/****************************************************************************************
* CANopenSocket CANopenCGI.c hacking
* 说明：
* 分析一下CANopenSocket中的CANopenCGI部分是怎么工作的。
*
* 2017-3-23 深圳 南山平山村 曾剑锋
***************************************************************************************/
/*
* Client socket command interface (Apache CGI) for CANopenSocket.
*
* @file CANopenCGI.c
* @author Janez Paternoster
* @copyright 2016 Janez Paternoster
*
* This file is part of CANopenNode, an opensource CANopen Stack.
* Project home page is <https://github.com/CANopenNode/CANopenNode>.
* For more information on CANopen see <http://www.can-cia.org/>.
*
* CANopenNode is free and open source software: you can redistribute
* it and/or modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <string.h>
#include <strings.h>
#include <fnmatch.h>
#include <sys/un.h>
#include <sys/socket.h>
#ifndef BUF_SIZE
#define BUF_SIZE 100000
#endif
/* Helper functions */
static void errExitErrno(char* msg) {
printf("%s: %s\n", msg, strerror(errno));
exit(EXIT_FAILURE);
}
static void errExit(char* msg) {
printf("%s\n", msg);
exit(EXIT_FAILURE);
}
/**
* 字符串拷贝并转换成大写
*/
static void strcpyToUpper(char *dest, const char *src) {
char in;
do {
in = *(src++);
*(dest++) = toupper(in);
} while(in != 0);
}
/**
* 字符串转换成大写
*/
static void strToUpper(char *str) {
char c;
do {
c = *(str);
*(str++) = toupper(c);
} while(c != 0);
}
/**
* 字符串转换成小写
*/
static void strToLower(char *str) {
char c;
do {
c = *(str);
*(str++) = tolower(c);
} while(c != 0);
}
/* Decode hex string 'str' of length 'len' and return numerical value.
* In case of error in string, set 'err' to 1. */
/**
* 将十六进制的字符串转成数字
*/
static unsigned int hex2dec(const char *str, int len, int *err){
unsigned int val = 0;
int i;
for(i=0; i<len; i++) {
char c = str[i];
if(c >= '0' && c <= '9') {
c = c - '0';
} else if (c >= 'A' && c <= 'F') {
c = c - ('A' - 10);
}
else {
*err = 1;
return 0;
}
val = val << 4 | c;
}
return val;
}
static void sendCommand(int fd, int sequence, char* command);
static void printUsage(void) {
printf(
"Usage: canopen.cgi?wnniiiissdd=xxxx[&rnniiiissdd=]\n"
" - w - One digit - 'W'rite or 'R'ead.\n"
" - nn - Two hex digits of node ID.\n"
" - iiii - Four hex digits of Object Dictionary Index.\n"
" - ss - Two hex digits of Object Dictionary Subindex.\n"
" - dd - One to three digits of data type.\n"
" - xxxx - Value to be written.\n"
"\n"
"Datatypes:\n"
" - b - Boolean.\n"
" - u8, u16, u32, u64 - Unsigned integers.\n"
" - i8, i16, i32, i64 - Signed integers.\n"
" - r32, r64 - Real numbers.\n"
" - t, td - Time of day, time difference.\n"
" - vs - Visible string (between double quotes).\n"
" - os, us, d - Octet string, unicode string, domain."
);
}
/******************************************************************************/
int main (int argc, char *argv[], char *env[]) {
char socketPath[260] = {0}; /* Name of the local domain socket. */
FILE *fp;
int fdSocket;
struct sockaddr_un addr;
char *queryString;
int queryStringAllocated = 0;
/* whitelist and blacklist are arrays of null separated strings, which
* contains patterns for comparision with commands from query string. */
char *whitelist;
char *blacklist;
int whitelistLen;
int blacklistLen;
/* Print mime */
/**
* 输出http协议的头
*/
printf("Content-type:text/plain\n\n");
/* Get program options from configuration file */
/**
* 处理配置文件
*/
fp = fopen("canopen.conf", "r");
if(fp == NULL) {
errExitErrno("Can't open configuration file");
}
else {
const char spaceDelim[] = " \t\n\r\f\v";
char buf[1000];
int wlSize = 1000; /* byte length */
int blSize = 1000;
int wlDataSize = 0;
int blDataSize = 0;
whitelist = (char *) malloc(wlSize);
blacklist = (char *) malloc(blSize);;
// 最开始wlDataSize长度都是0，随着allow检测到的配置越来越多，长度会越来越长
whitelistLen = 0; /* number of tokens in list */
blacklistLen = 0;
if(whitelist == NULL || blacklist == NULL) {
errExitErrno("Whitelist or Blacklist can't be allocated.");
}
// 每次读取一行
while(fgets(buf, sizeof(buf), fp) != NULL) {
char *token;
token = strtok(buf, spaceDelim);
if(token == NULL) {
}
/**
* 获取socketPath配置
*/
else if(strcasecmp(token, "socketPath") == 0) {
if(strlen(socketPath) != 0) {
errExit("Duplicate 'socketPath' in canopen.conf.");
}
strncpy(socketPath, strtok(NULL, spaceDelim), sizeof(socketPath));
socketPath[sizeof(socketPath)-1] = 0;
}
else if(strcasecmp(token, "allow") == 0) {
// 保存上一次的wlDataSize长度，随着allow检测到的配置越来越多，长度会越来越长
int prevDataSize = wlDataSize;
// 获取value
token = strtok(NULL, spaceDelim);
