
