init(): initial commit

2026-02-20 23:14:19 +03:00
commit fd8de1052a
36 changed files with 1713 additions and 0 deletions
@@ -0,0 +1,18 @@
+CFLAGS := "-Wall -O2"
+PROGRAM := "sockets_demo"
+
+build:
+	gcc {{CFLAGS}} -o {{PROGRAM}} main.c
+
+run: build
+	sudo ./{{PROGRAM}}
+
+clean:
+	rm -f {{PROGRAM}}
+
+udp-server:
+	nc -u -l -p 12002
+
+tcp-server:
+	nc -l -p 12001
+
@@ -0,0 +1,133 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <netinet/ip_icmp.h>
+
+#define SRC_PORT 12000
+
+void stream_socket() {
+    printf("\n=== STREAM SOCKET (TCP) ===\n");
+
+    int sock = socket(AF_INET, SOCK_STREAM, 0);
+    if (sock < 0) {
+        perror("socket");
+        return;
+    }
+
+    struct sockaddr_in src = {0};
+    src.sin_family = AF_INET;
+    src.sin_addr.s_addr = inet_addr("127.0.0.1");
+    src.sin_port = htons(SRC_PORT);
+    if (bind(sock, (struct sockaddr*)&src, sizeof(src)) < 0) {
+        perror("bind");
+        close(sock);
+        return;
+    }
+
+    struct sockaddr_in server = {0};
+    server.sin_family = AF_INET;
+    server.sin_port = htons(12001);
+    inet_pton(AF_INET, "127.0.0.1", &server.sin_addr);
+
+    printf("[*] Connecting to 127.0.0.1:12001...\n");
+    if (connect(sock, (struct sockaddr*)&server, sizeof(server)) == 0) {
+        printf("[+] Connected successfully!\n");
+        const char *msg = "привет никифор";
+        send(sock, msg, strlen(msg), 0);
+        char buf[256] = {0};
+        recv(sock, buf, sizeof(buf) - 1, 0);
+        printf("[Response]:\n%s\n", buf);
+    } else {
+        perror("connect");
+    }
+
+    close(sock);
+}
+
+void datagram_socket() {
+    printf("\n=== DATAGRAM SOCKET (UDP) ===\n");
+
+    int sock = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sock < 0) {
+        perror("socket");
+        return;
+    }
+
+    struct sockaddr_in src = {0};
+    src.sin_family = AF_INET;
+    src.sin_addr.s_addr = inet_addr("127.0.0.1");
+    src.sin_port = htons(SRC_PORT);
+    if (bind(sock, (struct sockaddr*)&src, sizeof(src)) < 0) {
+        perror("bind");
+        close(sock);
+        return;
+    }
+
+    struct sockaddr_in dest = {0};
+    dest.sin_family = AF_INET;
+    dest.sin_port = htons(12002);
+    inet_pton(AF_INET, "127.0.0.1", &dest.sin_addr);
+
+    const char *msg = "ялквмом!";
+    printf("[*] Sending UDP datagram to 127.0.0.1:12002...\n");
+    sendto(sock, msg, strlen(msg), 0, (struct sockaddr*)&dest, sizeof(dest));
+    printf("[+] Datagram sent, waiting for response...\n");
+
+    char buf[256];
+    socklen_t addrlen = sizeof(dest);
+
+    while (1) {
+        ssize_t n = recvfrom(sock, buf, sizeof(buf) - 1, 0, (struct sockaddr*)&dest, &addrlen);
+        if (n > 0) {
+            buf[n] = '\0';
+            printf("[Response]: \n%s\n", buf);
+            break;
+        } else {
+            sleep(0.1);
+        }
+    }
+
+    close(sock);
+}
+
+void raw_socket() {
+    printf("\n=== RAW SOCKET (ICMP) ===\n");
+
+    int sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+    if (sock < 0) {
+        perror("socket");
+        return;
+    }
+
+    struct sockaddr_in dest = {0};
+    dest.sin_family = AF_INET;
+    inet_pton(AF_INET, "8.8.8.8", &dest.sin_addr);
+
+    struct icmphdr icmp_hdr = {0};
+    icmp_hdr.type = ICMP_ECHO;
+    icmp_hdr.code = 0;
+    icmp_hdr.checksum = 0xFFFF;
+
+    printf("[*] Sending ICMP echo request to 8.8.8.8...\n");
+    ssize_t sent = sendto(sock, &icmp_hdr, sizeof(icmp_hdr), 0,
+                          (struct sockaddr*)&dest, sizeof(dest));
+
+    if (sent > 0)
+        printf("[+] ICMP packet sent\n");
+    else
+        perror("sendto");
+
+    close(sock);
+}
+
+int main() {
+    stream_socket();
+    sleep(1);
+    datagram_socket();
+    sleep(1);
+    raw_socket();
+
+    return 0;
+}