Digests » 209
Today I landed yet another small change to libcurl internals that further reduces the number of small mallocs we do. This time the generic linked list functions got converted to become malloc-less (the way linked list functions should behave, really).
Spatial indices are a family of algorithms that arrange geometric data for efficient search. For example, doing queries like “return all buildings in this area”, “find 1000 closest gas stations to this point”, and returning results within milliseconds even when searching millions of objects.
I wrote the initial version of SSH (Secure Shell) in Spring 1995. It was a time when telnet and FTP were widely used. Anyway, I designed SSH to replace both telnet (port 23) and ftp (port 21). Port 22 was free. It was conveniently between the ports for telnet and ftp. I figured having that port number might be one of those small things that would give some aura of credibility. But how could I get that port number? I had never allocated one, but I knew somebody who had allocated a port.
A less common approach that both makes BitTorrent harder to grasp, but worthy of study, is Cohen's use of idempotence. A process is idempotent when applying it more than once causes no further changes.
After doing hundreds of security code reviews for companies ranging from small start-ups to large banks and telcos, and after reading hundreds of stack overflow posts on security, I have composed a list of the top 10 crypto problems I have seen.