ref: 606901dc5da9cb09acb5593c5cf74ce1b52ca6e2
dir: /appl/svc/webget/webget.b/
implement Webget;
# Protocol
#
# Client opens /chan/webget and writes one of
# GET 0 reqid url types cachectl authcookie\n
# or
# POST bodylength reqid url types cachectl authcookie\n
# body
#
# The possibilities for cachectl are
# max-stale=seconds
# client is willing to accept a response whose age exceeds
# its freshness lifetime (by at most specified seconds)
# without revalidation
# max-age=seconds
# client is unwilling to accept a response whose age
# (now - generation time) exceeds specified seconds
# without revalidiation
# no-cache
# unconditional reload
# Both max-stale and max-age may be specified (separated by comma),
# but no-cache must appear by itself.
#
# Authcookie is optional. If present, it goes in an Authorization: header.
#
# The appropriate transport mechanism gets the entity and
# responds with one of
# OK bodylength reqid type url\n
# body
# or
# ERROR reqid message\n
#
# (In the ERROR case, the message might be "Unauthorized: challenge\n",
# where challenge is of the form "BASIC realm=xxx (param, param, ...)\n".
# The user can be prompted for a name:password, and the request repeated
# with authcookie containing the base64 encoding of name:password).
include "sys.m";
sys: Sys;
FD: import sys;
include "draw.m";
include "string.m";
S: String;
include "bufio.m";
B: Bufio;
include "dial.m";
DI: Dial;
include "message.m";
M: Message;
Msg: import M;
include "url.m";
U: Url;
ParsedUrl: import U;
include "webget.m";
include "wgutils.m";
W: WebgetUtils;
Fid, Req: import W;
include "transport.m";
fhash := array[128] of ref Fid;
Transports: adt
{
scheme: int;
m: Transport;
};
transports: array of ref Transports;
transtab := array[] of {
(Url->HTTP, "/dis/svc/webget/http.dis"),
(Url->HTTPS, nil), # nil means: same as previous
(Url->FILE, "/dis/svc/webget/file.dis"),
(Url->FTP, "/dis/svc/webget/ftp.dis")
};
Transpreq: adt
{
index: int;
fid: ref Fid;
r: ref Req;
next: cyclic ref Transpreq;
};
Rchunk: con 30;
# Transpmax: con 5; # max number of simultaneously spawned transports
Transpmax: con 1; # max number of simultaneously spawned transports
logfile: con "/services/webget/webget.log";
DO_LOG: con 1;
stderr: ref FD;
# to start ever-present webget
init(nil: ref Draw->Context, nil: list of string)
{
dummyctl := chan of int;
spawn start(dummyctl);
<- dummyctl;
<- dummyctl;
