create manual internet connectivity test

Makefile

@@ -1,11 +1,15 @@
 install: build
+	install -D -m 0644 --target-directory="${HOME}/.local/bin" has_internet
 	install -D -m 0644 --target-directory="${HOME}/.local/bin" target/release/Hentai add_and_download_url.sh download_website.sh
 	install -D -m 0644 --target-directory="${HOME}/.config" Hentai.conf
 
 build:
+	gcc --std gnu23 -o has_internet has_internet.c
+	strip has_internet
 	cargo build --release
 	strip target/release/Hentai
 
 uninstall:
+	rm -f "${HOME}"/.local/bin/has_internet
 	rm -f "${HOME}"/.local/bin/Hentai "${HOME}"/.local/bin/add_and_download_url.sh "${HOME}"/.local/bin/download_website.sh
 	rm -f "${HOME}"/.config/Hentai.conf

has_internet.c

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netdb.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+bool has_internet() {
+    int ret;
+    
+    // https://www.man7.org/linux/man-pages/man3/getaddrinfo.3.html
+    struct addrinfo hints;
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = 0;
+    hints.ai_protocol = 0;
+    struct addrinfo *res, *rp;
+    ret = getaddrinfo("hopeless-cloud.xyz", "80", 0, &res);
+    if (ret != 0) {
+        // fprintf(stderr, "Couldn't getaddrinfo()\n");
+        return false;
+    }
+    int sockfd;
+    for (rp = res; rp != NULL; rp = rp->ai_next) {
+        // https://www.man7.org/linux/man-pages/man2/socket.2.html
+        sockfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+        if (sockfd == -1) { continue; }
+        
+        // https://www.man7.org/linux/man-pages/man2/connect.2.html
+        if (connect(sockfd, rp->ai_addr, rp->ai_addrlen) == 0) { break; }
+        
+        close(sockfd);
+    }
+    freeaddrinfo(res);
+    if (rp == NULL) {
+        // fprintf(stderr, "Couldn't connect socket\n");
+        return false;
+    }
+    
+    // https://www.man7.org/linux/man-pages/man2/write.2.html
+    char *req_msg = "GET / HTTP/1.1\r\n\r\n";
+    if (write(sockfd, req_msg, strlen(req_msg)) != strlen(req_msg)) {
+        // fprintf(stderr, "Couldn't fully write to socket\n");
+        return false;
+    }
+    
+    // https://www.man7.org/linux/man-pages/man2/recv.2.html
+    size_t count = 1000000;
+    char buf[count];
+    if (recv(sockfd, buf, count-1, MSG_WAITALL) == -1 ) {
+        // fprintf(stderr, "Couldn't read from socket\n");
+        return false;
+    }
+    // printf("%s\n", buf);
+    close(sockfd);
+    return true;
+}
+
+int main() {
+    if (has_internet()) {
+        printf("has internet\n");
+        return 0;
+    } else {
+        printf("no internet\n");
+        return 1;
+    }
+}