pcap2mjr: avoid misaligned access

meetecho · Nov 16, 2023 · c81a0e0 · c81a0e0
1 parent e274a93
commit c81a0e0
Showing 1 changed file with 16 additions and 11 deletions.
diff --git a/postprocessing/pcap2mjr.c b/postprocessing/pcap2mjr.c
@@ -198,6 +198,11 @@ int main(int argc, char *argv[])
 		sizeof(struct udphdr) + 12, pkt_size = 0;
 	gboolean header_written = FALSE;
 	gint64 start_ts = 0, pkt_ts = 0;
+    pcap2mjr_ethernet_header eth;
+    struct sll_header lcc;
+    struct ip v4;
+    struct ip6_hdr v6;
+    janus_pp_rtp_header rtp;
     while(working && (ret = pcap_next_ex(pcap, &header, &buffer)) >= 0) {
 		count++;
 		if(header->len != header->caplen) {
@@ -222,27 +227,27 @@ int main(int argc, char *argv[])
 		int protocol = 0;
 		if(link == DLT_EN10MB) {
 			/* Ethernet */
-			pcap2mjr_ethernet_header *eth = (pcap2mjr_ethernet_header *)temp;
-			protocol = ntohs(eth->type);
+			memcpy(&eth, temp, sizeof(pcap2mjr_ethernet_header));
+			protocol = ntohs(eth.type);
 			temp += sizeof(pcap2mjr_ethernet_header);
 			pkt_size -= sizeof(pcap2mjr_ethernet_header);
 		} else {
 			/* Linux Cooked Capture */
-			struct sll_header *lcc = (struct sll_header *)temp;
-			protocol = ntohs(lcc->sll_protocol);
+			memcpy(&lcc, temp, sizeof(struct sll_header));
+			protocol = ntohs(lcc.sll_protocol);
 			temp += sizeof(struct sll_header);
 			pkt_size -= sizeof(struct sll_header);
 		}
 		if(protocol == 0x0800) {
 			/* IPv4 */
-			struct ip *v4 = (struct ip *)temp;
-			protocol = v4->ip_p;
+			memcpy(&v4, temp, sizeof(struct ip));
+			protocol = v4.ip_p;
 			temp += sizeof(struct ip);
 			pkt_size -= sizeof(struct ip);
 		} else if(protocol == 0x86DD) {
 			/* IPv6 */
-			struct ip6_hdr *v6 = (struct ip6_hdr *)temp;
-			protocol = v6->ip6_ctlun.ip6_un1.ip6_un1_nxt;
+			memcpy(&v6, temp, sizeof(struct ip6_hdr));
+			protocol = v6.ip6_ctlun.ip6_un1.ip6_un1_nxt;
 			temp += sizeof(struct ip6_hdr);
 			pkt_size -= sizeof(struct ip6_hdr);
 		} else {
@@ -261,14 +266,14 @@ int main(int argc, char *argv[])
 		temp += sizeof(struct udphdr);
 		pkt_size -= sizeof(struct udphdr);
 		/* Make sure this is an RTP packet */
-		janus_pp_rtp_header *rtp = (janus_pp_rtp_header *)temp;
-		if(rtp->version != 2 || (rtp->type >= 64 && rtp->type < 96)) {
+		memcpy(&rtp, temp, sizeof(janus_pp_rtp_header));
+		if(rtp.version != 2 || (rtp.type >= 64 && rtp.type < 96)) {
 			if(show_warnings) {
 				JANUS_LOG(LOG_WARN, "Not an RTP packet, skipping packet #%"SCNu32"\n", count);
 			}
 			continue;
 		}
-		pssrc = htonl(rtp->ssrc);
+		pssrc = htonl(rtp.ssrc);
 		if(ssrc == 0) {
 			ssrc = pssrc;
 			JANUS_LOG(LOG_INFO, "Autodetected SSRC %"SCNu32"\n", ssrc);