}
# sends a 1 on ctl when ready to serve,
# 0 if there was some problem starting.
start(ctl: chan of int)
{
sys = load Sys Sys->PATH;
stderr = sys->fildes(2);
ok := 1;
ntransp := 0;
tqueuehd: ref Transpreq = nil;
tqueuetl: ref Transpreq = nil;
log : ref Sys->FD;
if(DO_LOG)
log = sys->create(logfile, Sys->OWRITE, 8r666);
io := sys->file2chan("/chan", "webget");
if(io == nil) {
sys->fprint(stderr, "webget: failed to post: %r\n");
ok = 0;
}
B = load Bufio Bufio->PATH;
if(B == nil) {
sys->fprint(stderr, "webget: failed to load Bufio: %r\n");
ok = 0;
}
S = load String String->PATH;
if(S == nil) {
sys->fprint(stderr, "webget: failed to load String: %r\n");
ok = 0;
}
M = load Message Message->PATH;
if(M == nil) {
sys->fprint(stderr, "webget: failed to load Message: %r\n");
ok = 0;
}
M->init(B, S);
U = load Url Url->PATH;
if(U == nil) {
sys->fprint(stderr, "webget: failed to load Url: %r\n");
ok = 0;
}
U->init();
W = load WebgetUtils WebgetUtils->PATH;
if(W == nil) {
sys->fprint(stderr, "webget: failed to load WebgetUtils: %r\n");
ok = 0;
}
if(!ok) {
ctl <-= 0;
return;
}
W->init(M, S, B, U, DI, log);
loadtransmod();
donec := chan of ref Fid;
ctl <-= 1;
altloop:
for(;;) alt {
(nil, data, fid, wc) := <-io.write =>
if(wc == nil) {
finish(fid);
continue altloop;
}
ndata := len data;
c := lookup(fid);
W->log(c, "\nREQUEST: " + string data);
iw := c.writer;
n := len c.reqs;
if(iw == n) {
newrs := array[n + Rchunk] of ref Req;
newrs[0:] = c.reqs[0:n];
c.reqs = newrs;
}
r := c.reqs[iw];
err := "";
if(r == nil) {
# initial part (or all) of a request
r = ref Req(iw, "", 0, "", "", "", "", "", nil, nil, nil);
c.reqs[iw] = r;
# expect at least the prefix line to be in data
prefix := "";
for(i := 0; i < ndata; i++) {
if(int data[i] == '\n') {
prefix = string data[0:i];
if(i+1 < ndata) {
r.body = array[ndata-i-1] of byte;
r.body[0:] = data[i+1:ndata];
}
break;
}
}
if(prefix == "")
err = "no prefix line";
else if(prefix == "FINISH") {
writereply(wc, len data, "");
finish(fid);
continue altloop;
}
else {
(nl, l) := sys->tokenize(prefix, "∎");
if(nl != 6 && nl != 7)
err = "wrong number of fields in " + prefix;
else {
r.method = hd l;
l = tl l;
r.bodylen = int hd(l);
l = tl l;
r.reqid = hd l;
l = tl l;
r.loc = hd l;
l = tl l;
r.types = hd l;
l = tl l;
r.cachectl = hd l;
l = tl l;
if(l != nil)
r.auth = hd l;
locurl := U->makeurl(r.loc);
if(locurl.scheme == U->MAILTO)
err = "webget shouldn't get mailto";
else if(locurl.scheme == U->NOSCHEME ||
(locurl.scheme != U->FILE && (locurl.host == "" || locurl.pstart != "/")))
err = "url not absolute: " + r.loc;
r.url = locurl;
}
}
if(err != "")
err = "webget protocol error: " + err;
}
else {
# continuation of request: more body
olen := len r.body;
newa := array[olen + ndata] of byte;
newa[0:] = r.body[0:olen];
newa[olen:] = data[0:ndata];
r.body = newa;
}
if(err == "" && len r.body == r.bodylen) {
# request complete: spawn off transport handler
c.writer++;
scheme := r.url.scheme;
found := 0;
for(i := 0; i < len transports; i++) {
if(transports[i].scheme == scheme) {
found = 1;
break;
}
}
if(found == 0)
err = "don't know how to fetch " + r.loc;
else {
if(ntransp < Transpmax) {
W->log(c, "transport " + string scheme + ": get " + r.loc);
spawn transports[i].m->connect(c, r, donec);
ntransp++;
}
else {
# too many active transports: queue this until later
tr := ref Transpreq(i, c, r, nil);
if(tqueuetl == nil)
tqueuehd = tqueuetl = tr;
else {
tqueuetl.next = tr;
tqueuetl = tr;
}
}
}
}
if(err != "") {
writereply(wc, -1, err);
W->log(c, err);
c.reqs[iw] = nil;
}
else
writereply(wc, ndata, "");
(nil, nbyte, fid, rc) := <-io.read =>
if(rc == nil) {
finish(fid);
continue altloop;
}
c := lookup(fid);
c.nbyte = nbyte;
c.rc = rc;
readans(c);
c := <- donec =>
ntransp--;
if(tqueuehd != nil) {
tr := tqueuehd;
tqueuehd = tr.next;
if(tqueuehd == nil)
tqueuetl = nil;
W->log(c, "transport: get " + tr.r.loc);
spawn transports[tr.index].m->connect(tr.fid, tr.r, donec);
ntransp++;
}
readans(c);
c = nil;
}
}
loadtransmod()
{
transports = array[len transtab] of ref Transports;
j := 0;
prevt : ref Transports = nil;
for(i := 0; i < len transtab; i++) {
(scheme, path) := transtab[i];
if(path == nil) {
if(prevt != nil)
transports[j++] = ref Transports(scheme, prevt.m);
}
else {
t := load Transport path;
if(t == nil) {
sys->fprint(stderr, "failed to load %s: %r\n", path);
continue;
}
t->init(W);
ts := ref Transports(scheme, t);
transports[j++] = ts;
prevt = ts;
