Linux C语言实现urlencode和urldecode
本文主要记录一下urlencode和urldecode的C语言实现，作为一个简易工具使用。
1. urlencode编码的基本规则
URL编码做了如下操作：
-
字符
"a"-"z"，"A"-"Z"，"0"-"9"，"."，"-"，"*"，和"_"都不被编码，维持原值； -
空格
" "被转换为加号"+"。 -
其他每个字节都被表示成
"%XY"格式的由3个字符组成的字符串，编码为UTF-8(特别需要注意： 这里是大写形式的hexchar)。
2. urlencode编码
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
static unsigned char hexchars[] = "0123456789ABCDEF";
/**
* @brief URLEncode : encode the base64 string "str"
*
* @param str: the base64 encoded string
* @param strsz: the str length (exclude the last \0)
* @param result: the result buffer
* @param resultsz: the result buffer size(exclude the last \0)
*
* @return: >=0 represent the encoded result length
* <0 encode failure
*
* Note:
* 1) to ensure the result buffer has enough space to contain the encoded string, we'd better
* to set resultsz to 3*strsz
*
* 2) we don't check whether str has really been base64 encoded
*/
int URLEncode(const char *str, const int strsz, char *result, const int resultsz)
{
int i,j;
char ch;
if(strsz < 0 || resultsz < 0)
return -1;
for(i = 0,j = 0;i<strsz && j < resultsz;i++)
{
ch = *(str + i);
if((ch >= 'A' && ch <= 'Z') ||
(ch >= 'a' && ch <= 'z') ||
(ch >= '0' && ch <= '9') ||
ch == '.' || ch == '-' || ch == '*' || ch == '_')
result[j++] = ch;
else if(ch == ' ')
result[j++] = '+';
else{
if(j + 3 <= resultsz)
{
result[j++] = '%';
result[j++] = hexchars[(unsigned char)ch >> 4];
result[j++] = hexchars[(unsigned char)ch & 0xF];
}
else{
return -2;
}
}
}
if(i == 0)
return 0;
else if(i == strsz)
return j;
return -2;
}
// return < 0: represent failure
int main(int argc,char *argv[])
{
int fd = -1;
char buf[1024],result[1024*3];
int ret;
int i = 0;
if(argc != 2)
{
printf("please input the encoding filename\n");
return -1;
}
if((fd = open(argv[1],O_RDONLY)) == -1)
{
printf("open file %s failure\n",argv[1]);
return -2;
}
while((ret = read(fd,buf,1024)) >= 0)
{
if(ret == 0)
break;
ret = URLEncode(buf,ret,result,1024*3);
if(ret < 0)
break;
for(i = 0;i<ret;i++)
printf("%c",result[i]);
}
if(ret < 0)
{
printf("encode data failure\n");
}
close(fd);
return ret;
}3. urldecode解码
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
static unsigned char hexchars[] = "0123456789ABCDEF";
/**
* @brief URLDecode : decode the urlencoded str to base64 encoded string
*
* @param str: the urlencoded string
* @param strsz: the str length (exclude the last \0)
* @param result: the result buffer
* @param resultsz: the result buffer size(exclude the last \0)
*
* @return: >=0 represent the decoded result length
* <0 encode failure
*
* Note:
* 1) to ensure the result buffer has enough space to contain the decoded string, we'd better
* to set resultsz to strsz
*
*/
int URLDecode(const char *str, const int strsz, char *result, const int resultsz, const char **last_pos)
{
int i,j;
char ch;
char a;
*last_pos = str;
if(strsz < 0 || resultsz < 0)
return -1;
for(i = 0,j = 0;i<strsz && j<resultsz;j++)
{
ch = *(str + i);
if(ch == '+')
{
result[j] = ' ';
i += 1;
}
else if(ch == '%')
{
if(i+3 <= strsz)
{
ch = *(str + i + 1);
if(ch >= 'A' && ch <= 'F')
{
a = (ch - 'A')+10;
}
else if(ch >= '0' && ch <= '9')
{
a = ch - '0';
}
else if(ch >= 'a' && ch <= 'f')
{
a = (ch - 'a') + 10;
}
else{
return -2;
}
a <<= 4;
ch = *(str + i + 2);
if(ch >= 'A' && ch <= 'F')
{
a |= (ch - 'A') + 10;
}
else if(ch >= '0' && ch <= '9')
{
a |= (ch - '0');
}
else if(ch >= 'a' && ch <= 'f')
{
a |= (ch - 'a') + 10;
}
else{
return -2;
}
result[j] = a;
i += 3;
}
else
break;
}
else if((ch >= 'A' && ch <= 'Z') ||
(ch >= 'a' && ch <= 'z') ||
(ch >= '0' && ch <= '9') ||
ch == '.' || ch == '-' || ch == '*' || ch == '_'){
result[j] = ch;
i+=1;
}
else{
return -2;
}
}
*last_pos = str + i;
return j;
}
// return < 0: represent failure
int main(int argc,char *argv[])
{
int fd = -1;
char buf[4096],result[4096];
char *start_pos;
const char * last_pos;
int ret,sz;
int i = 0;
if(argc != 2)
{
printf("please input the encoding filename\n");
return -1;
}
if((fd = open(argv[1],O_RDONLY)) == -1)
{
printf("open file %s failure\n",argv[1]);
return -2;
}
start_pos = buf;
last_pos = NULL;
while((ret = read(fd,start_pos,buf + 4096 - start_pos)) >= 0)
{
if(ret == 0)
{
if(start_pos == buf)
break;
else
{
ret = -3;
break;
}
}
sz = URLDecode(buf,start_pos - buf + ret,result,4096,&last_pos);
if(sz < 0)
{
ret = -4;
break;
}
if(last_pos != start_pos + ret)
{
memcpy(buf,last_pos,start_pos + ret - last_pos);
start_pos = buf + (start_pos + ret - last_pos);
}
else{
start_pos = buf;
}
for(i = 0;i<sz;i++)
printf("%c",result[i]);
}
if(ret < 0)
{
printf("decode data failure\n");
}
close(fd);
return ret;
}4. 说明
值得指出的是，实际上在对URL进行urlencode的时候（例如: http://127.0.0.1:8000/file/测试/只用于测试.txt?username=小明)，不能简单的调用上面的URLEncode()函数，否则可能把:、/这样的字符也进行编码，而实际上
一个对如http://这样的部分是不需要进行修正的。
5. Go语言中的一个urlencode
package main
import (
"fmt"
"net/url"
)
func main(){
urlStr := "http://127.0.0.1:17480/userDownload/F6678E6FD4054150BA37521FBA8A67A6/tsp_test_file/批量上传走joss文件 -003-KZyxg.docx?certification=v1645f22bf4084cc7cf38092cd1b52ef6e3e"
urlObj, err := url.Parse(urlStr)
if err != nil{
fmt.Printf("part url failure: %s\n", err.Error())
return
}
fmt.Println(urlObj.String())
}编译运行：
http://127.0.0.1:17480/userDownload/F6678E6FD4054150BA37521FBA8A67A6/tsp_test_file/%E6%89%B9%E9%87%8F%E4%B8%8A%E4%BC%A0%E8%B5%B0joss%E6%96%87%E4%BB%B6%20-003-KZyxg.docx?certification=v1645f22bf4084cc7cf38092cd1b52ef6e3e
[参看]:
