Basic example icmp server and client ====================================== .. tab-set:: .. tab-item:: IPv4 RAW_AF_INET ICMP * In this program, you are going to learn .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow * How to create a Socket ? .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow * How to send a data ? .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow * How to recv a data ? .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow * How to use socket APIs ? * `socket `_ * `sendto `_ * `recvfrom `_ .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`program 1: icmp single server and single client : single data transfer ` * :ref:`program 2: icmp single server and single client : multiple data transfer ` .. _ipv4_raw_af_inet_icmp_single_data_transfer: .. tab-set:: .. tab-item:: program 1 : icmp single server and single client : single data transfer .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`IPV4 RAW_AF_INET ICMP SOCKET FAQs ` * :ref:`Program1 : Step 1: Sequence Diagram for SERVER.c ` * :ref:`Program1 : Step 2: Program for Server.c ` * :ref:`Program1 : Step 3: Compile and Execute Server.c ` * :ref:`Program1 : Step 4: Sequence Diagram for CLIENT.c ` * :ref:`Program1 : Step 5: Program for Client.c ` * :ref:`Program1 : Step 6: Compile and Execute Client.c ` * :ref:`Summary ` .. _ipv4_raw_af_inet_icmp_multiple_data_transfer: .. tab-set:: .. tab-item:: program 2 : icmp single server and single client : multiple data transfer .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`IPV4 RAW_AF_INET ICMP SOCKET FAQs ` * :ref:`Program2 : Step 1: Sequence Diagram for SERVER.c ` * :ref:`Program2 : Step 2: Program for Server.c ` * :ref:`Program2 : Step 3: Compile and Execute Server.c ` * :ref:`Program2 : Step 4: Sequence Diagram for CLIENT.c ` * :ref:`Program2 : Step 5: Program for Client.c ` * :ref:`Program2 : Step 6: Compile and Execute Client.c ` * :ref:`Summary ` .. _basic_example_ipv4_raw_af_inet_icmp_socket: .. tab-set:: .. tab-item:: IPV4 RAW_AF_INET ICMP SOCKET : FAQs .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us answer few basic questions in this socket .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow What does ``socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)`` do? .. dropdown:: See Answer This call creates a raw socket in the IPv4 address family ``(AF_INET)`` that can receive ``ICMP (Internet Control Message Protocol)`` packets directly. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Why use ``AF_INET`` as the address family? .. dropdown:: See Answer ``AF_INET`` specifies that the socket will work with IPv4 addresses. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow What is the purpose of ``SOCK_RAW`` in the socket type? .. dropdown:: See Answer ``SOCK_RAW`` allows the socket to operate at a lower level by providing direct access to the packet, including the IP and transport layer headers. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Why specify ``IPPROTO_ICMP`` as the protocol? .. dropdown:: See Answer It filters the socket to receive only ICMP packets, allowing applications to handle ICMP messages directly. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Can this socket send ICMP packets as well? .. dropdown:: See Answer Yes, the same socket can be used to send and receive ICMP packets. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow How does this socket differ from a standard UDP or TCP socket? .. dropdown:: See Answer Unlike UDP or TCP sockets, a raw socket provides direct access to the IP and ICMP headers, making it suitable for low-level packet handling. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Is error checking needed after creating the socket? .. dropdown:: See Answer Yes, checking for errors ensures that the socket is created successfully before proceeding with further operations. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Can this socket be used for other protocols besides ICMP? .. dropdown:: See Answer While created specifically for ICMP, the socket can be adapted for handling other IP protocols by changing the IPPROTO parameter. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Why close the socket after processing? .. dropdown:: See Answer Closing the socket ensures proper resource cleanup and releases the associated system resources. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow How is the source IP address extracted from the received packet? .. dropdown:: See Answer The source IP address can be extracted by parsing the IP header within the received packet. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Can this socket receive ICMP messages from any source? .. dropdown:: See Answer Yes, the socket can receive ICMP packets from any source as it operates at the network layer. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Why cast to struct iphdr and struct icmphdr in packet processing? .. dropdown:: See Answer Casting allows the code to interpret the received buffer as IP and ICMP headers, facilitating packet analysis. .. _program1_ipv4_raw_af_inet_icmp_socket_server_sequence_diagram: .. tab-set:: .. tab-item:: Program1 : Step 1: Sequence Diagram for SERVER.c .. plantuml:: @startuml !theme spacelab start :socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); :recvfrom(server_socket, buffer, sizeof(buffer), 0, NULL, NULL); :(void)close(server_socket); stop @enduml .. _program1_ipv4_raw_af_inet_icmp_socket_server_code: .. tab-set:: .. tab-item:: Program1 : Step 2: Program for Server.c * There are many functions used in socket. We can classify those functions based on functionalities. * Create Socket * Recv data_packet * Close socket * ``socket()`` is used to create a new socket. For example, .. code-block:: c server_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); * ``recvfrom`` is used in network programming to receive data from a connected socket. For example, .. code-block:: c ret = recvfrom(server_socket, buffer, sizeof(buffer), 0, NULL, NULL); * ``close`` is used to close the socket To free up system resources associated with the socket. For example, .. code-block:: c (void)close(server_socket); * See the full program below, .. literalinclude:: single_data_transfer/server/server.c :language: c :emphasize-lines: 45, 46, 47, 54, 55, 89 .. _program1_ipv4_raw_af_inet_icmp_socket_server_side_compile_and_execute: .. tab-set:: .. tab-item:: Program1 : Step 3: Compile and Execute Server.c .. code-block:: c :emphasize-lines: 1, 3 $ gcc -o server server.c $ sudo ./server Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! added ip header recvied icmp hex dump 45 00 00 2E F1 2A 40 00 40 01 4B A2 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 .. _program1_ipv4_raw_af_inet_icmp_socket_client_sequence_diagram: .. tab-set:: .. tab-item:: Program1 : Step 4: Sequence Diagram for CLIENT.c .. plantuml:: @startuml !theme spacelab start :socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); :sendto(client_socket, buffer, sizeof(struct icmphdr) + strlen("Hello from client!"), 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); :(void)close(client_socket); stop @enduml .. _program1_ipv4_raw_af_inet_icmp_socket_client_code: .. tab-set:: .. tab-item:: step 5: program for client.c * There are many functions used in socket. We can classify those functions based on functionalities. * Create Socket * Sendto data_packet * Close socket * ``socket`` is used to create a new socket. For example, .. code-block:: c client_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); * ``sendto`` is used to send the encoded message to the specified server address and port using a socket. For example, .. code-block:: c ret = sendto(client_socket, buffer, sizeof(struct icmphdr) + strlen("Hello from client!"), 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); * ``close`` is used to close the socket To free up system resources associated with the socket. For example, .. code-block:: c (void)close(client_socket); * See the full program below, .. literalinclude:: single_data_transfer/client/client.c :language: c :emphasize-lines: 75, 76, 77, 104, 105, 106, 107, 108, 122 .. _program1_ipv4_raw_af_inet_icmp_socket_client_side_compile_and_execute: .. tab-set:: .. tab-item:: Program1 : Step 6: Compile and Execute Client.c .. code-block:: c :emphasize-lines: 1, 3 $ gcc -o client client.c $ sudo ./client 127.0.0.1 IP Address: 127.0.0.1 sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 .. _program2_ipv4_raw_af_inet_icmp_socket_server_sequence_diagram: .. tab-set:: .. tab-item:: Program2 : Step 1: Sequence Diagram for SERVER.c .. plantuml:: @startuml !theme spacelab start :socket(AF_INET, SOCK_RAM, IPPROTO_ICMP); :i = 0; while (while (i < NUM_MESSAGES)) is (yes) :recvfrom(server_socket, buffer, sizeof(buffer), 0, NULL, NULL); :++i; endwhile :(void)close(server_socket); stop @enduml .. _program2_ipv4_raw_af_inet_icmp_socket_server_code: .. tab-set:: .. tab-item:: Program2 : Step 2: Program for Server.c * There are many functions used in socket. We can classify those functions based on functionalities. * Create Socket * Recv data_packet * Close socket * ``socket()`` is used to create a new socket. For example, .. code-block:: c server_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); * ``recvfrom`` is used in network programming to receive data from a connected socket. For example, .. code-block:: c ret = recvfrom(server_socket, buffer, sizeof(buffer), 0, NULL, NULL); * ``close`` is used to close the socket To free up system resources associated with the socket. For example, .. code-block:: c (void)close(server_socket); * See the full program below, .. literalinclude:: multiple_data_transfer/server/server.c :language: c :emphasize-lines: 47, 48, 49, 58, 59, 100 .. _program2_ipv4_raw_af_inet_icmp_socket_server_side_compile_and_execute: .. tab-set:: .. tab-item:: Program2 : Step 3: Compile and Execute Server.c .. code-block:: c :emphasize-lines: 1, 3 $ gcc -o server server.c $ sudo ./server Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 0 time added ip header recvied icmp hex dump 45 00 00 2E 78 36 40 00 40 01 C4 96 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 1 time added ip header recvied icmp hex dump 45 00 00 2E 78 37 40 00 40 01 C4 95 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 2 time added ip header recvied icmp hex dump 45 00 00 2E 78 38 40 00 40 01 C4 94 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 3 time added ip header recvied icmp hex dump 45 00 00 2E 78 39 40 00 40 01 C4 93 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 4 time added ip header recvied icmp hex dump 45 00 00 2E 78 3A 40 00 40 01 C4 92 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 5 time added ip header recvied icmp hex dump 45 00 00 2E 78 3B 40 00 40 01 C4 91 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 6 time added ip header recvied icmp hex dump 45 00 00 2E 78 3C 40 00 40 01 C4 90 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 7 time added ip header