PPP, fixed some compiler warnings

Using -Wall -pedantic -Wparentheses -Wsequence-point
-Wswitch-default -Wextra -Wundef -Wshadow -Wpointer-arith
-Wbad-function-cast -Wc++-compat -Wwrite-strings -Wold-style-definition
-Wmissing-prototypes -Wredundant-decls -Wnested-externs -Wno-address

src/include/lwip/opt.h

@@ -1927,6 +1927,13 @@
 #define ECP_SUPPORT                     0
 #endif
 
+/**
+ * DEMAND_SUPPORT==1: Support dial on demand. CURRENTLY NOT SUPPORTED! DO NOT SET!
+ */
+#ifndef DEMAND_SUPPORT
+#define DEMAND_SUPPORT                  0
+#endif
+
 /**
  * LQR_SUPPORT==1: Support Link Quality Report. Do nothing except exchanging some LCP packets.
  */

src/include/netif/ppp/fsm.h

@@ -74,7 +74,7 @@
 typedef struct fsm {
     ppp_pcb *pcb;		/* PPP Interface */
     const struct fsm_callbacks *callbacks;	/* Callback routines */
-    char *term_reason;		/* Reason for closing protocol */
+    const char *term_reason;	/* Reason for closing protocol */
     u8_t seen_ack;		/* Have received valid Ack/Nak/Rej to Req */
 				  /* -- This is our only flag, we might use u_int :1 if we have more flags */
     u16_t protocol;		/* Data Link Layer Protocol field value */
@@ -120,7 +120,7 @@ typedef struct fsm_callbacks {
 		(fsm *);
     int  (*extcode)		/* Called when unknown code received */
 		(fsm *, int, int, u_char *, int);
-    char *proto_name;		/* String name for protocol (for messages) */
+    const char *proto_name;	/* String name for protocol (for messages) */
 } fsm_callbacks;
 
 
@@ -165,7 +165,7 @@ void fsm_init(fsm *f);
 void fsm_lowerup(fsm *f);
 void fsm_lowerdown(fsm *f);
 void fsm_open(fsm *f);
-void fsm_close(fsm *f, char *reason);
+void fsm_close(fsm *f, const char *reason);
 void fsm_input(fsm *f, u_char *inpacket, int l);
 void fsm_protreject(fsm *f);
 void fsm_sdata(fsm *f, u_char code, u_char id, u_char *data, int datalen);

src/include/netif/ppp/lcp.h

@@ -159,7 +159,7 @@ typedef struct lcp_options {
 } lcp_options;
 
 void lcp_open(ppp_pcb *pcb);
-void lcp_close(ppp_pcb *pcb, char *reason);
+void lcp_close(ppp_pcb *pcb, const char *reason);
 void lcp_lowerup(ppp_pcb *pcb);
 void lcp_lowerdown(ppp_pcb *pcb);
 void lcp_sprotrej(ppp_pcb *pcb, u_char *p, int len);    /* send protocol reject */

src/include/netif/ppp/ppp.h

@@ -53,6 +53,10 @@
 #define PPP_OPTIONS         0
 #endif
 
+#ifndef PPP_NOTIFY
+#define PPP_NOTIFY          0
+#endif
+
 #ifndef PPP_REMOTENAME
 #define PPP_REMOTENAME      0
 #endif
@@ -69,10 +73,6 @@
 #define PPP_MAXCONNECT      0
 #endif
 
-#ifndef DEMAND_SUPPORT
-#define DEMAND_SUPPORT      0
-#endif
-
 #ifndef PPP_ALLOWED_ADDRS
 #define PPP_ALLOWED_ADDRS   0
 #endif

src/include/netif/ppp/ppp_impl.h

@@ -277,11 +277,11 @@ struct protent {
     /* Open the protocol */
     void (*open) (ppp_pcb *pcb);
     /* Close the protocol */
-    void (*close) (ppp_pcb *pcb, char *reason);
+    void (*close) (ppp_pcb *pcb, const char *reason);
 #if PRINTPKT_SUPPORT
     /* Print a packet in readable form */
     int  (*printpkt) (u_char *pkt, int len,
-			  void (*printer) (void *, char *, ...),
+			  void (*printer) (void *, const char *, ...),
 			  void *arg);
 #endif /* PRINTPKT_SUPPORT */
     /* FIXME: data input is only used by CCP, which is not supported at this time,
@@ -291,8 +291,8 @@ struct protent {
     void (*datainput) (ppp_pcb *pcb, u_char *pkt, int len);
     u8_t enabled_flag;		/* 0 if protocol is disabled */
 #if PRINTPKT_SUPPORT
-    char *name;			/* Text name of protocol */
-    char *data_name;		/* Text name of corresponding data protocol */
+    const char *name;		/* Text name of protocol */
+    const char *data_name;	/* Text name of corresponding data protocol */
 #endif /* PRINTPKT_SUPPORT */
 #if PPP_OPTIONS
     option_t *options;		/* List of command-line options */
@@ -552,17 +552,17 @@ int  str_to_epdisc (struct epdisc *, char *); /* endpt disc. from str */
 #endif
 
 /* Procedures exported from utils.c. */
-void ppp_print_string(char *p, int len, void (*printer) (void *, char *, ...), void *arg);   /* Format a string for output */
-int ppp_slprintf(char *buf, int buflen, char *fmt, ...);            /* sprintf++ */
-int ppp_vslprintf(char *buf, int buflen, char *fmt, va_list args);  /* vsprintf++ */
+void ppp_print_string(char *p, int len, void (*printer) (void *, const char *, ...), void *arg);   /* Format a string for output */
+int ppp_slprintf(char *buf, int buflen, const char *fmt, ...);            /* sprintf++ */
+int ppp_vslprintf(char *buf, int buflen, const char *fmt, va_list args);  /* vsprintf++ */
 size_t ppp_strlcpy(char *dest, const char *src, size_t len);        /* safe strcpy */
 size_t ppp_strlcat(char *dest, const char *src, size_t len);        /* safe strncpy */
-void ppp_dbglog(char *fmt, ...);    /* log a debug message */
-void ppp_info(char *fmt, ...);      /* log an informational message */
-void ppp_notice(char *fmt, ...);    /* log a notice-level message */
-void ppp_warn(char *fmt, ...);      /* log a warning message */
-void ppp_error(char *fmt, ...);     /* log an error message */
-void ppp_fatal(char *fmt, ...);     /* log an error message and die(1) */
+void ppp_dbglog(const char *fmt, ...);    /* log a debug message */
+void ppp_info(const char *fmt, ...);      /* log an informational message */
+void ppp_notice(const char *fmt, ...);    /* log a notice-level message */
+void ppp_warn(const char *fmt, ...);      /* log a warning message */
+void ppp_error(const char *fmt, ...);     /* log an error message */
+void ppp_fatal(const char *fmt, ...);     /* log an error message and die(1) */
 #if PRINTPKT_SUPPORT
 void ppp_dump_packet(const char *tag, unsigned char *p, int len);
                                 /* dump packet to debug log if interesting */