shithub: tlssrv.sni

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First prototype supporting multiple SSL certificates selected via SNI.

--- a/README

+++ b/README

@@ -1,73 +1,119 @@

-This is WIP attempting to extend tlssrv to support the Server Name

-Identifier (SNI) extension.  With this extension it is possible to use

-multiple SSL certificates with a single IP address.

+A variant of tlssrv(8) supporting the Server Name Identifier (SNI)

+extension.  With this extension it is possible to use multiple SSL

+certificates with a single IP address.

-# Key Functions

+# Example Setup

-tlshand.c:/^tlsClientExtensions

-tlshand.c:/^checkClientExtensions

-tlshand.c:/^tlsConnectionFree

+The easiest way to fetch and renew a **TLS** certificate on

+[9front](http://9front.org) is via

+[acmed(8)](http://man.9front.org/8/acmed). We are going to

+create two SSL certificates, that is mux.9lab.org and

+mux.bytelabs.org, for the same IP address.

-# Data Types

+Initially an account key must be generated:

-tlshand.c:/^typedef struct TlsConnection

-/sys/include/libsec.h:/^typedef struct TLSconn

+```

+% ramfs -p ; cd /tmp

+% auth/rsagen -t \

+    'service=acme role=sign hash=sha256 acct=igor@9lab.org' \

+    >account.key

+% auth/rsa2jwk account.key \

+    >/sys/lib/tls/acmed/igor@9lab.org.pub

+```

-# Approach

+The `account.key` must be loaded into

+[factotum(4)](http://man.9front.org/4/factotum); however, it is best

+to store it in [secstore(1)](http://man.9front.org/1/secstore) instead

+of storing it unencrypted on the file system:

-The function tlshand.c:/^checkClientExtensions must

-be extended to decode the server name indication. For this

-the 'tlshand.c:/^typedef struct TlsConnection' needs to

-be extended to hold the server name.

+```

+% auth/secstore -g factotum

+secstore password:

+% cat account.key >> factotum

+% auth/secstore -p factotum

+secstore password:

+% read -m factotum > /mnt/factotum/ctl

+```

-tlshand.c:/^tlsConnectionFree needs to free any potential

-`TlsConnection.serverName`.

+Please consult the [secstore(1)](http://man.9front.org/1/secstore) man

+page as well as the excellent [9front FQA secstore

+documentation](http://fqa.9front.org/fqa8.html#8.4.7) if the above

+doesn't make sense or doesn't work for you.

-We are going to allow multiple certificates to be specified

-to tlssrv. A certificate encodes its domain in its subject:

+Next, generate [rsa(8)](http://man.9front.org/8/rsa) key (i.e.

+`certificate.key`) and certificate signing request (i.e.

+`mux.9lab.org.csr`, `mux.bytelabs.org`) files:

- % auth/pemdecode 'CERTIFICATE' /sys/lib/tls/acmed/mux.9lab.org.crt | auth/x5092pub

-key proto=rsa size=2048 ek=10001 n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subject=mux.9lab.org

+```

+% auth/rsagen -t 'service=tls role=client owner=*' \

+    >certificate.key

+% auth/rsa2csr 'CN=mux.9lab.org' certificate.key \

+    >/sys/lib/tls/acmed/mux.9lab.org.csr

+% auth/rsa2csr 'CN=mux.bytelabs.org' certificate.key \

+    >/sys/lib/tls/acmed/mux.bytelabs.org.csr

+```

-Sample code that shows how to extract the domain from the

-subject can be found in /sys/src/cmd/auth/acmed.c:/^getcert

+Again, you are urged to store the

+[rsa(8)](http://man.9front.org/8/rsa) key in

+[secstore(1)](http://man.9front.org/1/secstore):

-static void

-getcert(char *csrpath)

-{

-	char *csr, *dom[64], subj[2048];

-	uchar *der;

-	int nder, ndom, fd;

-	RSApub *rsa;

-	Hdr loc = { "location" };

-	JSON *o;

+```

+% auth/secstore -g factotum

+secstore password:

+% cat certificate.key >> factotum

+% auth/secstore -p factotum

+secstore password:

+% read -m factotum > /mnt/factotum/ctl

+```

-	if((fd = open(csrpath, OREAD|OCEXEC)) == -1)

-		sysfatal("open %s: %r", csrpath);

-	if((der = slurp(fd, &nder)) == nil)

-		sysfatal("read %s: %r", csrpath);

-	close(fd);

+See [rsa(8)](http://man.9front.org/8/rsa) and

+[tlssrv(8)](http://man.9front.org/8/tlssrv) for more examples on how

+to use RSA keys.

