From 3b178a142dd72c5409cb1d3243530157c888324e Mon Sep 17 00:00:00 2001
From: jmjatlanta <jmjatlanta@gmail.com>
Date: Thu, 24 Aug 2017 14:36:03 -0500
Subject: [PATCH] Added helper method to compare ipfs address without IP
 address

---
 include/multiaddr/multiaddr.h | 14 ++++++++++++++
 multiaddr.c                   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/include/multiaddr/multiaddr.h b/include/multiaddr/multiaddr.h
index fafc0fe..61c9b0d 100644
--- a/include/multiaddr/multiaddr.h
+++ b/include/multiaddr/multiaddr.h
@@ -87,6 +87,20 @@ int multiaddress_get_ip_port(const struct MultiAddress* in);
  */
 char* multiaddress_get_peer_id(const struct MultiAddress* in);
 
+/**
+ * Check to see how these two addresses compare
+ * @param a side A
+ * @param b side B
+ * @returns <0 if B > A; >0 if A > B; 0 if A == B
+ */
 int multiaddress_compare(const struct MultiAddress* a, const struct MultiAddress* b);
 
+/**
+ * Check to see how these two addresses compare, ignoring IP address, only looking at ID hash
+ * @param a side A
+ * @param b side B
+ * @returns <0 if B > A; >0 if A > B; 0 if A == B
+ */
+int multiaddress_compare_id(const struct MultiAddress* a, const struct MultiAddress* b);
+
 #endif
diff --git a/multiaddr.c b/multiaddr.c
index 5b7beb9..27ce698 100644
--- a/multiaddr.c
+++ b/multiaddr.c
@@ -347,6 +347,12 @@ int multiaddress_decapsulate(struct MultiAddress * result, char * srci)
 	}
 }
 
+/**
+ * Check to see how these two addresses compare
+ * @param a side A
+ * @param b side B
+ * @returns <0 if B > A; >0 if A > B; 0 if A == B
+ */
 int multiaddress_compare(const struct MultiAddress* a, const struct MultiAddress* b) {
 	if (a == NULL && b == NULL)
 		return 0;
@@ -364,3 +370,28 @@ int multiaddress_compare(const struct MultiAddress* a, const struct MultiAddress
 	}
 	return 0;
 }
+
+/**
+ * Check to see how these two addresses compare, ignoring IP address,
+ * only looking at the first /ipfs/ID hash
+ * @param a side A
+ * @param b side B
+ * @returns <0 if B > A; >0 if A > B; 0 if A == B
+ */
+int multiaddress_compare_id(const struct MultiAddress* a, const struct MultiAddress* b) {
+	char* a_id = multiaddress_get_peer_id(a);
+	char* b_id = multiaddress_get_peer_id(b);
+	if (a_id == NULL && b_id == NULL)
+		return 0;
+	if (a_id == NULL && b_id != NULL)
+		return -1;
+	if (a_id != NULL && b_id == NULL)
+		return 1;
+	int retVal = strcmp(a_id, b_id);
+	if (a_id != NULL)
+		free(a_id);
+	if (b_id != NULL)
+		free(b_id);
+	return retVal;
+}
+