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Couple enhancements as I integrate this to MQTT-C.
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- add a shutdown function to close and teardown stuff
- tweak/enhance some error messages
- better reactive handling to certain message types
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@voutilad
voutilad committed Dec 8, 2023
1 parent c2401b1 commit 8a340f6
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Showing 2 changed files with 71 additions and 30 deletions.
89 changes: 63 additions & 26 deletions dws.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -54,9 +54,9 @@ static const char server_handshake[] = "HTTP/1.1 101 Switching Protocols";

static const char HANDSHAKE_TEMPLATE[] =
"GET %s HTTP/1.1\r\n"
"Host: %s\r\n"
"Host: %s:%d\r\n"
"Upgrade: websocket\r\n"
"Connection: upgrade\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Key: %s\r\n"
"Sec-WebSocket-Protocol: %s\r\n"
"Sec-WebSocket-Version: 13\r\n\r\n";
Expand All @@ -68,6 +68,7 @@ static const char B64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0
static ssize_t ws_read(struct websocket *, void *, size_t);
static ssize_t ws_read_all(struct websocket *, void *, size_t);
static ssize_t ws_read_txt(struct websocket *, void *, size_t);
static void ws_shutdown(struct websocket *);


static void __attribute__((noreturn))
Expand Down Expand Up @@ -200,8 +201,11 @@ ws_read(struct websocket *ws, void *buf, size_t buflen)
return DWS_WANT_POLL;
break;
}
else if (sz == -1)
else if (sz == -1) {
// TODO: check some common errno's and return something better.
printf("%s: err %s\n", __func__, strerror(errno));
return -1;
}
}

_buf += sz;
Expand All @@ -225,7 +229,9 @@ ws_read_all(struct websocket *ws, void *buf, size_t buflen)
char *_buf;

if (buflen > INT_MAX)
crap(1, "ws_read: buflen too large");
crap(1, "%s: buflen too large", __func__);
if (buflen == 0)
crap(1, "%s: buflen == 0?!", __func__);

_buf = (char*) buf;
_buflen = (ssize_t) buflen;
Expand Down Expand Up @@ -489,8 +495,8 @@ dumb_frame(uint8_t *frame, const uint8_t *data, size_t len)
* fatal error otherwise.
*/
int
dumb_handshake(struct websocket *ws, const char *host, const char *path,
const char *proto)
dumb_handshake(struct websocket *ws, const char *host, int port,
const char *path, const char *proto)
{
int len, ret = 0;
char key[25], buf[HANDSHAKE_BUF_SIZE];
Expand All @@ -500,14 +506,14 @@ dumb_handshake(struct websocket *ws, const char *host, const char *path,
dumb_key(key);

len = snprintf(buf, sizeof(buf), HANDSHAKE_TEMPLATE,
path, host, key, proto);
path, host, port, key, proto);
if (len < 1)
return -1;

// Send our upgrade request.
sz = ws_write(ws, buf, len);
if (sz != len)
crap(1, "dumb_handshake");
crap(1, "dumb_handshake: ws_write");

memset(buf, 0, sizeof(buf));
len = ws_read_txt(ws, buf, sizeof(buf));
Expand All @@ -517,8 +523,10 @@ dumb_handshake(struct websocket *ws, const char *host, const char *path,
/* XXX: If we gave a crap, we'd validate the returned key per the
* requirements of RFC6455 sec. 4.1, but we don't.
*/
if (memcmp(server_handshake, buf, sizeof(server_handshake) - 1))
ret = -2;
if (memcmp(server_handshake, buf, sizeof(server_handshake) - 1)) {
printf("%s: bad handshake:\n%s\n", __func__, buf);
ret = -2;
}

return ret;
}
Expand All @@ -541,7 +549,7 @@ dumb_handshake(struct websocket *ws, const char *host, const char *path,
* -3 if it failed to connect(2).
*/
int
dumb_connect(struct websocket *ws, char *host, char *port)
dumb_connect(struct websocket *ws, const char *host, const char *port)
{
int s;
struct addrinfo hints, *res;
Expand Down Expand Up @@ -576,6 +584,7 @@ dumb_connect(struct websocket *ws, char *host, char *port)
if (fcntl(s, F_SETFL, O_NONBLOCK) == -1)
return -3;

