Tinyhttpd-源码阅读笔记
2016-07-05 19:12
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简介
这是一个用c实现的简单的http服务器 业务流程大约是创建socket 然后把监听链接,有链接就把connfd给accept_request线程 由accept_request处理线程 然后线程再根据GET和POST方法,有没有参数传递过来,是不是可执行文件来确定需不需要启动进程处理数据 不需要执行权限的,直接把页面返回,需要执行的,交个子进程执行,结果返回给父进程,返回给浏览器
报文
请求index时的报文 GET / HTTP/1.1 Host: 192.168.36.42:57046 Connection: keep-alive Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Upgrade-Insecure-Requests: 1 User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.86 Safari/537.36 Accept-Encoding: gzip, deflate, sdch Accept-Language: zh-CN,zh;q=0.8 -------------------------------------------------------------------- 请求cgi时的报文 POST /color.cgi HTTP/1.1 Host: 192.168.36.42:60566 Connection: keep-alive Content-Length: 6 Cache-Control: max-age=0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Origin: http://192.168.36.42:60566 Upgrade-Insecure-Requests: 1 User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.86 Safari/537.36 Content-Type: application/x-www-form-urlencoded Referer: http://192.168.36.42:60566/ Accept-Encoding: gzip, deflate Accept-Language: zh-CN,zh;q=0.8 color= ------------------------------------------------ 回复请求cgi的报文 HTTP/1.0 200 OK
源码
#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 <string.h> #include <strings.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" void accept_request(int); 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); /* 读一行 */ void headers(int , const char *); void not_found(int); /* 404 */ void serve_file(int, const char *); int startup(u_short *); void unimplemented(int); /* 501 */ 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; /* 请求的是否是可执行文件 */ char *query_string = NULL; #if 0 /* Debug 打印接收到的浏览器信息请求 */ recv(client, buf, 1024, MSG_PEEK); printf("%s\n", buf); #endif numchars = get_line(client, buf, sizeof(buf)); i = 0, j = 0; /* 从消息头中分割出是GET还是POST */ while (!ISspace(buf[j]) && (i < sizeof(method)-1)) { method[i] = buf[j]; i++, j++; } method[i] = '\0'; if (strcasecmp(method, "GET") && strcasecmp(method, "POST")) { /* 既不是GET也不是POST, * 回应浏览器 501 消息 */ unimplemented(client); return ; } if (strcasecmp(method, "POST") == 0) { cgi = 1; /* post,就要执行文件 */ } i = 0; while (ISspace(buf[j]) && (j < sizeof(buf))) { j++; /* 越过空格 */ } /* 找出GET后面的url */ while (!ISspace(buf[j]) && (i < sizeof(url)-1) && (j < sizeof(buf))) { url[i++] = buf[j++]; } url[i] = '\0'; if (strcasecmp(method, "GET") == 0) { /* 如果是GET */ query_string = url; /* 找在url中使用GET传送来的参数 */ while ((*query_string != '?') && (*query_string != '\0')) { query_string++; } /* 如果真有参数,那就需要执行CGI来处理 */ if (*query_string == '?') { cgi = 1; *query_string = '\0'; /* 从?号截断*/ query_string++; /* 保存参数的首地址 */ } } /* 把"/"修改成相对于服务器的路径 "/"--> "htdocs/" */ sprintf(path, "htdocs%s", url); if (path[strlen(path)-1] == '/') { /* 如果以"#/", 自动补成"#/index.html" */ strcat(path, "index.html"); } if (stat(path, &st) == -1) { /* 如果读取文件信息失败 */ /* stat失败,首先把client消息头都读完 */ while ((numchars > 0) && strcmp("\n", buf)) { numchars = get_line(client, buf, sizeof(buf)); } not_found(client); /* 返回404页面 */ } else { /* stat成功, 有这个文件 */ /* 如果这个文件是文件夹, * 就默认请求的是这个文件夹的index.html*/ if ((st.st_mode & S_IFMT) == S_IFDIR) strcat(path, "/index.html"); /* 如果请求的文件是可执行文件 */ if ((st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) || (st.st_mode & S_IXOTH)) { cgi = 1; /* 再次把cgi设置成1 */ } if (!cgi) { /* 如果cgi是0, 传入的cgi文件路径和sock文件描述符 */ serve_file(client, path); } else { /*client, cgi文件路径, 请求的方法 ?后面跟的参数*/ execute_cgi(client, path, method, query_string); } close(client); } } 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, i, numchars = 1; int content_length = -1; char c; buf[0] = 'A'; buf[1] = '\0'; /* 如果是GET,那参数就在url中传递,已经提取到了query_string * 把剩余的消息头丢掉 * */ if (strcasecmp(method, "GET") == 0) { while ((numchars > 0) && strcmp("\n", buf)) numchars = get_line(client, buf, sizeof(buf)); } else { /* POST 参数在消息实体中传递 */ numchars = get_line(client, buf, sizeof(buf)); while ((numchars > 0) && strcmp("\n", buf)) { buf[15] = '\0'; /* 把内容按行读,筛选出Content-Length这个字段 * 得到消息实体的长度*/ if (strcasecmp(buf, "Content-Length:") == 0) content_length = atoi(&(buf[16])); numchars = get_line(client, buf, sizeof(buf)); } /* content_length=-1, 说明消息头中没有Content-Length这个字段 */ if (content_length == -1) { bad_request(client); /* 给浏览器返回400,请求出现语法错误 */ return ; } } sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); /* 创建与子进程通信的管道 */ 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]; /* 