shithub: neoventi

ref: 0a0dc432673d0c5f0902b0d053e08c8fe41a0eea
dir: /server.c/

#include <u.h>
#include <libc.h>
#include <bio.h>
#include "neoventi.h"

// Handles an error on `conn` handling client request `tbuf`
// Only the tag must be preserved in the buffer
static void
vterr(VtConn conn, char *tbuf, char *msg, ...)
{
	u16int len;
	va_list args;
	va_start(args, msg);
	msg = vsmprint(msg, args);
	werrstr(msg);
	free(msg);
	va_end(args);
	if(tbuf != nil){
		len = snprint(tbuf+6, 0x10000, "neoventi: %r");
		tbuf[2] = VtRerror;
		tbuf[4] = len >> 8;
		tbuf[5] = len & 0xFF;
		len += 4;
		tbuf[0] = len >> 8;
		tbuf[1] = len & 0xFF;
		if(write(conn.fd, tbuf, len+2) != len+2)
			fprint(2, "failed to report error: %r");
	}
	longjmp(conn.bounce, 1);
}

static void
vthangup(VtConn conn)
{
	longjmp(conn.bounce, 2);
}

// Convenience function: reads a venti packet from conn into buf
static void
vtrecv(VtConn conn, char *buf)
{
	u16int len;
	switch(read(conn.fd, buf, 2)){
	case 0:
		vthangup(conn);
	case 1:
		vterr(conn, nil, "received a single byte for message size");
	case 2:
		len = (buf[0] << 8 | buf[1]);
		if(read(conn.fd, buf + 2, len) != len)
			vterr(conn, nil, "failed to read message: %r");
	}
}

static void
vtversion(VtConn conn)
{
	char c;
	// Response is one line of unknown size; discard bytes until EOL
	if(fprint(conn.fd, "venti-02-neoventi\n") == 18)
		while(read(conn.fd, &c, 1) == 1)
			if(c == '\n')
				return;
	// If the handshake fails, make it clear there's a problem and give up
	fprint(conn.fd, "FUCK OFF\n");
	vterr(conn, nil, "handshake failed");
}

static void
vtread(VtConn conn, char *buf)
{
	u8int *score;
	VtArena arena;
	u64int addr;
	u16int size;
	u8int blocks;
	score = (u8int*)buf + 4;
	if(!vtreadlookup(score, &arena, &addr, &size, &blocks))
		sysfatal("todo graceful read errors");
	// Response: VtRread, msg tag, data
	buf[0] = (size+2)>>8;
	buf[1] = (size+2) & 0xFF;
	buf[2] = VtRread;
	readclump((uchar*)buf+4, arena, addr, blocks);
	if(write(conn.fd, buf, size + 4) != size+4)
		vterr(conn, buf, "failed to write data");
}

static int
vtconnhandle(VtConn conn, char *buf)
{
	switch(buf[2]){
	case VtTread:
		vtread(conn, buf);
		return 1;
	case VtTgoodbye:
		vthangup(conn);
	case VtTsync:
		vterr(conn, buf, "TODO: sync not supported yet");
	default:
		vterr(conn, buf, "TODO safely hang up vtconns");
	}
	return 0;
}

static void
vthello(VtConn conn, char *buf)
{
	vtversion(conn);
	vtrecv(conn, buf);
	if(buf[2] != VtThello)
		vterr(conn, buf, "received message before hello: %d", buf[2]);
	if(buf[4] != 0 || buf[5] != 2 || buf[6] != '0' || buf[7] != '2')
		vterr(conn, buf, "unsupported protocol version requested in Thello: %d %d %d %d", buf[4], buf[5], buf[6], buf[7]);
	buf[2] = VtRhello;
	buf[6] = 'n';
	buf[7] = 'o';
	buf[1] = 8;
	if(write(conn.fd, buf, 10) != 10)
		vterr(conn, buf, "failed to rhello: %r");
}

static void
handle(int ctl, char *dir)
{
	char buf[MaxPacketSize];
	VtConn conn;
	switch(setjmp(conn.bounce)){
	case 0:
		break;
	case 1:
		fprint(2, "abandoning client: %r\n");
	case 2:
		close(conn.fd);
		return;
	default:
		fprint(2, "internal error: unexpected bounce code\n");
		break;
	}
	conn.fd = accept(ctl, dir);
	if(conn.fd < 0)
		vterr(conn, nil, "failed to accept connection: %r");
	vthello(conn, buf);
	while(1){
		vtrecv(conn, buf);
		if(!vtconnhandle(conn, buf)){
			close(conn.fd);
			return;
		}
	}
}

void
serve(char *addr)
{
	char adir[NETPATHLEN], dir[NETPATHLEN];
	int fd, ctl;
	fd = announce(addr, adir);
	if(fd < 0)
		sysfatal("%r");
	procsetname("neoventi/server");
	for(ctl = listen(adir, dir); ctl >= 0; ctl = listen(adir, dir)){
		// TODO: handle the client in a worker, allow multiple clients
		handle(ctl, dir);
		close(ctl);
	}
	fprint(2, "server has died\n");
}