feat: TCP Client Server Half Duplex Communication (TheAlgorithms#853)

* TCP Client Server Half Duplex Comm * reverting .vscode/settings.json in reference to request * Set gitignore back to original state * Update .vscode/settings.json Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Making all the requested changes * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Made Requested Changes - Added Documentation & Comments * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * updating DIRECTORY.md * Changes Made & Updated as Requested * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Updated Documentation Format - Comments made in correct format * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Comment formatting updated * Update client_server/tcp_half_duplex_client.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Update client_server/tcp_half_duplex_server.c Co-authored-by: David Leal <[email protected]> * Updated Data Type - uint32_t for socket descriptors Co-authored-by: David Leal <[email protected]> Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Gaminee · Sep 7, 2021 · 0bcf737 · 0bcf737
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diff --git a/DIRECTORY.md b/DIRECTORY.md
@@ -3,6 +3,8 @@
 ## Client Server
   * [Client](https://github.com/TheAlgorithms/C/blob/master/client_server/client.c)
   * [Server](https://github.com/TheAlgorithms/C/blob/master/client_server/server.c)
+  * [Tcp Half Duplex Client](https://github.com/TheAlgorithms/C/blob/master/client_server/tcp_half_duplex_client.c)
+  * [Tcp Half Duplex Server](https://github.com/TheAlgorithms/C/blob/master/client_server/tcp_half_duplex_server.c)
   * [Udp Client](https://github.com/TheAlgorithms/C/blob/master/client_server/udp_client.c)
   * [Udp Server](https://github.com/TheAlgorithms/C/blob/master/client_server/udp_server.c)
 

diff --git a/client_server/tcp_half_duplex_client.c b/client_server/tcp_half_duplex_client.c
@@ -0,0 +1,153 @@
+/**
+ * @file
+ * @author [Nikhill Vombatkere](https://github.com/NVombat)
+ * @brief Client-side implementation of [TCP Half Duplex
+ * Communication](http://www.tcpipguide.com/free/t_SimplexFullDuplexandHalfDuplexOperation.htm)
+ * @see tcp_half_duplex_server.c
+ *
+ * @details
+ * The algorithm is based on the simple TCP client and server model. However,
+ * instead of the server only sending and the client only receiving data,
+ * the server and client can both send data but only one at a time. This is
+ * implemented by using a particular ordering of the `send()` and `recv()`
+ * functions. When one of the clients or servers is sending, the other can only
+ * receive and vice-versa. In this way, the Half Duplex Form of communication
+ * can be represented using the TCP server-client model & socket programming
+ */
+
+#include <netdb.h>  /// For structures returned by the network database library - formatted internet addresses and port numbers
+#include <netinet/in.h>  /// For in_addr and sockaddr_in structures
+#include <stdint.h>      /// For specific bit size values of variables
+#include <stdio.h>  /// Variable types, several macros, and various functions for performing input and output
+#include <stdlib.h>  /// Variable types, several macros, and various functions for performing general functions
+#include <string.h>  /// Various functions for manipulating arrays of characters
+#include <sys/socket.h>  /// For macro definitions related to the creation of sockets
+#include <sys/types.h>  /// For definitions to allow for the porting of BSD programs
+#include <unistd.h>  /// For miscellaneous symbolic constants and types, and miscellaneous functions
+
+#define PORT 8100  /// Define port over which communication will take place
+
+/**
+ * @brief Utility function used to print an error message to `stderr`.
+ * It prints `str` and an implementation-defined error
+ * message corresponding to the global variable `errno`.
+ * @returns void
+ */
+void error()
+{
+    perror("Socket Creation Failed");
+    exit(EXIT_FAILURE);
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main()
+{
+    /** Variable Declarations */
+    uint32_t
+        sockfd;  ///< socket descriptors - Like file handles but for sockets
+    struct sockaddr_in
+        server_addr;  ///< basic structures for all syscalls and functions that
+                      /// deal with internet addresses. Structures for handling
+                      /// internet addresses
+    char serverResponse[10000],
+        clientResponse[10000];  ///< Character arrays to read and store string
+                                /// data for communication
+
+    /**
+     * The TCP socket is created using the socket function.
+     *
+     * AF_INET (Family) - it is an address family that is used to designate the
+     * type of addresses that your socket can communicate with
+     *
+     * SOCK_STREAM (Type) - Indicates TCP Connection - A stream socket provides
+     * for the bidirectional, reliable, sequenced, and unduplicated flow of data
+     * without record boundaries. Aside from the bidirectionality of data flow,
+     * a pair of connected stream sockets provides an interface nearly identical
+     * to pipes.
