1 files changed, 143 insertions, 0 deletions
diff --git a/src/detection/dns/dns_linux.c b/src/detection/dns/dns_linux.c
new file mode 100644
index 0000000..41e008c
--- /dev/null
+++ b/src/detection/dns/dns_linux.c
@@ -0,0 +1,143 @@
+#include "detection/dns/dns.h"
+
+#include "common/io.h"
+#include "common/mallocHelper.h"
+#include "common/strutil.h"
+#include "common/debug.h"
+
+#ifdef __HAIKU__
+    #define RESOLV_CONF "/system/settings/network/resolv.conf"
+#else
+    #define RESOLV_CONF "/etc/resolv.conf"
+#endif
+
+static const char* detectDnsFromConf(const char* path, FFDNSOptions* options, FFlist* results) {
+    FF_DEBUG("Attempting to read DNS config from %s", path);
+
+    FF_AUTO_CLOSE_FILE FILE* file = fopen(path, "r");
+    if (!file) {
+        FF_DEBUG("Failed to open %s: %s", path, strerror(errno));
+        return "fopen(path, r) failed";
+    }
+
+    if (results->length > 0) {
+        FF_DEBUG("Clearing existing DNS entries (%u entries)", results->length);
+        FF_LIST_FOR_EACH (FFstrbuf, item, *results) {
+            ffStrbufDestroy(item);
+        }
+        ffListClear(results);
+    }
+
+    FF_AUTO_FREE char* line = NULL;
+    size_t len = 0;
+
+    while (getline(&line, &len, file) != -1) {
+        if (ffStrStartsWith(line, "nameserver")) {
+            char* nameserver = line + strlen("nameserver");
+            while (*nameserver == ' ' || *nameserver == '\t') {
+                nameserver++;
+            }
+            if (*nameserver == '\0') {
+                continue;
+            }
+
+            char* comment = strchr(nameserver, '#');
+            if (comment) {
+                *comment = '\0';
+            }
+
+            if ((ffStrContainsC(nameserver, ':') && !(options->showType & FF_DNS_TYPE_IPV6_BIT)) ||
+                (ffStrContainsC(nameserver, '.') && !(options->showType & FF_DNS_TYPE_IPV4_BIT))) {
+                continue;
+            }
+
+            FFstrbuf* item = FF_LIST_ADD(FFstrbuf, *results);
+            ffStrbufInitS(item, nameserver);
+            ffStrbufTrimRightSpace(item);
+            FF_DEBUG("Found DNS server: %s", item->chars);
+        }
+    }
+
+    FF_DEBUG("Found %u DNS servers in %s", results->length, path);
+    return NULL;
+}
+
+const char* ffDetectDNS(FFDNSOptions* options, FFlist* results) {
+    FF_DEBUG("Starting DNS detection");
+
+    const char* error = detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT RESOLV_CONF, options, results);
+    if (error != NULL) {
+        FF_DEBUG("Error detecting DNS: %s", error);
+        return error;
+    }
+
+#if __linux__ && !__ANDROID__
+    // Handle different DNS management services
+    if (results->length == 1) {
+        const FFstrbuf* firstEntry = FF_LIST_FIRST(FFstrbuf, *results);
+
+        if (ffStrbufEqualS(firstEntry, "127.0.0.53")) {
+            FF_DEBUG("Detected systemd-resolved (127.0.0.53), checking actual DNS servers");
+            // Managed by systemd-resolved
+            if (detectDnsFromConf("/run/systemd/resolve/resolv.conf", options, results) == NULL) {
+                return NULL;
+            }
+        } else if (ffStrbufEqualS(firstEntry, "127.0.0.1")) {
+            FF_DEBUG("Detected possible NetworkManager (127.0.0.1), checking actual DNS servers");
+            // Managed by NetworkManager
+            if (detectDnsFromConf("/var/run/NetworkManager/resolv.conf", options, results) == NULL) {
+                return NULL;
+            }
+        }
+    }
+
+    // Check other possible DNS configuration files
+    if (results->length == 0) {
+        FF_DEBUG("No DNS servers found, trying alternative config files");
+
+        // Try resolvconf
+        FF_DEBUG("Trying resolvconf configuration");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/run/resolvconf/resolv.conf", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+
+        // Try dnsmasq
+        FF_DEBUG("Trying dnsmasq configuration");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/var/run/dnsmasq/resolv.conf", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+
+        // Try openresolv
+        FF_DEBUG("Trying openresolv configuration");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/etc/resolv.conf.openresolv", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+    }
+#elif defined(__FreeBSD__) || defined(__DragonFly__) || defined(__NetBSD__) || defined(__OpenBSD__)
+    // Handle BSD-specific DNS configurations
+    if (results->length == 0) {
+        FF_DEBUG("No DNS servers found, trying BSD-specific config files");
+
+        // FreeBSD and other BSDs may use resolvconf service
+        FF_DEBUG("Trying BSD resolvconf configuration");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/var/run/resolvconf/resolv.conf", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+
+        // Some BSDs store DNS configuration here
+        FF_DEBUG("Trying BSD nameserver configuration");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/var/run/nameserver", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+
+        // Try common BSD paths
+        FF_DEBUG("Trying BSD common paths");
+        if (detectDnsFromConf(FASTFETCH_TARGET_DIR_ROOT "/etc/nameserver", options, results) == NULL && results->length > 0) {
+            return NULL;
+        }
+    }
+#endif
+
+    FF_DEBUG("DNS detection completed with %u servers found", results->length);
+    return NULL;
+}