把子进程的标准输入和标准输出都重定向到管道上 * 进行读参数, 写数据的操作*/ dup2(cgi_output[1], 1); dup2(cgi_input[0], 0); close(cgi_output[0]); close(cgi_input[1]); /* 拼接回应的请求方式 */ sprintf(meth_env, "REQUEST_METHOD=%s", method); putenv(meth_env); /* 添加meth_env到子进程的环境变量中 */ /* 如果是GET方法 * 就把从URL中提取的参数放到QUERY_STRING这个环境变量里*/ if (strcasecmp(method, "GET") == 0) { sprintf(query_env, "QUERY_STRING=%s", query_string); putenv(query_env); } else { /* POST 把消息实体的长度设置为环境变量*/ sprintf(length_env, "CONTENT_LENGTH=%d", content_length); putenv(length_env); } /* exec把cgi的这个应用拉起来 */ execl(path, path, NULL); } else { /* parent */ /* 关闭不需要的管道读写端 */ 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); } } /* 发送文件中的内容 */ void cat(int client, FILE *resource) { char buf[1024]; fgets(buf, sizeof(buf), resource); while (!feof(resource)) { send(client, buf, strlen(buf), 0); fgets(buf, sizeof(buf), resource); } } int get_line(int sock, char *buf, int size) { int i = 0, n; char c = '0'; while ((i < size-1) && (c != '\n')) { n = recv(sock, &c, 1, 0); /* 一个字节一个字节的从sock中读内容 */ if (n > 0) { /* 读到内容 */ if (c == '\r') { /* 读到'\r',就代表这一行结束, * 如果后面有\n就读出来, * 如果没有,就自己加上'\n' */ /* MSG_PEEK 返回的数据并不会在系统内删除, * 如果再次调用recv()会返回相同的数据*/ 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'; /* 字符串补0 */ return (i); /* 返回读到的字符串 */ } void serve_file(int client, const char *filename) { FILE *resource = NULL; int numchars = 1; char buf[1024]; buf[0] = 'A'; buf[1] = '\0'; /* 读取并且丢弃消息头 */ while ((numchars > 0) && strcmp("\n", buf)) { numchars = get_line(client, buf, sizeof(buf)); } resource = fopen(filename, "r"); if (resource == NULL) not_found(client); /* 打开失败, 返回404 */ else { headers(client, filename); /* 发送消息头 */ cat(client, resource); /* 发送文件内容 */ } fclose(resource); } 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"); /* 如果port=0, htons动态分配一个端口 * 从httpd中得到端口号*/ if (*port == 0) { 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("listed"); return (httpd); } int main(void) { 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); /* 获得socketfd 和端口号*/ printf("httpd running on port %d\n", port); /* 监听服务器的sock,把接收到client_sock交给线程处理 */ while (1) { client_sock = accept(server_sock, (struct sockaddr*)&client_name, &client_name_len); if (client_sock == -1) { error_die("accept"); } if (pthread_create(&newthread, NULL, accept_request, client_sock) != 0) { perror("pthread_create"); } } close(server_sock); return 0; } /*-----------------------------------------------------*/ void bad_request(int client) /* 400 */ { char buf[1024]; sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n"); sprintf(buf, "%sContent-type: text/html\r\n\r\n", buf); sprintf(buf, "%s<P>Your browser sent a bad request, such as a POST without a Content-Length.\r\n", buf); send(client, buf, strlen(buf), 0); } /* 执行CGI出错 返回500 */ void cannot_execute(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 500 Internal Server Error\r\n"); sprintf(buf, "%sContent-type: text/html\r\n\r\n", buf); sprintf(buf, "%s<P>Error prohibited CGI execution.\r\n", buf); send(client, buf, strlen(buf), 0); } void headers(int client, const char *filename) /* 200恢复头*/ { char buf[1024]; sprintf(buf, "HTTP/1.0 200 OK\r\n"); sprintf(buf, "%s%s", buf, SERVER_STRING); sprintf(buf, "%sContent-Type: text/html\r\n\r\n", buf); send(client, buf, strlen(buf), 0); } void not_found(int client) /* 404 not found */ { char buf[1024]; sprintf(buf, "HTTP/1.0 404 NOT FOUND\r\n"); sprintf(buf, "%sSERVER_STRING", buf); sprintf(buf, "%sContent-Type: text/html\r\n\r\n", buf); sprintf(buf, "%s<HTML><TITLE>Not Found</TITLE>\r\n", buf); sprintf(buf, "%s<BODY><P>The server could not fulfill\r\n", buf); sprintf(buf, "%syour request because the resource specified\r\n", buf); sprintf(buf, "%sis unavailable or nonexistent.\r\n", buf); sprintf(buf, "%s</BODY></HTML>\r\n", buf); send(client, buf, strlen(buf), 0); } void unimplemented(int client) /* 501 */ { char buf[1024]; sprintf(buf, "HTTP/1.0 501 Method Not Implemented\r\n"); sprintf(buf, "%s%s", buf, SERVER_STRING); sprintf(buf, "%sContent-Type: text/html\r\n\r\n", buf); sprintf(buf, "%s<HTML><HEAD><TITLE>Method Not Implemented\r\n", buf); sprintf(buf, "%s</TITLE></HEAD>\r\n", buf); sprintf(buf, "%s<BODY><P>HTTP request method not supported.\r\n", buf); sprintf(buf, "%s</BODY></HTML>\r\n", buf); send(client, buf, strlen(buf), 0); } void error_die(const char *sc) { perror(sc); exit(1); }
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