Add memmem() implementation

0xA50C1A1 commented 7 months ago

Please sign (check) the below before submitting the Pull Request:

[x] I have signed the ntop Contributor License Agreement at https://github.com/ntop/legal/blob/main/individual-contributor-licence-agreement.md
[x] I have read the contributing guide lines at https://github.com/ntop/nDPI/blob/dev/CONTRIBUTING.md
[x] I have updated the documentation (in doc/) to reflect the changes made (if applicable)

Describe changes:

Although this implementation has O(n*m) complexity in the worst case, in the typical nDPI scenario (searching for a string or byte sequence in a payload with a typical maximum length of 1460/1472 bytes) it performed much better than the other implementations.

Here is the result of a small benchmark searching for the string eso.live in an 852 byte long array (packet from The Elder Scrolls Online pcap sample):

0xA50C1A1 commented 7 months ago

Uh, I don't think it's related to my PR:

protocols/http.c:68:80: error: unused parameter ‘ndpi_struct’ [-Werror=unused-parameter]
   68 | static void ndpi_set_binary_data_transfer(struct ndpi_detection_module_struct *ndpi_struct,
      |