GUACAMOLE-1686: Add common function for opening TCP sockets.

src/libguac/Makefile.am

@@ -70,6 +70,7 @@ libguacinc_HEADERS =                  \
     guacamole/socket-constants.h      \
     guacamole/socket.h                \
     guacamole/socket-fntypes.h        \
+    guacamole/socket-tcp.h            \
     guacamole/socket-types.h          \
     guacamole/stream.h                \
     guacamole/stream-types.h          \
@@ -128,6 +129,7 @@ libguac_la_SOURCES =   \
     socket-broadcast.c \
     socket-fd.c        \
     socket-nest.c      \
+    socket-tcp.c       \
     socket-tee.c       \
     string.c           \
     timestamp.c        \

src/libguac/guacamole/socket-tcp.h

@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef __GUAC_SOCKET_TCP_H
+#define __GUAC_SOCKET_TCP_H
+
+#include "config.h"
+
+#include <stddef.h>
+
+/**
+ * Given a hostname or IP address and port, attempt to connect to that
+ * system, returning an open socket if the connection succeeds, or a negative
+ * value if it fails. If it fails the errno variable will be set.
+ *
+ * @param hostname
+ *     The hostname or IP address to which to attempt connections.
+ *
+ * @param port
+ *     The TCP port to which to attempt to connect.
+ *
+ * @return
+ *     A valid socket if the connection succeeds, or a negative integer if it
+ *     fails.
+ */
+int guac_socket_tcp_connect(const char* hostname, const char* port);
+
+#endif // __GUAC_SOCKET_TCP_H

src/libguac/socket-tcp.c

@@ -0,0 +1,102 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "config.h"
+#include "guacamole/error.h"
+#include "guacamole/socket.h"
+
+#include <errno.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+int guac_socket_tcp_connect(const char* hostname, const char* port) {
+
+    int retval;
+
+    int fd = EBADFD;
+    struct addrinfo* addresses;
+    struct addrinfo* current_address;
+
+    char connected_address[1024];
+    char connected_port[64];
+
+    struct addrinfo hints = {
+        .ai_family   = AF_UNSPEC,
+        .ai_socktype = SOCK_STREAM,
+        .ai_protocol = IPPROTO_TCP
+    };
+
+    /* Get addresses for requested hostname and port. */
+    if ((retval = getaddrinfo(hostname, port, &hints, &addresses))) {
+        guac_error = GUAC_STATUS_INVALID_ARGUMENT;
+        guac_error_message = "Error parsing address or port.";
+        return retval;
+    }
+
+    /* Attempt connection to each address until success */
+    current_address = addresses;
+    while (current_address != NULL) {
+
+        /* Resolve hostname */
+        if ((retval = getnameinfo(current_address->ai_addr,
+                current_address->ai_addrlen,
+                connected_address, sizeof(connected_address),
+                connected_port, sizeof(connected_port),
+                NI_NUMERICHOST | NI_NUMERICSERV))) {
+
+            guac_error = GUAC_STATUS_INVALID_ARGUMENT;
+            guac_error_message = "Error resolving host.";
+            continue;
+        }
+
+        /* Get socket */
+        fd = socket(current_address->ai_family, SOCK_STREAM, 0);
+        if (fd < 0) {
+            freeaddrinfo(addresses);
+            return fd;
+        }
+
+        /* Connect */
+        if (connect(fd, current_address->ai_addr,
+                        current_address->ai_addrlen) == 0) {
+
+            /* Done if successful connect */
+            break;
+
+        }
+
+        close(fd);
+        current_address = current_address->ai_next;
+
+    }
+
+    /* Free addrinfo */
+    freeaddrinfo(addresses);
+
+    /* If unable to connect to anything, set error status. */
+    if (current_address == NULL) {
+        guac_error = GUAC_STATUS_REFUSED;
+        guac_error_message = "Unable to connect to remote host.";
+    }
+
+    /* Return the fd, or the error message if the socket connection failed. */
+    return fd;
+
+}