From: Mark Wooding <mdw@distorted.org.uk>
Date: Sat, 17 May 2014 12:17:07 +0000 (+0100)
Subject: Make adns__sockaddr_ntop use a caller-supplied buffer.
X-Git-Tag: wip.base.getaddrinfo~12
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/adns/commitdiff_plain/62e2764d90d496e46a62e6a2bc1ff1c5ecda908d

Make adns__sockaddr_ntop use a caller-supplied buffer.

Using an internal static buffer violates the (weak) thread-safety
guarantees.
---

diff --git a/src/event.c b/src/event.c
index 7050ca8..43b9637 100644
--- a/src/event.c
+++ b/src/event.c
@@ -339,6 +339,7 @@ int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
   int want, dgramlen, r, i, udpaddrlen, serv, old_skip;
   byte udpbuf[DNS_MAXUDP];
+  char addrbuf[MAX_ADDRSTRLEN];
   struct udpsocket *udp;
   adns_sockaddr udpaddr;
   
@@ -414,7 +415,7 @@ int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
 	     serv++);
 	if (serv >= ads->nservers) {
 	  adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
-		     adns__sockaddr_ntoa(&udpaddr.sa, udpaddrlen));
+		     adns__sockaddr_ntoa(&udpaddr.sa, udpaddrlen, addrbuf));
 	  continue;
 	}
 	adns__procdgram(ads,udpbuf,r,serv,0,*now);
diff --git a/src/general.c b/src/general.c
index cbe735a..7703254 100644
--- a/src/general.c
+++ b/src/general.c
@@ -38,12 +38,11 @@
 
 /* Core diagnostic functions */
 
-const char *adns__sockaddr_ntoa(struct sockaddr *sa, size_t n)
+const char *adns__sockaddr_ntoa(struct sockaddr *sa, size_t n, char *buf)
 {
-  static char buf[64];
   int err;
 
-  err = getnameinfo(sa, n, buf, sizeof(buf), 0, 0, NI_NUMERICHOST);
+  err = getnameinfo(sa, n, buf, MAX_ADDRSTRLEN, 0, 0, NI_NUMERICHOST);
   assert(!err);
   return buf;
 }
@@ -61,6 +60,7 @@ void adns__lprintf(adns_state ads, const char *fmt, ...) {
 
 void adns__vdiag(adns_state ads, const char *pfx, adns_initflags prevent,
 		 int serv, adns_query qu, const char *fmt, va_list al) {
+  char buf[MAX_ADDRSTRLEN];
   const char *bef, *aft;
   vbuf vb;
   
@@ -96,7 +96,7 @@ void adns__vdiag(adns_state ads, const char *pfx, adns_initflags prevent,
   if (serv>=0) {
     adns__lprintf(ads,"%sNS=%s",bef,
 		  adns__sockaddr_ntoa(&ads->servers[serv].addr.sa,
-				      ads->servers[serv].len));
+				      ads->servers[serv].len, buf));
     bef=", "; aft=")\n";
   }
 
diff --git a/src/internal.h b/src/internal.h
index f8f34c7..bddb197 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -73,6 +73,7 @@ typedef unsigned char byte;
 #define DNS_IP6_ARPA "ip6", "arpa"
 
 #define ADDR_MAXRRTYPES 2
+#define MAX_ADDRSTRLEN 64
 
 #define STRINGIFY(x) REALLY_STRINGIFY(x)
 #define REALLY_STRINGIFY(x) #x
@@ -411,7 +412,9 @@ int adns__setnonblock(adns_state ads, int fd); /* => errno value */
 
 /* From general.c: */
 
-const char *adns__sockaddr_ntoa(struct sockaddr *sa, size_t n);
+const char *adns__sockaddr_ntoa(struct sockaddr *sa, size_t n, char *buf);
+/* Buffer must be at least MAX_ADDRSTRLEN bytes long. */
+
 void adns__vlprintf(adns_state ads, const char *fmt, va_list al);
 void adns__lprintf(adns_state ads, const char *fmt,
 		   ...) PRINTFFORMAT(2,3);
diff --git a/src/setup.c b/src/setup.c
index 21db53c..267f3da 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -60,26 +60,27 @@ static void addserver(adns_state ads, struct sockaddr *sa, int n) {
   int i;
   adns_rr_addr *ss;
   const afinfo *ai;
+  char buf[MAX_ADDRSTRLEN];
 
   ai = find_afinfo(sa->sa_family);
   if (!ai) {
     adns__diag(ads,-1,0,
 	       "nameserver %s for unknown address family %d ignored",
-	       adns__sockaddr_ntoa(sa, n), sa->sa_family);
+	       adns__sockaddr_ntoa(sa, n, buf), sa->sa_family);
   }
   
   for (i=0; i<ads->nservers; i++) {
     if (ads->servers[i].addr.sa.sa_family == sa->sa_family &&
 	ai->sockaddr_equalp(sa, &ads->servers[i].addr.sa)) {
       adns__debug(ads,-1,0,"duplicate nameserver %s ignored",
-		  adns__sockaddr_ntoa(sa, n));
+		  adns__sockaddr_ntoa(sa, n, buf));
       return;
     }
   }
   
   if (ads->nservers>=MAXSERVERS) {
     adns__diag(ads,-1,0,"too many nameservers, ignoring %s",
-	       adns__sockaddr_ntoa(sa, n));
+	       adns__sockaddr_ntoa(sa, n, buf));
     return;
   }
 
@@ -134,6 +135,7 @@ static int nextword(const char **bufp_io, const char **word_r, int *l_r) {
 static void ccf_nameserver(adns_state ads, const char *fn,
 			   int lno, const char *buf) {
   struct addrinfo *ai, ai_hint = { 0 };
+  char addrbuf[MAX_ADDRSTRLEN];
   int err;
 
   ai_hint.ai_family = AF_UNSPEC;
@@ -148,7 +150,7 @@ static void ccf_nameserver(adns_state ads, const char *fn,
   }
 
   adns__debug(ads,-1,0,"using nameserver %s",
-	      adns__sockaddr_ntoa(ai->ai_addr, ai->ai_addrlen));
+	      adns__sockaddr_ntoa(ai->ai_addr, ai->ai_addrlen, addrbuf));
   addserver(ads, ai->ai_addr, ai->ai_addrlen);
   freeaddrinfo(ai);
 }