-	if((rsa = X509reqtoRSApub(der, nder, subj, sizeof(subj))) == nil)

-		sysfatal("decode csr: %r");

-	rsapubfree(rsa);

-	if((csr = encurl64(der, nder)) == nil)

-		sysfatal("encode %s: %r", csrpath);

-	free(der);

+Finally, the certificate for your domain can now be fetched.  This

+requires [webfs(4)](http://man.9front.org/4/webfs) to be mounted as

+the [ACME

+protocol](https://en.wikipedia.org/wiki/Automatic_Certificate_Management_Environment)

+uses HTTP to talk to the provider.

-	dprint("subject: %s\n", subj);

-	if((ndom = getfields(subj, dom, nelem(dom), 1, ", ")) == nelem(dom))

-		sysfatal("too man domains");

+```

+% webfs

+% auth/acmed igor@9lab.org /sys/lib/tls/acmed/mux.9lab.org.csr \

+    >/sys/lib/tls/acmed/mux.9lab.org.crt

+% auth/acmed igor@9lab.org /sys/lib/tls/acmed/mux.bytelabs.org.csr \

+    >/sys/lib/tls/acmed/mux.bytelabs.org.crt

+```

-	if((o = submitorder(dom, ndom, &loc)) == nil)

-		sysfatal("order: %r");

-	if(dochallenges(dom, ndom, o) == -1)

-		sysfatal("challenge: %r");

+The above incantation is also used to *renew* the certificate.

-	if(submitcsr(o, csr) == -1)

-		sysfatal("signing cert: %r");

-	if(fetchcert(loc.val) == -1)

-		sysfatal("saving cert: %r");

+Let's display the certificate:

-	free(csr);

-}

\ No newline at end of file

+```

+% auth/pemdecode 'CERTIFICATE' /sys/lib/tls/acmed/mux.9lab.org.crt | auth/x5092pub

+key proto=rsa size=2048 ek=… n=… subject=mux.9lab.org

+```

+

+At last, to [listen(8)](http://man.9front.org/8/listen) on https port

+443 for requests modify the file `/bin/service/tcp443` as follows:

+

+```

+% cat /bin/service/tcp443

+#!/bin/rc

+exec /bin/tlssrv -c/sys/lib/tls/acmed/mux.9lab.org.crt -ltcp80 -r`{cat $3/remote} /bin/tcp80 `{cat $3/remote}>>[2]/sys/log/tcp80

+```

+

+# Caveats

+

+A main or fallback certificate can be specified to tlssrv(8)

+via the `-c` option. If an SNI is provided we try to find it

+as follows:

+

+```

+  snprint(path, sizeof(path), "/sys/lib/tls/acmed/%s.crt", c->serverName);

+```

+

+That means the certificate has to be present in the `/sys/lib/tls/acmed/`

+folder with the name `SNI.crt` where SNI is the the server name indicator

+provided by the client.

+

+It is not yet possible to override the path to certificates.

--- a/tlshand.c

+++ b/tlshand.c

@@ -746,11 +746,19 @@

 	}

 	if(checkClientExtensions(c, m.u.clientHello.extensions) < 0)

 		goto Err;

-	if(trace)

-		trace("ClientHello server name indicator %s\n", c->serverName);

-    // TODO: implement function that selects the right certificate

-    // from an array of certificate names given the SNI

 	if(certlen > 0){

+		/* override default server certificate with SNI (@igor) */

+		if(c->serverName){

+			char path[512];

+			snprint(path, sizeof(path), "/sys/lib/tls/acmed/%s.crt", c->serverName);

+			if(trace)

+				trace("ClientHello server name indicator %s using %s\n", c->serverName, path);

+			PEMChain *chain = readcertchain(path);

+			if (chain){

+				cert = chain->pem;

+				certlen = chain->pemlen;

+			}

+		}

 		/* server certificate */

 		c->sec->rsapub = X509toRSApub(cert, certlen, nil, 0);

 		if(c->sec->rsapub == nil){