UDPREAD(3)

💖 UDPREAD(3) 💖

okay bestie, welcome to UDPREAD(3) from the Library Functions Manual — the section 3 library-call zone. this page is about udpread and udpwrite, aka reading and writing UDP packets, and it’s honestly a little iconic. 🦋

✨ NAME ✨

• udpread, udpwrite — read and write UDP packets, no cap. 💅

🌸 SYNOPSIS 🌸

here’s the exact setup, bestie — copy it like your life depends on it:

#include <u.h>

#include <libc.h>

#include <ip.h>

typedef struct Udphdr Udphdr;
struct Udphdr
{
    uchar   raddr[IPaddrlen];/* remote address and port */
    uchar   laddr[IPaddrlen];/* local address and port */
    uchar   rport[2];
    uchar   lport[2];
};

long        udpread(int fd, Udphdr *hdr, void *data, long n)

long udpwrite(int fd, Udphdr *hdr, void *data, long n)

🦋 DESCRIPTION 🦋

okay so udpread and udpwrite read and write UDP packets from the UDP network connection established on file descriptor fd. that’s lowkey the whole main-character situation. ✨

• udpread reads at most n bytes of packet body into data, stores the header in hdr, and returns the number of bytes stored in data. she’s giving “read the packet, keep the header, count the bytes.” 🎀
• udpwrite writes the n bytes stored in data in a UDP packet with header hdr. that’s it, that’s the write. 💌

🚨 important vibe check: the Udphdr frames the addresses as local and remote instead of source and destination. so the hdr filled in for a packet read by udpread can be used unchanged in udpwrite to send a response back to the sender of the original packet. like, the header you got from reading? you can literally reuse it to clap back at the sender. periodt. 💅

🌈 SOURCE 🌈

/src/lib9/udp.c

🎀 SEE ALSO 🎀

• ip(3) — go read that too, bestie. 🫶

mwah 💋 — this has been UDPREAD(3), Library Functions Manual edition, source file /src/lib9/udp.c; no date listed, and that’s the cute little sign-off. 💖