commit cd6f9b0334b79f24cf4c6a3a098bc3aa11e6f477
from: Martijn van Duren <martijn@openbsd.org>
date: Wed Oct 23 07:25:28 2019 UTC

Fix couple off by 1s.
Found and fix tested by Mikolaj Kucharski mikolaj <at> kucharski <dot> name

commit - 2cd46d73b60506fa8da4a5f9dba082d709502b53
commit + cd6f9b0334b79f24cf4c6a3a098bc3aa11e6f477
blob - 6556177889fc16102f015eda4e368e3d68b9451f
blob + cd8936cf464c880415aeeae99c4c3de9758604e1
--- Makefile
+++ Makefile
@@ -1,3 +1,4 @@
+LOCALBASE?=	/usr/local/
 PROG=	filter-dkimsign
 MAN=	filter-dkimsign.8
 BINDIR=	${LOCALBASE}/libexec/smtpd/
blob - 067c71b06ad1ea0df8fc7b69e999e6b2b39067ab
blob + 890474469a6d8b245f380cfc663aaa34664b7ef0
--- main.c
+++ main.c
@@ -412,7 +412,7 @@ dkim_parse_header(struct dkim_message *message, char *
 			fieldname = 1;
 		for (r = w = 0; line[r] != '\0'; r++) {
 			if (line[r] == ':' && fieldname) {
-				if (line[w - 1] == ' ')
+				if (w > 0 && line[w - 1] == ' ')
 					line[w - 1] = ':';
 				else
 					line[w++] = ':';
@@ -424,7 +424,7 @@ dkim_parse_header(struct dkim_message *message, char *
 			}
 			if (line[r] == ' ' || line[r] == '\t' ||
 			    line[r] == '\r' || line[r] == '\n') {
-				if (r != 0 && line[w - 1] == ' ')
+				if (r != 0 && w != 0 && line[w - 1] == ' ')
 					continue;
 				else
 					line[w++] = ' ';
@@ -434,7 +434,7 @@ dkim_parse_header(struct dkim_message *message, char *
 			} else
 				line[w++] = line[r];
 		}
-		linelen = line[w - 1] == ' ' ? w - 1 : w;
+		linelen = (w != 0 && line[w - 1] == ' ') ? w - 1 : w;
 		line[linelen] = '\0';
 	} else
 		linelen = strlen(line);
@@ -495,7 +495,7 @@ dkim_parse_body(struct dkim_message *message, char *li
 			} else
 				line[w++] = line[r];
 		}
-		linelen = line[w - 1] == ' ' ? w - 1 : w;
+		linelen = (w != 0 && line[w - 1] == ' ') ? w - 1 : w;
 		line[linelen] = '\0';
 	} else
 		linelen = strlen(line);