Implemented DHT

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(RN-Praxis)
 set(CMAKE_C_STANDARD 11)
 
-add_executable(webserver webserver.c http.c util.c data.c)
+add_executable(webserver webserver.c http.c util.c data.c dht.c lookup.c)
 target_compile_options(webserver PRIVATE -Wall -Wextra -Wpedantic)
 target_link_libraries(webserver PRIVATE -lm)
 

dht.c

@@ -1,14 +1,77 @@
 #include "dht.h"
+#include <stdio.h>
+#include <string.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
 
-#define cpy(x, y, z) char *x_c = x; char *y_c = y; while(*y_c && z--) *x_c++ = *y_c++
+// #define cpy(x, y, z) char *x_c = x; char *y_c = y; while(*y_c && z--) *x_c++ = *y_c++
 
-void lookup_request_init(lookup_request* lr, int node_id, char *node_ip, int node_port, uint16_t hash_id, char *node_request)
+void build_lookup_request(lookup_request* lr){
+    char *lrreq = lr->node_request;
+    snprintf(lr->node_request, HTTP_MAX_SIZE, "%d|%hd|%d|%s|%d\r\n\r\n", lr->message_type, lr->hash_id, lr->node_id, lr->node_ip, lr->node_port);
+}
+
+void lookup_request_init(lookup_request* lr, int message_type, int node_id, char *node_ip, int node_port, uint16_t hash_id, char *node_request)
 {
-    int size = NODE_IP_MAX_SIZE;
+    lr->message_type = message_type;
     lr->node_id = node_id;
-    { cpy(lr->node_ip, node_ip, size); }
+    strncpy(lr->node_ip, node_ip, NODE_IP_MAX_SIZE);
     lr->node_port = node_port;
     lr->hash_id = hash_id;
-    size = HTTP_MAX_SIZE;
+    if(node_request != NULL)
-    cpy(lr->node_request, node_request, size);
+        strncpy(lr->node_request, node_request, HTTP_MAX_SIZE);
+    build_lookup_request(lr);
+}
+
+void extract_lookup_request(lookup_request* lr, char* request){
+    sscanf(request, "%d|%hd|%d|%s|%d\r\n\r\n", &lr->message_type, &lr->hash_id, &lr->node_id, lr->node_ip, &lr->node_port);
+}
+
+int call_network(lookup_request* lr, char *ip, int port){
+    int succ_sock;
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+    int numbytes;
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_DGRAM;
+
+    char port_str[6];
+    snprintf(port_str, sizeof port_str, "%d", port);
+
+    if ((rv = getaddrinfo(ip, port_str, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "Func: call_network - getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((succ_sock = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) {
+            perror("Func: call_network - socket");
+            continue;
+        }
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "Func: call_network - failed to create socket\n");
+        return 2;
+    }
+
+    if ((numbytes = sendto(succ_sock, lr->node_request, strlen(lr->node_request), 0, p->ai_addr, p->ai_addrlen)) == -1) {
+        perror("Func: call_network - sendto");
+        exit(1);
+    }
+
+    freeaddrinfo(servinfo);
+    close(succ_sock);
+
+    return 0;
+}
+
+void clone_lookup_request(lookup_request* dest, lookup_request* source){
+    memcpy(dest, source, sizeof(lookup_request));
 }

dht.h

@@ -5,6 +5,7 @@
 #define NODE_IP_MAX_SIZE 16
 
 typedef struct{
+    int message_type;
     int node_id;
     char node_ip[NODE_IP_MAX_SIZE];
     int node_port;
@@ -14,7 +15,13 @@ typedef struct{
     char node_request[HTTP_MAX_SIZE];
 }lookup_request;
 
-void lookup_request_init(lookup_request*, int node_id, char *node_ip, int node_port, uint16_t hash_id, char *node_request);
+void lookup_request_init(lookup_request*, int message_type, int node_id, char *node_ip, int node_port, uint16_t hash_id, char *node_request);
-void create_lookup_request(lookup_request*, char *request);
+void build_lookup_request(lookup_request*);
+
+void extract_lookup_request(lookup_request*, char*);
+
+int call_network(lookup_request*, char*, int);
+
+void clone_lookup_request(lookup_request* dest, lookup_request* source);
 