// TODO: store host, port etc. on the Websocket object
ws->s = s;
ws->ctx = NULL;
memset(&ws->addr, 0, sizeof(ws->addr));
Expand All @@ -598,7 +607,8 @@ dumb_connect(struct websocket *ws, char *host, char *port)
* insecure: set to non-zero to disable cert verification
*/
int
dumb_connect_tls(struct websocket *ws, char *host, char *port, int insecure)
dumb_connect_tls(struct websocket *ws, const char *host, const char *port,
int insecure)
{
int ret;
ret = dumb_connect(ws, host, port);
Expand Down Expand Up @@ -678,7 +688,7 @@ dumb_send(struct websocket *ws, const void *payload, size_t len)
*
* Returns:
* the number of bytes received in the payload (not including frame headers),
* -1 on failure to read(2) data,
* -1 on failure to read(2) data, DWS_WANT_POLL or DWS_SHUTDOWN.
*/
ssize_t
dumb_recv(struct websocket *ws, void *buf, size_t buflen)
Expand All @@ -695,10 +705,30 @@ dumb_recv(struct websocket *ws, void *buf, size_t buflen)
// Now to validate the frame...
if (!(frame[0] & 0x80)) {
// XXX: We don't currently fragmentation
crap(1, "dumb_recv: fragmentation unsupported");
crap(1, "%s: fragmentation unsupported", __func__);
}

switch (frame[0] & 0x0F) {
case TEXT:
crap(1, "%s: unsupported TEXT frame!", __func__);
// unreached
case CLOSE:
// Unexpected, but possible if the server hates us apparently!
ws_shutdown(ws);
return DWS_SHUTDOWN;
case PING:
// Also unexpected! WTF.
return DWS_WANT_PONG;
case PONG:
// This...should not happen, but process the message.
// Fallthrough
case BINARY:
// Fallthrough
default:
// Ok. We have something we *think* we can work with!
payload_len = frame[1] & 0x7F;
}

payload_len = frame[1] & 0x7F;
if (payload_len == 126) {
// Need the next two bytes to get the actual payload size, which
// arrives in network byte order.
Expand All @@ -710,10 +740,11 @@ dumb_recv(struct websocket *ws, void *buf, size_t buflen)
} else if (payload_len > 126)
crap(1, "%s: unsupported payload size", __func__);

// We can now read the the payload.
// We can now read the the payload, if there is one.
payload_len = MIN(payload_len, buflen);
if (payload_len == 0)
return payload_len;
return 0;

n = ws_read_all(ws, buf, (size_t) payload_len);
if (n < payload_len)
return -1;
Expand Down Expand Up @@ -783,6 +814,20 @@ dumb_ping(struct websocket *ws)
#define HOW SHUT_RDWR
#endif

static void
ws_shutdown(struct websocket *ws)
{
// Now close/shutdown our socket.
if (ws->ctx)
tls_close(ws->ctx);

// Don't care if shutdown fails. Other side may have closed some things first.
shutdown(ws->s, HOW);

ws->ctx = NULL; // XXX does this leak anything?
ws->s = -1;
}

/*
* dumb_close
*
Expand Down Expand Up @@ -842,15 +887,7 @@ dumb_close(struct websocket *ws)
return -4;
}

// Now close/shutdown our socket.
if (ws->ctx)
tls_close(ws->ctx);

// Don't care if shutdown fails. Other side may have closed some things first.
shutdown(ws->s, HOW);

ws->ctx = NULL; // XXX does this leak anything?
ws->s = -1;
ws_shutdown(ws);

return 0;
}
12 changes: 8 additions & 4 deletions dws.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
* Well Text frames require utf-8 support, which is hella gross.
*/
enum ws_opcode {
TEXT = 0x1,
BINARY = 0x2,
CLOSE = 0x8,
PING = 0x9,
Expand All @@ -52,11 +53,14 @@ struct websocket {
// TODO: add basic auth details?
};

#define DWS_WANT_POLL -2
#define DWS_WANT_POLL -2
#define DWS_WANT_PONG -3
#define DWS_SHUTDOWN -4

int dumb_connect(struct websocket *ws, char*, char*);
int dumb_connect_tls(struct websocket *ws, char*, char*, int);
int dumb_handshake(struct websocket *s, const char*, const char*, const char*);
int dumb_connect(struct websocket *ws, const char*, const char*);
int dumb_connect_tls(struct websocket *ws, const char*, const char*, int);
int dumb_handshake(struct websocket *s, const char*, int, const char*,
const char*);

ssize_t dumb_send(struct websocket *ws, const void*, size_t);
ssize_t dumb_recv(struct websocket *ws, void*, size_t);
Expand Down

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