Add implementation of interface_reader::read_interfaces()

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

2 files changed, 62 insertions, 4 deletions

diff --git a/src/interface_reader.cpp b/src/interface_reader.cpp
index f685ad0..7c976da 100644
--- a/src/interface_reader.cpp
+++ b/src/interface_reader.cpp
@@ -1,17 +1,72 @@
 #include "interface_reader.hpp"
+#include "interface.hpp"
 #include "interface_read_error.hpp"
-#include <string>
+
 #include <vector>
 #include <optional>
-#include <sys/types.h>
+#include <iostream>
+#include <fmt/core.h>
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE     /* To get defns of NI_MAXSERV and NI_MAXHOST */
+#endif // _GNU_SOURCE
+
+#include <arpa/inet.h>
 #include <ifaddrs.h>
+#include <linux/if_link.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
 
-interface_reader::interface_reader(std::vector<std::string> interfaces) : interfaces(interfaces) {
+interface_reader::interface_reader(std::vector<std::string> interfaces) : interface_names(interfaces), interfaces() {
 }
 
 std::optional<interface_read_error>
 interface_reader::read_interfaces(void)
 {
+    struct ifaddrs* interface_addresses;
+    int getifaddrs_result;
+
+    getifaddrs_result = getifaddrs(&interface_addresses);
+
+    if (getifaddrs_result == -1) {
+        // error while reading interfaces
+        return std::optional(interface_read_error("Reading interfaces failed"));
+    }
+
+    char host[NI_MAXHOST];
+
+    for (struct ifaddrs *ifa = interface_addresses; ifa != NULL; ifa = ifa->ifa_next) {
+        if (ifa->ifa_addr == NULL)
+            continue;
+
+        std::string interface_name = ifa->ifa_name;
+
+        std::optional<std::string> address;
+        int family = ifa->ifa_addr->sa_family;
+        if (family == AF_INET || family == AF_INET6) {
+            int s = getnameinfo(ifa->ifa_addr,
+                    (family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6),
+                    host, NI_MAXHOST,
+                    NULL, 0, NI_NUMERICHOST);
+
+            if (s != 0) {
+                std::string errmsg = fmt::format("getnameinfo() failed for interface '{}': {}", interface_name, gai_strerror(s));
+                return std::optional<interface_read_error>(interface_read_error(errmsg));
+            }
+
+            address = std::optional<std::string>(std::string(host));
+        }
+
+        interface ifc(interface_name, address);
+        this->interfaces.push_back(ifc);
+    }
+
+    freeifaddrs(interface_addresses);
+
     return {};
 }
 
diff --git a/src/interface_reader.hpp b/src/interface_reader.hpp
index eed9ad1..149cc43 100644
--- a/src/interface_reader.hpp
+++ b/src/interface_reader.hpp
@@ -3,6 +3,7 @@
 #include <string>
 #include <vector>
 #include <optional>
+#include "interface.hpp"
 #include "interface_read_error.hpp"
 
 class interface_reader {
@@ -12,7 +13,9 @@ class interface_reader {
         std::optional<interface_read_error> read_interfaces(void);
 
     private:
-        std::vector<std::string> interfaces;
+        std::vector<std::string> interface_names;
+
+        std::vector<interface> interfaces;
 };
 
 #endif // GETIF_INTERFACE_READER_H