 #endif //DHT_H

lookup.c

@@ -0,0 +1,58 @@
+#include "lookup.h"
+
+void init_lookup_table()
+{
+    table = malloc(sizeof(lookup_head));
+    if (table == NULL) return;
+    table->head = NULL;
+}
+
+void push_lookup(lookup_request *request)
+{
+    if (free_space == 0)
+    {
+        lookup_table *infront = table->head;
+        while (infront->next != NULL && infront->next->next != NULL)
+        {
+            infront = infront->next;
+        }
+
+        free(infront->next->request);
+        free(infront->next);
+        infront->next = NULL;
+        // if malloc fails this does not leak space
+        free_space++;
+    }
+
+    lookup_table *new = (lookup_table*)malloc(sizeof(lookup_table));
+    if (new == NULL) return;
+    new->request = request;
+    new->next = table->head;
+    table->head = new;
+    free_space--;
+}
+
+lookup_request *find_lookup(const uint16_t hash_id)
+{
+    const lookup_table *current = table->head;
+    while (current != NULL && current->request->hash_id != hash_id)
+        current = current->next;
+    return current == NULL ? NULL : current->request;
+}
+
+void free_lookup_table()
+{
+    if (table == NULL) return;
+    lookup_table *current = table->head;
+
+    while (current != NULL)
+    {
+        lookup_table *temp = current;
+        current = current->next;
+        free(temp->request);
+        free(temp);
+    }
+    free(table);
+    table = NULL;
+    free_space = TABLE_SIZE;
+}

lookup.h

@@ -0,0 +1,29 @@
+#ifndef LOOKUP_H
+#define LOOKUP_H
+#include "dht.h"
+
+#define TABLE_SIZE 10
+
+typedef struct lookup_table
+{
+    lookup_request *request;
+    struct lookup_table *next;
+}lookup_table;
+
+typedef struct lookup_head
+{
+    lookup_table *head;
+}lookup_head;
+
+static lookup_head *table;
+static int free_space = TABLE_SIZE;
+
+void init_lookup_table();
+
+void push_lookup(lookup_request *request);
+
+lookup_request *find_lookup(const uint16_t hash_id);
+
+void free_lookup_table();
+
+#endif //LOOKUP_H

webserver.c

@@ -16,6 +16,8 @@
 #include "data.h"
 #include "http.h"
 #include "util.h"
+#include "dht.h"
+#include "lookup.h"
 
 #define elif else if
 
@@ -31,7 +33,7 @@ bool _DO_UDP = false;
 
 int _NODE_ID;
 const char *_NODE_IP;
-const char *_NODE_PORT;
+int _NODE_PORT;
 
 #define MAX_RESOURCES 100
 
@@ -87,23 +89,52 @@ void send_reply(int conn, struct request *request) {
         uint16_t resource_hash = hash_uri(request->uri);
         neighbor responsible = check_neighborhood(resource_hash);
 
+        lookup_request *req = find_lookup(resource_hash);
+        if (req != NULL)
+        {
+            if (req->message_type != 1)
+            {
+                printf("404\n");
+                reply = "HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n";
+                offset = strlen(reply);
+            }
+            else
+            {
+
+            }
+        }
+
         if (responsible == res) {
             sprintf(reply, "HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n");
             offset = strlen(reply);
             printf("200\n");
         }
         elif(responsible == res_303)
+        {
+            int suc_id = _SUCC_ID;
+            if (resource_hash <= suc_id || suc_id >= 0 && suc_id < _NODE_ID)
+            {
+                printf("404\n");
+                reply = "HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n";
+                offset = strlen(reply);
+            }
+            else
             {
                 sprintf(reply, "HTTP/1.1 303 See Other\r\nLocation: http://%s:%d%s\r\nContent-Length: 0\r\n\r\n", _SUCC_IP, _SUCC_PORT, request->uri);
                 offset = strlen(reply);
                 printf("303\n");
             }
+        }
         elif(responsible == not_res)
         {
             sprintf(reply, "HTTP/1.1 503 Service Unavailable\r\nRetry-After: 1\r\nContent-Length: 0\r\n\r\n");
             offset = strlen(reply);
             printf("503\n");
             // TODO: Call other dht
+            lookup_request lookreq;
+            lookup_request_init(&lookreq, 0, _NODE_ID, (char*)_NODE_IP, _NODE_PORT, resource_hash, NULL);
+
+            call_network(&lookreq, _SUCC_IP, _SUCC_PORT);
         }
         else {
             printf("404\n");
@@ -364,16 +395,15 @@ neighbor check_neighborhood(uint16_t hash) {
     int suc_id = _SUCC_ID;
 
     if(pre_id == suc_id){
-        if(hash <= id && hash > suc_id) return res_303;
+        if(hash > id && hash <= suc_id) return res_303;
-        if(hash > id && hash <= suc_id) return not_res;
+        return res;
-        return res_303; // hash is in between suc and 0
     }
 
     // TODO: check correctness
     if ((pre_id == id && suc_id == id) || (id < pre_id && ((hash > pre_id && hash < 65535)) || hash <= id) || (hash > pre_id && hash <= id))
         return res;
 
