字符串处理函数¶

NASL可以像处理数字一样处理字符串。所以你可以安心的使用==, < , >操作符。

例子:

a = "version 1.2.3";
b = "version 1.4.1";

if(a < b)
{
        #
        # Will be executed, since version 1.2.3 is lower
        # than version 1.4.1
}

c = "version 1.2.3";

if(a==c)
{
        # Will also be evaluated
}

也可以获取字符串的某个字符，类似C:

a = "test";
b = a[1];  # b equals to "e"

也可以加减两个字符串:

a = "version 1.2.3";
b = a - "version ";   # b equals "1.2.3"

a = "this is a test";
b = " is a ";
c = a - b;            # c equals to "this test"

a = "test";
a = a+a;              # a equals to "testtest"

除此之外，还有><操作符。NASL定义了很多函数去构造和修改字符串。

处理正则表达式的ereg()函数¶

模式匹配通过ereg()函数完成。语法如下:

result = ereg(pattern:<pattern>, string:<string>)

正则匹配是egrep风格。细节请参考 egrep 手册.。

例子:

if(ereg(pattern:".*", string:"test"))
{
  display("Always executed\n");
}

mystring = recv(socket:soc, length:1024);
if(ereg(pattern: "SSH-.*-1\..*", string : mystring))
{
        display("SSH 1.x is running on this host");
}

egrep()函数¶

egrep()函数返回多行文本中匹配的第一行。当用于单行文本时，作用类似ereg()函数。如果没有匹配项，则返回FALSE。语法如下:

str = egrep(pattern : <pattern>, string: <string>)

例子:

soc = open_soc_tcp(80);
str = string("HEAD / HTTP/1.0\r\n\r\n");
send(socket:soc, data:str);

r = recv(socket:soc, length:1024);
server = egrep(pattern:"^Server.*", string : r);

if(server)display(server);

crap()函数¶

crap()函数在测试缓冲区溢出很方便。它的语法如下：

crap(<length>)
crap(length:<length>, data:<data>)

例子:

a = crap(5);                            # a = "XXXXX";
b = crap(4096);                         # b = "XXXX...XXXX" (4096 X's)
c = crap(length:12, data:"hello");      # c = "hellohellohe" (length: 12);

string()函数¶

该函数用于从字符或者字符串中产生一个新的字符串。语法为：

string(<string1>, [<string2>, ..., <stringN>])

该函数会转义特殊字符，例如n 或者 t。

例子：

name = "Renaud";

a = string("Hello, I am ", name, "\n");         # a equals to "Hello, I am Renaud"
                                                # (with a new line at the end)
b = string(1, " and ", 2, " makes ", 1+2);      # b equals to "1 and 2 makes 3"
c = string("MKD ", crap(4096), "\r\n");         # c equals to "MKD XXXXX.....XXXX"
                                                # (4096 X's) followed by a carriage
                                                # return and a new line

strlen()函数¶

返回字符串的长度。

例子:

a = strlen("abcd"); # a is equal to 4

raw_string()函数¶

整数转换成字符串。

例子：

a = raw_string(80, 81, 82); # a equals to 'PQR'

strtoint()函数¶

该函数用于将一个NASL整数转换成二进制整数。语法为：

value = strtoint(number:<nasl_integer>, size:<number_of_bytes>);

这个函数适合同raw_string()配合使用。size参数是NASL整形的字节数，必填参数，可以是1,2,4。

tolower()函数¶

该函数用于将字符串转换成小写。语法是:

tolower(<string>)

返回值是参数<string>的小写字符串。

例子:

a = "Hello";
b = tolower(a); # b equals to "hello"

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