Adds signaling to demo

Adds simple HTTP/1.0 signaling to demo. Demo long-polls demo server
(demo.liburtc.org) for an offer and posts an answer. Similarily,
long-polls and posts candidates.

7 files changed, 360 insertions, 85 deletions

diff --git a/examples/.gitignore b/examples/.gitignore
index b04600a..1549b67 100644
--- a/examples/.gitignore
+++ b/examples/.gitignore
@@ -1 +1 @@
-sandbox
+demo
diff --git a/examples/Makefile.am b/examples/Makefile.am
index f2e28b1..945cc7f 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -1,11 +1,5 @@
 # Builds a minimal example program
-#bin_PROGRAMS    = example
-#example_CFLAGS  = -I$(top_srcdir)/src/include $(LWS_CFLAGS)
-#example_LDADD   = $(top_builddir)/src/liburtc.la $(LWS_LIBS)
-#example_SOURCES = server.c
-
-# Builds a minimal example program
-bin_PROGRAMS    = sandbox
-sandbox_CFLAGS  = -I$(top_srcdir)/src
-sandbox_LDADD   = $(top_builddir)/src/liburtc.la
-sandbox_SOURCES = sandbox.c
+bin_PROGRAMS    = demo
+demo_CFLAGS  = -I$(top_srcdir)/src
+demo_LDADD   = $(top_builddir)/src/liburtc.la
+demo_SOURCES = demo.c
diff --git a/examples/callee.c b/examples/callee.c
deleted file mode 100644
index 4fb7ddf..0000000
--- a/examples/callee.c
+++ /dev/null
@@ -1,62 +0,0 @@
-/**
- * Simple callee example (web browser is caller). Sends video to caller upon
- * incoming calls.
- *
- * Copyright (c) 2019-2021 Chris Hiszpanski. All rights reserved.
- * 
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- * 
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- * 
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- */
-
-#include <signal.h>
-#include <unistd.h>
-
-#include "urtc.h"
-
-
-int main() {
-	sigset_t ss;
-	int signal;
-
-	const char *stun[] = {
-		"stun.liburtc.org",
-		NULL
-	};
-
-	sigemptyset(&ss);
-	sigaddset(&ss, SIGINT);
-	sigaddset(&ss, SIGTERM);
-	sigaddset(&ss, SIGQUIT);
-
-        // create a new peer connection (no actual network communication yet)
-	urtc_peerconn_t *pc = urtc_peerconn_create(NULL);
-
-	// connect to signaling service
-
-	sigwait(&ss, &signal);
-
-	urtc_peerconn_destroy(pc);
-
-	return 0;
-}
-
-/* vim: set expandtab ts=8 sw=4 tw=0 : */
diff --git a/examples/demo.c b/examples/demo.c
new file mode 100644
index 0000000..34b85de
--- /dev/null
+++ b/examples/demo.c
@@ -0,0 +1,250 @@
+/**
+ * Simple callee example (web browser is caller). Sends video to caller upon
+ * incoming calls.
+ */
+
+#include <errno.h>                      // errno
+#include <poll.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>                      // printf
+#include <string.h>
+#include <unistd.h>
+
+#include <netdb.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "urtc.h"
+
+// STUN servers
+const char *stun[] = {
+	"stun.liburtc.org",
+	NULL
+};
+
+static int http_connect(const char *hostname) {
+    int err, fd;
+	struct addrinfo *res, *res0;
+
+	struct addrinfo hints = {
+		.ai_family   = AF_UNSPEC,
+		.ai_socktype = SOCK_STREAM,
+		.ai_protocol = IPPROTO_TCP
+	};
+
+    // resolve hostname to IPv4/IPv6 address
+	if (err = getaddrinfo(hostname, "http", &hints, &res0), err) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(errno));
+        return -1;
+	}
+
+	for (res = res0; res; res = res->ai_next) {
+		// attempt to open socket
+		fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+		if (-1 == fd) {
+			continue; // failed. onto the next result.
+		}
+
+		// attempt to connect socket
+		if (-1 == connect(fd, res->ai_addr, res->ai_addrlen)) {
+		    close(fd);
+		    fd = -1;
+		    continue; // failed. onto the next result.
+		}
+
+        break; // success. return.
+	}
+
+	// free resolved addresses
+	freeaddrinfo(res0);
