feat: set TOS

LICENSE

@@ -652,7 +652,7 @@ Also add information on how to contact you by electronic and paper mail.
   If the program does terminal interaction, make it output a short
 notice like this when it starts in an interactive mode:
 
-    <program>  Copyright (C) <year>  <name of author>
+    libicmp  Copyright (C) 2026  lohhiiccc
     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
     This is free software, and you are welcome to redistribute it
     under certain conditions; type `show c' for details.

README.md

@@ -1,7 +1,7 @@
 # libicmp
 
-Non-blocking ICMPv4 library for building ping, traceroute, and network
+ICMPv4 library for building ping, traceroute, and network diagnostic tools.
-diagnostic tools.
+Supports both non-blocking (default) and blocking socket modes.
 
 ## Dependencies
 
@@ -28,12 +28,14 @@ make test
 
 ```c
 icmp_handle_t *icmp_create(void);
+icmp_handle_t *icmp_create_block(void);
 void           icmp_destroy(icmp_handle_t *h);
 int            icmp_get_fd(const icmp_handle_t *h);
 ```
 
-`icmp_create()` opens a raw ICMP socket and returns an opaque handle.
+`icmp_create()` opens a raw ICMP socket in non-blocking mode and returns an
-`icmp_get_fd()` exposes the underlying file descriptor for use with
+opaque handle. `icmp_create_block()` does the same but leaves the socket in
+blocking mode`icmp_get_fd()` exposes the underlying file descriptor for use with
 `select()` or `poll()`. Errors are retrieved via `icmp_strerror()`.
 
 ### Send
@@ -71,12 +73,13 @@ on error.
 ## Modules
 
 ### handle/
-Handle lifecycle: `icmp_create()`, `icmp_destroy()`, `icmp_get_fd()`.
+Handle lifecycle: `icmp_create()`, `icmp_create_block()`, `icmp_destroy()`,
-Owns the opaque `icmp_handle_t` struct and the error state attached to it.
+`icmp_get_fd()`. Owns the opaque `icmp_handle_t` struct and the error state
+attached to it.
 
 ### socket/
-Raw socket creation, non-blocking configuration, and the DF (Don't
+Raw socket creation, optional non-blocking configuration (`O_NONBLOCK`), and
-Fragment) flag via `IP_MTU_DISCOVER`.
+the DF (Don't Fragment) flag via `IP_MTU_DISCOVER`.
 
 ### send/
 Packet building and transmission. Assembles the ICMP header and payload,

includes/icmp.h

@@ -50,6 +50,7 @@ typedef void (*icmp_callback_t)(const icmp_reply_t *reply, void *userdata);
 
 /* Handle lifecycle */
 icmp_handle_t *icmp_create(void);
+icmp_handle_t *icmp_create_block(void);
 void icmp_destroy(icmp_handle_t *h);
 int icmp_get_fd(const icmp_handle_t *h);
 
@@ -75,6 +76,7 @@ int icmp_error_extract_offending(const icmp_reply_t *reply,
 
 /* Socket options */
 int icmp_set_dont_fragment(icmp_handle_t *h);
+int icmp_set_tos(icmp_handle_t *h, uint8_t tos);
 
 /* Error handling */
 const char *icmp_strerror(const icmp_handle_t *h);

sources.mk

@@ -9,6 +9,7 @@ SRCS += $(SRC_DIR)/error/should_retry.c
 SRCS += $(SRC_DIR)/socket/create.c
 SRCS += $(SRC_DIR)/socket/configure.c
 SRCS += $(SRC_DIR)/socket/set_dont_fragment.c
+SRCS += $(SRC_DIR)/socket/set_tos.c
 SRCS += $(SRC_DIR)/handle/create.c
 SRCS += $(SRC_DIR)/handle/destroy.c
 SRCS += $(SRC_DIR)/handle/get_fd.c

src/handle/create.c

@@ -8,10 +8,11 @@
 /* Forward declarations */
 static int alloc_icmp_handle(struct icmp_handle **h);
 static void init_icmp_handle(struct icmp_handle *h);
+static struct icmp_handle *create_handle(void);
 /* -------------------- */
 
-icmp_handle_t *
+static struct icmp_handle *
-icmp_create(void)
+create_handle(void)
 {
 	struct icmp_handle *h;
 
@@ -26,6 +27,17 @@ icmp_create(void)
 		return NULL;
 	}
 
+	return h;
+}
+
+icmp_handle_t *
+icmp_create(void)
+{
+	struct icmp_handle *h = create_handle();
+
+	if (NULL == h)
+		return NULL;
+
 	if (-1 == socket_configure(h))
 	{
 		close(h->fd);
@@ -36,6 +48,12 @@ icmp_create(void)
 	return (icmp_handle_t *)h;
 }
 
+icmp_handle_t *
+icmp_create_block(void)
+{
+	return (icmp_handle_t *)create_handle();
+}
+
 static int
 alloc_icmp_handle(struct icmp_handle **h)
 {

src/send/core/send_packet.c

@@ -37,11 +37,12 @@ handle_send_error(struct icmp_handle *h)
 	int saved_errno;
 
 	saved_errno = errno;
-	if (EAGAIN == saved_errno || EWOULDBLOCK == saved_errno)
+	if (EAGAIN == saved_errno || EWOULDBLOCK == saved_errno
+			|| ENOBUFS == saved_errno)
 	{
 		icmp_set_error_fmt(h, ICMP_ERR_EAGAIN,
 				"Send would block (buffer full, retry later)");
-		return -1;
+		return 1;
 	}
 	icmp_set_error_fmt(h, ICMP_ERR_SEND, "sendto() failed: %s",
 			strerror(saved_errno));

src/send/core/send_to_destination.c

@@ -8,15 +8,19 @@ send_to_destination(struct icmp_handle *h, const void *packet, size_t len,
 		struct in_addr dest, uint8_t ttl)
 {
 	struct sockaddr_in	addr;
+	int					ret;
 
 	if (send_set_socket_ttl(h, ttl) < 0)
 		return -1;
 
 	send_prepare_destination(&addr, dest);
 
-	if (send_packet(h, packet, len, &addr) < 0)
+	ret = send_packet(h, packet, len, &addr);
-		return -1;
 
-	icmp_clear_error(h);
+	switch (ret)
-	return 0;
+	{
+		case -1: return -1;
+		case 1: return 1;
+		default: icmp_clear_error(h); return 0;
+	}
 }

src/socket/set_tos.c

@@ -0,0 +1,25 @@
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include <string.h>
+
+#include "internal/icmp_internal.h"
+
+int
+icmp_set_tos(struct icmp_handle *h, uint8_t tos)
+{
+	int	val;
+	int	saved_errno;
+
+	if (NULL == h)
+		return -1;
+	val = (int)tos;
+	if (0 > setsockopt(h->fd, IPPROTO_IP, IP_TOS, &val, sizeof(val)))
+	{
+		saved_errno = errno;
+		icmp_set_error_fmt(h, ICMP_ERR_SOCKET,
+				"Failed to set TOS: %s", strerror(saved_errno));
+		return -1;
+	}
+	return 0;
+}