+     *
+     * 0 (Protocol) - Specifies a particular protocol to be used with the
+     * socket. Specifying a protocol of 0 causes socket() to use an unspecified
+     * default protocol appropriate for the requested socket type.
+     */
+    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+    {
+        error();
+    }
+
+    /**
+     * Server Address Information
+     *
+     * The bzero() function erases the data in the n bytes of the memory
+     * starting at the location pointed to, by writing zeros (bytes
+     * containing '\0') to that area.
+     *
+     * We bind the server_addr to the internet address and port number thus
+     * giving our socket an identity with an address and port where it can
+     * listen for connections
+     *
+     * htons - The htons() function translates a short integer from host byte
+     * order to network byte order
+     *
+     * htonl - The htonl() function translates a long integer from host byte
+     * order to network byte order
+     *
+     * These functions are necessary so that the binding of address and port
+     * takes place with data in the correct format
+     */
+    bzero(&server_addr, sizeof(server_addr));
+    server_addr.sin_family = AF_INET;
+    server_addr.sin_port = htons(PORT);
+    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+
+    printf("Client is running...\n");
+
+    /**
+     * Connects the client to the server address using the socket descriptor
+     * This enables the two to communicate and exchange data
+     */
+    connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
+
+    printf("Client is connected...\n");
+
+    /**
+     * Communication between client and server
+     *
+     * The bzero() function erases the data in the n bytes of the memory
+     * starting at the location pointed to, by writing zeros (bytes
+     * containing '\0') to that area. The variables are emptied and then
+     * ready for use
+     *
+     * First the CLIENT receives the servers message and displays it (recv())
+     *
+     * The CLIENT is then prompted to type in a message and send it to the
+     * server. (send())
+     *
+     * The server and client can communicate till one of them exits the
+     * connection
+     *
+     * Since the exchange of information between the server and client take
+     * place one at a time this represents HALF DUPLEX COMMUNICATION
+     */
+    while (1)
+    {
+        bzero(&serverResponse, sizeof(serverResponse));
+        bzero(&clientResponse, sizeof(clientResponse));
+
+        /// Receive Message
+        recv(sockfd, serverResponse, sizeof(serverResponse), 0);
+        printf("\nServer message: %s \n", serverResponse);
+
+        /// Send Message
+        printf("\nEnter message here: ");
+        fgets(clientResponse, 10000, stdin);
+        send(sockfd, clientResponse, strlen(clientResponse) + 1, 0);
+    }
+
+    /// Close Socket
+    close(sockfd);
+    printf("Client is offline...\n");
+    return 0;
+}
diff --git a/client_server/tcp_half_duplex_server.c b/client_server/tcp_half_duplex_server.c
@@ -0,0 +1,177 @@
+/**
+ * @file
+ * @author [NVombat](https://github.com/NVombat)
+ * @brief Server-side implementation of [TCP Half Duplex
+ * Communication](http://www.tcpipguide.com/free/t_SimplexFullDuplexandHalfDuplexOperation.htm)
+ * @see tcp_half_duplex_server.c
+ *
+ * @details
+ * The algorithm is based on the simple TCP client and server model. However,
+ * instead of the server only sending and the client only receiving data,
+ * The server and client can both send data but only one at a time. This is
+ * implemented by using a particular ordering of the `send()` and `recv()`
+ * functions. When one of the clients or servers is sending, the other can only
+ * receive and vice-versa. In this way, the Half Duplex Form of communication
+ * can be represented using the TCP server-client model & socket programming
+ */
+
+#include <netdb.h>  /// For structures returned by the network database library - formatted internet addresses and port numbers
+#include <netinet/in.h>  /// For in_addr and sockaddr_in structures
+#include <stdint.h>      /// For specific bit size values of variables
+#include <stdio.h>  /// Variable types, several macros, and various functions for performing input and output
+#include <stdlib.h>  /// Variable types, several macros, and various functions for performing general functions
+#include <string.h>  /// Various functions for manipulating arrays of characters
+#include <sys/socket.h>  /// For macro definitions related to the creation of sockets
+#include <sys/types.h>  /// For definitions to allow for the porting of BSD programs
+#include <unistd.h>  /// For miscellaneous symbolic constants and types, and miscellaneous functions
+
+#define PORT 8100  /// Define port over which communication will take place
+
+/**
+ * @brief Utility function used to print an error message to `stderr`.
