Printing out IP addresses in C isn’t too hard- you can use inet_ntoa for easy results. inet_ntoa uses a static buffer however, so trying to use it more than once in the same printf statement causes problems. You can split each inet_ntoa call into a new printf, or you can write some macros to do the job<\/p>\n
[code lang=”cpp”]<\/p>\n
#define IPFMT “%i.%i.%i.%i”
\n#define IP(a) ((ntohl(a.s_addr) >> 24) & 0xff),\\
\n((ntohl(a.s_addr) >> 16) & 0xff),\\
\n((ntohl(a.s_addr) >> 8) & 0xff),\\
\n(ntohl(a.s_addr) & 0xff) [\/code]<\/p>\n
You might use this like:
\n[code lang=”cpp”]
\nprintf(IPFMT ” -> ” IPFMT “\\n”,\tIP(ipptr->ip_src), IP(ipptr->ip_dst));
\n[\/code]<\/p>\n
The preprocessor turns this into something like the following:<\/p>\n
[code lang=”cpp”]<\/p>\n
printf(“%i.%i.%i.%i” ” -> ” “%i.%i.%i.%i” “\\n”,
\n((ntohl(ipptr->ip_src.s_addr) >> 24) & 0xff),
\n((ntohl(ipptr->ip_src.s_addr) >> 16) & 0xff),
\n((ntohl(ipptr->ip_src.s_addr) >> 8) & 0xff),
\n(ntohl(ipptr->ip_src.s_addr) & 0xff),
\n((ntohl(ipptr->ip_dst.s_addr) >> 24) & 0xff),
\n((ntohl(ipptr->ip_dst.s_addr) >> 16) & 0xff),
\n((ntohl(ipptr->ip_dst.s_addr) >> 8) & 0xff),
\n(ntohl(ipptr->ip_dst.s_addr) & 0xff));
\n[\/code]<\/p>\n
Looks a bit messy, and the IPFMT macro might throw a few people off at first, but anyone familiar with PRIu64 and the like should manage it ok. I’ll probably through this into libtrace at some point, as a helper function.<\/p>\n","protected":false},"excerpt":{"rendered":"
Some macros to print IP addresses in C<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[7],"tags":[],"_links":{"self":[{"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/posts\/2"}],"collection":[{"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/comments?post=2"}],"version-history":[{"count":0,"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/posts\/2\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/media?parent=2"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/categories?post=2"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.meta.net.nz\/~daniel\/blog\/wp-json\/wp\/v2\/tags?post=2"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}