recvied icmp hex dump 45 00 00 2E 78 3D 40 00 40 01 C4 8F 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 8 time added ip header recvied icmp hex dump 45 00 00 2E 78 3E 40 00 40 01 C4 8E 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Received ICMP message Source IP: 127.0.0.1 Type: 8 Code: 0 Original Data: Hello from client! Recevied 9 time added ip header recvied icmp hex dump 45 00 00 2E 78 3F 40 00 40 01 C4 8D 7F 00 00 01 7F 00 00 01 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 .. _program2_ipv4_raw_af_inet_icmp_socket_client_sequence_diagram: .. tab-set:: .. tab-item:: Program2 : Step 4: Sequence Diagram for CLIENT.c .. plantuml:: @startuml !theme spacelab start :socket(AF_INET, SOCK_RAM, IPPROTO_ICMP); :i = 0; while (while (i < NUM_MESSAGES)) is (yes) :sendto(client_socket, buffer, sizeof(struct icmphdr) + strlen("Hello from client!"), 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); :++i; endwhile :(void)close(client_socket); stop @enduml .. _program2_ipv4_raw_af_inet_icmp_socket_client_code: .. tab-set:: .. tab-item:: step 5: program for client.c * There are many functions used in socket. We can classify those functions based on functionalities. * Create Socket * Sendto data_packet * Close socket * ``socket`` is used to create a new socket. For example, .. code-block:: c client_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); * ``sendto`` is used to send the encoded message to the specified server address and port using a socket. For example, .. code-block:: c ret = sendto(client_socket, buffer, sizeof(struct icmphdr) + strlen("Hello from client!"), 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); * ``close`` is used to close the socket To free up system resources associated with the socket. For example, .. code-block:: c (void)close(client_socket); * See the full program below, .. literalinclude:: multiple_data_transfer/client/client.c :language: c :emphasize-lines: 75, 76, 77, 105, 106, 107, 108, 109, 128 .. _program2_ipv4_raw_af_inet_icmp_socket_client_side_compile_and_execute: .. tab-set:: .. tab-item:: Program2 : Step 6: Compile and Execute Client.c .. code-block:: c :emphasize-lines: 1, 3 $ gcc -o client client.c $ sudo ./client 8080 127.0.0.1 IP Address: 127.0.0.1 sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 0 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 1 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 2 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 3 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 4 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 5 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 6 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 7 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 8 time sending icmp hex dump 08 00 00 00 00 00 00 00 48 65 6C 6C 6F 20 66 72 6F 6D 20 63 6C 69 65 6E 74 21 Sent 9 time .. tab-set:: .. tab-item:: Enhanced Socket Flexibility with ``AF_INET`` and ``PF_INET`` Domains .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Default Domain:** By default, the socket is configured to work in the ``AF_INET`` domain, handling all types of network data. **Additional Domain Support:** We expand the socket's capabilities to also function in the ``PF_INET`` domain, allowing it to operate similarly to ``AF_INET``. **Socket Creation:** We set up a network connection point known as a socket using ``socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)``. **Working Scenario:** Despite the change in domain to ``PF_INET``, the socket continues to operate the same way, handling general network data. .. _basic_example_ipv4_raw_af_inet_icmp_summary: .. tab-set:: .. tab-item:: Summary ============== ================================================================================================================== Socket API Learning ============== ================================================================================================================== socket Create a new socket recvfrom It provides information about the source (sender) of the data, including the sender's IP address and port number. sendto Send the encoded message to the specified server address and port using a socket. ============== ================================================================================================================== .. card:: See Also * Previous topic * :doc:`../../../sockets/af_unix_udp/epoll/epoll` * Current topic * :doc:`../../../sockets/ipv4_raw_af_inet_icmp/Basic_example/Basic_example` * Next topic * :doc:`../../../sockets/ipv4_raw_af_inet_icmp/select/select` * Other sockets * :doc:`../../../sockets/ipv4_raw_af_inet_raw` * :doc:`../../../sockets/ipv4_raw_af_inet_tcp` * :doc:`../../../sockets/ipv4_raw_af_inet_udp` * :doc:`../../../sockets/ipv6_af_inet6_tcp` * :doc:`../../../sockets/ipv6_af_inet6_udp` * :doc:`../../../sockets/ipv6_raw_af_inet6_icmp` * :doc:`../../../sockets/ipv6_raw_af_inet6_tcp` * :doc:`../../../sockets/ipv6_raw_af_inet6_udp` * :doc:`../../../sockets/ipv6_raw_af_inet6_raw` * :doc:`../../../sockets/raw_af_packet_raw_htons_ETH_P_ALL` * :doc:`../../../sockets/raw_af_packet_tcp_htons_ETH_P_ALL` * :doc:`../../../sockets/raw_af_packet_udp_htons_ETH_P_ALL` * Other IPCs * :doc:`../../../Message_queues/Message_queues` * :doc:`../../../NamedPipes/NamedPipes` * :doc:`../../../Netlink/Netlink` * :doc:`../../../Shared_Memory/Shared_Memory` * :doc:`../../../Shared_Memory_2_FDS/Shared_Memory_2_FDS` * :doc:`../../../SocketPair/SocketPair` * :doc:`../../../Timerfd/Timerfd`