+
+    return fd;
+}
+
+static int http_post(
+    const char *hostname,
+    const char *path,
+    const char *body
+) {
+    const char *tmpl = 
+        "POST %s HTTP/1.0\r\n"
+        "Host: %s\r\n"
+        "Content-Length: %d\r\n"
+        "Content-Type: text/plain\r\n"
+        "\r\n";
+
+    int fd, rv = -1;
+    char req[128];
+
+    if (fd = http_connect(hostname), -1 == fd) {
+        return -1;
+    }
+
+    // construct request
+    if (-1 == snprintf(req, sizeof(req), tmpl, path, hostname, strlen(body))) {
+        fprintf(stderr, "bad request template\n");
+        goto _unwind_socket;
+    }
+
+    // send request
+    if (rv = send(fd, req, strlen(req), 0), -1 == rv) {
+        perror("send");
+        goto _unwind_socket;
+    }
+
+    // send request body
+    if (rv = send(fd, body, strlen(body), 0), -1 == rv) {
+        perror("send");
+        goto _unwind_socket;
+    }
+
+_unwind_socket:
+    shutdown(fd, SHUT_RDWR);
+    close(fd);
+
+_done:
+    return rv;
+}
+
+/**
+ * HTTP GET request
+ *
+ * Resolves simple signaling server hostname to IPv4/IPv6 address and connects
+ * to its HTTP port.
+ *
+ * \param[out] response Buffer into which response is written.
+ * \param[in] size Max size of response.
+ * \param hostname Server hostname (e.g. "demo.liburtc.org")
+ * \param path HTTP path (e.g. "/offer")
+ *
+ * \return Socket file descriptor, or -1 on error. Caller must close file
+ *         descriptor.
+ */
+static int get(
+    char *response,
+    size_t size,
+    const char *hostname,
+    const char *path
+) {
+    const char *tmpl = 
+        "GET %s HTTP/1.0\r\n"
+        "Host: %s\r\n"
+        "\r\n";
+
+    int err, fd, rv = -1;
+    char req[128];
+
+    if (fd = http_connect(hostname), -1 == fd) {
+        return -1;
+    }
+
+    // construct request
+    if (-1 == snprintf(req, sizeof(req), tmpl, path, hostname)) {
+        fprintf(stderr, "bad request template\n");
+        goto _unwind_socket;
+    }
+
+    // send request
+    if (rv = send(fd, req, strlen(req), 0), -1 == rv) {
+        perror("send");
+        goto _unwind_socket;
+    }
+
+    // get response
+    if (rv = recv(fd, response, size, 0), -1 == rv) {
+        perror("recv");
+        goto _unwind_socket;
+    }
+
+_unwind_socket:
+    shutdown(fd, SHUT_RDWR);
+    close(fd);
+
+_done:
+    return rv;
+}
+
+
+/**
+ * (callback) Handles incoming ICE candidates.
+ *
+ * \param cand[in] ICE candidate.
+ * \param arg[in] User argument.
+ */
+void handle_ice_candidate(const char *cand, void *arg) {
+    urtc_peerconn_t *pc = (urtc_peerconn_t *)arg;
+
+    urtc_add_ice_candidate(pc, cand);
+}
+
+static int longpoll(char *response, size_t size, const char *path) {
+    int n;
+
+    while (true) {
+        n = get(response, size, "demo.liburtc.org", path);
+        if (-1 == n || 0 == n) {
+            perror("get");
+            continue;
+        }
+
+        // blindly strip http headers
+        char *body = strstr(response, "\r\n\r\n");
+        strcpy(response, body + 4);
+
+        // ignore empty responses (i.e. long-poll timeout)
+        if (0 == strlen(response)) {
+            continue;
+        }
+
+        break;
+    }
+
+    return n;
+}
+
+char offer[4096];
+char answer[4096];
+
+int main(int argc, char **argv) {
+    int n;
+
+    // create a new peer connection (no actual network communication yet)
+    urtc_peerconn_t *pc = urtc_peerconn_create(stun);
+
+    // TODO add tracks here
+
+    // get offer
+    n = longpoll(offer, sizeof(offer), "/offer");
+    fprintf(stderr, "%s\n", offer);
+
+    if (urtc_set_remote_description(pc, offer)) {
+        fprintf(stderr, "error: set remote description\n");
