Add global error handling

src/lib/error.c

@@ -0,0 +1,103 @@
+/**
+ * sesimos - secure, simple, modern web server
+ * @brief Error interface
+ * @file src/lib/error.c
+ * @author Lorenz Stechauner
+ * @date 2023-01-08
+ */
+
+#include "error.h"
+#include "http.h"
+
+#include <errno.h>
+#include <openssl/ssl.h>
+#include <openssl/err.h>
+#include <maxminddb.h>
+
+static const char *error_ssl_strerror(int err) {
+    switch (err) {
+        case SSL_ERROR_ZERO_RETURN:
+            return "closed";
+        case SSL_ERROR_WANT_READ:
+            return "want read";
+        case SSL_ERROR_WANT_WRITE:
+            return "want write";
+        case SSL_ERROR_WANT_CONNECT:
+            return "want connect";
+        case SSL_ERROR_WANT_ACCEPT:
+            return "want accept";
+        case SSL_ERROR_WANT_X509_LOOKUP:
+            return "want x509 lookup";
+        case SSL_ERROR_WANT_ASYNC:
+            return "want async";
+        case SSL_ERROR_WANT_ASYNC_JOB:
+            return "want async job";
+        case SSL_ERROR_WANT_CLIENT_HELLO_CB:
+            return "want client hello callback";
+        case SSL_ERROR_WANT_RETRY_VERIFY:
+            return "want retry verify";
+        case SSL_ERROR_SSL:
+            return ERR_reason_error_string(ERR_get_error());
+        default:
+            return "unknown error";
+    }
+}
+
+static const char *error_http_strerror(int err) {
+    switch (err) {
+        default:
+            return "unknown error";
+    }
+}
+
+const char *error_str(int err_no, char *buf, int buf_len) {
+    buf[0] = 0;
+    unsigned char mode = (unsigned char) (err_no >> 24);
+    int e = err_no & 0x00FFFFFF;
+    if (mode == 0x00) {
+        // normal
+        strerror_r(e, buf, buf_len);
+        return buf;
+    } else if (mode == 0x01) {
+        // ssl
+        return error_ssl_strerror(e);
+    } else if (mode == 0x02) {
+        // mmdb
+        return MMDB_strerror(e);
+    } else if (mode == 0x03) {
+        // http
+        return error_http_strerror(e);
+    }
+    return buf;
+}
+
+void error_ssl(int err) {
+    if (err == SSL_ERROR_NONE) {
+        errno = 0;
+    } else if (err == SSL_ERROR_SYSCALL) {
+        // errno already set
+    } else {
+        errno = 0x01000000 | err;
+    }
+}
+
+void error_mmdb(int err) {
+    if (err == MMDB_SUCCESS) {
+        errno = 0;
+    } else if (err == MMDB_IO_ERROR) {
+        // errno already set
+    } else {
+        errno = 0x02000000 | err;
+    }
+}
+
+int error_http(int err) {
+    if (err == 0) {
+        errno = 0;
+    } else if (err == HTTP_ERROR_SYSCALL) {
+        // errno already set
+    } else {
+        errno = 0x03000000 | err;
+    }
+    return -1;
+}