+ * It prints `str` and an implementation-defined error
+ * message corresponding to the global variable `errno`.
+ * @returns void
+ */
+void error()
+{
+    perror("Socket Creation Failed");
+    exit(EXIT_FAILURE);
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main()
+{
+    /** Variable Declarations */
+    uint32_t sockfd,
+        conn;  ///< socket descriptors - Like file handles but for sockets
+    char server_msg[10000],
+        client_msg[10000];  ///< character arrays to read and store string data
+                            /// for communication
+    struct sockaddr_in server_addr,
+        client_addr;  ///< asic structures for all syscalls and functions that
+                      /// deal with internet addresses. Structures for handling
+                      /// internet addresses
+
+    /**
+     * The TCP socket is created using the socket function
+     *
+     * AF_INET (Family) - it is an address family that is used to designate the
+     * type of addresses that your socket can communicate with
+     *
+     * SOCK_STREAM (Type) - Indicates TCP Connection - A stream socket provides
+     * for the bidirectional, reliable, sequenced, and unduplicated flow of data
+     * without record boundaries. Aside from the bidirectionality of data flow,
+     * a pair of connected stream sockets provides an interface nearly identical
+     * to pipes
+     *
+     * 0 (Protocol) - Specifies a particular protocol to be used with the
+     * socket. Specifying a protocol of 0 causes socket() to use an unspecified
+     * default protocol appropriate for the requested socket type
+     */
+    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+    {
+        error();  ///< Error if the socket descriptor has a value lower than 0 -
+                  /// socket wasnt created
+    }
+
+    /**
+     * Server Address Information
+     *
+     * The bzero() function erases the data in the n bytes of the memory
+     * starting at the location pointed to, by writing zeros (bytes
+     * containing '\0') to that area
+     *
+     * We bind the server_addr to the internet address and port number thus
+     * giving our socket an identity with an address and port where it can
+     * listen for connections
+     *
+     * htons - The htons() function translates a short integer from host byte
+     * order to network byte order
+     *
+     * htonl - The htonl() function translates a long integer from host byte
+     * order to network byte order
+     *
+     * These functions are necessary so that the binding of address and port
+     * takes place with data in the correct format
+     */
+    bzero(&server_addr, sizeof(server_addr));
+    server_addr.sin_family = AF_INET;    /// Domain/Family to be used
+    server_addr.sin_port = htons(PORT);  /// Port to be used
+    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+
+    printf("Server is running...\n");
+
+    /**
+     * This binds the socket descriptor to the server thus enabling the server
+     * to listen for connections and communicate with other clients
+     */
+    if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
+    {
+        error();  /// If binding is unsuccessful
+    }
+
+    /**
+     * This is to listen for clients or connections made to the server
+     *
+     * The limit is currently at 5 but can be increased to listen for
+     * more connections
+     *
+     * It listens to connections through the socket descriptor
+     */
+    listen(sockfd, 5);
+
+    printf("Server is listening...\n");
+
+    /**
+     * When a connection is found, a socket is created and connection is
+     * accepted and established through the socket descriptor
+     */
+    conn = accept(sockfd, (struct sockaddr *)NULL, NULL);
+
+    printf("Server is connected...\n");
+
+    /**
+     * Communication between client and server
+     *
+     * The bzero() function erases the data in the n bytes of the memory
+     * starting at the location pointed to, by writing zeros (bytes
+     * containing '\0') to that area. The variables are emptied and then
+     * ready for use
+     *
+     * First the SERVER is prompted to type a message which is read from
+     * stdin and then sent over the connection that was established - the socket
+     * - to be received by the client (send())
+     *
+     * The SERVER then waits for the client to reply. It then receives the reply
+     * in the string variable and displays it (recv())
+     *
+     * The server and client can communicate till one of them exits the
+     * connection
+     *
+     * Since the exchange of information between the server and client take
+     * place one at a time this represents HALF DUPLEX COMMUNICATION
+     */
+    while (1)
+    {
+        bzero(&server_msg, sizeof(server_msg));
+        bzero(&client_msg, sizeof(client_msg));
+
+        /// Send message
+        printf("\nEnter message here: ");
+        fgets(server_msg, 10000, stdin);
+        send(conn, server_msg, strlen(server_msg) + 1, 0);
+
+        /// Receive Message
+        recv(conn, client_msg, sizeof(client_msg), 0);
+        printf("\nClient Message: %s\n", client_msg);
+    }
+
+    /// Close socket
+    close(sockfd);
+    printf("Server is offline...\n");
+    return 0;
+}