feat: Add support for hostname rotation

Author: MikeWang000000

include/globvar.h

@@ -35,7 +35,7 @@ struct fh_context {
     /* -d */ int daemon;
     /* -f */ int skipfw;
     /* -g */ int nohopest;
-    /* -h */ const char *hostname;
+    /* -h */ const char *hostname[32];
     /* -i */ const char *iface[32];
     /* -k */ int killproc;
     /* -m */ uint32_t fwmark;

src/globvar.c

@@ -35,7 +35,7 @@ struct fh_context g_ctx = {.exit = 0,
                            /* -d */ .daemon = 0,
                            /* -f */ .skipfw = 0,
                            /* -g */ .nohopest = 0,
-                           /* -h */ .hostname = NULL,
+                           /* -h */ .hostname = {NULL},
                            /* -i */ .iface = {NULL},
                            /* -k */ .killproc = 0,
                            /* -m */ .fwmark = 0x8000,

src/mainfun.c

@@ -91,7 +91,7 @@ int main(int argc, char *argv[])
 {
     unsigned long long tmp;
     int res, opt, exitcode;
-    size_t iface_cnt;
+    size_t hname_cnt, iface_cnt;
     const char *iface_info, *direction_info, *ipproto_info;
 
     if (!argc || !argv[0]) {
@@ -102,7 +102,8 @@ int main(int argc, char *argv[])
         return EXIT_FAILURE;
     }
 
-    iface_cnt = 0;
+    hname_cnt = iface_cnt = 0;
+    memset(g_ctx.hostname, 0, sizeof(g_ctx.hostname));
     memset(g_ctx.iface, 0, sizeof(g_ctx.iface));
     exitcode = EXIT_FAILURE;
 
@@ -152,12 +153,29 @@ int main(int argc, char *argv[])
                 break;
 
             case 'h':
+                hname_cnt++;
+                if (hname_cnt >
+                    sizeof(g_ctx.hostname) / sizeof(*g_ctx.hostname)) {
+                    fprintf(stderr, "%s: too many hostnames specified.\n",
+                            argv[0]);
+                    print_usage(argv[0]);
+                    return EXIT_FAILURE;
+                }
+
+                if (!optarg[0]) {
+                    fprintf(stderr, "%s: hostname cannot be empty.\n",
+                            argv[0]);
+                    print_usage(argv[0]);
+                    return EXIT_FAILURE;
+                }
+
                 if (strlen(optarg) > _POSIX_HOST_NAME_MAX) {
                     fprintf(stderr, "%s: hostname is too long.\n", argv[0]);
                     print_usage(argv[0]);
                     return EXIT_FAILURE;
                 }
-                g_ctx.hostname = optarg;
+
+                g_ctx.hostname[hname_cnt - 1] = optarg;
                 break;
 
             case 'i':
@@ -302,7 +320,7 @@ int main(int argc, char *argv[])
         return EXIT_FAILURE;
     }
 
-    if (!g_ctx.payloadpath && !g_ctx.hostname) {
+    if (!g_ctx.payloadpath && !hname_cnt) {
         fprintf(stderr, "%s: option -h is required.\n", argv[0]);
         print_usage(argv[0]);
         return EXIT_FAILURE;

src/rawsend.c

@@ -78,23 +78,34 @@ static void ipaddr_to_str(struct sockaddr *addr, char ipstr[INET6_ADDRSTRLEN])
 }
 
 
-static int setup_http_buff(void)
+static int setup_http_buff(int rotate)
 {
+    static const size_t maxcnt = sizeof(g_ctx.hostname) /
+                                 sizeof(*g_ctx.hostname);
     static const char *http_fmt = "GET / HTTP/1.1\r\n"
                                   "Host: %s\r\n"
                                   "Accept: */*\r\n"
                                   "\r\n";
+    static size_t i = 0;
 
     FILE *fp;
     int res;
 
     if (!g_ctx.payloadpath) {
-        http_len = snprintf(http_buff, HTTP_BUFSIZ, http_fmt, g_ctx.hostname);
+        http_len = snprintf(http_buff, HTTP_BUFSIZ, http_fmt,
+                            g_ctx.hostname[i]);
         if (http_len < 0 || (size_t) http_len >= HTTP_BUFSIZ) {
             E("ERROR: snprintf(): %s", "failure");
             return -1;
         }
 
+        if (rotate) {
+            i++;
+            if (i == maxcnt || !g_ctx.hostname[i]) {
+                i = 0;
+            }
+        }
+
         return 0;
     }
 
@@ -131,6 +142,22 @@ static int setup_http_buff(void)
 }
 
 
+static int rotate_hostname(void)
+{
+    int res;
+
+    if (!g_ctx.payloadpath && g_ctx.hostname[1]) {
+        res = setup_http_buff(1);
+        if (res < 0) {
+            E(T(setup_http_buff));
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+
 static int send_ack(struct sockaddr_ll *sll, struct sockaddr *saddr,
                     struct sockaddr *daddr, uint8_t ttl, uint16_t sport_be,
                     uint16_t dport_be, uint32_t seq_be, uint32_t ackseq_be)
@@ -222,7 +249,7 @@ int fh_rawsend_setup(void)
         return -1;
     }
 
-    res = setup_http_buff();
+    res = setup_http_buff(0);
     if (res < 0) {
         E(T(setup_http_buff));
         goto free_buff;
@@ -377,6 +404,12 @@ int fh_rawsend_handle(struct sockaddr_ll *sll, uint8_t *pkt_data, int pkt_len)
         E_INFO("%s:%u <===ACK(*)=== %s:%u", src_ip, ntohs(tcph->source),
                dst_ip, ntohs(tcph->dest));
 
+        res = rotate_hostname();
+        if (res < 0) {
+            E(T(rotate_hostname));
+            return -1;
+        }
+
         for (i = 0; i < g_ctx.repeat; i++) {
             res = send_http(sll, daddr, saddr, snd_ttl, tcph->dest,
                             tcph->source, tcph->ack_seq, ack_new);