这段代码中这两行是什么意思？

Question

[:http_payload.index("\r\n\r\n")+2]中的“:”和“+2”是什么意思？ .split("/")[1]中的"("/")"和"[1]"是什么意思?

def get_http_headers(http_payload):
    try:
        # split the headers off if it is HTTP traffic
        headers_raw = http_payload[:http_payload.index("\r\n\r\n")+2]

        # break out the headers
        headers = dict(re.findall(r"(?P<name>.*?): (? P<value>.*?)\r\n", headers_raw))

    except:
        return None

    return headers

def extract_image(headers, http_payload):
    image = None
    image_type = None

    try:
        if "image" in headers["Content-Type"]:
            # grab the image type and image body
            image_type = headers["Content-Type"].split("/")[1]

            image = http_payload[http_payload.index("\r\n\r\n")+4:]



            except:
                pass
    except:
        return None, None

    return image, image_type

Answer 1

http_payload[:http_payload.index("\r\n\r\n")+2] slices 字符串 http_payload 这样只有字符串的头部到第一次出现的“\r\n\r\n”和第一个“[=25” =]”仍然存在。字符串的 .index() 方法将 return 字符串中模式首次出现的索引。

示例：

test = "abcdefg"
# slicing:
print(test[1:3])  # will output 'bc'

# index:
print(test.index('bc'))  # will output 1 (index of start of substring 'bc')

# either start or end (or both) of the slice can be left out, so the following is equivalent:
print(test[:2] == test[0:2])  # will output True

.split("/")[1] 将在“/”字符和 return 一个列表中拆分一个字符串，从中可以访问索引为 1 的项目。例如看下面的代码：

test = "/this/is/a/path"
print(test.split("/"))  # will output ["this", "is", "a", "path"]
print(test.split("/")[0])  # will output "is" since element of index 1 of the resulting list is accessed.

这段代码中这两行是什么意思？

What do these two lines mean in this code?

python

penetration-testing

python-2.7

python-3.x