-    if ((id < suc_id && hash > id && hash <= suc_id) || (hash > id || hash <= suc_id))
+    if ((id < suc_id && hash > id && hash <= suc_id) || (id > suc_id && (hash > id || hash <= suc_id)))
         return not_res;
 
     return dunno;
@@ -403,45 +433,60 @@ static void handle_udp_request(int _sock){
 
     // HASH Received
     // TODO: alter buffer
-    uint16_t hash = atoi(buffer);
+    lookup_request lr = {0};
-    printf("Hash: %u\n", hash);
+    extract_lookup_request(&lr, buffer);
+
+    printf("Received:\n\tMessage-type: %d\n\tlookup-hash: %hd\n", lr.message_type, lr.hash_id);
+
+    // DO LOOKUP
+    if (lr.message_type == 0)
+    {
         // Check belonging
-    int pre_id = _PRED_ID;
+        const int suc_id = _SUCC_ID;
-    int suc_id = _SUCC_ID;
+        char *callback_ip = lr.node_ip;
-    neighbor responsibility = check_neighborhood(hash);
+        int callback_port = lr.node_port;
+
+        lookup_request backfire = {0};
+
+        if (lr.node_id == suc_id)
+        {
+            // Send back 404 not found
+            clone_lookup_request(&backfire, &lr);
+            backfire.message_type = -1;
+        }
+        else
+        {
+            const neighbor responsibility = check_neighborhood(lr.hash_id);
 
             if (responsibility == res) {
-        char res[] = "HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n";
+                lookup_request_init(&backfire, 1, _NODE_ID, (char*)_NODE_IP, _NODE_PORT, _PRED_ID, lr.node_request);
-        if (sendto(_sock, res, strlen(res), 0, (struct sockaddr *) &caller_addr, addrlen) == -1) {
-            perror("Func: handle_udp_request - failed to send 200 data to caller!");
-            exit(EXIT_FAILURE);
             }
-        printf("Sent: %s", res);
-    }
-/*
- TODO: return 404
-    elif (responsibility == res_303) {
-        fprintf(stderr, "Sent 303!\n");
-        char res[1024] = {0};
-        snprintf(res, 1024, "HTTP/1.1 303 See Other\r\nLocation: http://%s:%s/%d\r\nContent-Length: 0\r\n\r\n", _NODE_IP, _NODE_PORT, suc_id);
-        if(sendto(_sock, res, strlen(res), 0, (struct sockaddr *) &caller_addr, addrlen) == -1){
-            perror("Func: handle_udp_request - failed to send 303 data to caller!");
-            exit(EXIT_FAILURE);
-        }
-        printf("Sent: %s", res);
-    }
-    */
             elif (responsibility == not_res) {
-        // TODO: DIRECT TO NEXT NODE
+                // is succ responsible
-        const char res[] = "HTTP/1.1 503 Service Unavailable\r\nRetry-After: 1\r\nContent-Length: 0\r\n\r\n";
+                if (lr.hash_id <= suc_id)
-        if(sendto(_sock, res, strlen(res), 0, (struct sockaddr *) &caller_addr, addrlen) == -1)
                 {
-            perror("Func: handle_udp_request - failed to send 503 data to caller!");
+                    lookup_request_init(&backfire, 1, suc_id, _SUCC_IP, _SUCC_PORT, _NODE_ID, lr.node_request);
-            exit(EXIT_FAILURE);
                 }
-        printf("Sent: %s", res);
+                else
+                {
+                    lookup_request_init(&backfire, 1, suc_id, _SUCC_IP, _SUCC_PORT, _NODE_ID, lr.node_request);
+                    callback_ip = _SUCC_IP; // TODO: Check validity
+                    callback_port = _SUCC_PORT;
+                }
+            }
+        }
+        call_network(&backfire, callback_ip, callback_port);
+    }
+    elif (lr.message_type == 1)
+    {
+        lookup_request *toLookup = malloc(sizeof(lookup_request));
+        clone_lookup_request(toLookup, &lr);
+
+        push_lookup(toLookup);
+    }
+    else
+    {
 
-        //call_other_dht();
     }
 }
 
@@ -457,11 +502,13 @@ int main(int argc, char **argv) {
         return EXIT_FAILURE;
     }
 
+    init_lookup_table();
+
     if(argc == 3) _NODE_ID = 0;
     elif(argc == 4) _NODE_ID = atoi(argv[3]);
 
     // Set this DHT-Nodes ID
-    _NODE_PORT = argv[2];
+    _NODE_PORT = atoi(argv[2]);
     _NODE_IP = argv[1];
 
     struct sockaddr_in addr = derive_sockaddr(argv[1], argv[2]);
@@ -534,6 +581,6 @@ int main(int argc, char **argv) {
             }
         }
     }
-
+    free_lookup_table();
     return EXIT_SUCCESS;
 }