}
}
}
# Answer a read request c.nbyte bytes, reply to go to c.rc.
# If c.readr is not -1, it is the index of a req with the currently
# being consumed reply.
# c.nread contains the number of bytes of this message read so far.
readans(c: ref Fid)
{
n := c.nbyte;
if(n <= 0)
return;
ir := c.readr;
if(ir == -1) {
# look for ready reply
for(i := 0; i < c.writer; i++) {
r := c.reqs[i];
if(r != nil && r.reply != nil)
break;
}
if(i == c.writer) {
return;
}
ir = i;
}
r := c.reqs[ir];
m := r.reply;
if(m == nil) {
W->log(c, "readans bad state: nil reply");
readreply(c, nil, "");
return;
}
if(m.prefixbytes == nil && m.prefixline != "")
m.prefixbytes = array of byte m.prefixline;
plen := len m.prefixbytes;
blen := m.bodylen;
ntot := plen + blen;
nread := c.nread;
if(nread == 0)
W->log(c, "\nREPLY: " + m.prefixline);
nrest := ntot - nread;
if(nrest <= 0) {
W->log(c, "readans bad state: 0 left");
readreply(c, nil, "");
return;
}
if(n > nrest)
n = nrest;
n1 := plen - nread;
if(n1 > 0) {
if(n1 > n)
n1 = n;
readreply(c, m.prefixbytes[nread:nread + n1], "");
c.nread += n1;
}
else {
bpos := nread - plen;
n2 := blen - bpos;
if(n > n2)
n = n2;
readreply(c, m.body[bpos:bpos+n], "");
c.nread += n;
}
if(c.nread >= ntot) {
c.reqs[ir] = nil;
c.readr = -1;
c.nbyte = 0;
c.nread = 0;
c.rc = nil;
# move back write pointer as far as possible
if(c.writer == ir+1) {
while(ir >= 0 && c.reqs[ir] == nil)
ir--;
c.writer = ir+1;
}
}
else
c.readr = ir;
}
# Reply to a write command.
writereply(wc: Sys->Rwrite, n: int, err: string)
{
wc <-= (n, err);
}
readreply(c: ref Fid, a: array of byte, err: string)
{
rc := c.rc;
if(rc != nil)
rc <-= (a, err);
c.nbyte = 0;
}
lookup(fid: int): ref Fid
{
h := fid%len fhash;
for(f := fhash[h]; f != nil; f = f.link)
if(f.fid == fid)
return f;
f = ref Fid(fid, fhash[h], array[Rchunk] of ref Req, 0, -1, 0, 0, nil);
fhash[h] = f;
W->log(f, "\nNEW CLIENT");
return f;
}
finish(fid: int)
{
W->log(nil, "finish");
h := fid%len fhash;
prev: ref Fid;
for(f := fhash[h]; f != nil; f = f.link) {
if(f.fid == fid) {
f.rc = nil;
W->log(f, "client finished");
if(prev == nil)
fhash[h] = f.link;
else
prev.link = f.link;
return;
}
}
}