mqtt: add support for username and password

Minor-edits-by: Daniel Stenberg
Added test 2200 to 2205

Closes #7243

1 files changed, 180 insertions, 30 deletions

diff --git a/lib/mqtt.c b/lib/mqtt.c
index d49a5f1cc..9a3ca222f 100644
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -143,32 +143,197 @@ static int mqtt_getsock(struct Curl_easy *data,
   return GETSOCK_READSOCK(FIRSTSOCKET);
 }
 
+static int mqtt_encode_len(char *buf, size_t len)
+{
+  unsigned char encoded;
+  int i;
+
+  for(i = 0; (len > 0) && (i<4); i++) {
+    encoded = len % 0x80;
+    len /= 0x80;
+    if(len)
+      encoded |= 0x80;
+    buf[i] = encoded;
+  }
+
+  return i;
+}
+
+/* add the passwd to the CONNECT packet */
+static int add_passwd(const char *passwd, const size_t plen,
+                       char *pkt, const size_t start, int remain_pos)
+{
+  /* magic number that need to be set properly */
+  const size_t conn_flags_pos = remain_pos + 8;
+  if(plen > 0xffff)
+    return 1;
+
+  /* set password flag */
+  pkt[conn_flags_pos] |= 0x40;
+
+  /* length of password provided */
+  pkt[start] = (char)((plen >> 8) & 0xFF);
+  pkt[start + 1] = (char)(plen & 0xFF);
+  memcpy(&pkt[start + 2], passwd, plen);
+  return 0;
+}
+
+/* add user to the CONN packet */
+static int add_user(const char *username, const size_t ulen,
+                    unsigned char *pkt, const size_t start, int remain_pos)
+{
+  /* magic number that need to be set properly */
+  const size_t conn_flags_pos = remain_pos + 8;
+  if(ulen > 0xffff)
+    return 1;
+
+  /* set username flag */
+  pkt[conn_flags_pos] |= 0x80;
+  /* length of username provided */
+  pkt[start] = (unsigned char)((ulen >> 8) & 0xFF);
+  pkt[start + 1] = (unsigned char)(ulen & 0xFF);
+  memcpy(&pkt[start + 2], username, ulen);
+  return 0;
+}
+
+/* add client ID to the CONN packet */
+static int add_client_id(const char *client_id, const size_t client_id_len,
+                         char *pkt, const size_t start)
+{
+  if(client_id_len != MQTT_CLIENTID_LEN)
+    return 1;
+  pkt[start] = 0x00;
+  pkt[start + 1] = MQTT_CLIENTID_LEN;
+  memcpy(&pkt[start + 2], client_id, MQTT_CLIENTID_LEN);
+  return 0;
+}
+
+/* Set initial values of CONN packet */
+static int init_connpack(char *packet, char *remain, int remain_pos)
+{
+  /* Fixed header starts */
+  /* packet type */
+  packet[0] = MQTT_MSG_CONNECT;
+  /* remaining length field */
+  memcpy(&packet[1], remain, remain_pos);
+  /* Fixed header ends */
+
+  /* Variable header starts */
+  /* protocol length */
+  packet[remain_pos + 1] = 0x00;
+  packet[remain_pos + 2] = 0x04;
+  /* protocol name */
+  packet[remain_pos + 3] = 'M';
+  packet[remain_pos + 4] = 'Q';
+  packet[remain_pos + 5] = 'T';
+  packet[remain_pos + 6] = 'T';
+  /* protocol level */
+  packet[remain_pos + 7] = 0x04;
+  /* CONNECT flag: CleanSession */
+  packet[remain_pos + 8] = 0x02;
+  /* keep-alive 0 = disabled */
+  packet[remain_pos + 9] = 0x00;
+  packet[remain_pos + 10] = 0x3c;
+  /*end of variable header*/
+  return remain_pos + 10;
+}
+
 static CURLcode mqtt_connect(struct Curl_easy *data)
 {
   CURLcode result = CURLE_OK;
-  const size_t client_id_offset = 14;
-  const size_t packetlen = client_id_offset + MQTT_CLIENTID_LEN;
+  int pos = 0;
+  int rc = 0;
+  /*remain length*/
+  int remain_pos = 0;
+  char remain[4] = {0};
+  size_t packetlen = 0;
+  size_t payloadlen = 0;
+  size_t start_user = 0;
+  size_t start_pwd = 0;
   char client_id[MQTT_CLIENTID_LEN + 1] = "curl";
   const size_t clen = strlen("curl");
-  char packet[32] = {
-    MQTT_MSG_CONNECT,  /* packet type */
-    0x00,              /* remaining length */
-    0x00, 0x04,        /* protocol length */
-    'M','Q','T','T',   /* protocol name */
-    0x04,              /* protocol level */
-    0x02,              /* CONNECT flag: CleanSession */
-    0x00, 0x3c,        /* keep-alive 0 = disabled */
-    0x00, 0x00         /* payload1 length */
-  };
-  packet[1] = (packetlen - 2) & 0x7f;
-  packet[client_id_offset - 1] = MQTT_CLIENTID_LEN;
+  char *packet = NULL;
+
+  /* extracting username from request */
+  const char *username = data->state.aptr.user ?
+    data->state.aptr.user : "";
+  const size_t ulen = strlen(username);
+  /* extracting password from request */
+  const char *passwd = data->state.aptr.passwd ?
+    data->state.aptr.passwd : "";
+  const size_t plen = strlen(passwd);
+
+  payloadlen = ulen + plen + MQTT_CLIENTID_LEN + 2;
+  /* The plus 2 are for the MSB and LSB describing the length of the string to
+   * be added on the payload. Refer to spec 1.5.2 and 1.5.4 */
+  if(ulen)
+    payloadlen += 2;
+  if(plen)
+    payloadlen += 2;
+
+  /* getting how much occupy the remain length */
+  remain_pos = mqtt_encode_len(remain, payloadlen + 10);
+
+  /* 10 length of variable header and 1 the first byte of the fixed header */
+  packetlen = payloadlen + 10 + remain_pos + 1;
+
+  /* allocating packet */
+  if(packetlen > 268435455)
+    return CURLE_WEIRD_SERVER_REPLY;
+  packet = malloc(packetlen);
+  if(!packet)
+    return CURLE_OUT_OF_MEMORY;
+  memset(packet, 0, packetlen);
+
+  /* set initial values for CONN pack */
+  pos = init_connpack(packet, remain, remain_pos);
 