// 计算value长度并+1，最后一个字节用于存放字符串结束符，这个长度叠加到wlDataSize中
wlDataSize += (strlen(token) + 1);
// 长度大于预设字符串长度，双倍扩容并重新分配，不过从这里开看最大也就是双倍的扩容长度
while(wlDataSize > wlSize) {
wlSize *= 2;
whitelist = (char *) realloc(whitelist, wlSize);
if(whitelist == NULL) {
errExitErrno("Whitelist can't be allocated.");
}
}
// 拷贝当前的匹配数据到whitelist中
strcpyToUpper(&whitelist[prevDataSize], token);
whitelistLen ++;
}
/**
* 类是于白名单
*/
else if(strcasecmp(token, "deny") == 0) {
int prevDataSize = blDataSize;
token = strtok(NULL, spaceDelim);
blDataSize += (strlen(token) + 1);
while(blDataSize > blSize) {
blSize *= 2;
blacklist = (char *) realloc(blacklist, blSize);
if(blacklist == NULL) {
errExitErrno("Blacklist can't be allocated.");
}
}
strcpyToUpper(&blacklist[prevDataSize], token);
blacklistLen ++;
}
}
}
fclose(fp);
/* Create and connect client socket */
/**
* 创建本地socket
*/
fdSocket = socket(AF_UNIX, SOCK_STREAM, 0);
if(fdSocket == -1) {
errExitErrno("Socket creation failed");
}
/**
* 配置本地socket
*/
memset(&addr, 0, sizeof(struct sockaddr_un));
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, socketPath, sizeof(addr.sun_path) - 1);
/**
* 连接本地socket
*/
if(connect(fdSocket, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
errExitErrno("Socket connection failed");
}
/* get query string */
/**
* 获取网络请求数据
*/
queryString = getenv("QUERY_STRING"); /* HTTP GET method. */
if(queryString != NULL && strlen(queryString) == 0) {
queryString = malloc(BUF_SIZE);
if(queryString == NULL) {
errExitErrno("queryString can't be allocated.");
}
queryStringAllocated = 1;
fgets(queryString, BUF_SIZE, stdin); /* HTTP POST method. */
}
if(queryString == NULL && argc >= 2) {
queryString = argv[1]; /* If no query string, try first argument. */
}
/* get commands from query string */
/**
* 解析网络请求数据
*/
if(queryString != NULL && strlen(queryString) > 0) {
char *command;
int sequence = 1;
/* put whole query string to upper case */
/**
* 将请求数据转为大写的格式
*/
strToUpper(queryString);
command = strtok(queryString, "&");
while(command != NULL) {
int i;
int offset;
int passed = 0;
/* Test whitelist and blacklist */
/**
* 一个一个偏移着找
*/
offset = 0;
for(i=0; i<whitelistLen; i++) {
char *patern = &whitelist[offset];
if(fnmatch(patern, command, 0) == 0) {
passed = 1;
break;
}
offset += strlen(patern) + 1;
}
/**
* 检查黑名单
*/
if(passed == 1) {
offset = 0;
for(i=0; i<blacklistLen; i++) {
char *patern = &blacklist[offset];
if(fnmatch(patern, command, 0) == 0) {
passed = -1; /* not allowed */
break;
}
offset += strlen(patern) + 1;
}
}
/* Send command or error message */
if(strlen(command) < 9) {
printf("? %s [%d] ERROR: 101 - Syntax error in command.\n", command, sequence);
}
else if(passed == 1) {
sendCommand(fdSocket, sequence, command);
}
else {
printf("%c %c%c%c%c%c%c%c%c [%d] ERROR: 100 - Access restriction, command %s.\n",
command[0], command[1], command[2], command[3], command[4],
command[5], command[6], command[7], command[8],
sequence, (passed==0)?"not on whitelist":" on blacklist");
}
command = strtok(NULL, "&");
sequence ++;
}
}
else {
printUsage();
}
close(fdSocket);
free(whitelist); // 释放白名单
free(blacklist); // 释放黑名单
if(queryStringAllocated == 1) {
free(queryString);
}
exit(EXIT_SUCCESS);
}
static void sendCommand(int fd, int sequence, char* command) {
int i, err;
char comm;
unsigned int nodeId, idx, sidx;
char dataType[4];
char *value = "";
char buf[BUF_SIZE];
/* Parse command. It is at least 8 characters long. */
/**
* 解析命令
*/
err = 0;
comm = command[0];
if(comm != 'R' && comm != 'W') {
err = 1;
}
nodeId = hex2dec(&command[1], 2, &err);
if(nodeId < 1 || nodeId > 127) {
err = 1;
}
idx = hex2dec(&command[3], 4, &err);
sidx = hex2dec(&command[7], 2, &err);
for(i=0; i<sizeof(dataType); i++) {
char c = command[9+i];
if(c == '=' || c == 0) {
dataType[i] = 0;
if(c == '=') {
value = &command[10+i];
}
break;
}
dataType[i] = c;
}
if(i > 3) {
err = 1;
dataType[0] = 0;
}
if(strlen(value) > (sizeof(buf) - 50)) {
err = 1;
}
/* Write command according to CiA309-3. */
/**
* 命令转换，转换成canopend能接收的命令格式
*/
if(err == 0) {
size_t wlen, rlen;
strToLower(dataType);
wlen = sprintf(buf, "[%d] 0x%02X %c 0x%04X 0x%02X %s %s\n",
sequence, nodeId, tolower(comm), idx, sidx, dataType, value);
if (write(fd, buf, wlen) != wlen) {
errExit("Socket write failed");
}
rlen = read(fd, buf, sizeof(buf));
if(rlen == -1) {
errExit("Socket read failed");
}
printf("%c %02X%04X%02X %s",
comm, nodeId, idx, sidx, buf);
}
else {
printf("? %s [%d] ERROR: 101 - Syntax error in command.\n",
command, sequence);
}
}
