Use raw sockets for server

No more buffering, but auto-reply needs to be turned
off; see run_server.sh.

1 files changed, 9 insertions, 7 deletions

diff --git a/icmp.c b/icmp.c
index e64580c..63436ac 100644
--- a/icmp.c
+++ b/icmp.c
@@ -2,6 +2,7 @@
 #include <stddef.h>
 #include <string.h>
 #include <assert.h>
+#include <unistd.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <netinet/ip_icmp.h>
@@ -99,10 +100,6 @@ struct icmp_reply icmp_communicate(int sock, const char *ip_address, int seqnum,
 int icmp_send_echo_reply(const char *ip_address, int id, int seqnum, const void *data_, size_t length) {
 	const uint8_t *data = (const uint8_t*)data_;
 
-	int sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
-	int zero = 0;
-	assert(setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &zero, sizeof zero) >= 0);
-
 	struct sockaddr_in addr;
 	make_sockaddr(&addr, ip_address);
 
@@ -120,9 +117,14 @@ int icmp_send_echo_reply(const char *ip_address, int id, int seqnum, const void
 
 	msg.checksum = ~compute_checksum(&msg, total_length);
 
-	if (sendto(sock, &msg, ICMP_PAYLOAD_OFFSET + length, 0, (struct sockaddr*)&addr, sizeof addr) < 0) {
-		return -1;
-	}
+	int sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+	// The below is only necessary for sending on IPPROTO_RAW sockets
+	// int zero = 0;
+	// assert(setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &zero, sizeof zero) >= 0);
+
+	int ret = sendto(sock, &msg, ICMP_PAYLOAD_OFFSET + length, 0, (struct sockaddr*)&addr, sizeof addr);
+	close(sock);
+	if (ret < 0) return -1;
 
 	return 0;
 }