   result = Curl_rand_hex(data, (unsigned char *)&client_id[clen],
                          MQTT_CLIENTID_LEN - clen + 1);
-  memcpy(&packet[client_id_offset], client_id, MQTT_CLIENTID_LEN);
+  /* add client id */
+  rc = add_client_id(client_id, strlen(client_id), packet, pos + 1);
+  if(rc) {
+    failf(data, "Client ID length mismatched: [%lu]", strlen(client_id));
+    result = CURLE_WEIRD_SERVER_REPLY;
+    goto end;
+  }
   infof(data, "Using client id '%s'\n", client_id);
+
+  /* position where starts the user payload */
+  start_user = pos + 3 + MQTT_CLIENTID_LEN;
+  /* position where starts the password payload */
+  start_pwd = start_user + ulen;
+  /* if user name was provided, add it to the packet */
+  if(ulen) {
+    start_pwd += 2;
+
+    rc = add_user(username, ulen,
+                  (unsigned char *)packet, start_user, remain_pos);
+    if(rc) {
+      failf(data, "Username is too large: [%lu]", ulen);
+      result = CURLE_WEIRD_SERVER_REPLY;
+      goto end;
+    }
+  }
+
+  /* if passwd was provided, add it to the packet */
+  if(plen) {
+    rc = add_passwd(passwd, plen, packet, start_pwd, remain_pos);
+    if(rc) {
+      failf(data, "Password is too large: [%lu]", plen);
+      result = CURLE_WEIRD_SERVER_REPLY;
+      goto end;
+    }
+  }
+
   if(!result)
     result = mqtt_send(data, packet, packetlen);
+
+end:
+  if(packet)
+    free(packet);
+  Curl_safefree(data->state.aptr.user);
+  Curl_safefree(data->state.aptr.passwd);
   return result;
 }
 
@@ -228,21 +393,6 @@ static CURLcode mqtt_get_topic(struct Curl_easy *data,
 }
 
 
-static int mqtt_encode_len(char *buf, size_t len)
-{
-  unsigned char encoded;
-  int i;
-
-  for(i = 0; (len > 0) && (i<4); i++) {
-    encoded = len % 0x80;
-    len /= 0x80;
-    if(len)
-      encoded |= 0x80;
-    buf[i] = encoded;
-  }
-
-  return i;
-}
 
 static CURLcode mqtt_subscribe(struct Curl_easy *data)
 {