+    }
+    if (urtc_create_answer(pc, answer, sizeof(answer))) {
+        fprintf(stderr, "error: create answer\n");
+    }
+
+    http_post("demo.liburtc.org", "/answer", answer);
+    fprintf(stderr, "answer:\n%s\n", answer);
+    //urtc_set_local_description(pc, answer);
+
+
+    // block until signal
+    {
+	    int signal;
+	    sigset_t ss;
+	    sigemptyset(&ss);
+	    sigaddset(&ss, SIGINT);
+	    sigaddset(&ss, SIGTERM);
+	    sigaddset(&ss, SIGQUIT);
+	    sigwait(&ss, &signal);
+    }
+
+    // clean up
+	urtc_peerconn_destroy(pc);
+
+	return 0;
+}
+
+/* vim: set expandtab ts=4 sw=4 tw=0 : */
diff --git a/examples/demo.html b/examples/demo.html
index 03e07b9..0be9df8 100644
--- a/examples/demo.html
+++ b/examples/demo.html
@@ -4,12 +4,105 @@
     <title>liburtc demo</title>
     <script src="//webrtchacks.github.io/adapter/adapter-latest.js"></script>
     <script>
-      // call liburtc peer
+      // send offer and get answer
+      let sendOffer = offer => {
+        return new Promise((resolve, reject) => {
+          let xhr = new XMLHttpRequest();
+          xhr.onreadystatechange = function() {
+            if (xhr.readyState == XMLHttpRequest.DONE) {
+              resolve(new RTCSessionDescription({
+                type: "offer",
+                sdp: xhr.responseText
+              }));
+            }
+          };
+          xhr.open("POST", "http://localhost/offer");
+          xhr.setRequestHeader("Content-Type", "application/json");
+          xhr.send(JSON.stringify(offer));
+        });
+      };
+
+      function sendCandidate(candidate) {
+        let req = new XMLHttpRequest();
+        req.open("POST", "http://localhost/candidate");
+        req.setRequestHeader("Content-Type", "application/json");
+        req.send(JSON.stringify(candidate));
+      };
+
+      window.onload = function demo() {
+        // create new peer connection
+        let pc = new RTCPeerConnection({
+          iceCandidatePoolSize: 4,
+          iceServers: [
+            { urls: "stun:stun.liburtc.org" }
+          ]
+        });
+
+        // (callback) called upon discovery of new local ICE candidate
+        pc.onicecandidate = function(event) {
+          if (event.candidate) {
+            console.log("local candidate:\n%c%s", "color: brown", event.candidate.candidate);
+          }
+        };
+
+        // (callback) called upon reception of new remote video track
+        pc.ontrack = function(event) {
+          document.getElementById("remoteVideo").srcObject = event.streams[0];
+        };
+
+        // create offer and send to remote
+        pc.createOffer({ offerToReceiveVideo: true }).then(function(offer) {
+          console.log("local offer:\n%c%s", "color: orange", offer.sdp);
+          pc.setLocalDescription(offer);
+          sendOffer(offer).then(function(answer) {
+            console.log("remote answer:\n%c%s", "color: green", answer.sdp);
+            pc.setRemoteDescription(answer)
+              .catch(function(reason) {
+                console.log(reason);
+              });
+          });
+        }).catch(function(reason) {
+          console.log(reason);
+        });
+      }
     </script>
+    <style>
+      html, body {
+        font-family: Arial, Helvetica, sans-serif;
+        text-align: center;
+      }
+      main {
+        margin-left: auto;
+        margin-right: auto;
+        width: 80%;
+      }
+      p {
+        text-align: left;
+      }
+      video {
+        background-color: #eee;
+        border: solid 1px #bbb;
+        width: 100%;
+      }
+    </style>
   </head>
   <body>
     <h1>liburtc demo</h1>
 
+    <main>
+    <p>
+      In this demo, this web browser is the caller and liburtc is the callee.
+    </p>
+
+    <p>
+      This browser creates an offer and relays it to liburtc via a simple
+      signaling server (HTTP/1.0 long-polling). liburtc replies with an
+      answer, again via the signaling service.
+    </p>
+
     <video autoplay controls muted playsinline id="remoteVideo"></video>
+    </main>
+
+
   </body>
 </html>
diff --git a/src/urtc.c b/src/urtc.c
index 8cc6ff5..f3ffa99 100644
--- a/src/urtc.c
+++ b/src/urtc.c
@@ -425,20 +425,20 @@ int urtc_add_ice_candidate(struct peerconn *pc, const char *cand) {
     return -URTC_ERR_NOT_IMPLEMENTED;
 }
 
-int urtc_create_answer(struct peerconn *pc, char **answer) {
-    return -URTC_ERR_NOT_IMPLEMENTED;
+int urtc_create_answer(struct peerconn *pc, char *answer, size_t size) {
+    return sdp_serialize(answer, size, &pc->ldesc);
 }
 
-int urtc_create_offer(struct peerconn *pc, char **offer) {
+int urtc_create_offer(struct peerconn *pc, char *offer, size_t size) {
     return -URTC_ERR_NOT_IMPLEMENTED;
 }
 
 int urtc_set_remote_description(struct peerconn *pc, const char *desc) {
-    return -URTC_ERR_NOT_IMPLEMENTED;
+    return sdp_parse(&pc->rdesc, desc);
 }
 
 int urtc_set_local_description(struct peerconn *pc, const char *desc) {
-    return -URTC_ERR_NOT_IMPLEMENTED;
+    return sdp_parse(&pc->ldesc, desc);
 }
 
 void urtc_peerconn_destroy(struct peerconn *pc) {
diff --git a/src/urtc.h b/src/urtc.h
index 7760ca8..eae4e6b 100644
--- a/src/urtc.h
+++ b/src/urtc.h
@@ -151,12 +151,12 @@ int urtc_add_ice_candidate(urtc_peerconn_t *pc, const char *cand);
  * Akin to `createAnswer` method of `RTCPeerConnection` in WebRTC JS API.
  *
  * \param pc Peer connection
- * \param answer Pointer to string pointer pointing to generated answer.
- *               Memory internally managed (caller need not and must not free).
+ * \param answer Destination pointer for generated answer.
+ * \param size Bytes available at destination.
  *
  * \return 0 on success, negative on error.
  */
-int urtc_create_answer(urtc_peerconn_t *pc, char **answer);
+int urtc_create_answer(urtc_peerconn_t *pc, char *answer, size_t size);
 
 /**
  * Creates a local description for an offering peer connection
@@ -170,12 +170,12 @@ int urtc_create_answer(urtc_peerconn_t *pc, char **answer);
  * Akin to `createOffer` method of `RTCPeerConnection` in WebRTC JS API.
  *
  * \param pc Peer connection
- * \param offer Pointer to string pointer pointing to generated offer.
- *              Memory interally managed (caller need no and must not free).
+ * \param offer Destination pointer for generated offer.
+ * \param size Bytes available at destination.
  *
  * \return 0 on success, negative on error.
  */
-int urtc_create_offer(urtc_peerconn_t *pc, char **offer);
+int urtc_create_offer(urtc_peerconn_t *pc, char *offer, size_t size);
 
 /**
  * Sets local description for peer connection